MftHBHi HH LIBRARY OF TMC UNIVERSITY OF CALIFORNIA. ARMATURE WINDINGS OF ELECTRIC MACHINES BY H. F. PARSHALL h MEMBER AMERICAN INSTITUTE ELECTRICAL ENGINEERS, MEMBER INSTITUTION ELECTRICAL ENGINEERS GREAT BRITAIN, MEMBER AMERICAN SOCIETY OF MECHANICAL ENGINEERS, ETC. AND I H. M. HOBART, S.B. NEW YORK D. VAN NOSTRAND COMPANY LONDON ROBERT W. BLACKWELL 39 VICTORIA STREET, WESTMINSTER 1895 of raa UFI7IIRSIT7 77C *' * Engineering Library COPYRIGHT, 1896, BY D. VAN NOSTRANB COMPANY. TYPOGRAPHY BY J. S. CUSHING & Co.v NORWOOD, MASS., U.S.A. TABLE OP CONTEXTS LIST OF DIAGRAMS . UII7WSITY TABLE OF CONTENTS. INTRODUCTORY Multipolar commutating dynamos Limits of bipolar dynamos Considerations governing choice of windings Cases in which two-circuit windings may be employed Importance of symmetry Extent to which symmetry may be departed from in certain cases Gramme windings Lack of symmetry introduced by spider arms Utility of two- circuit, multiple windings Conditions affecting voltage between adjacent commutator segments Slotted armatures Interdependence of re-entrancy, conductors per slot, number of slots, and number of poles Interpretation of formulae in case of coils consisting of several conductors bound together Alternate-current armature windings. PART I. CONTINUOUS-CURRENT ARMATURE WINDINGS. CHAPTER I. SINGLE- WOUND GRAMME RINGS Characteristics Methods of cross-connecting Use of only two sets of brushes with multipolar dynamos Methods of reducing the number of commutator segments relatively to the number of winding sections Windings suitable for poorly balanced magnetic circuits Diminution of sparking by use of resistances. CHAPTER II. DOUBLE- WOUND GRAMME RINGS Multiple windings Their advantages Limiting conditions Importance of symmetry with small numbers of con- ductors Singly and multiply re-entrant windings Importance of avoiding the use of interpolations and cross-connections. CHAPTER III. TWO-CIRCUIT, SINGLE-WOUND, MULTIPOLAR RINGS Cases permitting the employment of two-circuit windings Characteristics Lack of symmetry of the armature coils Short-connection and long-connection types Effect of unequal air gaps Use of long-connection type advisable for high potential armatures Formulae and tables for use with the long-connection gramme winding Definition of " pitch," y Table for use in determining permissible angular distance between brushes with different numbers of p O l es Examples of two-circuit gramme windings Chief objection to the short-connection type is the great difference of potential existing between adjacent sections of the winding Modified types. iii iv TABLE OF CONTENTS. PAGE CHAPTER IV. TWO-CIRCUIT, MULTIPLE- WOUND, MULTIPOLAR RINGS 40 Formula Meaning of symbols Rule for re-en trancy Examples. CHAPTER V. DRUM ARMATURE WINDINGS 51 General observations Bipolar drum windings The von Ilefner-Alteneck winding Short-chord windings; their properties and limitations Windings in which the two active sides of a coil are diametrically opposite Term " conduc- tors" often used for convenience, when "groups of conductors" would be more exact "One-layer" and "two-layer" windings Windings in which the two short-circuited coils are situated on the same diameter. CHAPTER VI. MULTIPLE-CIRCUIT, SINGLE- WOUND, MULTIPOLAR DRUMS 71 Discussion Explanation of diagrammatical methods for representing multipolar drum windings Effect of different pitches with same number of face conductors Connection at ends always made between odd and even numbered con- ductors Other rules and limitations Magnitude of differences of potential between adjacent conductors. CHAPTER VII. MULTIPLE-CIRCUIT, MULTIPLE-WOUND, MULTIPOLAR DRUMS 77 Rules controlling conductors, pitches, and re-entrancy Irregularities of windings much exaggerated by the small number of conductors necessarily chosen for the illustrative diagrams Examples of various cases. CHAPTER VIII. TWO-CIRCUIT, SINGLE- WOUND, DRUM ARMATURES 87 Description of characteristics Comparison of the merits and faults of the two-circuit and multiple-circuit windings Formulae and rules for applying two-circuit single windings to drum armatures Choice of even integers for " y " involv- ing the use of different pitches at the two ends, but increasing the range of choice Comparison of the conditions with one pair and with several pairs of brushes upon the commutator Description of some two-circuit windings with cross-con- nected commutators possessing distinctive features with regard to the possible numbers of coils Description of a two-cir- cuit drum winding devised by Wenstrb'm. CHAPTER IX. INTERPOLATED COMMUTATOR SEGMENTS 107 A study of the distribution of potential in winding and commutator in the case of some two-circuit drum windings with interpolated commutator segments Discussion of results. CHAPTER X. TWO-CIRCUIT, MULTIPLE- WOUND, DRUM ARMATURES 114 General formula Meaning of symbols Rules Conditions of re-entrancy Scheme of symbolical representation of two-circuit multiple windings Numerous examples. CHAPTER XI. THE SAVERS WINDING 158 PART II. WINDINGS FOR ALTERNATE-CURRENT DYNAMOS AND MOTORS. CHAPTER XII. ALTERNATING-CURRENT WINDINGS 163 Comparison of alternating-current with continuous-current windings Special considerations involved in design of alternating-current windings Multi-coil and uni-coil windings Slotted (or ironclad) and smooth-core construction High and low voltage windings Alternating continuous-current commutating machines Explanation of diagrams Advantages of multi-coil construction in certain cases. TABLE OF CONTENTS. v PAGE CHAPTER XIII. SINGLE-PHASE WINDINGS 166 Examples of uni- and multi-coil windings Bar windings Windings that may be used interchangeably for single and multiphase work Advantages of symmetry and simplicity Windings that permit the armature to be built and shipped in segments Unevenly distributed windings. CHAPTER XIV. QUARTER-PHASE WINDINGS 213 Meaning of the term " uni-coil " when applied to multiphase windings Examples of quarter-phase windings, uni-coil and multi-coil Windings for quarter-phase, continuous-current, commutating machines Use of two-circuit and multiple- circuit windings for such machines Ratio of collector ring to commutator voltage in this class of commutating machines. CHAPTER XV. THREE-PHASE WINDINGS 245 Typical diagram Discussion of three-phase windings Rules regarding voltage " Y " connection Delta (A) connection Directions for making these connections Examples of three-phase windings Induction motors Three- phase, continuous-current, commutating machines Relation of voltage between collector rings to continuous-current voltage at commutator in case of three-phase, continuous-current, commutating machines. PART III. WINDING FORMULAE AND TABLES. CHAPTER XVI. FORMULA FOR ELECTROMOTIVE FORCE 275 Alternating-current windings Continuous-current windings Windings for alternating, continuous-current, commu- tating machines, quarter-phase and three-phase. CHAPTER XVII. METHOD OF APPLYING THE ARMATURE- WINDING TABLES . 277 Illustrative examples. CHAPTER XVIII. ARMATURE- WINDING TABLES 279 DRUM-WINDING CONSTANTS 280 SUMMARIZED CONDITIONS FOR TWO-CIRCUIT SINGLE WINDINGS 281 SUMMARIZED CONDITIONS FOR TWO-CIRCUIT DOUBLE WINDINGS 282 SUMMARIZED CONDITIONS FOR TWO-CIRCUIT TRIPLE WINDINGS 283 WINDING TABLES FOR TWO-CIRCUIT SINGLE WINDINGS 285 WINDING TABLES FOR TWO-CIRCUIT DOUBLE WINDINGS 295 WINDING TABLES FOR TWO-CIRCUIT TRIPLE WINDINGS 305 WINDING TABLES FOR MULTIPLE-CIRCUIT SINGLE WINDINGS 315 WINDING TABLES FOR MULTIPLE-CIRCUIT DOUBLE WINDINGS 331 WINDING TABLES FOR MULTIPLE-CIRCUIT TRIPLE WINDINGS 347 LIST OF DIAGRAMS. PART I. CHAPTER I. SINGLE- WOUND GRAMME RINGS. FIGtrRE 1. Gramme ring- 2. Gramme ring - 3. Gramme ring - 1. Gramme ring - 5. Gramme ring - 6. Gramme ring - 7. Gramme ring - 8. Gramme ring - - Four-circuit, single winding Four poles - Two-circuit, single winding Two poles - Four-circuit, single winding Four poles Cross-connected ........ - Four-circuit, single winding Four poles Cross-connected - Four-circuit, single winding Four poles - Four-circuit, single winding Four poles One-half normal number of commutator segments -Four-circuit, single winding Four poles One-fourth normal number of commutator segments . - Four-circuit, single winding Coils of one circuit from brush to brush, not in adjacent fields PACE 3 3 5 6 9 10 13 14 CHAPTER II. DOUBLE- WOUND GRAMME RINGS. 9. Gramme ring Two-circuit, doubly re-entrant, double winding Two poles . 10. Gramme ring Four-circuit, doubly re-entrant, double winding Four poles . 11. Gramme ring Four-circuit, singly re-entrant, double winding Four poles . 17 18 21 CHAPTER III. TWO-CIRCUIT, SINGLE-WOUND, MULTIPOLAR RINGS. 12. Gramme ring Two-circuit, single 13. Gramme ring Two-circuit, single 14. Gramme ring Two-circuit, single 15. Gramme ring Two-circuit, single 16. Gramme ring Two-circuit, single 17. Gramme ring Two-circuit, single 18. GramTne ring Two-circuit, single 19. Gramme ring Two-circuit, single imitator segments as coils No. of poles No. of coils Pitch No. of commu- = n. = n. =y. Utor segments. le winding Long-connection type ... 4 15 7 15 25 le winding Long-connection type . 10 51 10 51 26 le winding Long-connection type . 10 46 9 46 29 le winding Long-connection type (modified). 4 19 9 28 30 le winding Long-connection type (modified). 6 19 6 57 33 le winding Short-connection type . 4 34 7&9 17 34 le winding Short-connection type . 4 22 5 11 37 le winding Long-connection type (modified) - Four poles One-half as many com- 38 Vlll LIST OF DIAGRAMS. CHAPTER IV. TWO-CIRCUIT, MULTIPLE- WOUND, MULTIPOLAR RINGS. No. of poles No. of coils No. of wind- Ke- = H. =. ings = ;. cntranc)-. Pitch = y. - nami PAGE 20. Gramme ring Two-circuit, doubly re-entrant, double winding .4 26 2 OO 12 41 21. Gramme ring Two-circuit, singly re-entrant, double winding 4 24 2 11 42 22. Gramme ring Two-circuit, singly re-entrant, double winding .6 23 2 7 45 23. Gramme ring Two-circuit, singly re-entrant, triple winding .4 23 3 (QQ) 10 46 24. Gramme ring Two-circuit, singly re-entrant, triple winding Twice normaloiumber of commutator segments ... 4 23 3 (QQ) 10 49 CHAPTER V. DRUM ARMATURE WINDINGS. 25. Bipolar drum Two-circuit, single winding One layer Sixteen conductors . 53 26. Bipolar drum Two-circuit, single winding One layer Short chord Thirty-two conductors . . 54 27. Bipolar drum Two-circuit, single winding One layer Thirty conductors Two sides of coil diametrically opposite 57 28. Bipolar drum Two-circuit, single winding One layer Short chord Thirty conductors 58 29. Bipolar drum Two-circuit, single winding One layer Short chord Thirty conductors 61 30 (a, b, c, and I*M = . torB=C. 41 Multipolar drum Two-circuit, single winding . .4 34 9 . 89 42. Multipolar drum Two-circuit, single winding ..4 34 7&9 . 90 43. Multipolar drum Two-circuit, single winding . .6 68 11 .. . 93 44 Multipolar drum Two-circuit, single winding . .6 50 7&0 ..... . 94 LIST OF DIAGRAMS. ix No. of poles No. of conduc- Pitch 'KURT, =n _ tors = C. =y. PAGE 45. Multipolar drum Two-circuit, single winding . . 8 56 7 Cross-connected commutator 97 46. Multipolar drum Two-circuit, single winding . .8 48 5&7 Cross-connected commutator 98 47. Multipolar drum Two-circuit, single winding . .8 56 7 & 21 Cross-connected commutator 101 48. Multipolar drum Two-circuit, single winding . . 8 52 7 & 19 Cross-connected commutator 102 49. Multipolar drum Two-circuit, single winding Four-pole wire-wound armature ( Wenstrbm) . 105 CHAPTER IX. INTERPOLATED COMMUTATOR SEGMENTS. No. of poles p., . No. of conduc- No. of commu- = . tors=C. tator segments. 50. Multipolar drum Two-circuit, single winding 6 13 80 80 106 51. Multipolar drum Two-circuit, single winding ..... 6 7 44 f!li 1O4 MM9 4.0 n n 53. Multipolar drum Two-circuit, single winding 8 5 42 TX^ J.\J 84 113 CHAPTER X. TWO-CIRCUIT, MULTIPLE- WOUND, DRUM ARMATURES. No. of No. of No. of poles conductors windings Ke-entrancy. Pitch=y. = . =O. =m. 54. Multipolar drum Two-circuit, singly re-entrant, double winding, 4 32 2 7 115 55. Multipolar drum Two-circuit, singly re-entrant, double winding, 4 32 2 7 116 56. Multipolar drum Two-circuit, singly re-entrant, triple winding . 4 70 3 (S5) 15&17 119 57. Multipolar drum Two-circuit, triply re-entrant, triple winding .4 66 3 OOO 15 120 58. Multipolar drum Two-circuit, singly re-entrant, double winding, 6 58 2 (Q) 9 123 59. Multipolar drum Two-circuit, doubly re-entrant, double winding, 6 52 2 OO 7 & 9 124 60. Multipolar drum Two-circuit, triply re-entrant, triple winding .6 60 3 OOO 9 127 61. Multipolar drum Two-circuit, singly re-entrant, triple winding 6 54 3 (QQ) 7 & 9 128 62. Multipolar drum Two-circuit, triply re-entrant, triple winding . 6 78 3 OOO 11 & 13 131 63. Multipolar drum Two-circuit, singly re-entrant, quadruple winding ......... 6 50 4 COOO) 7 132 64. Multipolar drum Two-circuit, quadruply re-entrant, quadruple winding 6 56 4 OOOO 7 & 9 135 65. Multipolar drum Two-circuit, doubly- re-entrant, quadruple 9 & 11 136 66. Multipolar drum Two-circuit, quadruply re-entrant, quadruple winding 6 80 4 OOOO 11 & 13 139 67. Multipolar drum Two-circuit, quadruply re-entrant, quadruple winding 6 104 4 OOOO 15 & 17 140 68. Multipolar drum Two-circuit, quadruply re-entrant, quadruple winding 6 88 4 OOOO 15 & 17 143 69. Multipolar drum Two-circuit, triply re-entrant, sextuple winding, 6 66 6 9 144 70. Multipolar drum Two-circuit, doubly re-entrant, sextuple 9 & 11 147 71. Multipolar drum Two-circuit, singly re-entrant, sextuple winding, 6 78 6 Cooooo) 11 148 72. Multipolar drum Two-circuit, sextuply re-entrant, sextuple windine- 6 84 6 OOOOOO 11 & 13 151 X LIST OF DIAGRAMS. No. of poles No. of con- No. of wind- Re- Pitch = n. ductors=<7. ing8=?. entrancy. =y. PAGB 73. Multipolar drum Two-circuit, doubly re-entrant, double winding . 8 84 2 OO 9&11 152 74. Multipolar drum Two-circuit, singly re-entrant, double winding .8 84 2 (Q) 11 155 75. Multipolar drum Twc-circuit, singly re-entrant, double winding .8 92 2 11 156 CHAPTER XL THE SAYERS WINDING. 76. Diagram of the Sayers winding 159 PART II. CHAPTER XII. ALTERNATING-CURRENT WINDINGS. CHAPTER XHI. SINGLE-PHASE WINDINGS. 77. Uni-coil winding Two coils per group Sixteen poles Sixteen coils 167 78. Uni-coil winding One coil per group Twenty-four poles Twelve coils 168 79. Bar winding Twenty-four poles Twenty-four conductors 171 80. Overlapping, uni-coil winding Twenty-four poles Twelve coils 172 81. Two-coil winding One coil per group Sixteen poles Sixteen coils 175 82. Bar winding Sixteen poles Thirty-two conductors 176 83. Two-coil winding One coil per group Sixteen poles Sixteen coils 179 84. Overlapping, two-coil winding One coil per group Sixteen poles Sixteen coils 180 85. Bar winding Sixteen poles Thirty-two conductors 183 86. Overlapping, two-coil winding One coil per group Sixteen poles Sixteen coils 184 87. Overlapping, two-coil winding Two coils per group Sixteen poles Thirty-two coils 187 88. Overlapping, three-coil winding One coil per group Sixteen poles Twenty-four coils ...... 188 89. Bar winding Sixteen poles Forty-eight conductors 191 90. Overlapping, three-coil winding One coil per group Sixteen poles Twenty-four coils 192 91. Bar winding Sixteen poles Forty-eight conductors 195 92. Partially overlapping, three-coil winding One coil per group Sixteen poles Twenty-four coils .... 196 93. Bar winding Sixteen poles Forty-eight conductors 199 94. Partially overlapping, three-coil winding One coil per group Sixteen poles Twenty-four coils .... 200 95. Three-coil winding One coil per group Sixteen poles Twenty-four coils 203 96- Non-overlapping winding with one and one-half coils per pole piece Two coils per group Twenty poles Thirty coils . 204 97. Unevenly distributed, two-coil winding Twelve poles Twelve coils 207 98. Unevenly distributed bar winding Eight poles Twenty-four conductors 208 99. Unevenly distributed two-coil winding Sixteen poles Sixteen coils 211 CHAPTER XIV. QUARTER-PHASE WINDINGS. 100. Overlapping, uni-coil winding One coil per group Sixteen poles Sixteen coils 212 101. Bar winding Sixteen poles Thirty-two conductors 215 102. Non-overlapping, uni-coil winding Two coils per group Eight poles Sixteen coils 216 103. Overlapping, uni-coil winding Two coils per group Sixteen poles Thirty-two coils 219 104. Two-coil winding Twelve poles Twenty-four coils 220 LIST OF DIAGRAMS. xi PAGE 105. Two-coil winding Twelve poles Twenty-four coils 223 106. Bar winding Twelve poles Forty-eight conductors 224 107. Bar winding Twelve poles Forty-eight conductors 227 108. Bar winding Twelve poles Forty-eight conductors 228 109. Bar winding Twelve poles Forty-eight conductors 231 110. Three-coil winding Eight poles Twenty-four coils 232 111. Three-coil winding Eight poles Twenty-four coils 235 112. Bar winding Eight poles Forty-eight conductors 236 113. Bar winding Eight poles Sixty-four conductors .............. 239 114. Two-circuit winding for quarter-phase, continuous-current, commutating machine Six poles Sixty-eight conductors 240 115. Twelve-circuit winding for quarter-phase, continuous-current, commutating machine Twelve poles 144 conductors . 243 CHAPTER XV. THREE-PHASE WINDINGS. 116. Uni-coil winding Twenty poles Thirty coils 244 117. Diagrams showing " delta " (A) and " Y " connections ............. 247 118. Bar winding Twenty poles Sixty conductors 248 119. Non-overlapping winding Two coils per group Twenty poles Thirty coils One and one-half coils per pole piece per phase 251 120. Bar winding Twenty poles Sixty conductors 252 121. Two-coil winding Eight poles Twenty-four coils 255 122. Bar winding Eight poles Forty-eight conductors 256 123. Two-coil winding Eight poles Twenty-four coils 259 124. Bar winding Eight poles Forty-eight conductors 260 125. Bar winding Six poles Fifty-four conductors 263 126. Bar winding Four poles Fifty-one conductors 264 127. Bar winding Six poles Fifty-one conductors 267 128. Two-circuit winding for a three-phase, continuous-current, commutating machine Six poles Sixty-eight conductors 268 129. Six-circuit winding for a three-phase, continuous-current, commutating machine Six poles 108 conductors . , 271 INTRODUCTORY. THE present treatise is the outcome of an investigation made a number of years ago, before the principles of the armature winding of multipolar commutating dynamos were generally understood by electricians. At that time it appeared that the demand for dynamos of greater current output could only be met satisfactorily by dynamos of the multipolar type, since with bipolars beyond a certain output the number of commutator segments compatible with freedom from sparking was found to be incompatible with the maximum armature reaction which experience has shown to be permissible. After some study it was concluded the only feature of the multipolar dynamo requiring special study was that of the armature windings. A considerable number of diagrams were prepared and classified ; the advantages and disadvantages of each, and the comparative fitness of these windings for different purposes, noted. Inasmuch as it was found convenient to refer to this data frequently, and on account of the comparative inaccessibility of such information when in the form of notes, we decided that it would be a great convenience to electricians generally if our notes were published in book form. We therefore proceeded to do this ; but owing to the intervention of certain circumstances contingent to our position in an industrial concern, it became necessary to lay aside this work until those competent to judge of its nature should feel able to permit us to proceed as we had wished. The delay has not been disadvantageous, since in the meantime we have not laid the work aside ; on the contrary, we have made a study of the properties of a number of the more important windings, so that the original manuscript has been largely added to. In the section on continuous-current armature windings our endeavor has been to include only those windings that possess some practical merit, and we have frequently pointed out the advantages and disad- vantages peculiar to certain classes of windings. The thought will probably occur to the reader, which one of these windings should be selected for a given .voltage after the number of poles and the magnitude of the magnetic flux at the poles have been assigned a proper value. We cannot point out the fitness of each winding for a given purpose, since this is more or less dependent upon the magnetic characteristics peculiar to any particular design. Thus in some machines of particularly good characteristics two-circuit windings have been used in the generation of comparatively large currents with some success, when had the magnetic charac- teristics of the dynamos been ordinarily good, the use of the two-circuit winding would have been attended with results entirely unsatisfactory. xiii xiv INTRODUCTORY. In general, we may state, the type of winding should be determined with reference to the magnitude of the current to be generated. Any deviation from a perfectly symmetrical arrangement of the armature conductors should be inversely proportional to the magnitude of the currents to be generated. When the currents to be generated are large, the coils should be similarly situated with respect to each other, and should all have the same resistance and inductance. It has been frequently found that when the conductors are dissimilarly situated with respect to each other or to any other body that can affect the armature conductors inductively, the wearing away of the commutator is uneven, the trouble increasing more and more as the currents in the conductors are increased, or the resistance of the collecting brushes diminished. Especially in armatures in which there are more than two coils in a slot this uneven wearing away of the commutator has been noticed. In this case the coils are of slightly unequal area, due to the progression of the winding from slot to slot. In gramme windings the lack of symmetry may be due to some of the coils being longer than the others, or carried near the spider arms. It may, therefore, be stated generally that when a given result has to be obtained without experimenting, such windings as these are to be avoided when the currents in the conductors have to be of any considerable magnitude. The utility of the double, triple, and quadruple windings shown and described depends very largely upon the maximum arc upon the commutator over which uniform contact resistance can be obtained. With the thickness of segments now common in practice, only double and triple windings appear to be of practical value, since, in general, brushes cannot be relied upon to maintain a uniform contact over an arc of much more than three-quarters of an inch in width. When the width of the brush has to exceed this amount, it is found that it bridges imperfectly from commutator bar to commutator bar in the same winding, thereby causing sparking. A feature peculiar to these windings, as well as to some of the two-circuit single windings, is that the voltage between adjacent commutator sections is affected by the angular distance between the different sets of collecting brushes. With some of these windings the voltage between adjacent commutator sections varies simply according to the field strength when the angle between the different sets of brushes corresponds to the angle between the centers of the poles. In other windings the voltage between adjacent commutator sections varies by jumps, but may be made to vary according to the field strength by slightly varying the position of some one set of brushes with respect to the other sets. This feature of the different windings is a subject for special investigation, and is of more or less importance, according to the nature of the winding and the average voltage between commutator bars. We have frequently made mention of the number of slots. With respect to slotted armatures in general, it is to be remembered that an additional condition to that for smooth-core armatures has to be fulfilled ; i.e. the total number of the conductors to suit the equations for re-entrancy has to be divisible by the number of conductors possible to place in a slot, this number being dependent upon the number of poles. The number of conductors permissible per slot for two-circuit windings for different numbers of poles is shown in a table. We have omitted any reference to mechanical details of construction of armature windings, since these permit of great variety, without in any way modifying the results. Further, they are a part of the stock in trade of the electrical manufacturer. The drum windings considered are principally those in which the end connections are interchangeable, and INTKODUCTOEY. xv are in the form of evolutes, as in the Eickemeyer and Hopkinson windings, description of which will be found in Weymouth's "Drum Armatures and Commutators" ("The Electrician" Printing and Publishing Company, London, 1893). In general, such windings possess the advantages that all coils are of equal inductance and resistance, are equally accessible, have equal radiating surfaces, and are most easily repaired. When a coil consists of a number of conductors, bound together so as to be considered a single unit mechanically, it is so considered in the text, and in the formulae for the arrangement of conductors. These windings appear to have been invented by Bollmann, Desroziers, Fritsche, Pischon, Eickemeyer, and others ; but inasmuch as it is a disputed question as to which of these inventors has the right to claim priority, and as there may be more or less litigation before the question is settled, we have considered it best to omit all discussion as to who may have invented any of the windings. Where with a winding is given the name of a supposed inventor, it is simply because that winding has been known under that name, and not because the writers possess any special evidence to show by whom the winding was invented. After the possibility of litigation has ceased we hope to do justice to all inventors concerned, giving to each his proper proportion of credit for the work he has done. We believe that the tables on drum windings are a feature that should meet with especial favor, since after the number of conductors required for a given type of winding has been determined, the proper pitches for any style of winding can be found in the tables. Further, by referring opposite to this number of con- ductors in the different tables it may be ascertained at a glance whether, by slightly changing the end connections, the winding may be adapted to some other voltage. Such features, peculiar to certain numbers of conductors, are frequently in practice of the greatest importance. As a practical example take the following case : In a six-pole machine with 104 armature conductors, the winding may be connected for a two-circuit single winding by making the pitch 17 on each end, or for a two-circuit, doubly re-entrant double winding, by making the pitch 17 on one end and 19 on the other; this second arrangement being suitable for the same watt output as the first, at one-half the voltage. In the section on alternate-current armature windings are included a number of windings that have now only a limited application in practice, as it is thought that, on account of the very limited literature on this subject, a description of all windings of any practical use will be appreciated. With respect to the work in general, we should be glad to receive the suggestions and criticisms of all who are interested in this subject. The following articles on armature windings have been consulted in the preparation of this book, and are mentioned here for reference : ARNOLD Die Ankerwicklungen der Gleichstrom-Dynamomasohinen. Berlin, 1891. FRITSCHE Die Gleichstrom-Dynamomaschine. Berlin, 1889. KAPP Practical Electrical Engineering, Vol. II., p. 43. London, 1893. KITTLER Handbuch der Elektrotechnik, Vol. I. Stuttgart, 1892. RECHNIEWSKI L'Electricien, Vol. V. Jan. 14, 1893 el seq. THOMPSON Dynamo-Electric Machinery. London, 1892. WEYMOUTH The Electrician, Vol. *X". Nov. 7 to Dec. 19, 1890. PAET I. CONTINUOUS-CURRENT ARMATURE WINDINGS. CHAPTER I. SINGLE-WOUND GRAMME RINGS. THESE are the simplest windings in use, and will require only a very few diagrams and explanations. Many complex connections have been proposed, but only such forms will be discussed as are of general practical use. The plain gramme ring, with a single winding, is shown in Figs. 1 and 2, from which it may be seen that the construction, as far as concerns location of coils, connectors, and commutator segments, is independent of the number of poles. The number of coils should be a multiple of the number of poles in order to maintain s Fig. I FOUR-CIRCUIT, SINGLE-WINDING, Fig. 2 TWO-CIRCUIT, SINGLE-WINDING, symmetry among all the branches from brush to brush. The number of commutator segments is equal to the number of coils. It is desirable to minimize the turns per coil, and consequently the inductance of the short- 1 ,'circuited elements, by as large a number of segments as practicable. A further discussion of these two diagrams would be superfluous, beyond calling attention to the progressive nature of the rise of potential around the ring, whereby the contiguous wires have only the small difference of potential of one turn, making the question of insulation very simple. 8 ARMATURE WINDINGS OF ELECTRIC MACHINES. [OHAP. In cases where it is desirable to use but two brushes in multipolar rings with more than two circuits, the method of cross-connecting, shown in Fig. 3, may be used. The num- ber of commutator segments remains equal to the number of coils. An inspection of the diagram will show that it really consists in connecting in parallel those coils occupying cor- responding positions in the various fields. It would seldom be desirable to utilize this method of connection, except in very small machines, as the use of only one pair of sets of brushes would necessitate lengthening the commutator in order to retain the proper extent of brush contact surfaces. ^45*^ or ma USI7BRSITY] Fig. 3 FOUR CIRCUIT, SINGLE WINDING. Fig. 4 FOUR CIRCUIT SINGLE WINDING CHAP, i.] SINGLE-WOUND GKAMME KINGS. Figure 4 differs from Fig. 3 only in the use of two cross- connecting leads instead of one. This diagram would some- times be of advantage, inasmuch as it utilizes the available space more completely and symmetrically. Each cross- connecting conductor could be of smaller cross-section than if only one were used. Both this and the preceding method have the disadvantage that the two parallel sections have unequal resistance, due to one section having the long cross-connecting leads in series with it, and the other merely the regular short leads to the commutator. Failure to give due attention to this point often causes serious trouble. AKMATUBE WINDINGS OF ELECTKIC MACHINES. [CHAP. i. Figure 5 gives a winding which is wrong, but which has been given in the treatises of many of the specialists on windings, none of whom, except Herr Arnold, criticise it. The fault is that the positions of the coils bear such a relation to the positions of their respective commutator seg- ments, that during each revolution of the armature the position given in the figure is the only one in which the brushes are properly placed with regard to the diameter of commutation. In order that the brushes should always be in a position to properly perform their commutative function, they would have to be revolved in a direction opposite to that of the armature, and with a velocity equal to it. The characteristic of the winding is that it brings together into one segment each pair of cross-connected segments of the previous diagram. As above stated, however, this dia- gram is worthless, except to call attention to its character, so that the text-books in which it is described shall not be mis- leading. See ARNOLD Die Ankerwicklungen der Gleichstrom-Dynamoma- schinen, Fig. 42. KITTLER Handbuch der Elektrotechnik, 1892, Fig. 401 C. FRITSCHE Die Gleichstrom-Dynamomaschiuen, Fig 64. W//A Fig. 5 FOUR CIRCUIT SINGLE WINDING. Fig. 6 FOUR CIRCUIT SINGLE WINDING. CHAP, i.] SINGLE-WOUND GRAMME KINGS. 11 In Fig. 6 the number of commutator segments is made equal to half the number of coils by connecting two coils in series between each pair of adjacent segments. The coils so connected in series are situated in adjoining fields of opposite polarity. This winding has the disadvantage that coils at quite different potentials are adjacent, as may be seen by fol- lowing through the various armature circuits from brush to brush. This increases the difficulty of insulating. The volts per bar also, for the same number of conductors per coil, are twice as high as in the simple gramme ring. If it is necessary, for any reason, to halve the number of bars, it would be pref- erable to combine two adjacent coils into one, and retain the advantages of the simple gramme ring connection. But in cases where the shape of the frame necessitates somewhat unequal magnetic circuits, this connection averages up the unequal induction in the various coils, and therefore tends to diminish the sparking which might, with a simple gramme ring in such an unbalanced magnetic system, be considerable. If * = number of coils, and n = number of poles, then any coil is connected across to one ( - 1 ) in advance of it, and \>i J the two free ends of this pair of coils are connected to adjacent commutator segments. 12 AEMATUKE WINDINGS OF ELECTRIC MACHINES. [CHAP. Figure 7 is merely a step in advance of Fig. 6, and the advantages and disadvantages pointed out in the discussion of Fig. 6 apply in still greater degree to Fig. 7. It will be seen that the number of commutator segments is reduced to one-fourth of the number of coils by the con- necting in series of four coils, one in each field, between two adjacent segments of the commutator. As in the previous figure, the rule for connecting the coils is to connect each coil to one ( - 1 ) in advance. \n J Fig. 7 FOUR CIRCUIT SINGLE WINDING. WMWM. Fig. 8 FOUR CIRCUIT, SINGLE WINDING, CHAP, i.] SINGLE-WOUND GRAMME EINGS. 15 Figure 8 represents a winding in which the coils of one circuit, from brush to brush, instead of being adjacent to each other, are situated in different fields. For instance, the circuits through the armature in the position shown are, 8 1 6 j 2 7 121 1 9 4 11 I It is important to note that when the armature has entered the posi- tion in which four coils are short-circuited, the short-circuiting of any coil occurs, not at any one brush, but through the pair of brushes of like polarity. This would enable sparking to be diminished by connecting the two positive brushes together through a suitable resistance (ohmic or inductive), and lead- ing off to the load from the middle point of this resistance. The magnitude of the resistance, if ohmic, would be limited only by the permissible loss therein. High resistance leads to the commutator, and high-resistance brushes have been used with considerable success ; but in both of these cases heat has to be developed in undesirable localities. But in the above method of connection, the insertion of this resistance externally to the brushes will not increase the heating of the machine. This resistance is also so located that it could be adjusted in experimental work, and the differ- ence in sparking noted by having a short-circuiting switch shunted around the resistance. Another advantage of this winding is that pointed out in the remarks on Fig. 6, that in cases where the shape of the frame necessitates somewhat unequal magnetic circuits, this connection will average up the unequal induction in the various coils, and thereby diminish the sparking that would otherwise occur. CHAPTER II. DOUBLE- WOUND GRAMME RINGS. FIGURE 9 and the immediately following diagrams relate to a class of very great importance, which are known as double, triple, quadruple, etc., windings. Very satisfactory results have been attained by the use of windings of this class. The most important advantage of the double winding is that the current is commutated at two different parts of the bearing surface of the brush ; each independent volume of current being, therefore, only one-half of what it would be for a single winding. The importance of this feature has in practice been found to be very great. Another important feature of this winding is that the successive commutator bars of one winding are not adjacent to each other, but alternate with the bars of the other winding ; the two windings being put in parallel by the use of wide brushes. The result is that a section is very unlikely to be short-circuited by dirt or an arc. It also makes a very flexible winding, owing to the readiness with which any number of parallels may be arranged. Thus, in a six-pole field, we may have four, six, eight, etc., parallels. It is necessary for a double winding that the brush should bear over a surface greater than the width of one segment (plus insulation); for a triple winding, greater than the width of two segments, etc. In Fig. 9, which represents a two-circuit, doubly re-entrant, double-wound, simple gramme ring, the circuits through the armature are, 9 10 1 2 31 8 7 6 5 4 J ' 10' 1' 2' 3' 1 7' 6' 5' 4'J After the armature has revolved through - -^=9, coils 3 and 8 will be short-circuited, and the circuits through the armature will become, |9 10 1 2 -i 17 5 4 -i 9 ' 18' 10' 7' 1' 6' 2' 5' 4'P Thus it will be seen that there will be a lack of balance between the two windings. First they will be of equal length ; after 9 revolution, one will have one less section in series between the brushes ; 9 later they will be equal again ; and after still another 9 the other winding will have the smaller number of turns. This lack of symmetry will be less apparent as the number of sections is increased, and becomes of very little importance with the large numbers of conductors employed in practical work. 10 Fig. 9 TWO CIRCUIT DOUBLE WINDING Of THS ^ I7BRSJ Fig. 10 FOUR CIRCUIT DOUBLE WINDING. VlIIAl'. II.] DOUBLE-WOUND GRAMME RINGS. 19 Figure 10 shows a similar winding in a four-pole field. The circuit through the armature in the position shown is, | 16 17 18 19 20 \ ~ 1 15 14 13 12 H\> + f 16' 17' ( 15' 14' 18' 13' 19' 12' 20' / ^> + 11 '^ | 6 7 8 9 10 x 15 4 3 2 ls O>.+ ! 6' 7' 8' 9' 10"^> + 15' 4' 3' 2' v<^ After turning through 360 4 ^ ", coils 15', 20', 5', and 40 x 2 10' will be short-circuited , and the circuits through the arma- ture will be, f 16 17 18 19 20-v " 1 15 14 13 12 1K v > + r 16' 17' " 1 14' 13' 18' 12' 19' 11' I/> + f 6 7 " 1 5 4 8 3 9 2 i ;\ >+ f 6' 7' 8' 9' ^S+ 1 4' 3' 2' 1' ^ Here can be seen again the lack of symmetry noted in re- marks on Fig. 9. 20 ARMATURE WINDINGS OF ELECTRIC MACHINES. [cllAl 1 . II. A very useful winding is that shown in Fig. 11. It, also, is a four-circuit double winding. It is one of a class with very interesting properties. It differs from the double winding shown in Fig. 10, in that the two windings are components of one re-entrant system. Any one section is no longer exclusively an element of one of two windings, but changes from one winding. to the other four times per revolution, being short-circuited at the neutral point for a brief period at the occurrence of eacli of these transfers. These features are secured by adding one section to the doubly re-entrant double winding shown in Fig. 10, and, as in that figure, making the connections, not between adjacent sections, but always by passing over one section. The number of sections being odd, it will be seen that after having progressed twice around the ring, all sections will have been passed through, and the winding will have arrived at the other terminal of the section from which it started. Triple, quadruple, and higher orders of windings may be treated analogously. 1 The circuits through the armature in the position shown in Fig. 11 are, f-i 11 1 9 12 8 J21 1 " I 20 19 r 5 6 " ( 4 3 f 16 17 -lie 14 Coil 10 is, at this instant, short-circuited. An instant later coil 10 becomes active, and coil 2 becomes short-circuited. The circuits through the armature then become, -I 10 1 9 11 8 [21 1 " I 20 19 1 5 6 4 3 rie 17 1 15 14 1 The order in which the various coils will be short-circuited is 10, 2, 15, 7, 20, 12, 4, 17, etc., no that the 21 coils will each have been short-circuited once when the armature shall have revolved through 360 = 90. Therefore the angular interval between corresponding positions of two successive short 90o circuits is ~o~^'^' 1 Such windings will be designated as singly re-entrant, to distinguish them from others, such as those of Figs. 9 and 10, which are doubly re-entrant. Fig. 1 1 FOUR CIRCUIT DOUBLE WINDING UHI7BR3ITY 22 ARMATURE WINDINGS OF ELECTRIC MACHINES [CHAP. n. All of the windings so far described have as many cir- cuits through the armature as there are pole pieces, and form a class by themselves known as multiple-circuit wind- ings. Four-pole fields have usually been considered, but the modifications of the diagrams and text to apply them to larger numbers of poles, are obvious. In general, the number of sets of brushes equals the number of poles and the number of circuits through the armature. Different numbers of segments and brushes are due to modifications, and do not affect the underlying character of the windings as a class. Some of these modifications have been described. Others can be worked out as the occasion requires. Too much importance cannot be attached to the general rule that interpolations and cross-connections are almost always very undesirable. CHAPTER III. TWO-CIRCUIT, SINGLE-WOUND, MULTIPOLAR RINGS. THE next windings to be considered form a class which, independently of the number of poles, have only two circuits through the armature. These are known as two-circuit windings. Such windings possess 2 the practical advantage that the number of conductors, as compared with multiple-circuit windings, is only 2 as great, hence the space required for insulation is only -^- as great as with the multiple-circuit windings, in consequence of which the diameter of the armature, or the depth of space occupied by the armature conductors, may be less than with the multiple -circuit windings, thereby diminishing the cost of material. Further, on account of the lesser number of conductors, the cost of the labor of winding is corre- spondingly diminished. In practice, the two-circuit gramme windings have been applied only to armatures of small output, under which condition lack of symmetry of the armature coils with respect to the points of commutation is not particularly objectionable. Only two sets of collecting brushes are necessary for the collection of current ; in practice generally but two sets have been used. In the " short-connection " l type of two-circuit gramme windings, the circuits from brush to brush consist of conductors influenced by all the poles, so that the electromotive forces generated in the two circuits are necessarily equal, a feature that may prove advantageous when the depth of air-gap is so small that any slight eccentricity of the armature affects the magnetic flux at the different poles. In the " long-connection " type of two-circuit gramme winding, the two circuits from brush to brush consist of conductors influenced by only one-half of the poles, so that the electromotive forces generated in the two circuits are unequal, unless the sum of the lines at the poles of the same sign is equal to the sum of the lines at the poles of the opposite sign. In magnetic circuits of ordinarily good design this condition is fulfilled even though the fluxes at the different poles are unequal. So the winding is prac- tically as good as the " short-connection " winding, and possesses certain other advantages stated in the text, that make its use preferable. For armatures the outputs of which are so great that several sets of collecting brushes are required, these windings possess the same disadvantages as two-circuit drum windings, a discussion of which is to be found under that caption. 1 Called "short-connection" type because coils in adjacent fields are connected together. This distinguishes it from the "long-connection" type, in which coils twice as far apart are connected together. 24 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. in. Figure 12 represents one of the most practicable two-circuit windings for multipolar-ring armatures. It may be designated as the long-connection type of the two-circuit gramme winding, and one of its chief advantages is, that no great differences of potential exist between adjacent coils. In the figure is shown the case of a four-pole, two-circuit, single-wound, long-connection ring armature. In the position chosen, the circuits through the armature are, _ f 11 4 12 5 13 6 14 1 .29 1 8 15 7 Coils 3 and 10, in series, are at this instant short-circuited by the negative brush. A little later, coils 7 and 15 will be short-circuited by the positive brush. When this occurs, the negative brush will bear upon the middle of a segment. The number of commutator segments is equal to the number of coils, and must be odd for armatures with an even number of pairs of poles ; but may be odd or even for armatures with an odd number of pairs of poles. The relation that must subsist in two-circuit, multipolar-ring, long-connection windings, between the number of coils () and the number of poles (n), is, n + 1 where y = pitch. (The pitch is the number of coils tp be advanced through in arranging the end connections. In the diagram, for instance, the pitch y = 7, and the end of coil 1 is joined to the beginning of coil 1 + 7 = 8; the end of 8 to the beginning of 8 + 7 = 15; the end of 15 to the beginning of 15 + 7 = 22 (or 7), etc.) Mr. Gisbert Kapp has prepared the following table for two-circuit, multipolar-ring, long-connection windings by substituting numerical values for n in the above formula : TWO-CIRCUIT, MuLTIPOLAK-RlNG, LONG-CONNECTION WINDINGS. MACHINE HAS 4 poles 6 poles 8 poles 10 poles 12 poles 14 poles The number of coils must be equal to 2y 1 3y 1 4 y 1 5y 1 6y 1 7 y 1 For two-circuit, multipolar-rm^r machines with long-connection windings, ?/, the pitch, may be any integer. (Note that these conditions do not hold for drum windings.) Mr. Kapp has also prepared the following table, showing the practicable choice of angular distances between brushes in these two-circuit, multipolar windings : NUMBER OF POLES. ANGULAR DISTANCE BETWEEN BRUSHES. 2 180 4 6 8 10 12 14 25.7 77 128 180 16 22.5 67.5 112 158 18 24, 60 100 140 180 20 54 90 126 162 The smaller possible angles, namely, 20 for 18 poles, and 18 for 20 poles, are in practice too small to be admissible, and are, therefore, not given in the table. 90 60 180 45 135 36 108 180 30 90 150 25.7 77 128 22.5 67.5 112 3-6- 60 100 ll 54 90 M Fig. 1 2 TWO CIRCUIT, SINGLE WINDING, V Fig-. 1 3 TWO CIRCUIT, SINGLE WINDING. CHAI-. in.] TWO-CIRCUIT, SINGLE-WOUND, MULTIPOLAR RINGS. 27 Figure 13 represents a two-circuit, single-wound, long- connection, ten-pole ring armature. Substituting in the formula for the number of coils the pitch, y = 10, and the number of poles, n = 10, gives = J*- 10 1 = 51 or 49. 51 coils are taken in this case. The end of coil 1 is joined to the beginning of coil 1 + 10 = 11; the end of 11 to the beginning of 21, etc. The brushes are shown 180 apart, and at the position given the negative brush short-circuits the coils 9, 19, 29, 39, and 49. The circuits through the armature are, f 8-18-28-38-48- 7-17-27-37-47-6-16-26-36^16-5-15-25-35-45-4-14-24 j i 51 )_iO-30-2< i-l ( 1-51-11-31-21-11-1-42-32-22-12-2-43-33-23-13-3-44-34 I This diagram and table show very clearly that with an odd number of pairs of poles and an odd number of coils, an odd number of coils are short-circuited at one time, so that, as the total number of coils is odd, an even number is left to be divided between the two armature circuits, which are, therefore, equal. Referring back to Fig. 12, it will be seen that in the case of an even number of pairs of poles, an even number of coils are short-circuited, and as the total number of coils is necessarily odd, an odd number remains to be divided between the two armature circuits, so that these are necessarily unequal. UNIVERSITY 28 ARMATUKE WINDINGS OF ELECTIUC MACHINES. [CHAP. in. If, however, in Fig. 13 the brushes are put 108 apart instead of 180, coil 24 would be taken from the cir- cuit given in the upper line of numbers and put in the other circuit. There would then be 24 coils in one circuit, and 22 in the other, instead of 23 in both. With the large number of coils used in practice, however, these slight in- equalities cause no trouble. If y were chosen odd, 9 for instance, s would equal 46 or 44. 8=1- y 1 = ^-9 1=46 or 44. 4 _ This is in accordance with the observation made above, that in the case of an odd number of pairs of poles the number of coils may be even. The diagram for this case is given in Fig. 14, where 8 = 46, w = 10, / = 9. In the posi- tion shown, coils 8, 17, 26, 35, and 44 are short-circuited by the negative brush, and coils 31, 40, 3, 12, and 21 by the positive brush. The circuits through the armature are, _ ( 7-16-25-34-43- 6-15-24-33-42-5-14-23-32-41-4-13-22 ] 1 45-30-27-18- 9-46-37-28-19-10-1-38-29-20-11-2-39-30 i H giving, as in Fig. 13, two equal paths through the arma- ture. Fig. 1 4 TWO CIRCUIT, SINGLE WINDING. Fig. 15 TWO CIRCUIT, SINGLE WINDING. CHA1'. Ill ] TWO-CIRCUIT, SINGLE-WOUND, MULTIPOLAE KINUS, In Fig. 15 is given a winding that has been used in practice with considerable success, owing partly to the extreme regularity of all connections, and still more to the fact that it involves the use of twice as many commutator segments as coils. Only one coil in series is short-circuited at each brush, and the volts per segment are one-half what they would be in the unmodified long-connection winding. The number of coils to be used is, as in the unmodified wind- ing, = ? y 1. Thus, in Fig. 15, = 4, y = 9, s = -j = 19. Coil 1 is connected to coil 10, etc. 9 + 1 It will also be noted that those segments '3CiO' 2 from each other are connected together. The number of segments = ~360~1 - s, of which -, at distances of ^~ from each other, are connected together. If every other one of the radial connec- tions from the coils to the commutator are discarded, the winding becomes once more the plain, long-connection, two- circuit, gramme winding. At the position shown, coil 13 is short-circuited by the negative brush, and the circuits through the armature are, 3-12-2-11-1-10-19- 9-18 4-14-5-15-4-1G- 7-17- 8 32 ABMATUKE WINDINGS OF ELECTRIC MACHINES. [OHAP. in. Figure 16 is an application of the same type of winding to a six-pole gramme ring. w = 6, # = 6, s = ^y 1 = | 6 + 1 = 19. There are 19xf = 57 segments. All segments distant from each other by =120 should be connected together. Some of the cross-connections are shown inside the armature. ft 2 At the position shown, coil 12 is short-circuited by the positive brush. The circuits through the armature are I 9_3_i6_iO-4-17-ll- 5-18 } \ 15-2- 8-14-1- 7-13-19- 6 J If the connections shown inside the commutator, together with one-third of the segments, had been omitted, there would have been an unequal distribution of potential about the commutator. Between two segments would be found a certain voltage, V, and between the next two 2 V; then V again, etc. If it should be desirable to diminish the number of commutator segments to one-half the number of coils, it may be done by the method of connection shown in Fig. 17, page 34, which will be recognized at once as the multipolar ring counterpart of the two-circuit winding as applied to multipolar drums. This winding will be referred to as a " short connection," two-circuit gramme winding. In the " long-connection " type, examples of which have just been given, connection has been made between coils situated in fields of like polarity. But in the "short-connection" type, connection is made between coils in adjacent fields. Both methods are feasible in ring windings, because the two ends of a coil located at a certain 'point of the periphery are accessible for connection at the commutator end if desired, but in drum windings only one end of a conductor located at a given point of the periphery is accessible at the commutator end, the other end of the conductor being necessarily connected across at the opposite end of the armature, and in consequence, also, must be connected over to a conductor in an adjacent field of unlike polarity, in order that the electromotive force, which is, say, from front to back in the first conductor, may add itself to that in the second conductor, which must therefore be from back to front; that is, the second conductor must be situated in a field of opposite polarity. Thus there are two sub-classes of two-circuit, multipolar ring windings, in the first of which (the " long-connection " winding) coils in fields of like polarity are connected in succession, and in the second of which, as in the two-circuit, multipolar drum winding, the conductors immediately succeeding each other are situated in fields of opposite polarity. In this " short-connection " winding for two-circuit multipolar rings the formula for determining the proper number of coils, , for any number of poles, n, is s = ny 2, where y, the pitch, may equal any integer, odd or even. In connecting up this " short-connection " type of winding the following additional rule should be borne in mind in the interpretation and application of the meaning of the pitch, y : The number of coils in this winding, being from the formula always even, if y is also even, it is necessary in connecting up to use as the pitch, alternately, ($ 1) and (y + 1) instead of always y. Otherwise, if the coils are numbered successively TWO CIRCUIT, SINGLE WINDING Fig. 1 7 TWO CIRCUIT, SINGLE WINDING. , HAP. in.] TWO-CIECUIT, SINGLE-WOUND, MULTIPOLAK RINGS. 35 from No. 1 on, the even-numbered coils would never be touched, if an odd-numbered conductor were started with, and vice versa. If y were used every time as the pitch, a double winding would be obtained. This case will be treated later. It may also be well to note that (/ 3) and (y + 3) could be used alternately as the pitch. It is thought, however, that no advantages, and several disadvantages, would result from such a choice of pitches. Figure 17 represents a two-circuit, single-wound, four-pole ring of the " short-connection " type just described. n = 4, y = 8, s = ny 2 = 4 x 8 + 2 = 34. This is the case referred to above, in which, s being even and also /, (j/ 1) and (y + 1) must be used alter- nately as the pitch in connecting up. The sequence of connections will be seen in the figure to be 1, 1 + 7 = 8, 8 + 9 = 17, 17 + 7=24, etc. Number of commutator segments = ^ = 17- In the position shown, coils 7, 14, 23, and 30, in series, are short-circuited at the negative brush, and the circuits through the armature are, _{ 5-1 132-2 5-12-21-28- 3-10-19-26-1- 8-17-24-33- 6 , .25-16- 9-34-27-18-11-2-29-20-13- 4^31-22-15 f There are 14 coils in one path and 16 in the other. A little later, coils 6, 33, 24, and 17^ in series, will be short-circuited by the positive brush, and coils 7, 14, 23, and 30 will take their place, the circuits through the armature then becoming, r 7_14_23-30- 5-12-21-28-3-10-19-26-1- 8 1 I 32-25-16- 9-54-27-18-11-2-29-20-13-4-31-22-15 J A further inspection of the diagram will show the unsymmetrical arrangement of the short-circuited and adjacent coils, causing the induction in some coils to act in opposition to that in others with which it is in series. This is less marked with large numbers of coils. The chief disadvantages of the "short-connection" winding are that adjacent coils have between them, periodically, the full E.M.F. of the armature, and that the end windings are complicated. 36 AEMATUEE WINDINGS OF ELECTRIC MACHINES. [CHAP. iir. Figure 18 represents another two-circuit, single-wound, "short-connection" gramme winding, in which s = ny2 = 4 x 5 2 = 22. In this case /, the pitch, is odd, and con- sequently the sequence of connections is 1, 1 + 5 = 6, 6 + 5 = 11, 11 + 5 = 16, etc., thus advancing each time by 5, and not, as in the case of Fig. 17, page 34, where y was even, alternately by (/ + !) and (y 1). Corresponding ends of coils are connected together; thus, the end of 1 and the end of 6, the beginning of 6 and the beginning of 11, etc. At the position shown, coils 5, 10, 15, and 20 are short-circuited by the negative brush, and the circuits through the armature are, f 22-17-12- 7-2-19-14- 9 } " | 3- 8-13-18-1- 6-11-16-21-4 1 The winding is subject to the disadvantages noted in connection with Fig. 17, page 34. Instead of having the objectionable crossings at the ter- minals of the coils, as shown in Fig. 18, page 37, alternate coils should be wound right and left handedly. This would only be useful in cases where all the connecting is done at one end, which should be avoided when possible. Fig. 1 8 TWO CIRCUIT, SINGLE WINDING. Fig. 1 9 TWO CIRCUIT, SINGLE WINDING. CHAP, in.] TWO-CIRCUIT, SINGLE-WOUND, MULTIPOLAR RINGS. 39 Instead of connecting together in pairs coils lying in fields of opposite polarity, as in Figs. 17 and 18, adjacent coils may be connected together as shown in Fig. 19, and these connected across to coils in the nearest field of like polarity. The number of commutator segments is equal to one-half of the number of coils. The inherent identity of this and the "long-connection" winding may be seen by doing away with the leads to the commutator segments, and substituting leads from the eleven points lettered a, b, o, d, etc. The result will be a simple " long-connection " gramme winding, with half as many coils of twice as many turns each. Therefore, the best way of laying out such a winding is to apply the rules for the "long-connection" winding, and make the connections shown in Fig. 19, instead of those of the regular " long-connection " gramme winding. This winding gives half as many commutator segments as coils. In the position shown, coils 5, 14, 15, and 2 are short- circuited by the positive brush, and the circuits through the armature are, 8-21-20-11-10- 1-22-13-12-3 1 > 9-18-19- 6- 7-16-17- 4 J CHAPTER IV. TWO-CIRCUIT, MULTIPLE-WOUND, MULTIPOLAR RINGS. THE next class is that of the two-circuit, multiple-wound, long-connection ring windings. The general formula is, n s=-xym, where 8 = number of coils, n = number of poles, y = pitch, m = number of windings. The "T" windings will consist of a number of independently re-entrant windings equal to the greatest common factor of " y " and " m." Therefore, when it is desired that the " m " windings shall combine to form one re-entrant system, it will be necessary that the G.C.F. of "y" and "m" shall be made equal tp 1. Figure 20 represents a two-circuit, doubly re-entrant, double-wound ring armature. 8=26, n=4, m=2. Greatest common factor of y (12) and m (2) is 2. Therefore the winding will be doubly re-entrant. At the position shown, coils 24 and 12, in series, are short-circuited by the negative brush. The circuits through the armature are, { 25-13-1-15-3-17 \ I 26-14-2-16-4-18 I t 10-22-8-2 1 11-23-9-21-7-19-5 ' H 40 Fig. 20 TWO CIRCUIT, DOUBLE WINDING. ,Fig. 2 1 TWO CIRCUIT, DOUBLE WINDING, CHAP. IV.] TWO-CIKCUIT, MULTIPLE-WOUND, MULTIPOLAE RINGS. 43 Figure 21 represents a two-circuit, singly re-entrant, double-wound ring armature. In this case y = ll, n = 4, and m = 2. 8=|xll2 = 20 or24. 24 coils are taken. G.C.F. of "/" and "m" being 1, the winding is singly re-entrant. In the position given, coils 9 and 22 are short-circuited at the negative brush, and 4 and 15 at the positive. The circuits through the armature are, f 20-7-18-5-16 - 1 21-8-19-6-17 f 11-24-13-2 1 10-23-12-1-14-3 44 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. iv. Figure 22 represents another two-circuit, singly re- entrant, double-wound ring armature. = 2, M =<), / = 7, s = 2 = x72 = 19or 23. "y" and "?" being prime, the winding is singly re- entrant. At the position shown, coils 4, 11, and 18 are short- circuited at the positive brush, and the circuits through the armature are: f 15-22-6-13-20 1 1 14-21-5-12-19 I 8- 1-17-10-3- 1 7-23-16- 9-2- I Two two-circuit, singly re-entrant, triple windings for gramme rings are given below without diagrams : n=3, n=6, y=7, *=^xy 3=^x7 + 3 = 24. Z i The connections would be, 1-8-15-22-5-12-19-2-9-16-23-6-13-20-3-10-17-24-7-14-21 ^t-11-18-1 m=3, w=10, y=10, 8=^x10-3=47. 1-11-21-31^1^-14-24-31-11-7-17-27-37^7-10-20-30-40-3 -13-23-33-43-6-16-26-36-46-9-19-29-39-2-12-22-32-^2 -5-15-25-35-45-8-18-28-38-1 Fig. 22 TWO CIRCUIT, DOUBLE WINDING. TWO CIRCUIT, TRIPLE WINDING. CHAR IV.] TWO-CIRCUIT, MULTIPLE-WOUND, MULTIPOLAR RINGS. 47 Figure 23 represents a two-circuit, singly re-entrant, triple winding. "m" and "y" being prime, the winding is singly re-entrant. In the position shown, coils 5 and 15, in series, are short-circuited by the positive brush. The circuits through the armature are, f 22-9-19-6-16 | 21-8-18 120-7-17 f 12- 2 11- 1-14-4 1 10-23-13-3 The extreme irregularity of the various circuits in multiple is not characteristic of the winding, but is merely due to the very small number of coils chosen. In practical cases it would be negligible. From the formula and conditions of page 40, and from the examples just given, it will be seen that two- circuit, multiple-wound, ring windings may be divided into the three following cases: CASE I. "y" and "m" are mutually prime. This gives a singly re-entrant winding of "m " multiple windings. Illustration: n = 4, y = l, m = 4, s = |x7+4 = 18. Connections are, - l-8-16-4-ll-l-7-14-3-10-17-6-l-2-9^1(^5-12-l. May be expressed symbolically as (OOP). CASE II. "#" a multiple of "TM." This gives "TO" independently re-entrant windings. Illustration : w = 4, y = 8, m=4, = f x8+4 = 20. Connections are, 1- 9-17-5-13-1 2-10-18-6-14-2 3-11-19-7-15-3 4_12-20-8-16-4 May be expressed symbolically as O O O O- CASE III. "/" and "w" have common factors. This gives a number of independently re-entrant windings, equal to the greatest common factor of " y " and " m." Illustration : The result is a two-circuit, quadruple winding with two independently re-entrant windings, because 2 is the greatest common factor of " y " and " m." The connections are, 1_7_13_3_9_15_5_11_1 an d 2-8-14-4-10-16-6-12-2 May be expressed symbolically as . Case II. is really a special instance of Case III. The above formula and controlling conditions will be found to hold for all numbers of poles, coils, pitches, and windings of the two-circuit, long-connection type of gramme-ring armature windings. 48 AKMATURE WINDINGS OF ELECTRIC MACHINES [CHAP. iv. Figure 24 is a two-circuit, singly re-entrant triple winding of the type described in connection with Figs. 15 and 16, which, it should be remembered, is only a modification of the long-connection type. n=4, / = =x 10 + 3=23. At the position shown, coil 21 is short-circuited at the negative brush, and coils 3 and 4 at the positive brush. The circuits through the armature are, 8-18- 5 - | 9-19- 6-16 20- 7-17 22-12- 2-15 11- 1-14 10-23-13 Figure 24 should be compared with Figs. 15 and 16. Fig. 24 TWO CIRCUIT, TRIPLE WINDING. CHAPTER V. DRUM ARMATURE WINDINGS. IN drum windings, all connections from bar to bar must be made upon the rear and front ends exclusively, it not being practicable to bring connections through inside from back to front as is the case with rings. Consideration of this limitation will show that the two sides of any one coil must be situated in fields of opposite polarity, so that the electromotive forces, generated in the active conductors of a coil by their passage through their respective fields, shall be in the same direction. In the case of a drum, it should also be noted that a coil is linked with the whole or nearly the whole flux from one pole piece, instead of, as in the ring armature, with only one- half of the flux. BIPOLAR DRUM WINDINGS. The winding of bipolar armatures is much less simple in the case of drums than in that of rings, and it will therefore be necessary to give considerable attention to the various methods in which such windings may be carried out. 51 52 AEMATUKE WINDINGS OF ELECTKIC MACHINES. [CHAP. v. Figure 25 represents essentially the winding devised by von Hefner- Alteneck. It is used chiefly for small, smooth-core, wire-wound armatures, and the element of the winding, represented in the diagram by a pair of face conductors, and a back connection consists usually, in practice, of a coil of several turns, compar- able in some respects to the coil of the ring windings ; but in the diagram only one turn per coil will be shown. This will also be advantageous, inasmuch as large, iron-clad, bar-wound, multipolar drum armatures are derived from, and diagrammatically are very analogous to, the wire-wound, smooth-core armatures now under consideration. An examination of Fig. 25 shows that, starting from a commutator segment, the winding proceeds over the front end to conductor No. 1 ; down No. 1 over the back to conductor No. 8, which, it should be noted, is adjacent to the conductor diametrically opposite No. 1. From No. 8 the winding returns to the next commutator segment, and is then carried to conductor No. 3 (skipping No. 2, which will later be joined over the back to a conductor almost diametrically opposite to it), down No. 3, over the back to No. 10, etc. From this it is seen that the " pitch " on the back end is 7 and on the front end is 5. In the position shown, the circuits through the armature are, r 10- 3-8- 1- 6-15 I " 1 7_14_9_16-11- 2 J The coil represented by the conductors 13 and 4 is short -circuited at the positive brush, and coil 12-5 at the negative brush. The customary convention is adopted in the diagram, indicating a current from the observer into the paper, and $ a current up out of the surface of the paper toward the observer. A serious fault of this winding is that large differences of potential exist between adjacent conductors (or, usually, groups of conductors). This would be of no importance with the small numbers of conductors represented in these diagrams, but in actual cases, large numbers of conductors are used, and are placed close together in order to waste no available space. Fig. 25 TWO CIRCUIT, SINGLE WINDING. Fig. 26 TWO CIRCUIT, SINGLE WINDING. CHAP, v.] DKUM AKMATUKE WINDINGS. 55 Figure 26 gives the diagram of a winding discussed by Swinburne. Its characteristic feature is the use of a small pitch (in the figure the pitch at the back end is 11, and at the front end it is 9), whereby the turns consist of con- ductors separated by a much smaller angular distance than in the von Hefner- Alteneck winding. An advantage of this winding is that there is much less crossing of the end connections than is the case where the pitch is taken larger. Thus the difficult question of insula- tion at the ends of the armature is greatly simplified. Still further, it has been pointed out by Swinburne that the demagnetizing effect of the armature on the field is reduced, as may be seen from the fact that the currents in the conductors in the demagnetizing belt between the pole tips, namely, 23, 24, 25, and 26, and in 7, 8, 9, and 10, are alternately in opposite directions, and thus neutralize each other. A serious disadvantage is that the short-circuited coils, 6-27 and 11-22, are considerably removed from the neutral line. This, together with the fact that the counter-electro- motive forces present in several conductors of the circuit between brushes detract from the volts per unit of length of armature wire, reduces to rather small limits the extent to which such connecting over short chords should be carried. In the position shown, the circuits through the armature are, _ i 20- 9-18- 7-16- 5-14- 3-12- 1-10-31- 8-29 1 " 1 13-24-15-26-17-28-19-30-21-32-23- 2-25- 4 J 07 THU [U3IVBRSITT] 56 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. v. In Fig. 27 it will be seen that the number of coils is odd (in the two preceding diagrams it was even), with the result that the two active sides of such coils may now be diametri- cally opposite. This would not, however, usually be advisable, as it makes many more crossings at the ends, and therefore in- creases the difficulty of insulating. Some advantage results from bringing the short-circuited coil (in the figure, coil 24-9 is short-circuited by the. nega- tive brush), exactly in the neutral line, this being, of course, only possible when the conductors forming its active sides are diametrically opposite. The circuits through the armature in the position shown are, f 22- 7-20- 5-18- 3-16-1-14-29-12-27-10-25 1 1 11-26-13-28-15-30-17-2-19- 4-21- 6-23- 8 J The pitch on the back end is 15, and on the front end it is -13. Owing to the number of segments being odd, only one coil is short-circuited at once, unless wide brushes are used. Fig. 27 TWO CIRCUIT, SINGLE WINDING. Fig. 28 TWO CIRCUIT, SINGLE WINDING, CHAP, v,] DEUM AEMATUHE WINDINGS. 59 In Fig. 28 there is also an odd number of coils (and therefore an odd number of commutator segments). But instead of connecting over the back from No. 1 to No. 16 (the conductor diametrically opposite No. 1) as in Fig. 17, connection is made over the back from No. 1 to No. 14, then over the front to No 3, etc , the pitch at the back end being 13, and on the front end 11. It is, therefore, a mild form of the Swinburne chord winding, as described in connection with Fig, 26. The end connections are better distributed and have fewer crossings than was the case in Fig. 27, where diametrically opposite conductors were connected into coils. In the position shown, coil 22-9 is short-circuited at the negative brush, and the circuits through the armature are, 11-24-13-26-15-28-17-30-19- 2-21- 4-23- 61 20- 7-18- 5-16- 3-14- 1-12-29-10-27- 8-25 I 60 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAI-. v. In Fig. 29 the winding is carried on over a still shorter chord, the pitch at the back end being 11 and at the front end 9. It is very instructive to compare Figs. 27, 28, and 29, all of which have 30 face conductors (15 coils). But in Fig. 27 diametrically opposite con- ductors are connected over the back, the back pitch being 15. Figure 28 is a weak chord winding, the back pitch being 13. Figure 29 is a decided chord winding, the back pitch being 11. The points to be compared are the positions of the short-circuited conductors with reference to the neutral line ; the amount of neutralizing of the effect of the demagnetizing belt between pole tips, and the comparative amount of crossing of connectors at the ends. In Fig. 27 it was shown that diametrically opposite conductors could be connected into coils if the number of coils were chosen odd. The same object may be attained with an even number of coils by winding them in two layers instead of in one layer, as has been the case in all the heretofore described bipolar drum armatures. It should be again noted that the term " conductors " is used in these explanations, although "groups of conductors " could often be substituted therefor in small, smooth-core, wire-wound armatures. Thus the set of " one-layer windings," just described, are those in which " conductors " or " groups of conductors " are, in the completed winding, arranged in one layer, although the individual wires of such a group may optionally occupy one or several layers. In the same way, the two-layer windings now to be described are those in which the com- pleted winding consists of " conductors " or " groups of conductors " arranged in two layers, although the actual depth of individual wires may, when desirable, be greater than two. F\g.29 TWO CIRCUIT, SINGLE WINDING. o. 13 O 10 Fig. 30 a,b, c and d. CHAP, v.] DKUM AKMATUKE WINDINGS. 63 In Fig. 30, diagrams a and b represent a single-layer bipolar drum winding with an odd number of coils, in which diametrically opposite conductors are connected together into coils. In diagram -a the first half of the winding is carried out and proceeds from a commutator bar to conductor No. 1, to 8, to 3, to 10, to 5, to 12, to 7, to 14, and is then ready for the second half. It will be seen that at this stage only every other coil is connected up, and that only one-half of the commutator segments are utilized. Diagram b shows the winding completed. This winding, which is of the type shown in Fig. 27, is given here for comparison with the two-layer winding shown in diagrams c and d. In Fig. c it will be seen that the first half is exactly the same as the first half of the one-layer winding (except that it contains eight conductors instead of seven), and at the completion of the first half all the conductors of the lower layer are connected up in the order 1-9-3-11-5-13-7-15, and only one-half of the commutator segments are connected in. The coils remaining for the second half, instead of lying between those of the first half, occupy an outer layer. Diagram d shows the completed winding, with all the coils and commutator segments utilized. 64 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. v. Figure 31 represents a two-layer winding with thirty-two conductors, with diametrically opposite conductors connected into coils over the back end. These back-end connections are not shown, because they would interfere with the clearness of the diagram. The connections are 1-17-319-5-21, etc. In the position shown, coil 259 is short-circuited at the negative brush and 20-10 at the positive brush, and the circuits through the armature are, f 23- 7-21- 5-19- 3-17-1-16-32-14-30-12-28 1 1 11-27-13-29-15-31-18-2-20- 4-22- 6-24- 8 I It will be seen from this table that maximum difference of potential exists between conductors lying directly over each other in different layers, such as 27 and 28, or 7 and 8. But adjacent conductors have only small differences of potential ; therefore, the two layers should be carefully insulated from each other. It is an advantage to have the conductors 25-9 and 26-10 of the two short-circuited coils all situated on one diameter, as they may therefore be brought diametrical, and therefore are capable of being short-circuited more nearly in the neutral position. A disadvantage of the winding is that, one-half being wound exclu- sively in the lower layer and the other half in the upper, they have unequal lengths and different peripheral speeds, and in those recurring positions in which the two circuits through the armature consist respect- ively of the lower and the upper layer, the condition will be unbalanced. In practice, however, it is frequently found expedient to use this con- nection because of the ease of winding, the inequality being made as small as possible. It will be shown later how this inequality may be obviated ; the winding will be, however, less easy to execute. Fig. 31 TWO CIRCUIT, SINGLE WINDING. Fig. 32 TWO CIRCUIT, SINGLE WINDING CIIAP. v.] DEUM AEMATURE WINDINGS. 67 In Fig. 32 the winding is of the Swinburne type, being connected over the ends along a short chord. Thus, starting from a commutator segment, it passes down No. 1, over the back to No. 13, over the front to No. 3, and so on through 3, 15, 5, 17, 7, 19, 9, 21, 11, 23 ; but coming over the front from 23 it would naturally go to 13 of the lower layer. This, however, is already used, so the winding continues by No. 14, which is directly over No. 13 in the top layer, and then on through 2516- 27-18-29-20-31-22. From 22 it would naturally go to No. 1, but, as the winding is not yet completed, it must go instead to No. 2, which is directly over No. 1, and then proceed from 2 through 24-4-26-6-28-8-30-10-32-12, and then it closes on itself at No. 1. This winding is not at all difficult, because, although the lower layer is not entirely completed before beginning to wind the upper layer, yet in that part of the armature on which it is desired to wind the upper layer, the lower layer is entirely completed, and for quite a distance beyond, so that there would be no trouble in inserting the necessary insulation, etc. In the position shown, coil 28-8 is short-circuited at the positive brush, and coil 23-11 at the negative brush. It is a disadvantage to Jiave the short-circuited coils so far from the neutral line. The circuits through the armature in. the given position are, f 21- 9-19- 7-17- 5-15- 3-13-1-12-32-10-30 ] 1 14-25-16-27-18-29-20-31-22-2-24- 4-26- 6 ! It will be seen that in this armature there can be no position in which one layer belongs exclusively to one circuit and the other to the other circuit. Therefore the discrepancy in lengths and peripheral speeds of the two circuits through the armature will, at the most unfavorable moment, be less than when diametrically opposite conductors are connected into coils. The winding has, in common with all chord windings, the advantage of less crossings of the end connections. The diagram shows particularly well the absence of demagnetizing action in the zone of con- ductors between pole tips. If, in Fig. 32, page 66, conductor No. 1 had been connected over the back to No. 15 instead of to No. 13, it would still have been a chord winding, but witli somewhat less marked characteristics than that of Fig. 32. All the advantages and disadvantages would have been on a smaller scale. 08 AttMATUJRE WINDINGS OF ELECTRIC MACHINES. [CHAP. v. Figure 33 represents a winding in which coils of the outer and inner layer are alternately connected. The rear- end connections are not drawn, but are diametrical. Thus the series is 1-15-4-18-5-1 9-8-22-9-23-12-26-1 3-27-1 circuited. The circuits through the armature are, 6-49- 8- 1-10- 45_ 2-43-50-ll^t | 22-15-24-17-26-1 1 11-18- 9-16- 7-14 _ i 40-33-42-35^4-37 I 29-36-27-34-25-32-23-30 The front-end pitch is ?/ = 9, and the back-end pitch is y=1. 71 72 ARMATUKE WINDINGS OF ELECTK1C MACHINES. [OUAP. vi. If the pitches had been taken 7 and 5 instead of 9 and 7, retaining the same number (50) of face conductors, the diagram given in Fig. 35 would have been the result. This, it will be seen, is an application of the chord winding to a multipolar arma- ture. The current in the conductors in the neutral zone is alternately in opposite direc- tions, so that the demagnetizing action of the armature is small. The end connections are shorter, occupying less room and reducing the armature resistance and cost of copper. The short-circuited conductors are, however, at some distance from the neutral lines, and, although the electromotive forces in each pair will partly neutralize each other, it would be advisable, in cases where such chord windings are adopted, to have as great distances between pole tips as other circumstances permit. In the given position, the short-circuited conductors are 4-49, 12-7, 20-15 28-23, 38- 33, 46-41. The armature circuits are, -1 G- 1- 8- 3-10- 47_ 2-45-50-43-4 J 22-17-24-19-26-21 " i 13-18-11-16- 9-14 -I 40-35-42-37-44-39- 31-36-29-34-27-32-25-3 The front-end pitch is y = 1, and the back-end pitch yb. If it should be considered desirable to have all the paths through the armature contain exactly the same number of conductors, then the number of face conductors should be chosen a multiple of the number of poles. But with a large number of conductors this would generally not be an important consideration. In modern practice the conductors in large multipolar machines frequently consist of bars arranged in slots. The end connections then become strips arranged in two or more spiral layers at each end. If there were only one conductor per slot, two layers at each end would still be necessary, as it would be the same as if the lower conductors were brought up side of the upper conductors, and every other conductor would, therefore, as before, be connected over in an opposite direction from its neighbor. For multiple-circuit, single-wound armatures there may be any even number of con- ductors per slot, and any number of slots. No new diagrams are necessary to show the cases of two or more conductors per slot, as Figs. 34 and 35 may be interpreted as having twenty-five slots and two conductors per slot, in which case odd-numbered conductors may be considered to belong to the upper layer, and even-numbered conductors to the lower layer. Connection is always made between odd and even numbered conductors, the pitch being always odd. The front-end and back-end pitches must differ by 2, and must have opposite signs. N 32y 18 N 281 Fig. 35 SIX CIRCUIT, SINGLE WINDING. N Fig. 36 SIX CIRCUIT, SINGLE WINDING. vi.] MULTIPLE-CIRCUIT, SINGLE-WOUND, MULTIPOLAR DRUMS. 75 Figure 36 represents a six-circuit, single-wound, drum winding with eighty con- ductors. The number of conductors is purposely taken large, so that a study of the diagram and winding table may show the magnitude of the differences of potential in neighboring conductors. At the given position, conductors 75-6, 9-20, 21-32, 35-46, 49-60, and 61-72 are short-circuited at the brushes. The circuits through the armature are, _ i 8-77-10-79-12- 1-14- 3-1(5- 5-18- 7- t 73- 4-71- 2-159-80-67-78-65-76-63-74 _ J 34-23^36-25-38-27-40-29-42-31-44-33 " { 19-30-17-28-15-26-13-24-11-22 r 62-51-64-53-66-55-68-57-70-59 " \ 47_58-15-56-43-54-41-52-39-50-37-4i An inspection of the above table will show that the full difference of potential exists at recurring intervals between each pair of sequential conductors, such as 7 and 8, or 47 and 48. In practice, such conductors will often consist of two bars lying one above the other in the same slot. This shows that such upper and lower layers in a slot should be carefully insulated. On the other hand, alternately sequential conductors, as 5 and 7, or 47 and 45, have between them only the small difference of potential of two conductors in series; so that, in practice, where such conductors usually belong both to the upper or both to the lower layer of the same slot, comparatively thin layers of insulation suffice. For instance, it is often the case in multiple-circuit windings that there are four conductors per slot, arranged two wide and two deep. This case would require that the horizontal layer of insulation between conductors should be much thickei than the vertical layer. For this class of windings (multiple-circuit, single-wound drums) a formula is super- fluous, and the following summary of conditions will suffice : There may be any even number of conductors, except that in ironclad windings the number of conductors must also be a multiple of the number of conductors per slot. The front and back pitches must both be odd, and must differ by 2 ; therefore the average pitch is even. ft The average pitch "y" should not be very different from -, where c = number of con- Q ductors, and n = number of poles. For chord windings, " y " should be smaller than - by as great an amount as other conditions will permit. CHAPTER VII. MULTIPLE-CIRCUIT, MULTIPLE- WOUND, MULTIPOLAR DRUMS. THE next windings to be considered are multiple-circuit, multiple-wound, multipolar drums. The following rules control these windings : The number of conductors, (7, must be an even number. The pitches must be odd. If y = front- end pitch, then (y 2m) = back-end pitch, where m = number of windings (double, triple, quadruple, etc.). These "wi" windings may form one re-entrant winding, "TO" independent re-entrant windings, or a number of re-entrant windings equal to some factor of " m," each of which re-entrant windings is composed of two or more components. To determine the proper number of conductors for any of the above cases, the following rule should be observed : If " m " equals the number of windings, and " C " equals the number of face conductors, then the number r of independently re-entrant winding* will be equal to the greatest common factor of and m. Fur instance, if a quadruple winding has 28 conductors, then the greatest common factor of (wi = 4) (C 28 \ and f = ^-=14) is 2, and the quadruple winding will consist of two independent double windings, each of the two being re-entrant. This may be represented symbolically as (G 24 ==12) and (i = 4) is 4, and the quadruple winding will be made up of four independent single windings. This may be represented symbolically as O O O O- I G ^6 \ If (7=26 and ?n = 4, the greatest common factor of (=^- = 13) and (i = 4) is 1, and the quadruple \m J& / winding will consist of one singly re-entrant quadruple winding. This may be represented symbolically The above rule applies to any winding (double, triple, quadruple, etc.). It is interesting to note that, for "multiple-V'<" windings, the rule for the number of multiple wind- ings is independent of the number of poles and of the pitch. The number of conductors, "(7," the average pitch, "y," and the number of poles, "n," should be so chosen that n x y shall be somewhere nearly equal to <7, being preferably a little smaller than (7. 77 78 AEMATURE WINDINGS OF ELECTHIC MACHINES. . vn. Figure 37 which, like Figs. 34 and 35, has six poles and fifty conductors, is a singly re-entrant triple winding. (7=50; m=3. Greatest common factor of and m is 1. Therefore, by the preceding rule, the result is one singly re-entrant triple winding. The winding may be represented sym- bolically as (QQ) . C 50 The average pitch should be a little less than = = 8.33, and the for- n b ward and backward pitches must differ by (2m =6). Therefore the front end pitch is taken # = 11, and the back-end pitch y= 5. In the given position, conductors 49 and 4 are short-circuited at a nega- tive brush, and 12 and 7 at a positive brush. The circuits through the armature are, 27-32 1 oq 04. I **tf^~*JTI^^ 31-36-25-30 J SIX CIRCUIT, TRIPLE WINDING. N Fig. 38 FOUR CIRCUIT, QUADRUPLE WINDING. U11AP. Vll.] Ml LT1PLE-C1RCU1T, MULTIPLE-WOUND, MULT1POLAK DRUMS. 81 Figure 38 is a four-circuit, doubly re-entrant quadruple winding in which C w = 4, (7=44, and TO = 4. The greatest common factor of - and "m," i.e., of m 22 and 4, is 2; therefore there are two independent, singly re-entrant, double windings. The winding may be represented symbolically by. These two windings are represented on the diagram by full and dotted lines. The front-end pitch has been taken 13, and the back-end pitch 5, the difference being necessarily 2 TO = 8. Inspection will show that the two windings are, 1_14_ 9-22-17-30-25-38-33-2-41-10-5-18-13-26-21-34-29-42-37-6-1 and 3-16-11-24-19-32-27-40-35-4^43-12-7-20-15-28-23-36-31^14-39-8-3 In the given position, 9-14 and 31-36 are short-circuited at the positive brushes. The circuits through the armature are, 4^3-12- 7 41- 2-33-38 39-44 37^2- 35-4i 26-21-34-29 The extreme irregularity exhibited in the diagrams and tables of the multiple windings is due to the necessarily small numbers of conductors chosen. With the magnitudes taken in practical work, everything will be sufficiently regular. . i^-^ ~=-4 ,>" Of TH1 v^v 82 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. vn. Figure 39 is the same quadruple winding as Fig. 38, except that the pitches are taken 15 and -7 instead of 13 and 5. This was drawn to emphasize the fact that there is nothing absolute in the choice of the pitch in these multiple circuit armatures, except that in the case of the multiple windings, the numerical differences between the forward and backward pitches must be equal to 2 m, where "w" is the number of windings. As before stated, the average pitch should not differ much from , and should be somewhat less, rather than greater. Figure 38, which partakes in a small degree of the nature of the short chord windings (as compared with Fig. 39), has a very much larger percentage of the conductors subjected to counter-induction than would be the case in actual practice with large numbers of conductors. For instance, the average pitch might often be represented by some such number as 75. If it were to be a quadruple winding, the two pitches should differ by 2 m or 8. Therefore the forward pitch would be taken 79, and the backward pitch 71, so that the order of the winding would lie 1-80-9-88, etc., whereas in the case of small numbers of conductors, such as in Fig. 38, the order of the winding was 114922-17-30, etc. It will be evident that the distinction between these two cases is, that with the larger number of conductors there are many forward and backward steps before the original loop is crossed, thus : But in the case of the small number of conductors the loop is crossed almost at once, thus : - In other words, with multiple windings and small numbers of conductors, the numerical differences between the forward and backward pitches is a large percentage of the average pitch, whereas with the large numbers of conductors used in practice, it is a very small percentage of the average pitch. The fact that irregularities are much exaggerated by the necessary choice of rather small numbers of conductors should be borne in mind in the study of these diagrams, particularly those of multiple windings. If, instead of the quadruple windings consisting of two independent doubly re-entrant windings of Figs. 38 and 39, one singly re-entrant quadruple winding is desired, a number of conductors must be u N * Fig. 39 FOUR CIRCUIT, QUADRUPLE WINDING. N N Fig. 40 SIX CIRCUIT, DOUBLE WINDING. CHAP. VII.] MULTIPLE-CIRCUIT, MULTIPLE- WO UNO, MULTIPOLAR DRUMS. 85 C chosen such that and "r" (4) shall be mutually prime. Take (7=42. Then =21, and m = 4, which are mutually prime. If the forward pitch is taken y = 1'3, and the backward pitch y5, the winding will be, l_14_9_22-17^30-25--38--33-4-41-12-7-20-15-28-23-36-31-2^39-10-5-18-13-2e _21^34-29-42-37-8-3-16-ll-24-19-52-27-10-35-6-l This would be represented symbolically as (Soo). w-\ would be a singly re-entrant quadruple winding. Q If four entirely independent windings are desired, and " m " must have 4 for their greatest common ^ factor. Taking (7=40, and making the front and back pitches respectively /=13 and y=5, the wind- big would be, 1_14_ 9-22-1 7-30-25-58-33- 6-1 3-16-U-24-19-32-27-40-35- 8-3 5-18-13-26-21^34-29- 2-37-10-5 7-20-15-28-23-36-51- 4-39-12-7 This could be represented symbolically as Q O O O > IU1( 1 would be a quadruply re-entrant, quadruple winding. In Fig. 40 is shown a six-circuit, sirfgly re-entrant, double winding. (7=50, w = 6, m = 2. The Q greatest common factor of and " m " being 1, the winding is singly re-entrant, and may be represented a symbolically as . The forward pitch is y = 9, and the backward pitch is y= 5. In the given position, conductors 49-4, 7-12, and 15-20 are short-circuited. The circuits through the armature are, 8- I 6 1-10- 5/ 45-50-41-46 1 47_ 2-13-48 i 24-19-28-23 1 22-17-26-21 J 13-18- 9-14 40-55-44-39 1 38-33-42-37 1 29-34-25-30 1 31-36-27^32 1 TJIIVBESITY CHAPTER VIII. TWO-CIRCUIT, SINGLE- WOUND, DRUM ARMATURES. THE " two-circuit " windings now to be considered are distinguished by the fact that the pitch is always forward, instead of alternately forward and backward, as in the "multiple-circuit" windings, just described. The sequence of connections leads the winding from a certain bar opposite one pole piece to a bar similarly situated opposite the next pole piece, and so on, so that as many bars as pole pieces are passed through before another bar in the original field is reached. Such progression around the armature is continued until all the bars are connected in, and the winding returns on itself. Two-circuit, drum windings, like the two-circuit, gramme-ring windings, have for a given voltage the fraction - as many conductors as multiple-circuit windings, with the attendant advantages, stated for the r H\i two-circuit, gramme-ring windings. The advantages, that the circuits from brush to brush consist of conductors influenced by all the poles, are when there is but one turn in each coil the same as in the two- circuit, short-connection ring winding. When there are several turns in the coil, the advantages are siibject to the same reservations as in the two-circuit, long-connection, ring winding. The advantages, due to such arrangements of the conductors, have been confined to machines of small electrical output. In machines of large electrical output, in which there are a number of sets of brushes of the same sign (otherwise the cost of the commutator is excessive), the advantages possible from equal currents in the circuits have been over- balanced by the increased sparking due to unequal division of the current between the different sets of brushes of the same sign. An examination of the diagrams will show that in the two-circuit windings the drop in the armature, likewise the armature reaction, is independent of any manner in which the current may be subdivided among the different sets of brushes, but depends only upon the sum of the currents at all the sets of brushes of the same sign. There are, in the two-circuit windings, no features that tend to cause the current to subdivide equally between the different sets of brushes of the same sign, and, in consequence, if there is any difference in contact resistance between the different sets of brushes, or if the brushes are not set with the proper lead with respect to each other, there will be an unequal division of the current. When there are as many sets of brushes as poles, the density at each pole must be the same, otherwise the position of the different sets of brushes must be shifted with respect to each other to correspond to the differ- ent intensities, the same as in the multiple-circuit windings. In practice it has been found difficult to prevent the shifting of the current from one set of brushes to another. The possible excess of current at any one set of brushes increases with the number of sets; likewise the possibility of excessive sparking. For this reason the statement has been sometimes made that the disadvantages of the two-circuit windings increase with the number of poles. 87 88 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. vm. From the above, it may be concluded that any change of the armature with respect to the poles will in the case of two-circuit windings be accompanied by shifting of the current between the different sets of brushes; therefore to maintain a proper subdivision of the current the armature must be maintained in one position, with respect to the poles, and with exactness, since there is no counter action in the armature to prevent the unequal division of the current. In the case of multiple-circuit windings, it will be noted that the drop in any circuit, likewise the armature reaction in the field in which the current is generated, tends to prevent the excessive flow of current from the corresponding set of brushes. On account of these features, together with the con- sideration that when there are as many brushes as poles the two-circuit armatures require the same nicety of adjustment with respect to the poles as the multiple-circuit windings, the multiple-circuit windings are generally preferable, even when the additional cost is taken into consideration. Denoting the number of face conductors by " (7," the number of poles by " n" and the average pitch by u y," the formula controlling the two-circuit, single-wound, multipolar drum, is, C=ny2. It is preferable to have the pitch "y " the same at the two ends, because the two sets of end connections will then be of the same length, but the choice of the number of conductors "C"' for any particular case is less restricted (when the number of poles is greater than four) if the front and back pitches are permitted to differ by 2. Each pitch, must, moreover, be an odd number, as, in order that the winding may pass through all the conductors before returning upon itself, it must pass alternately through odd and even numbered con- ductors. Also when, as is usually the case, the bars occupy two layers, it is necessary to connect from a conductor of the upper to one of the lower layer so as to obviate interference in the positions of the spiral end connections. Where different pitches are used at the front and back ends, each being odd, the average " y " appearing in the formula will be even. In Fig. 41 is given a two-circuit, single winding for a four-pole drum. The pitch is #=!' at. both ends. = 34 or 38. Thirty-four conductors were taken. If it is necessary to have thirty-four conductors, it would be better to take the average "y" equal to eight, and then to use ^ = 9 at one end and y = l at the other. It is thus possible to shorten the end connections at the end at which the shorter pitch is used, and thus avoid using an unnecessary amount of copper. This will also make the armature resistance less, and will give more room for the end connections. Fig. 41, TWO CIRCUIT, SINGLE WINDING. Fig. 42 TWO CIRCUIT, SINGLE WINDING, CHAP, viii.] TWO-CIRCUIT, SINGLE-WOUND, DRUM ARMATURES. 91 In Fig. 42 this has been done, the front-end pitch being y = 3 as before, but the back-end pitch being y = 7. The average pitch is y = %- C'=H2 = 4x82 = 30 or 34. Thirty-four conductors have been taken. If thirty-eight conductors should be preferable to thirty-four, then the best arrangement would be to use i/ = 9 at both ends. (7=wy2 = 4x92 = 34or 38. This case has not been drawn, but it would be the proper method for thirty-eight conductors, as the only other way would be to have a front-end pitch ?/ = ll and a back-end pitch # = 9, giving an average pitch y = 10. C = n^2 = 4xlO2 = 38or 42. This last choice, i.e. pitches of and 11, would be undesirable, as the connections at the end with a pitch of 11 would be unnecessarily long. Therefore, as a general rule, the pitch should be chosen a little less than -, and when this would result in an even pitch, the pitch at one end may be made O + l) and at the other a end ({- TJFIVEESITY; 96 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAI-. vm. TWO-CIRCUIT WINDINGS WITH .CROSS-CONNECTED COMMUTATORS. Figures 45, 46, 47, and 48 are illustrative of a class of two-circuit windings that possess the distinctive feature that the number of coils may bear a relation to the number of poles not possible with the other two-circuit windings described. An examination of the dia- grams will show that the different coils of a winding may be subdivided in groups, each group having either as many coils as there are pairs of poles, or half as many, these different groups being connected in series by a cross-connected commutator. Figure 45 is an example of this class. As will be seen, it consists of an eight-pole drum armature, with fifty-six conductors connected up as a two-circuit, single winding. The underlying principle is best understood by noting one " element " of the winding, such as the eight polar conductors drawn with very heavy lines. It starts from a certain commutator segment, and after proceeding under each of the eight pole pieces, it returns to the adjacent segment. It should be further observed that, unlike the heretofore described two-circuit drum armatures, the conductors of this element are separated fnnn each other by an angular distance equal exactly to $-a = 45, instead of, as in the ordinary two-circuit drum windings, being separated by an angular distance a little greater or less than this. (7=56, w=8, y (the "pitch ") = s/ = 7. It should be particularly noted that, with this winding, a number of conductors is used which is an exact multiple of the number of poles. This, of course, is not possible with the ordinary two-circuit drum windings, which are controlled by the formula - C=ny 2. As will be seen from the diagram, this winding requires cross-connection of the com- mutator, but in many machines this disadvantage might be offset by the fact that, owing to the symmetrical arrangement of the conductors with reference to the pole pieces, the objectionable " selective commutation " of the ordinary type would probably be avoided. C 56 To return to a study of the diagram, it will be seen that there are = = 7 sets of ft O "elements" exactly the same as that above described, except that each is located at an angular distance of &%& from the preceding one. To facilitate comprehension of the diagram, these seven " elements " have been drawn in with different styles of lines, and are readily distinguishable. It is therefore obvious that, if it were not for the commutator cross-connections, the winding would consist of seven sets of eight conductors each, and that each such set has its two terminals at a pair of adjacent segments. These individual coils are put in the proper series relation between brushes by the commutator cross-connection. The resultant design is perfectly symmetrical. /\ X ,\ \ ^ \ \\ } J / \ ^ \ .S s* y \ i Fig. 45 .. . ... - Fig. 46 CHAP, via.] TWO-CIRCUIT, SINGLE-WOUND, DRUM ARMATURES. 99 Figure 46 differs only in having forty-eight conductors, with the necessary consequence that, the pitch being even (4^ = 6), it has to be different at the front and back. It is seven at the commutator end, and five at the other end. This slight irregularity makes the wording of the description of Fig. 45 not absolutely applicable to this diagram, the chief difference being that, although every pair of successive con- ductors are exactly similarly located with respect to a pair of poles as every other pair, the same cannot be said of every individual conductor of an element, the distance between them being successively greater and less than .100 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. vm. Figure 47 represents a two-circuit single-winding, identi- cal with Fig. 45, except that the connecting leads at the front end are twice as long. This is used in some " form " windings, where the two ends of a coil are brought out in front at a point half-way between the two slots holding the wires of a coil. The long front connections would never be used in bar windings, where each face conductor of the diagram represents only one conductor, for it would be a waste of copper. Short leads such as those of Fig. 45 would, for such bar windings, always be used. An " element " of the winding may be readily seen from the heavy lining in the diagram. Windings of same type as Fig. 47 could be made corre- sponding to Fig. 46, as well as to Fig. 45. In fact, the underlying principle of this winding is identical with that of the type illustrated by Figs. 45 and 46. UZTIVEP.SITY Fig. 48 CHAP, viii.] TWO-CIRCUIT, SINGLE-WOUND, DRUM ARMATURES. 103 Figure 48 represents a two-circuit single winding for an eight-pole machine, in which four conductors constitute an element. The number of conductors is here taken to be fifty-two. There are therefore 5 j 2 -=13 elements. It is a condition of this winding that the number of elements must be an odd number. From this it follows that the total number of conductors cannot be a multiple of the number of poles. It serves, therefore, for numbers of conductors with which the previously described winding (where C is a multiple of ri) could not be used. It probably, however, would not be so well balanced as in the case where C is a multiple of n. The commutator requires cross-connecting, as shown in the diagram. The cross-connections at the front end are of twice the usual length. 104 AKMATUEE WINDINGS OF ELECTRIC MACHINES. [CHAP. vm. WENSTROM TWO-CIRCUIT, WIRE-WOUND ARMATURE. Figure 49 represents a winding devised by Wenstrom to lessen the depth of the end windings of wire wound arma- tures. The particular case represented by the diagram had thirty-five lozenge-shaped slots, each containing four con- ductors. For the sake of clearness only the connections of the wires between two adjacent commutator segments are shown, and no difficulty will be found in completing the winding, by continuing on through the remaining segments. This method is, of course, only suitable for wire-wound armatures and like most such wire windings, it is difficult to repair. It is to be noted that these armatures, which have been quite extensively used, were completely ironclad, there being no slot opening. Fig. 49 Fig. 5O TWO CIRCUIT, SINGLE WINDING. CHAPTER IX. INTERPOLATED COMMUTATOR SEGMENTS. IN Fig. 50 is given a two-circuit single winding. w = 6, y = 13, C=ny2 = 6 x!32 = 76 or 80. Eighty conductors have been taken. This would naturally give forty commutator segments. Suppose speed, strength of field, and active length of conductors to be of such magnitudes as to generate one volt per conductor. OQ 19 Noting that, as shown in the figure, twelve conductors arc short-circuited, there will be - -=34 active Jt conductors in series between brushes- Therefore the total E.M.F. will be 34 volts. There would be (before -in c interpolating) ~ =5.67 segments between every two neutral points of the commutator. Therefore there I! would be =(i volts between every two adjacent segments. 5 . o 7 Suppose this to be higher than is desired. It might then be proposed to double the number of segments by the method of cross-connecting shown in Fig. 50. This will increase the number of segments to eighty. Following the circuit through from the negative to the positive brush, the conductors have been labeled 1 volt, - volts, 3 volts, etc., adding one volt for each conductor. Taking the potential of the negative brush as zero, this gives the potential of each conductor. Following down from each conductor to its attached segments, they have been numbered in a corresponding manner; thus the four segments connected to the two bars at 20 volts potential have been marked 20, etc. An examination of the figure will now make it apparent that proceeding from the neutral points (at zero potential) the voltage increases alternately by two and by four volts per segment, the average being three volts per segment. Therefore, although the average volts per segment have been decreased to one-half of what they were for forty segments, half of the segments have between them only one-third, and the remainder, two-thirds, of the original volts per segment Therefore, for a six-pole armature, the volts per segment cannot be halved by interpolation. And in order to reduce them to one-third throughout, it is not sufficient to cross- connect as shown in the figure, but it is necessary to triple the natural number of segments and cross-connect every three corresponding segments. This would be far from simple. 107 U3UVZKSITY 108 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAI-. ix. A fairly large number of conductors was taken in Fig. 50, in order to give a thorough explanation of the principles involved in interpolating segments. The further study of the subject can, however, be more satis- factorily carried on with small numbers of conductors. In Fig. 51 is shown another two-circuit, single winding, with w = 6, # = 7, C= ny 2 = 6 x 7 2 = 40 or 44. Forty -four conductors are taken. Without interpolation, twenty-two segments would be used. Here 3x22 = 66 seg- ments are used. This is arrived at by connecting together every three corresponding commutator segments. If, as in the preceding figure, only two segments had been cross-con- nected, the connections shown by the full lines would have sufficed. Crows- connecting every three corresponding segments involved the addition of the dotted line connections. This, as the diagram shows, doubles the total number of commutator cross-connections, and is therefore mechanically objectionable. But the volts between bars are now everywhere equal instead of being alternately F"and 2F"as in Fig. 50. This may be seen by an examination of the numbers on the conductors and segments, which have been arranged according to the conventional method described. Thus, proceeding from the segments under the negative brush, the voltage would increase regularly by two volts per segment up to the positive brush, so that whereas, in the former cases, the order was 2, 4, 8, 10, 14, 16, etc., it is now 2, 4, 6, 8, 10, 12, 14, 16, etc. TWO CIRCUIT, SINGLE WINDING. Fig. 52 TWO CIRCUIT, SINGLE WINDING. < 'HAP. ix.] INTERPOLATED COMMUTATOR SEGMENTS. Ill In Fig. 52 is given the diagram of a two-circuit, single- wound, eight-pole armature with forty-two conductors. C=n//2; 8x5 + 2 = 42. It is given to show that, with even numbers of pairs of poles, the number of commutator bars may be doubled by interpolation, and that the result will be to halve the volts between every two segments in- stead of producing the unsymmetrical result observed in the case of an odd number of pairs of poles. An examination of Fig. 52 will show that commutator segments 180 apart are cross-connected. The scheme of studying the relative potential of conductors and commu- tator segments is the same as that used in the case of the two preceding figures, and can be followed through without trouble. Some confusion may result from the fact that owing to the small number of conductors taken, the length of the two circuits through the armature are quite unequal, one path consisting of twelve conductors, and the other of fourteen. As the positive neutral points where these two paths meet must be at the same potential, all the segments at these positions have been indicated as being at a potential of fourteen volts, so that the sequence of figures giving the potentials of the segments is, in four of the eight cases, 0, 4, 8, 12, 14 ; increasing regularly by four volts until the very end, where the increase is but two volts. In the other four cases, for the same reason, the sequence is 0, 2, 6, 10, 14, showing the irregularity at the negative neutral points. .With the large number of conductors used in practice no misunderstanding would result. 112 AKMATURE WINDINGS OF ELECTKIC MACHINES. [CHAF. ix. With an even number of pairs of poles it is not necessary to be confined to using only twice the natural number of commutator segments. Thus in Fig. 53 is given the same eight-pole winding as in Fig. 52, with the exception that eighty-four segments are used instead of forty-two. The natural number ol segments would be twenty-one. As the conventions used in the previous descriptions are followed in mapping out the relative potentials of the various parts, no further explanations will be necessary. Fig. 53 T.WO CIRCUIT, SINGLE WINDING. CHAPTER X. TWO-CIRCUIT, MULTIPLE-WOUND, DRUM ARMATURES. THE next class is that of the two-circuit, multiple-wound, drum armature. The general formula is : C=ny -2m, where G = number of face conductors, n = number of poles, y = average pitch, m number of windings. The "m" windings will consist of a number of independently re-entrant windings, equal to the greatest common factor of "y" and "MI." Therefore, where it is desired that the "TO" windings shall combine to form one re-entrant system, it will be necessary that the greatest common factor of "y" and "TO" be made equal to 1. Also, when "#" is an even integer, the pitch must be taken alternately as (y 1) and In Fig. 54 is reproduced a winding described by E. Arnold (" Die Ankerwicklungen der Gleichstrom- Dynamomaschinen," p. 70, Fig. 80), and by Dr. Kittler ("Handbuch der Elektrotechnik," 2d ed., p. .">:;.">, Fig. 403, 5). It is classified by them as a four-circuit, single winding. They show four narrow brushe,s, and point out that the winding has the peculiarities that, in connecting up, the pitch is always taken forward, and that the short-circuiting of a coil occurs between opposite brushes of like polarity, instead of entirely at one brush, as is usually the case. They give no further instances of the application of this winding, except that Herr Arnold proposes for it the formula: Q and adds that if -^ and " y " have a common factor, a singly re-entrant winding is not obtained, several inde- pendently re-entrant windings being the result. lie follows this statement with a diagram having (7=28, n = 4, and y = 6. [28 = 4(6 + 1)], which gives two independently re-entrant windings, and shows, as before, four points of commutation. Returning to a consideration of Fig. 54, it may be seen that at the given position, conductors 5-12 and 21-28 are short circuited at the negative brushes, and 13-20 and 29-4 at the positive. The circuits through the armature are, 3-10-17-24^31- (r 30-23-16- 9- 2-27 14_ 7-32-25-18-11 19-26- 1- 8-15-22 114 \32 \30 (29 /2 ' 28 w, (27 N 26 24 10 12 N 20/ 13) 17 20, Fig. 55 TWO CIRCUIT, DOUBLE WINDING. CHAP, x.j TWO-CIRCUIT, MULTIPLE-WOUND, DRUM ARMATURES. 117 Now in Fig. 55 will be found the very same winding as in Fig. 54, with the excep- tion that two wide brushes are shown instead of four narrow ones. Short-circuiting of a coil now necessarily occurs at one brush, and a study of the winding shows that it is one of the singly re-entrant multiple-wound type, this particular one being a two-circuit, singly re-entrant, double winding. At the position shown, conductors 7-14-21-28 are short-circuited at the negative brush, and 15-22-29-4 at the positive. The circuits through the armature are : ( 3-10-17-24-31- G 30-23-16- 9- 2-27-20-13 32-25-18-11 5-12-19-26- 1- 8- It will be seen that, owing to the very small number of conductors, the winding is extremely irregular, but it will not be difficult to perceive that the nature of the course taken by the current through the armature remains essentially unaltered from that of Fig. 54, consisting, as there, of four paths with an average of six conductors in series per path. The current, however, enters the armature from one wide brush, which always /360\ spans more than one segment, and departs from a similar wide brush ( ) removed. \ n j But in the former case (Fig. 54), it entered two of the paths by one narrow negative r360~l brush, and the other two by another, situated distant. n It appears, therefore, conclusive that Fig. 54 is in all essential respects identical with a two-circuit, singly re-entrant, double winding, but this was probably not perceived by the above-mentioned authors: otherwise they would undoubtedly have extended the prin- ciple to higher orders of multiples and other numbers of poles. An eight-pole, two-circuit, singly re-entrant, triple winding (which would, of course, follow six paths through the conductors of the armature) would probably not have been considered possible, their con- ception of the winding apparently being that it was a multiple winding with as many paths through the conductors of the armature as the machine had poles. The formula and rules enunciated in this investigation follow naturally from the true conception of this winding, whereas the formula and condition stated by Herr Arnold may be seen, by a few attempts to apply it, to be entirely inadequate for the purpose of obtaining the necessary data for constructing such windings. OF 2TI7BRSIT 118 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. x. The two preceding figures (54 and 55) were given for the purpose of showing in how far the two-circuit, multiple windings have been understood in the past. The numbers of conductors were, however, entirely inadequate to fully illustrate the nature of the windings. As this class promises to have a somewhat wide application, it is proposed to give a good many examples, selecting for the purpose various values of "(7," "," "y" and "/," and briefly analyzing each case on the basis of the rules given on page 114. The symbolical representations heretofore used will be continued, thus : o will represent will represent will represent will represent will represent will represent will represent O O O O will represent 00 ooo a singly re-entrant single winding, a singly re-entrant double winding, a doubly re-entrant double winding, a singly re-entrant triple winding, a triply re-entrant triple winding, a singly re-entrant quadruple winding, a doubly re-entrant quadruple winding, a quadruply re-entrant quadruple winding. According to the above nomenclature, Fig. 40 would be a six-circuit, singly re-entrant, double winding [] J Fig- 37 would be a six-circuit, singly re-entrant, triple winding [ (QQ) ] ; and Fig. 38 a four-circuit, doubly re-entrant, quadruple winding []- The use of the middle expression, "singly, doubly, etc., re-entrant," is unavoidable for absolute definiteness, but it will in most cases be sufficiently definite to speak, for example, of a " six -circuit, triple winding" and a "two-circuit, quadruple winding," where absolute exact- ness would require them to be spoken of respectively as a " six-circuit, singly re-entrant, triple winding " and a "two-circuit, doubly re-entrant, quadruple winding." Figure 56 is a four-pole, two-circuit, singly re-entrant, triple winding. It is represented symbolically thus: (So). w = 4, and wi = 3. In order that it should be singly re-entrant, it was necessary for the greatest common factor of u m" and "y" to be 1. Therefore "/" was taken equal to 16. C=ny 2 m = 4x!6 2x3 = 58 or 70. Seventy conductors have been taken, and "y" is alternately 15 and 17, it being, of course, impossible to use 16. In the position shown, the conductors without arrowheads are short-circuited, and the circuits through the armature are : 67-50-35-18- 3-56-41-24 } G5-48-33-16- 1-54^39-22 63-46-31-14-69-52-37-20- 5^58-43-26 10-27^12-59- 4-21-36-53-68-15 8-25-40-57- 2-19-34-51-66-13 6-23-38-55-70-17-32^9-64-11 Fig. 56 TWO CIRCUIT, TRIPLE WINDIN IVERSITY Fig. 57 TWO CIRCUIT, TRIPLE WINDING. CHAP. X.] TWO-ClilCUIT, MULTIPLE-WOUND, DKUM AKMATUKES. 121 Figure 57 is a four-pole, two-circuit, triply re-entrant, triple winding. It would be represented symbolically as O O O- n = 4, and w = 3. In order that it should be triply re-entrant, it was necessary for the greatest common factor of "ra" and "#" to be 3. Therefore "y" was taken equal to 15. 3 = 54or 66. Sixty-six conductors have been taken. The three inde- pendently re-entrant windings have been shown by three different styles of lines. In the position shown, the conductors without arrow- heads are short-circuited, and the circuits through the armature are : 63-48-33-18- 3-54-39-24 61-46-31-16- 1-52-37-22 59_44_29-14-65-50-35-20- 5-56-41-26 10-25-40^55- 4-19-34-49-64-13- 8-23-38-53- 2-17-32-47-62-11- 6-21-36-51-66-15-30^15-60- 9- It is interesting to compare this winding and table with the preceding, and to notice how very slightly they differ. 122 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. x. Figure 58 is a six-pole, two-circuit, singly re-entrant, double winding. It would be represented symbolically as . n = 6, and m = 2. In order that it should be singly re-entrant, it was neces- sary for the greatest common factor of " m " and " y " to be 1. Therefore " y " was taken equal to 9. tf=w#2m=6x92x2=50 or 58. Fifty-eight conductors have been taken. In the position shown, the circuits through- the armature are : r 57-48-39-30-21-12- 3-52-13-34-25-16 55-46-37-28-19-10- 1-50-41-32-23-14 ->- 6-15-24-33-42-51- 2-11-20-29-38-47-56-7 . 4-13-22^31-40-49-58- 9 Fig. 58 TWO CIRCUIT, DOUBLE WINDING. Fig. 59 TWO CIRCUIT, DOUBLE WINDING. CHAP, x.j T \VO-C11UJUIT, MULTIPLE-WOUND, DKUM AKMATUKES. 125 Figure 59 is a six-pole, two-circuit, doubly re-entrant, double winding, the symbolical representation being Q O- n = G, and m = 2. In order that it should be doubly re- entrant, it was necessary for the greatest common factor of "m" and "y" to be 2. Therefore "y" was taken equal to 8. G-ny 2 m = \i x 8 2 x 2 = 44 or 52. Fifty -two conductors have been taken, and " y " is alter- nately 7 and 9, it being, of course, impossible to use / = 8. In the position shown, the conductors without arrow- heads are short-circuited, and the circuits through the armature are : I 51-44-35-28-19-12 49-42-33-26-17-10- 1^6-37-30-21-14 6-13-22-29-38-15- 2- 9-18-25-34-41-50- 5 I 4-11-20-27-36-13-52- 7 As frequently remarked in connection with other dia- grams having small numbers of conductors, the very unequal lengths of the different paths through the armature is entirely caused by this choice of a small number of con- ductors, and would, to a large extent, disappear with all practicable numbers of conductors. The two independently re-entrant windings are drawn respectively with full and with dotted lines. rawO I7BRSIT7] 126 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. x. Figure 60 is a six -pole, two-circuit, triply re-entrant, triple winding. It would be represented symbolically as Q O O- w = 6, and m=3. In order that it should be triply re-entrant, it was necessary for the greatest common factor of " m " and " y " to be 3. Therefore " y " was taken equal to 9. C'=ny2 = 6x92x3=48or 60. Sixty conductors have been taken. The three independently re-entrant windings have been represented by three different styles of lines. In the position shown, the circuits through the armature are : 59-50^11-32-23-14- 57-18-39-30-21-12- 55-46-37-28-19-10- 1-52-43-34-25-16 6-15-24-33-42-51-60- 9- 4-13-22-31-40-49-58- 7- 2-11-20-29-38-47-56- 5- Fig. 60 TWO CIRCUIT, TRIPLE WINDING. N Fig. 61 TWO CIRCUIT, TRIPLE WINDING. i IIA1-. X.] TWO-CIRCUIT, MULTIPLE-WOUND, DRUM ARMATURES. Figure 61 is a six-pole, two-circuit, singly re-entrant, triple winding It may be symbolically expressed as (QQ) w = 6, and TO =3. In order that it should be singly re- entrant, it was necessary for the greatest common factor of "wt" and "y" to be 1. Therefore "y" was taken equal to 8. = 6x82x3=42or 54. Fifty-four conductors have been taken, "y" is alter- nately 7 and 9, as it would, of course, be impossible to let y-8. In the position shown, the circuits through the armature are : 53-46-37-30-21-14 51_44_35_28-19-12 49-42-33-26-17-10- 1-48-39-32-23-16 8-15-24-31-10-47- 2-9- 6-13-22-29-38-45^54-7- 4_1 1-20-27-36-43-52-5- -I- 130 AKMATURE WINDINGS OF ELECTRIC MACHINES. [CIIAI-. x. Figure 62 is a six-pole, two circuit, triply re-entrant, triple winding. It would be represented symbolically as OOO- w = 6, m = 3. In order that it should be triply re- entrant, it was necessary for the greatest common factor of to be 3. Therefore "y" was taken equal "y" and to 12. m = 66 or 78. Seventy -eight conductors have been taken, and "y" is alternately 11 and 13, as it would not be possible to let The three independently re entrant windings have been represented by three different styles of lines. In the position shown, the short-circuited conductors are those without arrow-heads. The circuits through the arma- ture are : 75-64-51-40-27-16- 3-70-57^16-33-22- 73-62-49-38-25-14- 1-68-55-44-31-20- 71-60-47-36-23-12-77-66-53-42-29-18- 10-21-34^5-58-69- 4-15-28-39-52-63-76-9 8-19-32-43-56-67- 2-13-26-37-50-61-74-7 6-17-30-41-54-65-78-11 Fig. 62 TWO CIRCUIT, TRIPLE WINDING. Fig. 63 TWO CIRCUIT, QUADRUPLE WINDING CHAP. X.j TWO-CIRCUIT, MULTIPLE-WOUND, DRUM ARMATURES. 133 Figure 63 is a six-pole, two-circuit, singly re-entrant, quadruple winding. Symbolically = (QQQ). n = 6, and m = 4. In order that it should be singly re-entrant, it was necessary for the greatest common factor of "y" and "m" to be 1. Therefore "y" was taken equal to 7. C=ny2 ra = 6x72x4 = 34. or 50. Fifty conductors have been taken. In the position shown, the circuits through the armature are : 1_44_37_30- 49^42-35-28- 47-40^33-26- 45-38-31-24-17-10- 3-4G-39-32 8-15-22-29-36-43-^50- 7-14-21 6-13-20-27-34-41-48- 5-12-19 4-11-18-25 2- 9-16-23 134 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. x. Figure 64 is a six-pole, two-circuit, quadruply re-entrant, quadruple winding. It would be represented symbolically as O O O O- w = 6, and ra = 4. In order that it should be quadruply re entrant, it was necessary for the greatest common factor of " y " and " m " to be 4. Therefore " y " was taken equal to 8. 4 = 40or 56. Fifty -six conductors have been taken. " y '' is alter- nately 7 and 9, as it is obviously impossible to let ^ = 8. In the position shown, the circuits through the armature are : 55-48-39-32- 53-46-37-30- 3-52-13-36 49^42-33-26-17-10- 1-50-11-34 8-16-24-31-40^7-56- 7-16-23 6-13-22-29^38-45-54- 5-14-21 4-11-20-27 2- 9-18-25 Fig. 64. TWO CIRCUIT QUADRUPLE WINDING. JJU7BESITY] Fig. 65 TWO CIRCUIT, QUADRUPLE WINDING. CHAP. X.] TWO-CIRCUIT, MULTIPLE-WOUND, DRUM ARMATURES. 137 Figure 65 is a six-pole, two-circuit, doubly re-entrant, quadruple winding. It would be represented symbolically a.s. ?i = 6, and m = -i. In order that it should be doubly re-entrant, it was necessary for the greatest common factor of "y" and "m" to be 2. Therefore "/" was taken equal to 10. <7=w/2m=6xlO2x4 = 52 or 68. Sixty-eight conductors have been chosen, "*/" is alter- nately 9 and 11, because its average value, being even, could not be used. The two independently re-entrant windings have been represented respectively by light and by heavy lines. In the position shown, the circuits through the armature are : ( 67-58-47-38 63-54-43-34-23-14- 3-62-51-42 65-56-45-36-25-16- 5-64-53-44 61-52-41^32-21-12- 1-60^9-40 10-19-30-39-50^59- 2-11-22-31 6-15-26-35-46-55-66- 7-18-27 8-17-28-37-48-57-68- 9-20-29 4-13-24-33 138 AKMATUEE WINDINGS OF ELECTRICAL MACHINES. [CHAP. x. Figure 66 is a six-pole, two-circuit, quadruply re-entrant, quadruple winding [QOOO]- = 6, and m = 4. In order that it should be quadruply re-entrant, it was neces- sary that the greatest common factor of "y" and ''m" should be 4. Therefore "y" was taken equal to 12. <7=wy2w = 6xl22x4 = 64 or 80. Eighty conductors have been taken. " y " is alternately 11 and 13, its average value being even. The four independently re-entrant windings have been represented by four varieties of lines. In the position shown, the circuits through the armature are : 77-66-63-42-29-18- 5-74-61-50 75-64-51-40-27-16- 3-72-59^48 73-62-49-38-25-14- 1-70-57^16 71-60^7-36-23-12-79-68-55^4 10-21-34-45-^58-69- 2-13-26-37 8-19-32-43-^56-67-SO-ll-24-35 6-17^30-41-54-65-78- 9-22-33 4-15-28-39-52-63-76- 7-20^31 N N Fig. 66 TWO CIRCUIT, QUADRUPLE WINDING. Fig. 67 TWO CFRCUIT, QUADRUPLE W1NDFNG. CHAP. X.J TWO-CIRCUIT, MULTIPLE-WOUND, DRUM ARMATURES. 141 Figure 67 is a six -pole, two-circuit, quadruply re-entrant, quadruple winding. It would be represented symbolically as O O O O- w = 6, and m=4. In order that it should be quadruply re-entrant, it was necessary that the greatest common factor of "#" and "m" should be 4. Therefore " y " was taken equal to 16. C f =wy2?w = 6xl62x4 = 88 or 104. One hundred and four conductors have been taken, "y" is 17 at the front end, and 15 at the back end, thus aver- aging 16. The four independently re-entrant windings have been represented by four different styles of lines. In the position shown, the circuits through the armature are : 49-34-17- 2-89-74-57^12-25- 10- 47-32-15-104-87-72-55-40-23- 8- 45-30-13-102-85-70-53-38-21- 6- 43-28-1 1-100-83-68-51-36-19- 4-91-76-59-44-27-12 64-79-96- 7-24-39-56-71-88-103-16-31^8-63-80-95 62-77-94- 5-22-37-54-69-86-101 60-75-92- 3-20-35-52-67-84- 99 58-73-90- 1-18-33-50-65-82- 97 142 AEMATUEE WINDINGS OF ELECTEIC MACHINES. [c'HAl'. X. Figure 68 differs from Fig. 67 in the use of the negative instead of the positive sign in the formula. It is given to emphasize the fact that this has no influence on the type of winding. It requires, however, a greater length of copper for a given number of conductors. Like Fig. 67, it is a six-pole, two-circuit, quadruply re-entrant, quadruple wind- ing. It would be represented symbolically as O O O O- w = 6, and m = 4. In order that it should be quadruply re- entrant, it was necessary for the greatest common factor of " y " and " m " to be 4. Therefore " y " was taken equal to 16. C f =m/2TO=6xl62x4=:88or 104. Eighty-eight conductors have been taken, "y" is 17 at the front, and 15 at the back end. The four independently re-entrant windings have been represented by different kinds of lines. In the position shown, the circuits through the armature are:- I 58-73- 2-17-34-49-66-81 56_71_88-15-32-47-64-79 54_G9-S6-13-30-i5-62-77 52-67-84-11-28-43-60-75- 4-19-36-61-68-83 33-18- 1-74-57-12-25-10- 35-20- 3-76-^9-44-27-12- 37_22- 5-78-61-46-29-14- 39_24- 7-80-63^8-31-16-87-72-55-40-23- 8 N Fig. 68 TWO CIRCUIT, QUADRUPLE WINDING. N N N Fig. 69 TWO CIRCUIT, SEXTUPLE WINDING. CHAP. X.] TWO-CIRCUIT, MULTIPLE-WOUND, DRUM ARMATURES. 145 The next four diagrams (Figs. 69, 70, 71, 72) form a group of sextuple windings. It is thought that an examination of this group -will bring out very clearly the method of applying and the interpretation of the rules concerning two-circuit, multiple windings. The following table will be of assistance in studying them : Figure. n V m a G.C.F. of in and y. Name of Winding. Symbol. 69 6 9 6 66 3 Two-circuit, triply re-entrant, sextuple winding. 70 6 10 6 72 2 Two-circuit, doubly re-entrant, sextuple winding. (55) 71 6 11 6 78 1 Two-circuit, singly re-entrant, sextuple winding. CPJOQQP) 72 6 12 6 84 6 Two-circuit, sextuply re-entrant, sextuple winding. OOOOOO Figure 69 is a six-pole, two-circuit, triply re-entrant, sextuple winding. It would be symbolically repre- sented as . M = (>, and ?n = 6. In order that it should be triply re-entrant, it was necessary that the greatest common factor of u m " and " y " should be 3. Therefore " y " was taken equal to 9. 6=42 or 66. Sixty-six conductors were taken. The three independently re-entrant windings have been represented respectively by light, heavy, and broken lines. In the position shown, the circuits through the armature are : 59-50-41-32-23-14- 5-62-53-44 61-52-43-34 63-^54-45-36- -A 65-56-47-38 1-58-49-40 3-60^51^12 66- 9-18-27 2-11-20-29 4-13-22-31- 6-15-24-33 8-17-26-35 10-19-28-^37-46-^55-64- 7-16-25 146 ARMATURE WINDINGS OF ELECTRIC MACHINES [CHAP. x. Figure 70 is a six-pole, two-circuit, doubly re-entrant, sextuple winding. It would be represented symbolically as (55) (55) w = 6, and m = 6. In order that it should be doubly re-entrant, it was necessary that the greatest com- mon factor of "m" and "y" should be 2. Therefore "y" was taken equal to 10. C=ny 2 77i = 2x6 = 48 or 72. Seventy-two conductors have been taken. The two inde- pendently re-entrant windings have been represented respec- tively by full and dotted lines. In the given position, the circuits through the armature are: 63-54-43-34-23-14- 3-66-55-46 1 65-56-45-36-25-16- 5-68-57-48 67-58-47-38 69-60-49-10 71-62-51^2 1-64-53-44 --- 2-11-22-31 4-13-24-33 6-15-26-35 8-17-28-37 10-19-30-39 12-21-32-41-52-61-72- 9-20-29 N 67 (66 (64 -.63 (62 59 .4- 57 17 \ 55 . A54_. X 19 20\ 21 .5Q, -4-- -4- -r 22\ 23 24 25 |48> 261 47x ,x 27 N L46/ x 39/ 38j 37 33\ 32] X N Fig. 70 TWO CIRCUIT, SEXTUPLE WINDING. N N Fig. 71 TWO CIRCUIT. SEXTUPLE WINDING. N (JHA1-. X.] TWO-CIRCUIT, MULTIPLE-WOUND, DKUM AKMATUKES. 149 Figure 71 is a six-pole, two- circuit, singly re-entrant, sextuple winding. It would be represented symbolically as (QQQQQ). n = (J, and ?n = G. In order that it should be singly re-entrant, it was necessary that the greatest common factor of "w" and "y" should be 1. Therefore "y" was taken equal to 11. C=ny 2 m = Q x 11 2 x = 54 or 78. Seventy-eight conductors have been chosen. In the given position, the circuits through the armature are : 69-58-47-30-25-14- 3-70-59-48 71-60-49-38-27-10- 5-72-61-50 75-64-53-42- 77-66-55-44- 1-68-57-40- 12-23-34-45-50-()7-78-ll-22-33 10-21-32-43-54-65-76- 9-20-31 8-19-30-41 6-17-28-39 2-13-24-;j5 150 AEMATUKE WINDINGS OF ELECTRIC MACHINES. [CHAP. x. Figure 72 is a six-pole, two-circuit, sextuply re-entrant, sextuple winding. It would be represented symbolically as OOOOOO- n = 6, and m = 6. In order that it should be sextuply re-entrant, it was necessary that the greatest common factor of "wi" and "#" should be 6. Therefore "y" was taken equal to 12. C=ny 2m = 6 x 12 2 x 6 = 60 or 84. Eighty-four conductors have been taken. The six independently re-entrant windings are repre- sented respectively by different styles of lines. "#," of course, is taken alternately 11 and 13. In the given position, the circuits through the armature are : 73-62-49-38-25-14- 1-74-61-50 75-64-51-10-27-16- 3-76-63-52 77-66-53-42-29-18- 5-78-65-54 79-62^55-44 81-70-57-46- 83-72-59^8- 12-23-36-47-60-71-84-11-24-35 10_21^34-45-58-69-2- 9-22-33 8-19-32-43-56-67-80- 7-20-31 6-17-30-41 4_15_28-39 2-13-26-37 *v ^ rX/ ^ /+- '/ ?/ / x 49/ '\ 36) 47 y 46/ 0\ 39\- \/ N Fig.72 TWO CIRCUIT, SEXTUPLE WINDING. Fig. 73 TWO CIRCUIT, DOUBLE WINDING. CHAP. X.] TWO-CIRCUIT, MULTIPLE-WOUND, DRUM ARMATURES. 153 Figure 73 is an eight-pole, two-circuit, doubly re-entrant, double winding. It would be represented symbolically as O O- w = 8, and m = 2. In order that it should be doubly re-entrant, it was necessary that the greatest com- mon factor of "wi" and "y" should be 2. Therefore "y" was taken equal to 10. G=ny 2 m=8xlO 2x2 = 76 or 84. Eighty-four conductors have been taken. The two independently re-entrant windings are represented respectively by full and dotted lines. "/" is taken alternately 11 and 9, the average pitch being 10. In the given position, the circuits through the armature are: 8-17-28-37-48^57-68-77- 4-13-24-33-44-53-64-73-84- 9-20-29-40-49-60-69 ] 6-15-26-35-46-55-66-75- 2-11-22^31-42-51-62-71 81-72-61-52^41-32-21-12- 1-76-65-56-45-36-25-16- 5-80- 79-70-59^50-39^30-19-10-83-74-63-54-43-34-23-14- 3-78- 154 ARMATUKE WINDINGS OF ELECTRIC MACHINES. [CHAI-. x. Figure 74 is an eight-pole, two-circuit, singly re-entrant, double winding. It would be represented symbolically as . n = 3, and m = 2. In order that it should be singly re-entrant, it was necessary that the greatest common factor of "y " and " m " should be 1. Therefore "y " was taken equal to 11. <7=My2ra = 8xll2x2 = 84 or 92. Eighty -four conductors have been taken just as in the preceding figure. In the given position, the circuits through the armature are : 8-19-30-41-52-63-74- 1-12-23-34^45-56-67 6-17-28-39-50-61-72-83-10-21-32-43-54-65-76- 3-14-25-36-47-58-69- 81-70-59-48^37-26-15- 4-77-66-55-44-33-22-11-84-73-62-51^40-29-18- 7-80 79-68^57-46-35-24-13- 2-75-64-53-42-31-20- 9-82 Fig. 74 TWO CIRCUIT, DOUBLE WINDING. IVSESi Fig. 75 TWO CIRCUIT, DOUBLE WINDING. CHAP, x.] TWO-CIRCUIT, MULTIPLE-WOUND, DKUM AEMATURES. 157 Figure 74 was obtained by using the negative sign in the formula C=ny 2m. This is, as has been pointed out, rather wasteful of copper, and was only done to demonstrate the fact that in certain cases with a given number of conductors, either a singly or a doubly re-entrant, double winding may be used. In Fig. 75, the positive sign was used. It will, however, not be necessary to analyze it, it not being materially dif- ferent from Fig. 74. Numerous interesting deductions concerning two-circuit, multiple-wound, drum armatures may be made from the data contained in the tables in Chapter XVIII. CHAPTER XI. THE SAYERS WINDING. THE armature coils of dynamos have, in addition to their function of establishing the electromotive force required external to the armature, the function of setting up in the arc of commutation an electromotive force to reverse the current in them as they successively pass the collecting brushes (by arc of commutation is meant the arc in which the current in the armature coils is reversed, the extent of this arc being determined by tin- length of the arc of contact of the collecting brushes). In the ordinary methods of armature winding the electromotive force for reversing the current in the coils is obtained by giving the collecting brushes an angular lead, the amount of which depends upon the distribution of the magnetic flux in the air gap, the coefficient of self-induction of the armature coils when in the arc of commutation, and the rate of change of the current in the coils, while the current is being reversed. In generators this angular lead is in such direction that the magnetomotive force of the armature is opposed to the magnetomotive force of the field magnets to an extent proportional to the angle of lead, in consequence of which the reversing field becomes of diminished intensity for an increase of current in the armature, when it needs to be increased. Mr. Sayers, of Glasgow, has patented a winding in which the commutation of the current in the main armature coils is effected by an additional set of coils which may be termed commutating coils. These coils are applicable to any form of armature winding suitable for commutating machines. One of these coils is connected between each commutator bar and the connections joining the main armature coils in series with each other. These commutating coils are located on the periphery of the armature in such a position with respect to the main coils that the magnetomotive force of the main coils tends with increasing current to increase the flux through them, and further so that the magnetomotive force of the armature acts with the magnetomotive force of the field magnets instead of against it as in ordinary dynamos. It is possible, there- fore, through a certain range of output to sparklessly operate a generator at constant voltage without changing the lead of the brushes or the excitation of the field magnets. It may be noted that when one of the main coils is short-circuited by the collecting brushes it is through two of these commutating coils, and the electro- motive force from these coils effective for reversing the current in the main coil is the excess of the electro- motive force generated in the leading coil over that in the following coil. The position, then, of the reversing Held, if effective, is fixed as to angular extent between very narrow limits. It does not appear to the writers that the reversing field can be so localized for great changes of current in the armature as one might infer from rending the discussion of Mr. Sayers' paper at the Institution of Electrical Engineers. (See Vol. XXII., pages 377-441, Journal Ins. Elect. Engrs., London). Within certain limits, however, it appears that the magnetomotive force of the armature may be utilized in creating proper strength of reversing field. This method, as applied to a bi-polar drum winding, is illustrated in Fig. 76. It will be seen to consist of a regular drum winding, with the difference that the connections from the winding to the commutator segments, 158 CHAP. XI.] THE SAYERS WINDING. 159 instead of consisting of short leads, consist of auxiliary force conductors which pass from the winding, back- ward, a short distance against the direction of rotation, and then parallel to the regular face conductors to the back of the armature. The conductor then passes forward in the direction of rotation, and again crossing the armature, is carried to the commutator segment. In the diagram, the current in the coil A? has just been reversed. The coil A 1 is, by the two adjacent commutator segments under the brush, short-circuited while its main conductors are still moving through intense fields, tending to maintain the current in its original direction. But this short circuit contains, in series with the main coil, the two connections to the commutator segments, both of which are so linked with the magnetic flux from the pole piece, that electromotive forces are induced. Of the electromotive forces induced in the two commutator loops, that in the loop drawn in the figure is added to that of the short-cir- cuited main coil, but this loop is farther out of the magnetic field than the remaining loop (not drawn) of the short-circuited section. This latter_ loop, leading from the segment next adjacent on the left of that shown at Fig. 76. (7, being well under the pole pieces, has induced in it a strong electromotive force, which opposes that in the rest of the short-circuited section, and enables a current to be generated in the direction of that in the half of the armature circuit of which it is soon to become a part. In such a drum winding, Mr. Sayers refers to these commutator connections as " reverser bars." As they carry the current only during the short time that their corresponding sections are passjng under the brushes, they may be of much smaller cross-section than the main conductors. It will be seen from the above description that the winding is particularly adapted for use with ironclad armatures with very small air gaps, for the effectiveness of the arrangement is largely dependent upon the differential inductive action upon two successive reverser bars, and the more abrupt the demarcation of the magnetic flux, the greater will be this differential effect. It should be clearly understood that this winding is equally applicable to rings, discs, and other types of armature. PART II. WINDINGS FOR ALTERNATING-CURRENT DYNAMOS AND MOTORS. CHAPTER XII. ALTERNATING-CURRENT WINDINGS. IN general, any of the continuous-current armature windings may be employed for alternating-current work, but the special considerations leading to the use of alternating currents generally make it necessary to abandon the styles of winding best suited to continuous-current work, and to use windings specially adapted to the conditions of alternating-current practice. Attention should be called to the fact that all the re-entrant (or closed circuit) continuous-current wind- ings must necessarily be two-circuit or multiple-circuit windings, while alternating-current armatures may, and almost always do from practical considerations, have one-circuit windings, i.e. one circuit per phase. From this it follows that any continuous-current winding may be used for alternating-current work, but an alter- nating-current' winding cannot generally be used for continuous-current work. In other words, the windings of alternating-current armatures are essentially non-re-entrant (or open circuit) windings, with the exception of the ring-connected polyphase windings, which are re-entrant (or closed circuit) windings. These latter are, therefore, the only windings which are applicable to alternating-continuous current, commutating machines. Usually, high voltages are desired, and in such cases windings are generally adopted in which heavily insulated coils are imbedded in slots in the armature surface. Often, for single-phase alternators, one slot or coil per pole piece is used, as this permits of the most effective disposition of the armature conductors as regards generation of electromotive force. If more slots or coils are used, or, in the case of face windings, if the conductors are more evenly distributed over the face of the armature, the electromotive forces generated in the various conductors are in different phases, and the total electromotive force is less than the algebraic sum of the effective electromotive forces induced in each conductor. But, on the other hand, the subdivision of the conductors in several slots or angular positions per pole, or, in the case of face windings, their more uniform distribution over the peripheral surface, decreases the self-induction of the windings with its attendant disad- vantages. It also utilizes more completely the available space and tends to bring about a better distribution of the necessary heating of core and conductors. Therefore, in cases where the voltage and the corresponding necessary insulation "permit, the conductors are sometimes spread out to a greater or less extent from the elementary groups necessary in cases where very high potentials are used. Windings in which such a subdivision is adopted, will be referred to as having a multi-coil construction, as distinguished from the form in which the conductors are assembled in one group per pole piece, which latter will be called uni-coil windings. The terms uni- and multi-slot have been applied to alternating-current ironclad armatures, but the modified nomenclature described in the preceding paragraph will be preferable, in that it does not distinguish between armatures where the groups are arranged on the periphery, and those in which the groups are imbedded in slots. A little consideration will show the advisability of this nomenclature, as it will often permit one description to suffice for a winding which may be used either for ironclad or smooth-core construction. 163 164 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. MI. It will be seen later, that in most multiphase windings, multi-coil construction involves only very little sacrifice of electromotive force for a given total length of armature conductor, and in good designs is generally adopted to as great an extent as proper space allowance for the insulation will permit. Often in alternating current installations, step-up or step-down transformers, or both, are used, and in such cases the other extreme is approached, and the apparatus is built for very low voltages. This permits the use of very small space for insulation ; and conductors of large cross-section, often arranged with only one conductor per group, are used. Here the multi-coil construction is less difficult, although still attended to some extent with the disadvantage of obtaining less than the maximum possible voltage per unit length of armature conductor. Examples of windings adapted respectively to both of the above extremes will be given in the following chapters. It will now be readily understood that the ordinary continuous-current windings are not, in the great majority of cases, adaptable to the work to be done. They should, however, always be kept in mind, and will often be found to work in nicely in special cases. A class of apparatus, best termed alternating continuous-current, commutating machines, is now being found of much value in various ways. They are in a general way used for feeding continuous-current circuits, from single-phase or multiphase circuits (or vice versa), and also sometimes for feeding alternating circuits of one class (for example, single- or quarter-phase) from those of another (say three-phase). This type of armature may usually be best laid out by employing regular continuous-current windings and tapping them off in the proper manner. Examples will be given. A wide variety of styles of armature construction have been employed in alternating-current machinery. Rings, drums (both ironclad and smooth-core), discs, and very many other types have been successfully built. Iron cores are used by some makers, and carefully avoided by others. Internal and external rotating parts have each found advocates. This great variety renders detailed treatment difficult, and in the following dis- cussion it has been generally assumed that the windings are > laid on the periphery of a drum, either on the surface, or imbedded in slots, and that the necessary connections are made at the ends of the armature. These peripheral condflctors are represented diagrammatically by radial lines, and the end connections by crooked lines. Thus, re-entrant polygons drawn with heavy lines may be taken to represent coils of the desired number of turns, the lighter lines representing the connections of these coils to each other. In the case of bar windings, no difficulty will be found in understanding the diagrams, as they correspond quite nearly to the continuous-current windings. Small, heavy circles in the middle of the diagram represent collector rings. If a winding is desired, for a disc or some other type, the diagrams will generally be found amply suggestive. Pancake coils and other types of windings, not specifically described, may be readily planned by slight modifications of the diagrams. No examples have been given of gramme-ring alternating-current windings, as these may be found in text books, and are so easily understood as to require no discussion. Before concluding these general considerations, it is desirable to emphasize the following points regarding the relative merits of uni- and multi-coil construction : With a given number of conductors arranged in a multi-coil winding, less terminal voltage will be obtained at no load than would be the case if they had been arranged in a uni-coil winding, and the discrepancy will be greater in proportion to the number of coils into which the conductors per pole piece are subdivided, assuming that the spacing of the groups of conductors is uniform over the entire periphery. Thus, if the terminal voltage at no load be taken as 1 for a uni-coil construction, it will, for the same total number of conductors, be .707 for a two-coil, .667 for a three-coil, .654 for a four-coil, etc. But when the machine is loaded, the current in the armature causes reactions which play an important part CHAP, xii.] ALTERNATING-CURRENT WINDINGS. 165 in determining the voltage at the generator terminals, and this may only be maintained constant as the load comes on, by increasing the field excitation, often by a very considerable amount. Now, with a given number of armature conductors, carrying a given current, these reactions are greatest when the armature conductors are concentrated in one group per pole piece, that is, when the uni-coil construction is adopted, and they decrease to a considerable degree as the conductors are subdivided into small groups distributed over the entire arma- ture surface, that is, they decrease when the multi-coil construction is used. The ratios given above for the relative voltages at no load, for uni- and multi-coil construction, do not, therefore, represent the relative values of the windings under working conditions, and it is believed that careful consideration should in many cases be given to both styles of winding, before deciding upon the one best suited for the purpose. Multi-coil design also results in a much more equitable distribution of the conductors, and, in the case of ironclad construction, permits of coils of small depth and width which cannot fail to be much more readily maintained at a low temperature for a given cross-section of conductor, or, if desirable to take advantage of this point in another way, it should be practicable to use a somewhat smaller cross-section of conductor for a given temperature limit. And similarly, when we consider smooth-core construction, we find that the distribu- tion of conductors over the entire surface carries with it great advantages from a mechanical standpoint. UKI7BR3IT7 CHAPTER XIII. SINGLE-PHASE WINDINGS. FIGURE 77 is a diagram of a winding for single-phase alternating-current generators and synchronous motors, which has been very extensively used. It has one group per pole piece, consisting of adjacent halves of two coils of the proper number of turns. These are interconnected as shown by the light lines. The adjacent halves of the two coils are usually arranged side by side, but it might sometimes be of advantage to place them one over the other. The arrangement of two coils side by side has been satis- factorily applied in various types of ironclad armatures. In Figs. 102 and 119 are given examples of this style of winding connected respectively for quarter-phase and for three-phase work. It should be noted, however, that the same armature can be used for three-phase purposes only by having fields with different numbers of pole pieces. The avoidance of crossings at the ends, and the extreme simplicity of this style of winding, are its chief advantages. 166 Fig. 77 Fig. 78 CHAP, xiii.] SINGLE-PHASE WINDINGS. 169 In Fig. 78 is given another uni-coil winding, but here only one coil is placed in each slot. In many cases this might be preferable to the arrangement shown in Fig. 77, but the ends of the armatures are not so completely occupied by the ends of the coils, which wastes room and tends to bring about a less even distribution of the loss by heating. The use of only half as many coils is, of course, generally an advantage, on account of simplicity, but it is usually necessary for each coil to be wound deeper, which is objectionable from a thermal standpoint, as well as from the fact that a greater depth of space has to be allowed for the winding at the ends of the armature. It should not be overlooked that if half the number of pole pieces is odd, the armature coils could not be connected up in two parallels, which would in practice be a very considerable objection, as it would limit the use of the armature for other purposes than that contemplated in laying out the original design. One feature of this winding worthy of consideration is the great ease of insulation, it being, in this respect, superior to Fig. 77, one of the groups of which consists of adjacent halves of two coils, having between them the entire voltage of the armature. UKI7BRSITY 170 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. xin. Figure 79 is a bar winding, with one bar per pole piece, corresponding to the coil winding of Fig. 78. This would be used for low voltages, and in the case of generators of large capacity, such windings are practicable for high voltages. It is typical of the simplest form of a multipolar, single-phase alternator, and has been used in some very large machines. Fig. 79 Fig. SO CHAP, xiii.] SINGLE-PHASE WINDINGS. 173 Figure 80 is another uni-coil winding. It is given largely as a matter of interest ; for, as will be seen, it has undesir- able crossings and very long end connections, which would be very wasteful of copper unless the length of the magnet cores parallel to the shaft is great compared with the length of the pole arc. Even in such a case there would be no advantage over Fig. 78, unless for the fact that Fig. 80 is a very good winding for a three-phase alternator of one-third the number of poles, and the case might occur where it would be of advantage to use the same armature and winding for both cases. This would make an excellent three-phase winding for one-third as many poles, and would then be similar to the three-phase winding given in Fig. 116. The corresponding diagram for a bar winding, with one bar per pole piece, is sufficiently evident from Fig. 80, and, in view of its unimportance, will not be given. 174 ARMATURE WINDINGS OF ELECTRIC MACHINES [CHAP. xin. The following diagrams are multi-coil, single-phase alter- nators. As a class they have been very thoroughly discussed in the general remarks of the preceding chapter. Figure 81 represents a very simple two-coil winding. It is to be noted that this winding is mechanically identical, with the exception of the interconnection of the coils, with the winding of Fig. 78, but it is put in a frame with half as many poles as there are groups of conductors, instead of, as was the case in Fig. 78, being laid out for a frame with a number of poles equal to the number of groups of conductors. As already pointed out, such multi-coil windings do not at no load generate so great an electromotive force per unit of length of face conductor, as uni-coil windings. It has, how- ever, been also shown on page 164 that this objection does not have such great weight as would at first sight appear to be the case. Fig. 8 1 Fig. 82 CHAP, xm.] SINGLE-PHASE WINDINGS. 177 Figure 82 gives a bar winding with two bars per pole piece. It corresponds to the coil winding of Fig. 81. These two windings (Figs. 81 and 82) could probably be used to advantage in many cases, but, of course, their dis- advantages should be carefully considered. 178 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAI-. xin. Figure 83 represents another two-coil winding. It would seldom be used, as it has the faults and lacks the merit of the winding given in Fig. 81. If, however, the coils, instead of being evenly spaced, were brought into groups of two, not very far apart, it would, to some extent, have part of the advantages of the uni-coil construction, and would partly overcome some of the faults of the latter. If modified in this way, it would partake of the nature of the windings given in Figs. 97, 98, and 99, and the remarks made in connection with these figures should be referred to. If Figs. 81 and 82 should be similarly treated (that is, if the coils should be brought into groups of two coils each, not very far apart), the result would be a winding compa- rable to those given in Figs. 97 and 99. Pig. 83 Fig. 84 CHAP, xiii.] SINGLE-PHASE WINDINGS. 181 Figure 84 is a diagram of another two-coil winding. It is connected as a single-phase alternator, but except for the manner of interconnection of the coils it is identical with the quarter-phase winding given in Fig. 100. It will give the same voltage as would Fig. 100, if the two components of the quarter-phase winding should be connected in series. For this reason (that is, because when reconnected, it makes a good quarter-phase winding), it might sometimes be used, but of course, would, as stated in connection with previous windings, require a greater length of wire to gen- erate the same voltage than a uni-coil winding, and would naturally have a greater armature self-induction. But, of course, the decrease in self-induction due to the multi-coil construction would somewhat compensate for this increase. 182 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. xin. Figure 85 gives a diagram for a single-phase bar winding, corresponding to Fig. 84. It is only of interest as showing that it is identical with Fig. 82, except that the long-end connections which were at the collector ring end in Fig. 82 are now at the other end. It should be noted that all these multi-coil windings now under consideration would, for a given terminal voltage, require much more field excitation at no load than correspond- ing uni-coil windings. But at full load they would, in some cases, require little if any more field excitation than would be the case with uni-coil windings. As a result of these considerations it will be seen to be necessary in any par- ticular case to observe the requirements for the field exci- tation as regards permissible regulation, heating, etc., when deciding upon the type of armature winding to adopt. Fig. 86 ni.u-. xiii.] SINGLE-PHASE WINDINGS. 185 Figure 86 should be compared with Fig. 80. It is quite like the latter, except that it has two coils per pole piece instead of one. It would, of course, not be used, as it has such long end connections. The number of poles is sixteen. Such a winding with twelve, eighteen, or twenty-four poles could be used in a three-phase armature of one-third the number of poles by merely changing the interconnections of the coils. Figure 123 gives such a diagram for a three-phase alternator in an eight-pole frame. The mechanical arrangement of such windings as those given in Figs. 80, 86, and 123 is exceptionally good, although in the case of Figs. 80 and 86, they are much less simple, as single-phase windings, than those that do not cross. ISO ABM1TUBE WINDINGS OF KLKCTK1C MACHINES. [CIIAI-. xni. Figure 87 represents a winding with two groups of coils per pole, and two coils per group. It will be seen to lie iden- tical with the two-phase winding of Fig. 103, except that it in connected up as a single-phase winding. With the exception of the sequence of interconnection of the coils, it may be considered to bo two windings like Fig. 77, one of which is displaced !)0, so that its conductors lie half way between those of the other. Its end connections permit of good mechanical arrange- ment; very much, in fact, like that of Figs. 80, 80, and 123. ? e n Fig. 88' CHAP, xiii.] SINGLE-PHASE WINDINGS. 189 Figure 88 shows a useful three-coil winding. It has all the advantages and disadvantages already noted of multi-coil armatures. The end connections can be very nicely arranged, so as to permit of winding on forms and slipping them into slots. Only two different shapes of forms are necessary ; one-half of the coils would be wound in one of them, and the rest in the other. It will be seen that it is really the three-phase winding of Fig. 116 connected up as a single-phase winding. For this reason, among others, it might be expected to be of service where it would be of advantage to have armatures which could be used interchangeably for single- or three-phase work. Most three-phase windings could, of course, be similarly used. As a single-phase winding per se, Fig. 88 is excelled by the windings of Figs. 92 and 94, which require a smaller length of end conductors. Of TOT x uiflTlRSITTs 190 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. xin. Figure 89 is the bar winding corresponding to the coil winding of Fig. 88. It is not a generally useful winding. Among other faults it has three different lengths of end connections, half of them being very long. In this respect it is excelled by the winding given in Fig. 93. The end connections at one end are perfectly regular, but this would seldom be considered to compensate for the needlessly great length of copper employed. This winding is an example of the importance of thor- oughly examining many diagrams before adopting a winding for a certain case ; for it is not at once apparent that this winding could be improved upon, and if thought of first, might be chosen without further investigation. Fig. 89 Fig. 9O CHAP, xiii.] SINGLE-PHASE WINDINGS. 193 Figure 90 gives a coil winding very similar to that of Fig. 88. But the end crossings would render it very incon- venient, and the space at the ends of the armature is not so well utilized as it was in Fig. 88. This would tend to an undesirable concentration of the heating. Unlike Fig. 88, the winding would not interfere with the armature, being made in segments for convenience of ship- ment. But Figs. 92 and 94, which require less copper in the end connections, also possess this advantage, Fig. 94 to the greatest extent of all. 194 AEMATUIiE WINDINGS OF ELECTIUC MACHINES. [CHAP. xm. Figure 91 has all the faults of Figs. 89 and 90. It is the bar winding corresponding to Fig. 90. It is inferior to the winding shown in Fig. 93. It has the advantage that the winding is more symmet- rical as a whole than many better windings, and it is for this reason readily constructed and connected up, with little liability of error. It is a great help for the winder to be able to intelligently perform his work, and windings that are, electrically and mechanically, to a small extent inferior, might in some cases consistently be adopted because of the simplicity of winding. They also permit of the more ready locating and correcting of faults that are liable to develop during the practical operation of the machinery. Fig. 92 CHAP, xiii.] SINGLE-PHASE WINDINGS. 197 Figure 92 is another three-coil winding. It gives the same results as Figs. 88 and 90, but with less copper, as it has shorter end connections. It is also simpler, as there is much less overlapping at the ends. Only two sizes of coils are necessary. The chief point of inferiority to Figs. 88 and 90 is that it cannot be connected up as a three-phase armature. Even Fig. 92 is not so good as Fig. 94 (to be described later), which latter has still shorter end connections and less crossings. There is no good bar winding corresponding to Fig. 92. Figure 92 possesses the advantage noted in the discussion of Fig. 90, that the armature may be built and shipped in sections without interfering with the winding. 198 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. xin. Figure 93 is the best bar winding for three bars per pole piece. It is distinctly superior to Figs. 89 and 91, as it has much shorter end connections. It requires, moreover, only two different lengths of end connections, whereas Figs. 89 and 91 each require three. The following diagram is a section of a bar winding witli five bars per pole piece : Fig. 93 niXTl&SXTT Fig. 94 CHAP, xni.] SINGLE-PHASE WINDINGS. 201 Figure 94 is the coil winding corresponding to the bar winding of Fig. 93. This coil winding is superior to that of Figs. 88, 90, and 92, in that it gives the same result with much shorter end connections and with fewer crossings of the end connections. Like Fig. 92, it cannot be connected up as a three-phase alternator, it being in this respect inferior to Figs. 88 and 90. The winding of Fig. 94 could readily be built in sections in cases where it would be necessary to ship the armature in segments. 202 AKMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. xin. Figure 95 is a coil winding electrically equivalent to Figs. 88, 90, 92, and 94. Windings of this class may readily be derived from the example given in Fig. 95, for any desired number of coils per pole piece. It often works out well from a mechanical standpoint, and although the end connections are necessarily longer than in the preceding windings, it will frequently be found useful. The various coils might with advantage be grouped to a greater or less extent, in accordance with the principles exemplified in Figs. 97, 98, and 99, which, together with the accompanying text, should be consulted in this connection. Fig. 95 Fig. 96 ' CHAP, xin.] SINGLE-PHASE WINDINGS. 205 Figure 96 gives a coil winding with one and one-half coils per pole piece. It has two coils per group. It is really a winding such as Fig. 77, put in a field with two-thirds as many poles as the armature has coils. Thus in Fig. 96 there are thirty armature coils and twenty field poles. There is disadvantageous counter-induction which makes the use of more armature copper necessary than would be used in a uni-coil winding. The armature could, however, be used interchangeably in fields with n and with f w poles, which property permits of the use of the armature in cases where different speeds or periodicities may be called for. Also by changing the interconnections of the coils, an excellent three-phase armature is obtained. The three-phase connections of such a winding are given in Fig. 119. Moreover, owing to the fact that when one side of a coil is under a field pole, the other is between two poles, the self- induction of such a winding is low, and is fairly uniform for all positions of the armature. 206 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. xin. Many of the multi-coil windings given heretofore have been somewhat undesirable by reason of the counter-induc- tion, which made it necessary to have a greater length of conductor for a given voltage than would have been neces- sary if the conductors had been concentrated in one coil per pole piece. Figure 97 is a winding which, while retaining to a great extent many of the advantages of multi-coil windings, is usually as good with regard to its freedom from counter- induction as a uni-coil winding with evenly spread coils. It is in fact one of the two windings of the quarter-phase diagram of Fig. 104. Fig. 97 CHAP, xiii.] SINGLE-PHASE WINDINGS. 209 Figure 98 does not differ essentially from Fig. 97 as far as regards the point that it is intended to illustrate. It, also, is one of the two windings of a quarter-phase armature, being in fact derived from the quarter-phase diagram of Fig. 112. Other excellent diagrams of this type may be derived by considering one of the two windings of the quarter-phase armatures shown in Figs. 105, 106, 107, and 111. or UlflVBRSITT 210 ABMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. xin. Figure 99, like its predecessors, Figs. 97 and 98, has its coils arranged in groups in the periphery of the armature. It has to some extent their advantages and disadvantages. It differs from them in utilizing two-thirds of the available space, instead of one-half, and is more of a compromise with the uniformly distributed windings. It is obvious that windings such as the three just given may readily be derived from any of the evenly distributed multiphase windings by simply discarding one or more of the windings belonging to the respective phases of such diagrams. They may also be derived from many of the single-phase windings by shifting the coils laterally from the normal position into the desired groups. Fig. 99 Fig. 1 OO CHAPTER XIV. QUARTER-PHASE WINDINGS. FIGURE 100 represents a quarter-phase coil winding with one group of conductors per pole piece per phase. In accordance with the nomenclature already adopted, this would be known as a uni-coil winding ; although it has but one coil per pole piece per phase, it has two coils per pole piece. The two windings are represented, respectively, by full and broken lines. The winding is quite simple, but has the objection of crossings at the ends. In this respect it is inferior to the style of winding represented by the diagram of Fig. 102. Three collector rings could be used, one of them being common to each winding. In the diagrams, however, four collector rings will be shown, this being the method now generally used. In connection with a system employing three collector rings, the standard quarter-phase commu- tating machines (to be described later) could not be used. 213 214 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. xiv. Figure 101 is the bar winding corresponding to Fig. 100. It does not well utilize all of the available space on the armature ends. This is generally not a great objection in the case of uni-coil windings, as there is in such cases plenty of room on the ends, but, other things being equal, it is of course preferable to have windings uniformly distributed at the ends as well as on the surface. In this connection Fig. 109 should be studied, and it will be seen that by placing two conductors in a group a perfectly symmetrical design is obtained with one group per pole piece. A decided objection to this arrangement would be that adjacent conductors would have between them large differ- ences of potential, whereas in Fig. 101 there are but few points in which neighboring conductors have between them any considerable percentage of the total terminal voltage. Fig. 1O2 xiv.] QUARTER-PHASE WINDINGS. 217 Figure 102 is a non-overlapping quarter-phase winding with one group of conductors per pole piece per phase. It has the advantage over Fig. 100 that there are no crossings at the ends of the armature, and that it utilizes the end space more completely, thus bringing about a better distribution of the necessary heating losses in the copper. Its chief fault is that if the width of the pole face is over one-half of the distance between pole centers, the coils never embrace the total flux from one pole piece. However, at full load, the area occupied by the flux is narrower, and a greater portion would be included than at no load, so that this objection would not be so serious as would appear at first sight. Moreover, the necessary space allowance for the field winding will in many cases not permit the width of the pole piece to be sufficiently great to cause any trouble in this respect. Mechanically, this is an excellent winding, being, in fact, the single-phase winding given in Fig. 77, for double the number of poles. The remarks made in connection with Fig. 96 (single- phase alternating winding with one and one-half slots per pole piece) should also be considered in studying this wind- ing. Consult also Fig. 119 and corresponding text. 218 ABMATURE WINDINGS OF ELECTEIC MACHINES. [CHAP. xiv. Figure 103, which like Fig. 102 has two coils per group, is not open to the objection discussed on the preceding page. It has, however, crossings at the ends. It is to be preferred to Fig. 100 for the reason that the end space is more effectively utilized, but the additional crossings would require a somewhat greater length of wire than would be necessary in Fig. 100. Bar windings could be built corresponding to the coil windings of Figs. 102 and 103. They would not be symmetrical at both ends, but might advantageously prove applicable for certain cases. The two bars of a group could be placed either over each other, or side by side. With smooth-core construction the latter arrangement would be adopted, and often also in ironclad armatures with bar windings. Fig. 1 O3 Fig. 104 xiv.] QUARTER-PHASE WINDINGS. 221 Figure 104 is a quarter-phase coil winding with two con- ductors per pole piece per phase. It is entirely symmetrical, and utilizes all the winding space to the best advantage. The crossings at the ends are unavoidable, but may be made thoroughly satisfactory from a mechanical standpoint by preceding in the manner shown most clearly in the diagram of Fig. 123. Such windings are applicable to quarter-phase armatures with any even number of coils per pole piece per phase. In studying Fig. 104 it will be instructive to examine Fig. 97, which is one of the two windings of Fig. 104. 222 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. xiv. Figure 105 is electrically equivalent to Fig. 104. The winding might sometimes be used, although it would for most purposes be excelled by Fig. 104. It will be noted that the end connections are longer, and that they occupy a greater depth. Much of the end space is wasted. This winding is superior to that of Fig. 104, in that the coils are so located as to make it very plain how the connections should run. This would be of great assistance to the winder, and would, moreover, facilitate the detection and correction of faults that might develop in practical working. An armature with such a winding could be built and shipped in segments. Fig. 105 Fig. 1 O6 CHAP, xiv.] QUAETEE^PHASE WINDINGS. 225 Figure 106 is a bar winding differing but little in princi- ple from the coil winding of Fig. 105. The space is uni- formly* occupied at the collector ring end, but is not at the other end. This lack of uniformity in end connections is not of very great moment in bar windings with few bars per pole piece. Other things being equal, however, it would on the whole seem best to avoid it, although in special cases such disposi- tion of the end-connections allows room much needed for mechanical arrangements. UNIVERSITY 226 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. xiv. Figure 107 is a bar winding corresponding to Fig. 104. It is a good example of the fact that very symmetrical coil windings often correspond to very unsymmetrical bar wind- ings, and vice versa. But, as noted on the preceding page, this lack of symmetry is in such cases not a great objection, and has, incidentally, some redeeming features. One of the two windings of this diagram would, as men- tioned on page 209, work out very well for a single-phase armature. Fig. 107 Fig. 1 O8 CHAP, xiv.] QUARTER-PHASE WINDINGS. 229 Figure 108 is a much better bar winding than Fig. 107, though electrically equivalent. It will be seen to be unsymmetrical at two points at the end distant from the collector This irregularity consists in the end connections of the two adjacent bars starting off in the same direction, instead of, as in all other parts of the winding except these two, going in opposite directions. Four of the end connections have to be longer than the rest. This winding is practically the same as the following one, Fig. 109, except that the above -described irregularity is introduced instead of making use of the cross-connections shown in Fig. 109. VIZTlRSZT'y 230 AKMATUKE WINDINGS OF ELECTEIC MACHINES. [CHAP. xiv. Figure 109 is a symmetrical quarter-phase bar winding with two con- ductors per pole piece per phase. If used for an ironclad or projection armature, it may have four slots per pole piece with one conductor per slot, or two slots per pole piece with two conductors per slot. Examination will show that it is essentially a twelve-pole armature with four separate series of windings of twelve bars each. These four wind- ings are connected up into two windings of twenty-four conductors each. At the front end y = 5, and at the back end y=3, therefore average y=4. As pointed out in the discussion of Fig. 101, Figs. 108 and 109 have the fault that neighboring conductors have between them large percent- ages of the total potential of the armature, and this would sometimes be objectionable in cases of high potential windings. It will doubtless have been observed that in the case of quarter-phase windings, multi-coil construction does not have to so great an extent the fault pointed out in the case of corresponding single-phase windings, of useless counter-electromotive forces. The coils of one phase usually embrace practically the entire flux, because the two groups of conductors, forming respectively the two sides of a coil, are usually separated by a group forming one side of a coil belonging to the winding of the other phase. This advantage is possessed in a still greater degree by the three-phase windings, which will be discussed later. Exceptions to the above statement often occur in cases where single and multi-phase alternating windings are obtained from ordinary direct- current windings. Fig. 1O9 CHAP, xiv.] QUARTER-PHASE WINDINGS. 233 Figure 110 represents a quarter-phase coil winding with three slots per pole piece per phase. It does not utilize very uniformly the end space on the armature, the end connec- tions being three layers deep at some points and much less at others. An advantage of this winding is the well-defined nature of the coils, rendering it easy to see just how they should be connected. The winding might also be necessary, if it should be required that the armature should be built so that it could be shipped in segments. 234 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. xiv. Figure 111 is electrically equivalent to Fig. 110, but the end connections are only two layers deep, are shorter, and are better distributed over the ends of the armature. Where the number of coils per pole piece per phase must be odd, windings such as those given in Figs. 110 and 111 must for quarter-phase armatures often be chosen. It is quite apparent that, except in special cases, the style of diagram shown in Fig. Ill will give the best result. Fig. 1 1 1 Fig. 1 1 2 CHAP, xiv.] QUARTER-PHASE WINDINGS. 237 Figure 112 is a bar winding corresponding to the coil winding of Fig. 111. Although not symmetrical, the end connections are fairly well distributed, and there would be in but very few places any great percentage of the total difference of potential between adjacent conductors. Several different lengths of end connections would necessarily have to be employed. One of the two windings of this diagram has already been given in Fig. 98 in Chapter XIII. on Single-Phase Windings. ><* OF Tar 238 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CUAJP. xiv. Figure 113 represents a quarter-phase bar winding with four conductors per pole piece per phase. It is perfectly symmetrical, and may have one, two, or four conductors per slot, as desired. This winding is like that of Fig. 109, except that four sets of elementary windings are connected in series to form one of the two phases, instead of two sets, as was the case in Fig. 109. If one-half or one-quarter as great a terminal electro- motive force should be desired, two, or all four, of these elementary windings could be connected in parallel between the collector rings, instead of joining them in series as shown. W1VIRSIT7 CHAP, xiv.] TWO-CIRCUIT WINDING FOR COMMUTATING MACHINES. 241 TWO-CIRCUIT WINDING FOR QUARTER-PHASE CONTINU- OUS CURRENT COMMUTATING MACHINE. Figure 114 is the diagram for the winding for a commu- tating machine for deriving a continuous current from a quarter-phase alternating supply, or vice versa, or for a generator for supplying both continuous and quarter-phase systems. Examination will show that it is the two-circuit single winding of Fig. 43 (Chap. VIII.), tapped off from four approximately equidistant points to four collector rings. As the winding consists of sixty-eight conductors, there should be seventeen conductors in each section, but for the convenience of having all the connections to the collector rings made at one end, the divisions are 16, 16, 18, and 18. With the large numbers of conductors used in practice, the irregularity produced by one conductor more or less would be of less importance, though always undesirable. In such a winding four points only of the armature are tapped inde- pendently of the number of poles. Of TH3 v TOIXTIBSXTT! 242 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. xiv. TWELVE-CIRCUIT WINDING FOR QUARTER-PHASE CON- , TINUOUS-CURRENT COMMUTATING MACHINE. Figure 115 is another winding for a quarter-phase continuous-current commutating machine. It is funda- mentally a multiple-circuit, continuous-current winding, and requires four leads (one to each collector ring) for each pair of poles. It is to be remembered that in quarter-phase continuous- current commutating machines, the effective voltage between collector rings 180 apart equals the continuous-current voltage multiplied by .707 (or divided by 1.414). Fig. 1 1 5 Fig. 1 16 CHAPTER XV. THREE-PHASE WINDINGS. FIGURE 116 is a three-phase coil winding with one set of conductors per pole piece per phase. The coils belonging to the three windings may be distinguished from each other by the three different styles of lines. The armature is connected in a manner technically known as the " Y " connection. The characteristic of this style of connecting three-phase windings is that one end of each of the three windings is brought to a common connection, the other three ends being carried to three collector rings. Inasmuch as three-phase alternators have but recently been used to any considerable extent in practice, it may not be out of place to give as concisely as possible a few of the leading considerations involved in their practical construction and operation, as far as relates to the armature windings. One complete cycle is passed through by any armature conductor while passing from a certain point opposite one pole piece, say the middle of the north pole, to the corresponding point opposite the next pole piece of the same polarity. This angular distance is usually spoken of as 360, independently of the number of poles of the machine. Now, a three-phase armature winding is merely three single-phase windings, laid on the same armature, the conductors of the three windings, however, being located 120 (one-third of a cycle) behind each other. Any conductor of one winding is, therefore, at any instant, in a different phase from that of the conductors of the other windings. Thus, in the position represented in Fig. 116, the conductors represented by heavy lines are directly opposite the middle of the pole pieces, the light line conductors are located 120 behind them, and the dotted conductors are 120 behind the light conductors and 240 behind the heavy conductors. Now it follows from the relative positions of the conductors .of the three phases, that the electromotive forces generated in the three windings are 120 behind each other, and if they are sine waves, they may be represented, as in the following figure, by three sine curves displaced 120 behind each other. If the three circuits are equally loaded, these curves may also be considered to represent the corresponding instantaneous values of the current. 245 246 ARMATURE WINDINGS OF ELECTRIC MACHINES. [OHAI>. xv. It will be noted that at every instant, the algebraic sum of the three currents is zero. Now instead of having three pairs of lines and brushes and collector rings, one end of each of the three windings is brought to a common connection, and a conductor from this common connection could be used as a common return for each of the three circuits. But, since the resultant current at every instant is zero, this conductor becomes superfluous and is omitted. If the voltage between any ring and the common connection, that is, the voltage per phase, is equal to v, then the volts V between any pair of collector rings will be, V= V3 v or 1.732 v. The effective current will be equal in each of the three lines, and may be represented by 0. With a non-inductive load, the watts output, W, will be, 1.782 CV. V3 If the load is inductive, the current C, for a given output TF, will be greater than with a non-inductive load. A safe and easily understood way of connecting the three windings correctly to the three collector rings and the common connection, is to consider that the winding whose conductors occupy the position in the middle of the pole piece, is carrying the maximum current, and to indicate its direction on the winding diagram by an arrow. The currents at the same instant in the conductors immediately next to it on the right and left are in the same direction, and should be so marked by arrow-heads. Now, from the sine curves given above, it will be seen that where one curve has a maximum value, the other two have a value half as great, and in the opposite direction. Therefore consider that the current in the winding occupying the position at the middle of the pole face is flowing away from the common connection. Then the currents in the other two windings, which are each of half the magnitude of the former, must both be flowing into the common connection ; therefore join those ends of the three windings to the common connection, which will bring about this condition at this instant. Carry the other three ends to the three rings. This has been done in the upper diagram of Fig. 117, which represents a " Y " connected three-phase winding. Another way of connecting up three-phase armatures is to connect the three windings in series in a closed circuit, and at every third of the total way through the circuit thus formed, to carry off a lead to one of the collector rings. In the case of this, technically called the "delta" (A) connection, the current in the line (i.e. beyond the collector rings) is (7=V3e, or C Y =1.732e, where c = current in the winding. The volts per winding are in this case equal to the volts between each pair of collector rings ; that is, to the volts per phase. The watts output of a machine are, W= 3 cV= -- = 1 . 732 CV. V3 Examples of each of these two connections are given in Fig. 117. The upper diagram represents a " Y " connected three-phase armature, and the lower diagram represents the very same armature, but with a "delta" (A) connection. In connecting up the separate windings for a "delta" (A) connection, it is most convenient to choose the instant when the conductors of one phase are opposite the middle of a pole piece. Then assume these conductors to be carrying the maximum current, which is illustrated in the figure by the larger arrow-head. Fig. 1 1 8 CHAP. XV.] THREE-PHASE WINDINGS. 249 The other two windings are at the same instant having induced in them currents of only one-half this magnitude. The condition of affairs in line and in winding is, for the instant, as represented in the follow- ing diagram. From this it is seen, that, starting from the middle collector ring (corresponding to point a in the diagram), and following the direction of the current, we must pass through the heavy winding, carrying the large current to the outer ring (corresponding to point b of diagram). In the other direction, we must pass from the middle ring (i.e. point a), through the dotted winding, which carries one- half as great a current, to the inner collector ring (corresponding to point c of diagram). Then we must continue through the light wind- ing, still in the direction of the current, until we again reach the outer collector ring, or point b of diagram. Any of the following three-phase diagrams may be connected either " delta " or " Y,'' but they will usually be shown with the Y " connection. It is well to keep in mind that if a " Y " connected armature is changed over to the " delta " connection, it may with the same regulation and heating give 1.732 times as much current, but only 1 7QO times the voltage. The reverse holds true in changing from "delta" (A) to "Y." 1.732 Figure 118 is the bar winding corresponding to Fig. 116. It has one bar per pole piece per phase. This winding, while partaking of all the advantages and disadvantages of multi-coil construction, would be particularly unsatisfactory for a three-phase motor on account of the dead points that it would develop at starting. These dead points are much less marked with multi-coil windings and with windings like those in Figs. 119 and 120. In the case of induction motors, it is customary to make use of such windings as those given in Figs. 126 and 127, where smoother action is obtained partly by virtue of the choice of a number of conductors, prime, or nearly so, to the number of poles. 250 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. xv. Figure 119 is a non-overlapping, three-phase, coil wind- ing, with only one and one-half coils per pole piece per phase. It is the winding which was given with its single- phase connection, in Fig. 96. This should make a very excellent three-phase winding, as there is no crossing of the coils. It is a regular thirty-pole, single-phase winding, connected up as a three-phase armature for twenty poles. This diagram should be compared with Fig. 77, Fig. 96, and Fig. 102. It should be particularly suitable for use in three- phase motor work, as it should have very weakly defined dead points. In a projection armature, when a slot is opposite a certain pole piece, spaces between two slots will be opposite the adjacent pole pieces, thus giving a more equitable distribution of the magnetic flux. The inductance of such a winding is low and fairly uniform, for the reason that when one side of a coil occupies a position under a pole piece, the other side of the coil is between two pole pieces. Fig. 1 1 9 Fig. 1 2O CHAI-. xv.] THKEE-PHASE WINDINGS. 253 Figure 120 represents the corresponding bar winding. In the case of projection or ironclad armatures, it would have two bars per slot, which might be arranged one over the other or side by side. It is interesting to note that each slot would contain one bar of each of two windings, two bars of the same winding never occupying the same slot. All the remarks regarding the winding of Fig. 119 apply equally well to Fig. 120. 254 AKMATUKE WINDINGS OF ELECTRIC MACHINES. [CHAP. xv. Figure 121 is a three-phase coil winding, with two groups of conductors per pole piece per phase. The mechanical arrangement of the coils at the ends of the armature could not be designed nearly so satisfactorily from a mechanical point of view, as in the style of winding given in Fig. 123. It is believed that in most instances the style of winding shown in Fig. 123 will be found to give the best results. Fig. 1 22 CHAP, xv.] THKEE-PHASE WINDINGS. 257 Figure 122 is the bar winding corresponding to Fig. 121. The end connections are perfectly symmetrical and well dis- tributed at one end, but are far from it at the other. Its point of superiority over Fig. 124 is that it has, as a rule, no great differences of potential between adjacent conductors. As already stated, the irregular distribution of the end conductors is not, at least in the case of bar windings, so great an objection in cases where there are comparatively few bars per pole piece. And in this instance there is a sort of a regularity about their grouping, that might be found of advantage on account of the large spaces that it makes avail- able for mechanical arrangements. 258 AKMATURE WINDINGS OF ELECTEIC MACHINES. [CHAP. xv. Figure 123, which was devised by Mr. Thorburn Reid, who has devised a number of useful windings, is superior in the mechanical arrangement of the coils, to the winding of Fig. 121. The corresponding bar winding is not drawn, but it may be readily seen that it would have no very obvious advantages. Coil windings of the same style as that of Fig. 123 may be constructed with any number of coils per pole piece per phase, and are frequently superior to other arrangements. It is thought that the style of lining adopted in the diagram will indicate fairly well the arrangement of the end connections, if care is taken to note that the conductors of some groups of coils are carried directly over in the same plane as the face wires, to the conductors forming the other side of the group. The end conductors of the other coils have to be bent down out of the plane of the face conductors and then back again into their plane. The coils are usually wound in forms and then laid in place on the armature. Fig". 1 23 - ^ ""* f < ^' \ V V 7\ Fig. 1 24 CHAP, xv.] THREE-PHASE WINDINGS. 261 Figure 124 is a three-phase bar winding, with two bars per pole piece per phase. It is perfectly symmetrical, and may have either one or two conductors per group. It is inferior to Fig. 122, in that, from the nature of the winding, there are much greater differences of potential between adjacent conductors than in Fig. 122. In Fig. 124, the pitch is 5 at one end and 7 at the other. Two sets of conductors, each set having as many conductors as there are pole pieces, are joined in series to form each one of the three windings. If an armature for half the voltage had been wished, the two sets of con- ductors forming each winding would have been connected in parallel. This winding, as well as the next (Fig. 125), is of the same general character as those shown in Figs. 109 and 113. 262 ARMATUKE WINDINGS OF ELECTRIC MACHINES. [CHAP. xv. Figure 125 is similar in all respects to Fig. 124, except that it has three conductors per pole piece per phase. The pitch is 9 at both ends. It could be connected so as to give one-third as great a terminal electromotive force by joining the three elementary groups of which each winding is formed, in parallel, instead of in series. In connection with Figs. 124 and 125, emphasis should be laid on the fact that in virtue of the nature of these wind- ings, whereby adjacent conductors have between them large differences of potential, valuable space has to be sacrificed to make room for the proper thickness of insulation, which, with types of winding not possessing this character, could be usefully employed. Fig. 1 25 -W*i VHIVIESIT7] Fig. 126 CHAP, xv.] THREE-PHASE WINDINGS. 265 Figure 126 is a four-pole, three-phase bar winding of a very irregular character. It has fifty-one conductors, seventeen per phase. There are, therefore, unequal numbers of conductors, both per phase and per pole, opposite the different pole pieces. This style of winding has been used with success in induction motors, where it is important to choose a number of slots on the armature, which is prime, or nearly so, to the number of slots on the field. It may be well to state that, in the case of induction motors, the field, in the most success- ful types, consists merely of an assembly of annular punchings with radial slots within which the cylindrical drum armature revolves. It is practically a transformer, one of the elements, usually the secondary, being movable. It has become customary to call the moving element, the armature, and the stationary, the field. In the types, and for the voltages generally employed, it has been found best to use a coil winding for the field, the coils often being wound on forms and slipped into the slots. In the armature, which is practically a short-circuited secondary, the number of conductors and slots is determined by the permissible inductance, the actual voltage of the arma- ture being to a great extent immaterial. In certain types the ratio of field to armature conductors has been something like 6:1. It is in connection with such motors as these, that the winding diagram of Fig. 126 will be found of greatest service. There cannot well be more than one bar per slot, because of the irregularity of the end connections. WITBRSIT7 266 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. xv. Figure 127 is another three-phase bar winding with fifty- one conductors. It has six poles, and is even more irregular than the winding of Fig. 126. It, like Fig. 126, will find its chief use in the design of induction apparatus. Wind- ings, almost as irregular, might be used in large polyphase generators, where it is desired to have but one conductor per slot. Fig. 1 27 CHAP, xv.] TWO-CIBCUIT WINDING FOR COMMUTATING MACHINE. 209 TWO-CIRCUIT WINDING FOR THREE-PHASE CONTINUOUS- CURRENT, COMMUTATING MACHINE. Figure 128 represents the same winding as Fig. 114, except that here it is tapped off at three nearly equidistant points instead of at four, as was the case in Fig. 114. The result is a winding for a three-phase, continuous- current, commutating machine. The total sixty-eight bars are divided up into sets of twenty -two, twenty-two, and twenty-four conductors, respect- ively, which are represented on the diagram by heavy, light, and dotted lines. If the conductors are arranged in groups of two each, as would frequently be the case in projection armatures, where two conductors would often be placed together in each slot, it is of interest to note that these two conductors never belong to the same phase. 270 ABMATUKE WINDINGS OF ELECTRIC MACHINES. 1_CHA1'. XV. SIX-CIRCUIT WINDING FOR THREE-PHASE, CONTINUOUS-CURRENT, COMMUTATING MACHINE. Figure 129 is still another three-phase, continuous-current, commutating machine, but with a six-circuit winding. It requires three leads per pair of poles ; therefore, in this case, nine leads. It is quite analogous to the quarter-phase, continuous-current, corn- mutating machine of Fig. 115. It is of interest to notice the relation of the voltage between collector rings to the con- tinuous-current voltage at the commutator, in the case of three-phase, continuous-current, commutating machines. It will have been observed that they have "delta" connected windings. Let V= continuous-current voltage at the commutator ; then, taking the point of zero potential to be at the middle of the winding, the electromotive force of each half of the winding is . But the corresponding effective alternating electromotive force will be SB f-r This, therefore, will correspond to the voltage between common connection 2 V2 (point of zero potential), and collector ring, for an equivalent " Y " connected three-phase armature winding. Now the voltage between the collector rings of the " delta " connected armature winding will be V3 times as great as the voltage to the common connection of this equivalent " Y " winding, therefore the voltage between the collector rings will be, 2 V2 where V= continuous-current voltage at commutator. Inasmuch as a " delta " connected winding cannot be readily conceived to have a point of zero potential, the above subterfuge of substituting for it, the equivalent " Y " connected winding, will often be found to facilitate the handling of three-phase winding problems. When doing so, the equivalent " Y " potential and the equivalent " Y " current may be spoken of as attributes of a "delta" connected armature. In the accompanying figure, an equivalent " Y " connected winding is diagrammatically shown dotted within a " delta " connected winding. Fig. 1 29 PART III. WINDING FORMULA AND TABLES. U5I7BHSITY CHAPTER XVI. FORMULAE FOR ELECTROMOTIVE FORCE. COMPREHENSIVE formula for the calculation of the electromotive force set up in armatures may be derived from the formula for the voltage in a circuit, in which the variation of magnetic flux is a simple harmonic function of the time. These formulae are : 1. V= 6.28 TNM 10~ s , the maximum voltage set up in a cycle ; 2. V= 4.44 TNM lO' 8 , the effective voltage set up in a cycle ; 3. V= 4.00 TNM 10~ 8 , the mean or average voltage set up in a cycle,v ( where V is the voltage generated, in volts ; T the number of turns in series, M the number of cgs lines included or excluded by each of the T turns in a magnetic cycle, and N the number of magnetic cycles per second. In armatures of alternators, the effective, or square root of the mean square of the electromotive forces is required, since this is proportional to the effective voltage, i.e. the voltage to maintain current O (square root of the mean square of the current), in a non-inductive resistance. In this case it is supposed that the T turns are so situated as to be simultaneously affected by any change of the magnetic flux, otherwise the voltage for each of the turns differently situated must be calculated separately and properly combined to obtain the resultant voltage. In the case of multi-phase alternating-current machines, the voltage in each circuit should be calculated, and the resultant voltage derived according to the method of connection, and addition of vectors according to the angle by which the several phases differ from each other. In quarter-phase machines with common connection, the resultant voltage is V5, or 1.414 times the voltage generated in one circuit. In three-phase apparatus, the resultant voltage is the "same as the voltage generated in one circuit when the circuits are connected "delta"; and V3, or 1.732 times the voltage generated in one circuit when the circuits are connected " Y." In alternating-current commutating machines, the ratio of the voltage between the continuous and the, alternating current circuits is 1 : .707 in the case of single-phase and quarter-phase commutating machines, and 1 : .612 in the case of three-phase commutating machines. In other words, if the voltage at the con- 275 276 ARMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. xvi. tinuous current side is known, the voltage between collector rings will be .707 times as great in the case of single and quarter phase commutating machines, and will be .612 times as great in the case of three-phase commutating machines. In armatures of continuous-current dynamos, the voltage at the terminals is constant during any period considered, and is the integral of all the voltages successively set up in the different armature coils according to their position in the magnetic field; and since in this case only average voltages are considered, the resultant voltage is independent of any manner in which the magnetic flux may vary through the coils. Formula 3 is applicable to all continuous-current armatures, whether ring, drum or disc, two-circuit or multiple circuit, and whether the winding be single or multiple. The simplicity and wide applicability of these formula; make them preferable to many others that are difficult to interpret, because of the many accessory conditions that must be kept in mind. Although, by the constants given above, the voltages may be obtained at the alternating current, as well as at the continuous current terminals of commutating machines, the former, i.e. the voltages at the alter- nating current terminals, may be obtained from the following formulae, in which V is the required voltage between collector rings, T is the number of turns in series between collector rings, M is the magnetic flux from one pole piece into the armature, and N is the number of cycles per second : For single and quarter phase commutating machines, V= 2.83 TNM 10~ 8 . For three-phase commutating machines, V= 3.69 TNMr*. CHAPTER XVII. METHOD OF APPLYING THE ARMATURE WINDING TABLES. THE nature and use of the tables may be most easily understood by applying them to the solution of a few examples. EXAMPLE 1. If we wish a two-circuit, triple winding for a drum armature, with about 670 con- ductors and six poles, what is the exact number of conductors that must be employed to give us a singly re- entrant winding ? Turning to page 312, we find that a two-circuit, triple winding with 670 conductors, is impossible for six poles, but that 672 conductors may be used ; and to have the winding singly re-entrant, the front and back pitches must each equal 113. If the front and back pitches should be taken equal to 111, a triply re-entrant winding would result. EXAMPLE 2. We next wish to ascertain how many volts this machine will give when the armature is driven at 440 r.p.m., if the flux from each pole piece into the armature equals 2.25 megalines. The table of Drum Winding Constants on page 280 tells us that with 100 conductors, 100 r.p.m., and a flux equal to one megaline, the terminal volts will, for a six-pole machine, be equal to 1.667. Therefore, in the case before us, we have F=1.667 x 6.72 x 4.40 x 2.25 = 111 volts. From the same table we find that for a two-circuit, triple winding with six poles, we have .200 aver- age volts between commutator segments per megaline and per 100 r.p.m. So, in this case, we shall have .200x2.25x4.40 = 1.98 average volts between commutator segments. EXAMPLE 3. Certain conditions fix the flux of a dynamo from one pole piece into the armature at 8.30 megalines, and the speed at 100 r.p.m. If we wish to employ an eight-pole, two-circuit, double winding, how many conductors do we need, to obtain 150 volts ? Consulting the table of Drum Winding Constants, on page 280, we find that for eight-pole, two-circuit, double windings, we have 3.33 volts per 100 conductors with 100 r.p.m., and one megaline of flux. Therefore, we shall require x =544 conductors. By reference to page 301, it will be seen that for eight poles, the nearest number of conductors that we can use in order to have a two-circuit, double winding, is 540 or 548. Suppose we use 540 conductors. If we wish a doubly re-entrant winding, we shall take the pitch at one end equal to 67, and that at the other end equal to 69. EXAMPLE 4. A slotted armature is to have ten poles, and a two-circuit, triple winding, with eight conductors per slot. 277 278 AEMATURE WINDINGS OF ELECTRIC MACHINES. [CHAP. xvn. By reference to the table of Summarized Conditions for Two-Circuit, Triple Windings, on page 283, we find that it may be either singly or triply re-entrant, according to the number of conductors used. The winding is to have 424 conductors. Turning to page 310, it is seen that the pitch must be 43 at both ends, and that for 424 conductors the winding must be singly re-entrant. If the flux is 20.0 megalines, and the speed 105 r.p.m., we find from page 280 that the voltage will be 2.78x4.24x1.05x20.0 = 247 volts. The average volts per bar are .556x20.0x1.05 = 11.7 volts. EXAMPLE 5. An eight-pole armature has a multiple-circuit, double winding, with 1258 conductors. By consulting page 343, we find that it is singly re-entrant, and that the pitch should be 155 at one end, and 159 at the other. It is, of course, understood that these pitches are taken in opposite directions. One of them might have been indicated as positive, and the other as negative. It may be well to point out here that the letters F and B at the head of the tables, meaning respectively, " front " and " back," are interchange- able, meaning merely that the one figure represents the pitch at one end, and the other figure, that at the other end. This is true in regard to all the tables, both two-circuit and multiple-circuit. Returning to Example 5, the voltage of the machine, assuming the flux equals 7.85 megalines, and a speed of 300 r.p.m., is found by the table of Drum Winding Constants on page 280, to be . 833 x 12. 58 x 3. 00 x 7 ,85 = 247 volts. The average volts per bar are .1333 x 7.85 x 3.00 = 3.14 volts. EXAMPLE 6. A two-circuit, single winding is wanted, with four conductors per slot. From the table of Summarized Conditions for Two-Circuit, Single Windings, on page 281, it may be seen that this is only possible with 6, 10, 14, etc., poles ; being impossible with 4, 8, 12, 16, etc., poles. The winding is designed for fourteen poles, and 660 conductors. We find from page 329, that the pitch is 47 at both ends. The machine gives 160 volts, and the speed is 75 r.p.m. By the aid of the table on page 280, we find that the flux is equal to JnjT Jf^ = 2 .77 m egaline, Average volts per commutator segment = 3.27 x 2.77 x .75=6.80 volts. The above examples have all been chosen merely to illustrate the use of the tables, and the relative magnitudes employed in any one example are not such as would occur in practice. The tables on pages 280, 281, 282, and 283 are constructed on the assumption that no interpolated com- mutator segments are employed, and that no portion of the normal number of commutator segments is omitted, and when this is not the case, the results should be properly modified, as may readily be done. In all the tables, a proper interpretation of the term " conductors " should be made. As stated in the introductory chapter, " groups of conductors " may often be substituted therefor. It is believed that after becoming familiar with the arrangement of the tables, their use will be found to be of value in a great variety of problems connected with armature windings. Any single result can, however, be obtained by an application of the rules and formulae given in the text, but after these rules and formulae are once understood, it will be found that subsequent problems will generally be most conveniently solved by means of the tables. CHAPTER XVIII. ARMATURE WINDING TABLES. DRUM WINDING CONSTANTS. NUMBER OF POLES CLASS OF WINDING. 4 6 8 10 12 14 16 DRUM ARMATURES. VOLTS PER 100 CONDUCTORS PER 100 R. P. M. AND FLUX-ONE MEGALINE. 3 H Single 1.667 1.667 1.667 1.667 1.667 1.667 1.667 Eb ID 1- -i 2.14 Triple .0888 .200 .356 .556 .800 1.09 1.42 With Multiple Windings, the maximum Volts per bar is much more greatly in excess of the average Volts per bar than in Single Windings. This may be seen by a careful analysis of such Windings; which also shows that this may be more or less overcome by care- fuLmutual adjustment of the position of the Brushes. This would not, however, be practicable with present methods. DATA FOR APPLYING TWO-CIRCUIT, SINGLE WINDINGS, FOR DRUM ARMATURES. o o 3 U 2^-5 c ^ i < UCL h-g ** w $ 2? 2 i- o u ^ giiBs* 55S| I 2 UJ ^ O 2 > 2 NUMBER OF POLES CONDUCTORS PER SLOT ^O) > w mx-f-s 5gr a: II > "(r 4 1 2 6 10 14 3.33 .267 6 1 2 4 8 10 14 16 5.00 .600 8 1 2 6 10 14 6.67 1.068 10 1 2 4 6 8 12 14 16 8.33 1.668 12 1 2 10 14 1000 2.40 14 1 2 4 6 8 10 12 16 11.67 3.27 16 1 2 6 10 14 13.33 4.27 Q) Independent of number of Conductors From the above Table the following Rule may be deduced: In the ordinary two-circuit single winding, "C" is always such a number that the number of conductors per slot, and "n" the number of poles, cannot have a common factor greater than 2. UFJ7BRSIT7 DATA FOR APPLYING TWO-CIRCUIT, DOUBLE WINDINGS, FOR DRUM ARMATURES. iff! 0- liJ X < UJ tt- H Pis w - S; . u oi <| 2 mii 5f38 ;; 2 uj 2 > o NUMBER OF POLES CONDUCTORS PER SLOT 0. . - ui cns bgar >^" 1 2 4 6 8 10 12 14 16 4 (3D oo (3D oo <3D oo (3D 00 CD (3D 00 CD 00 00 oo G) 1.667 .1333 6 <3D o o 00 00 00 OO (3D o o (3D 00 2.50 300 8 (3D oo o o (3D o o <33 00 (5) 00 C5D oo OD 00 3.33 .534 10 (3D o o (3D o o OO (3D o o 00 oo (3D o o OO 4.17 .834 12 (5) o o (3D o o (3D 00 CD 00 (3D oo 5.00 1.200 14 GO o o (3D 00 00 (3D 00 oo (3D oo oo 00 5.83 1.635 16 (3D O 00 (3D oo (3D oo (3D oo (3D oo C5D 00 6.67 2.14 Independent of number of Conductors Moreover, in multiple Windings this value is merely nominal, as a careful analysis of Multiple Windings shows that if this value can be approached at all, it is only by means of more careful mutual adjustment of the Brushes than is practicable with present methods. DATA FOR APPLYING TWO-CIRCUIT, TRIPLE WINDINGS, FOR DRUM ARMATURES. VOLTS PER 100 CONORS. PER 100 R.P.M. WITH FLUX = 1 MEGALINE AVERAGE VOLTS BETWEEN COMMR. SEGTS. PER MEGALINE& PERIOD R. P. M. NUMBER OF POLES CONDUCTORS PER SLOT 1 2 4 6 8 10 12 14 16 4 (as) ooo (22) ooo OOO (22) 000 (22) 000 1.111 .0888 6 (22) 000 (22) ooo (22) ooo (22) 000 (20) ooo @) ooo (22) ooo (22) 000 (22) ooo 1.6(57 .200 8 d5> ooo (42) ooo OOO (22) ooo (22) 000 2.22 .356 10 (22) 000 (22) 000 (22) 000 OOO ooo OOO (22) ooo (22) 000 2.78 .556 12 (22) ooo (22) ooo ooo (22) 000 OOO (22) ooo (2ft) ooo 4.44 1.42 Independent of number of Conductors @ Moreover, in Multiple Windings this value is merely nominal, as a careful analysis of Multiple Windings shows that if this value can be approached at all, it is only by means of more careful mutual adjustment of the Brushes than is practicable with present methods. WINDING TABLES FOR TWO^CIRCUIT, SINGLE WINDINGS FOR DRUM ARMATURES. TABLE OF TWO-CIRCUIT, SINGLE WINDINGS, FOR DRUM ARMATURES. No. OF CONDUCTORS FRONT AND BACK PITCHES No. OF CONDUCTORS 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES F B F B F B F B F B F B F B 102 l& 25 2J 27 13 13 9 11 102 104 17 17 104 106 | 27 27 17 19 13 13 9 9 106 108 11 11 108 110 27 27 27 29 17 19 13 15 9 9 7 9 7 7 110 112 19 19 11 11 112 114 27 29 29 29 13 15 7 9 7 7 114 116 19 19 116 118 20 29 29 31 19 21 15 15 11 13 9 11 118 120 120 122 B 31 81 31 19 21 15 15 11 13 9 11 122 124 Jl 21 9 9 12i 126 31 31 81 33 15 17 7 9 126 128 21 21 13 13 9 9 128 130 31 33 33 33 21 23 15 17 11 11 7 9 130 132 13 13 132 134 a:-: 33 33 35 21 23 17 17 11 11 134 136 23 23 136 138 as 35 B 35 17 17 13 15 9 11 138 140 28 23 140 142 JD 35 i 28 25 17 19 13 15 11 13 9 11 9 9 142 144 144 146 35 87 37 37 23 25 17 19 11 13 9 9 146 148 25 25 15 15 148 150 87 37 87 39 19 19 150 152 25 25 .15 15 11 11 152 154 87 SB H 89 25 27 19 1!) 13 13 154 156 11 11 156 158 39 39 11 25 27 19 21 15 17 13 13 9 11 158 160 27 27 160 162 41 41 41 1!) 21 15 17 9 11 162 164 23 27 164 ICG 41 41 41 4:i 27 29 21 :'\ 13 15 11 13 166 168 17 17 168 170 41 43 43 43 27 ill 21 21 13 15 11 13 170 172 2!) 29 17 17 172 174 43 43 i 21 23 11 11 174 176 29 29 176 178 43 45 45 45 29 31 21 28 17 111 15 15 11 11 178 180 13 13 180 182 46 45 8 47 29 31 23 23 17 19 15 15 182 184 31 31 13 13 184 186 45 47 47 47 23 23 186 188 31 31 19 19 188 190 47 47 47 49 31 33 2:! 25 15 17 11 13 190 192 19 19 192 194 47 49 49 81 33 23 25 15 17 13 15 11 13 194 196 88 33 196 198 49 49 i 25 25 19 21 13 15 198 200 33 33 200 4 6 8 10 12 14 16 UNIVERSITY TABLE OF TWO-CIRCUIT, SINGLE WINDINGS, FOR DRUM ARMATURES. No. OF CONDUCTORS FRONT AND BACK PITCHES. No. OF CONDUCTORS 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES F B F B F B F B F B F B F B 202 40 51 8 51 33 35 25 25 19 21 17 17 202 204 l 204 206 61 51 51 58 33 35 25 27 17 17 13 13 206 208 35 35 21 21 15 15 208 210 61 68 &3 25 27 13 13 210 212 35 35 21 21 15 15 212 214 63 63 63 66 58 37 27 27 17 19 214 216 216 218 53 05 65 65 35 37 27 27 21 23 17 19 218 220 37 37 220 222 56 B 8? 27 29 21 23 15 17 13 15 222 224 37 37 224 226 i 1 37 39 27 29 19 19 15 17 13 15 226 228 23 23 228 230 67 67 i 37 55 29 29 19 19 230 2:!2 39 39 23 23 232 234 67 59 1 29 29 234 236 39 39 17 17 236 238 H 6 I 39 41 29 31 23 25 19 21 15 15 238 240 17 17 240 242 69 61 | 39 41 29 31 23 25 19 21 15 15 242 244 41 41 244 246 01 01 61 63 31 31 240 218 41 41 25 25 248 250 61 63 63 63 41 43 31 31 21 21 17 19 250 252 25 25 252 254 68 63 I 41 43 31 33 21 21 17 19 15 17 251 250 43 43 256 258 | | 31 33 25 27 15 17 258 2(10 43 43 260 2G2 | 66 7 43 45 33 33 25 27 21 2;! 262 2lil 19 19 264 200 | 67 67 43 45 33 33 21 23 266 208 45 45 27 27 19 19 268 270 67 67 til 69 33 35 17 17 270 272 45 45 27 27 272 274 67 89 58 45 47 33 35 23 23 17 17 274 276 276 278 | i 45 47 35 35 27 29 23 23 19 21 278 280 47 47 280 282 | 71 71 35 35 27 29 19 21 282 284 47 47 284 286 71 n 71 73 47 49 35 37 23 25 17 19 280 288 29 29 288 290 71 18 13 73 47 49 35 37 23 25 17 19 290 292 49 49 29 29 21 21 292 294 5 78 ?! 37 37 294 296 49 49 21 21 296 298 7* | 49 51 37 37 29 31 25 25 298 300 300 4 ' 6 8 40 12 14 16 TABLE OF TWO-CIRCUIT, SINGLE WINDINGS, FOR DRUM ARMATURES. No.OF CONDUCTORS FRONT AND BACK PITCHES No.OF CONDUCTORS 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES F B F B F B F B F B F B F B 302 75 77 49 51 37 39 29 31 25 25 19 19 302 304: 51 51 304 306 7T II 37 39 21 23 19 19 306 308 51 51 31 31 308 310 77 71 79 51 53 39 39 25 11 21 23 310 31'2 31 31 3ll> 314 71 79 19 7U 51 53 89 39 25 27 314 316 53 53 316 318 19 7U 79 81 39 41 31 33 19 21 318 320 53 53 23 23 320 322 71) si Bl 81 53 55 39 41 31 33 27 27 19 21 322 324 23 23 324 326 si 81 81 83 53 55 41 41 27 27 326 328 55 55 33 33 328 330 81 83 B 83 41 41 330 332 55 55 33 33 332 334 if 83 S5 55 57 41 43 27 29 23 25 21 21 334 336 336 338 83 86 85 86 55 57 41 43 33 35 27 29 23 25 21 21 338 340 57 57 310 342 85 86 tf5 gj 43 43 33 35 342 344 57 57 344 346 85 87 87 87 57 59 43 43 29 29 346 348 35 35 25 25 348 350 87 87 87 57 69 43 45 29 29 2\ 23 350 352 59 59 35 35 25 25 352 354 87 89 89 89 43 45 21 23 354 356 59 59 356 358 89 89 89 Ul 655 61 45 45 35 37 29 31 358 360 360 362 t!'J 91 '.'1 111 59 61 45 45 35 37 29 31 25 27 362 364 61 61 364 366 91 93 45 47 25 27 23 23 3i;i; 368 .61 61 37 37 368 370 n 03 93 g 61 63 46 47 31 31 23 23 370 372 37 37 372 374 93 8 61 03 47 47 31 31 374 376 68 63 27 27 376 378 93 95 ui '.'."i 47 47 37 39 378 380 63 63 27 27 380 382 05 9u 97 63 65 47 49 37 39 31 33 23 25 382 384 384 386 95 97 97 07 63 65 47 49 31 33 23 25 386 388 65 65 39 39 388 390 97 97 n 99 49 49 27 29 390 392 65 65 39 39 392 394 9 :;\ 422 l-l 71 71 424 426 107 1U7 107 53 53 426 428 71 71 43 43 428 430 107 107 107 109 71 73 53 55 35 37 27 27 430 432 43 43 31 31 432 434 107 109 109 109 71 73 53 55 35 37 27 27 434 436 73 73 :;i 31 436 4:js 109 109 10 in 5V) 55 43 45 438 440 73 73 440 1 \'2 109 111 111 in 7:; 75 55 55 43 45 37 37 442 444 444 446 111 111 111 113 73 75 55 57 37 37 31 33 27 29 446 448 75 75 45 45 41 S 450 111 113 113 113 55 57 31 33 27 29 450 I .v_> 75 75 45 45 452 454 113 113 113 115 75 77 57 57 37 39 454 456 456 458 113 115 116 115 75 77 57 57 45 47 37 .;'. 458 460 77 77 33 33 460 462 11& 115 115 117 57 59 45 47 29 1><) 462 464 77 77 33 33 464 466 116 117 117 11T 77 79 57 59 39 39 29 29 466 468 47 47 468 470 117 117 117 119 77 79 59 59 39 39 470 472 79 79 47 47 472 474 117 lift 11V 11U 59 59 33 35 474 476 79 79 476 478 ll'J i: i 119 121 79 81 ,VJ 61 47 49 39 41 88 35 29 31 478 ISO 480 is-J 121 121 121 79 81 59 61 47 !'.) 39 41 29 31 482 1SI 81 81 484 IM; i: 1 121 121 123 61 61 486 488 SI 81 49 49 35 35 488 490 121 123 123 123 81 83 61 61 II 41 490 I!I2 49 49 35 35 492 I'.M 123 123 123 125 81 83 61 63 41 41 31 31 494 496 83 83 496 498 B 125 i: 125 61 63 49 51 31 31 4S)8 500 83 83 500 4 6 8 10 12 14 16 TABLE OF TWO CIRCUIT, SINGLE WINDINGS, FOR DRUM ARMATURES. CO (E O l~ FRONT AND BACK PITCHES No. OFCONDUCTORS r CONDUC 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES O 6 z F B F B F B F B F B F B F B 502 1-J5 m 125 Ifi 83 85 63 63 49 51 41 43 35 37 502 504 504 506 IB 127 127 83 85 63 63 41 43 35 37 506 508 85 85 51 51 508 510 127 Hi? 127 120 63 65 31 33 510 512 85 85 51 51 512 514 uv 1-J'J lay 129 85 87 63 65 43 43 31 33 514 516 37 37 516 518 in 12'J ui 85 87 . 65 65 51 53 43 43 518 520 87 87 37 37 520 522 iiiu m 23 65 65 51 53 522 524 87 87 524 526 j3i . ui {33 87 89 65 67 43 45 33 33 526 528 53 53 528 530 IB 133 133 133 87 89 65 67 43 45 37 39 33 33 530 532 89 89 53 53 532 534 133 133 1311 135 67 67 37 39 534 536 89 89 536 538 136 13 135 89 ill 67 67 53 55 45 45 538 540 540 542 136 135 135 137 89 91 67 69 53 55 45 45 33 35 542 544 91 91 39 39 544 546 137 137 13' 67 69 33 35 546 548 91 91 55 55 39 39 548 550 137 13T 137 1311 91 m 69 69 45 47 550 552 55 55 552 554 137 131* 139 >38 91 93 69 69 45 47 554 556 93 93 556 558 UB 13 99 99 59C, 598 i 151 99 101 75 75 59 61 49 51 51)8 600 43 43 600 4 6 8 10 12 14 16 TABLE OF TWO CIRCUIT SINGLE WINDINGS FOR DRUM ARMATURES. No. Of CONDUCTORS FRONT AND BACK PITCHES No. OF CONDUCTORS 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES F B F B F B F B F B F B F B 602 149 161 161 151 99 101 75 75 59 61 49 51 002 604 101 101 43 43 604 606 ill 161 163 75 77 37 39 606 608 101 101 61 61 608 610 IB l&S 1W 163 101 103 75 77 51 51 37 39 010 612 61 61 612 OM I.--: 163 B 166 101 103 77 77 51 51 43 45 6U jiir, 103 103 616 618 163 165 155 166 77 77 61 63 43 45 018 620 103 103 620 622 165 155 165 167 103 105 77 79 61 63 51 53 39 39 0-22 624 024 626 { 167 167 157 103 105 77 79 51 53 39 39 026 628 105 105 63 63 45 45 628 630 167 167 157 151) 79 79 630 632 105 105 63 63 45 45 (532 634 157 168 15 105 107 79 79 53 53 634 636 636 638 m 16 ! 105 107 79 81 63 65 53 53 39 41 638 010 107 107 040 642 16 101 01 01 79 81 63 65 45 47 39 41 042 644 107 107 644 646 101 161 01 M 107 109 81 81 53 55 45 47 646 648 65 65 648 650 101 103 63 68 107 109 81 81 53 55 650 652 109 109 65 65 652 654 tea 108 68 06 81 83 41 41 054 050 109 109 47 47 656 G5S 103 106 | 109 111 81 83 65 67 55 55 41 41 658 660 47 47 000 6(i2 106 106 66 07 109 111 83 83 65 67 55 55 602 001 111 111 001 666 165 10T 107 167 83 83 GOO 668 111 111 67 67 OOS 670 107 109 111 113 83 85 55 57 47 49 41 43 070 672 67 67 672 674 107 109 169 169 111 11:5 83 85 55 57 47 49 41 43 674 676 113 113 676 07S 109 160 10U 171 85 85 67 69 678 680 113 113 680 682 iTl !?! 113 115 85 85 67 69 57 r,7 682 684 49 49 684 686 in 171 173 113 115 85 87 57 57 43 43 681) 688 115 115 69 6!) 49 4'.) 088 690 ITl 178 17S 173 85 87 43 43 690 692 115 115 69 69 692 694 ITS 178 n 176 115 117 87 87 57 59 694 696 696 698 178 176 176 ITi 115 117 87 87 69 71 57 59 49 51 698 700 117 117 700 4 6 8 10 12 14 16 TABLE OF TWO CIRCUIT SINGLE WINDINGS FOR DRUM ARMATURES. No. OF CONDUCTORS FRONT AND BACK PITCHES. CO o: i- 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES No. OF CONDUC F B F B F B F B F B F B F B 702 17:i 175 170 177 87 SD 69 71 49 51 43 45 702 704 117 117 704 706 175 177 177 177 117 111) 87 89 59 59 43 45 706 708 71 71 708 710 177 177 177 179 117 11!) 89 89 59 59 710 712 119 119 71 71 51 51 712 714 1T7 179 17'J 179 89 89 714 716 119 Hi) 51 61 716 718 179 17& ISt 119 121 89 91 71 73 59 61 45 45 718 720 720 722 17'J 181 181 11 li 121 89 91 71 73 59 61 45 45 722 724 121 121 724 726 ISl 183 91 91 51 53 726 728 121 121 73 73 728 730 na 163 121 123 91 91 61 61 51 53 730 . 732 73 73 732 734 nw 185 121 123 91 93 61 61 45 47 7J34 736 123 123 736 738 n 183 91 93 73 75 45 47 738 740 123 12:i 53 53 740 742 isj 187 123 125 93 93 73 75 61 63 742 744 53 53 744 746 17 187 123 126 93 93 61 63 746 748 125 125 75 75 748 750 187 lay 93 95 47 47 750 752 125 125 75 75 752 754 189 189 ISO 125 127 93 95 63 63 53 55 47 47 754 75i ; 756 758 isu iyi 125 127 95 95 75 77 63 63 53 55 758 760 127 127 760 762 ibu Iffl 191 95 95 75 77 762 764 127 127 764 76G 1UI 193 127 129 96 97 63 65 47 49 766 768 77 77 55 55 768 770 193 193 193 127 129 95 97 63 65 47 49 770 772 129 129 77 77 55 55 772 774 IH 193 IH . Ji 97 97 774 776 129 129 776 77* 1U' 195 129 131 97 97 77 79 65 65 778 780 780 782 IN 197 129 131 97 99 77 79 65 65 55 57 49 49 782 784 131 131 784 786 11*7 197 97 99 55 57 49 49 786 788 131 131 79 79 788 790 W iyy 131 133 99 99 65 67 790 792 79 79 792 794 100 199 131 133 99 99 65 67 794 796 133 133 57 57 796 798, 109 2D1 99 101 79 81 I!) 51 798 800 133 133 57 57 800 4 6 8 10 12 14 16 WINDING TABLES FOR TWO-CIRCUIT, DOUBLE WINDINGS FOR DRUM ARMATURES. TABLE OF TWO-CIRCUIT, DOUBLE WINDINGS, FOR DRUM ARMATURES. No.OF CONDUCTORS FRONT AND BACK PITCHES CO B o 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES CONDUC1 F RE- [NTRANC B F ENTRANC B F RE- ENTRANC B F RE- ENTRANC B F RE- B F RE- B F RE- ENTRANC B O 6 z 102 7 GD 7 102 104 ^'a GO J5 17 00 19 9 00 11 9 GD 9 104 106 17 GD 17 11 GO 11 106 108 r- oo 27 22 15 SS 13 Q 7 00 9 7 GD 7 108 110 19 GD 1!) 110 112 H GD R 17 CO 19 9 GO 9 112 114 11 GO 11 114 116 00 B 31 19 00 21 13 15 15 15 11 oo 13 9 00 11 7 00 9 7 OD 7 116 US 19 OO 19 118 120 31 GO 81 120 122 21 00 21 9 OD 9 122 124 29 31 00 | 19 00 21 15 13 *8 B 11 oo 13 9 00 11 7 00 9 m 126 13 GO 13 126 128 ill 33 CO 31 33 21 00 23 11 (3D 11 128 130 21 GO 21 9 GD 9 130 132 31 33 00 83 35 i? 4 17 17 7 oo 9 132 134 23 GO 23 13 GD 13 134 136 33 85 GO 33 35 21 00 23 13 oo 15 11 GD 11 9 oo 11 136 138 138 140 33 35 00 9 37 23 oo 25 17 17 n 17 19 11 00 13 9 GD 9 140 142 23 GD 23 142 144 35 37 GD 35 87 13 oo 15 9 oo 11 144 146 25 GD 25 15 GD 15 146 148 3J 37 00 37 3V 23 oo 25 17 1'J %s H 19 a 00 13 9 GD 9 148 150 11 GD 11 150 152 87 39 GD 37 gj 25 00 27 13 GD 13 152 154 25 GO 25 15 GO 15 154 156 37 39 00 39 41 19 19 iV8 19 2\ 15 00 17 9 00 11 156 158 27 00 27 11 GD 11 158 160 3? GD 30 41 25 00 27 13 GD 13 160 162 162 164 39 11 00 41 4U 27 oo 29 ID 21 S 21 15 oo 17 13 00 16 11 00 13 9 00 11 164 166 27 GO 27 17 GD 17 166 168 41 4:1 GO 4tf 168 170 29 GO 29 170 172 41 43 00 43 45 27 oo 29 21 21 S ft 13 00 15 11 00 13 11 GD 11 172 174 17 GO 17 174 176 u OO 4:1 46 29 00 31 17 00 19 15 GD 15 176 178 29 OO 29 13 GD 13 178 180 fl 45 oo 1? 21 2-1 %8 11 11 GD 11 180 182 31 OO 31 182 184 5 s OO 3 17 29 oo 31 17 00 19 15 GD 15 184 186 19 GD 19 13 GD 13 186 188 45 47 00 47 4V 31 oo 33 28 23 W 23 25 15 00 17 11 00 13 188 190 31 GO 31 190 192 I 00 47 40 13 oo 15 102 194 33 CD 33 12 GD 19 104 196 I 00 49 51 31 00 33 23 25 8 2:, - 25 19 00 21 15 oo 17 11 00 13 196 198 198 200 4!) 51 GD g 33 00 35 17 GD 17 13 oo 15 WO 4 6 8 10 12 14 16 TWO-CIRCUIT, DOUBLE WINDINGS, FOR DRUM ARMATURES. No. OF CONDUCTORS FRONT AND BACK PITCHES c/> 33 202 204 If 00 8 25 26 to | 19 OO 21 13 CE) 13 204 '200 35 CE> 35 21 CD 21 15 (SL> 15 206 208 i CO 53 33 00 35 17 GO 17 208 210 210 212 I 00 I 35 oo 37 1 & 27 27 17 oo 19 13 (3D 13 212 214 35 GO 35 21 GO 21 15 CE> 15 214 2 1C It CE> B 21 00 23 210 218 37 CD 37 218 220 B 00 I 35 00 37 9 m i 17 oo 19 15 oo 17 13 oo 15 220 222 222 224 1 CE> B 37 00 39 21 00 23 19 GO 19 22-1 22C, 37 CE> 37 23 GD 23 220 228 1 67 00 u B %8 n 15 oo .17 13 00 15 228 230 39 GO 39 230 2:12 I CE> B 37 oo 39 19 CD 10 232 234 23 GD 23 17 CJD 17 234 230 B oo 1 39 oo 41 I *8 B 23 00 25 19 oo 21 15 CJD 15 236 2:58 39 CJD 39 238 240 1 GO l 240 242 W 41 CD 41 17 CJD 17 242 B 00 H 39 00 41 26 81 S i 23 oo 25 19 oo 21 15 CE> 15 244 240 25 CO) 25 210 248 08 GD 1 41 oo 43 21 CD 21 17 00 19 248 250 41 GO 41 250 '252 1 oo 1 31 B 81 31 :<', 15 oo 17 252 254 43 GO 43 25 GO 25 251 25(1 B GD g 41 00 43 25 oo 27 21 GV> 21 17 oo 19 250 "258~ 258 260 B oo 8 43 oo 45 B & B 21 00 23 15 00 17 200 202 43 GO 43 19 CE> 19 262 2(i4 B GD or 25 oo 27 264 2liti 45 CE> 45 27 ru) 27 266 268 u 67 00 I 43 oo 45 | m 21 00 23 17 GO 17 268 U70 19 CE) 19 270 2V 2 & GO B 45 oo 47 23 CE) 23 272 274 45 GO 45 27 CD 27 274 2Vf, Si oo B 71 B % 27 oo 29 19 oo 91 17 GD 17 976 278 47 CO) 47 278 280 ?? GO 11 45 oo 47 93 CE> 93 280 282 989 284 69 71 oo i 47 00 49 n 27 oo 99 93 oo 95 19 00 91 17 oo 19 984 280 47 GO 47 29 CE) '211 986 288 i GO IS >ss 290 49 GO 49 91 CJD 91 >1IO 292 71 73 00 78 76 47 00 49 B s& i 93 oo 95 17 oo 19 >9-2 294 29 CD 29 204 296 it GO B 49 oo 51 29 oo 31 95 C5") 95 200 298 49 GO 49 91 GD 9 1 298 300 75 oo 77 a #8 87 39 19 GD 19 300 4 6 8 10 12 14 16 TWO-CIRCUIT, DOUBLE WINDINGS, FOR DRUM ARMATURES. No. OF CONDUCTORS FRONT AND BACK PITCHES CONDUCTORS 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES F :TM~.C, B F RE- B F RE- ENTRANC B F EI.TM~.CY B F RE- NTHANCY B F RE- ENTRANCY B F RE- ENTRANCY B O o Z 302 51 CD 51 302 304 "5 77 CD -7 49 oo 51 29 00 31 25 GO 25 21 00 23 304 306 31 CD 31 306 308 7! 00 a 51 00 53 I W B 25 00 27 19 CD 19 308 310 51 CD 51 310 312 77 79 GO 3 21 00 23 312 314 53 CD 53 31 CD 31 314 316 n 00 g 51 oo 53 3 39 SB 1 31 oo 33 25 00 27 19 00 21 316 318 23 CD 23 318 320 i CD ^ 53 00 55 27 CD 27 320 A-l-1 58 CD 53 322 324 H oo 8 ?? W a 31 00 33 19 oo 21 324 326 55 CD 55 33 CD 33 23 CD 23 326 328 u 83 CD i 53 00 55 27 CD 27 328 330 330 332 HI 83 00 8? 86 55 oo 57 41 S8 1 27 00 29 23 oo 25 21 CD 21 332 334 55 CD 55 33 CD 33 334 336 8" CD I 33 oo 35 336 338 57 CD 57 338 340 i 00 i? 55 oo 57 i t& 43 43 27 oo 29 23 00 25 21 CD 21 340 342 342 344 i GO 1 57 00 59 33 00 35 29 CO 29 344 346 57 CD 57 35 CD 35 25 CD 25 34G 348 i 00 i S3 W i 21 oo 23 348 350 59 CD 59 350 352 i GO I 57 oo 59 29 CO 29 352 354 35 CD 35 2B CD 25 354 356 i oo SB ui 59 oo 61 %8 8 35 oo 37 29 oo 31 21 oo 23 356 358 59 CD 59 358 360 i CD 39 fll 25 00 27 3GO 362 61 CD 61 302 364 89 | oo 93 59 oo 61 8 S8 i 35 oo 37 29 00 31 23 CD 23 364 366 37 CD 37 366 368 91 03 CD 91 0:1 61 00 63 31 CO 31 25 oo 27 308 370 61 GO 61 370 372 H 93 oo i 45 47 as 7 47 23 CD 23 372 374 63 CD 63 37 CO 37 27 CD 27 374 376 1 CD 61 00 63 37 oo 39 31 CD 31 376 378 378 380 | 00 95 tt7 63 00 65 1 #8 47 49 31 00 33 23 00 25 380 382 63 GO 63 27 CO 27 382 384 1 GO lit 37 oo 39 384 386 65 CiD 65 39 GD 39 386 388 95 97 00 % 63 00 65 I IB | 31 oo 33 27 00 29 23 00 25 388 390 390 392 97 99 CD Si 65 00 67 33 CD 33 392 394 65 CD 65 39 CO 3"9 394 396 H oo 3 i 8 I 39 oo 41 27 00 29 25 GO 25 396 398 67 CD 67 398 400 ifl GO | 65 00 67 33 GO 33 400 4 6 8 10 12 14 16 TWO-CIRCUIT, DOUBLE WINDINGS, FOR DRUM ARMATURES. No.OF CONDUCTORS FRONT AND BACK PITCHES CO tr o 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES CONDUC F RE- LNTRANC1 B F RE- ;NTRANC> B F RC- ENTRANCY B F RE- ENTRANCY B F ENTRANC B F :.TRANCr B F RE- ENTRANC B o 6 z. 402 29 Cft) 29 402 lot oo 115 67 OO 69 l %8 i 39 OO 11 33 OO 35 25 GO 25 404 406 67 C53 67 41 ca) 41 406 408 I CB i$ 408 410 69 ca) 69 29 Cft) 29 410 112 M 00 IS 67 oo 69 51 61 a* B 58 33 oo 35 25 00 27 112 414 41 ro 41 414 416 1 GO IS 69 oo 71 41 00 43 35 o 35 29 00 31 416 418 69 C5) 69 418 120 i oo S* I 58 63 63 25 00 27 420 422 71 ca> 71 122 424 iffi ro) 106 1UT 0!) oo 71 41 00 43 35 GO 35 29 oo 31 421 120 12 W 73 oo 75 37 Cft) 37 440 112 73 Cft) 73 442 444 109 111 oo in 113 i *8 .... 67 43 00 45 31 oo 33 27 oo 29 111 IK; 75 C5) 75 45 CO) 45 416 448 111 11* C5) 111 Q] 73 oo 75 37 GO 37 448 150 450 .152 {15 00 113 116 75 00 77 R ^ II 37 oo 39 31 oo 33 27 00 29 452 .15-1 75 Cft) 75 45 Cft) 45 454 456 11 : Hi Cft) 113 115 45 oo 47 456 458 77 Cft) 77 33 Cft) 33 458 460 113 115 oo H 75 oo 77 1 S8 B 37 oo 39 29 GO 29 460 162 102 464 ii? Co) i 77 oo 79 45 00 17 39 Cft) 39 464 Kit; 77 GO 77 47 GO 47 33 Cft) 33 466 468 i!? oo 117 lift i j | 29 Cft) 29 468 470 79 C 79 170 472 117 119 OO fii 77 oo 79 39 GO 39 33 oo 86 172 474 47 Cft) 47 474 476 i oo 18 79 oo 81 B 47 00 49 39 oo 41 29 oo 31 476 478 79 Cft) 79 178 480 Cft) 119 121 33 oo 35 180 482 81 CO 81 182 181 119 121 oo 121 12:1 79 oo 81 1 fi Q 61 47 oo 49 39 oo 11 29 oo 31 181 180 49 Cft) 49 35 Cft) 35 48li 488 121 <;; CD ffi 81 oo 83 41 GO 41 188 490 81 ca) 81 490 492 I oo ffl a ffl & 31 (S3 31 192 494 83 rr> 83 49 cm 49 35 Cft) 35 494 496 133 1*6 GO 123 125 81 oo 83 19 00 51 41 Cft) 41 196 498 198 500 i 00 126 127 83 oo 85 a &S 03 (. ; 41 oo 43 35 oo 37 31 Cft) 31 500 4 6 8 10 12 14 16 TWO-CIRCUIT, DOUBLE WINDINGS, FOR DRUM ARMATURES. No. OF CONDUCTORS FRONT AND BACK PITCHES CONDUCTORS 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES F RE- B F RE- ENTRANCV B F ENTRANCY B F ENTRANCE B F RE- B F BE- ENTRANCY B F RE- ENTHANCY B O z 502 83 GD 83 502 504 126 m (33 i 9 00 51 504 506 85 (33 85 51 fo) 51 506 508 125 r.7 oo 127 129 83 00 85 03 03 SB 63 05 41 00 43 35 OO 37 31 OO 33 508 510 510 512 127 129 C53 127 129 85 00 87 43 GO 43 512 514 85 (33 85 51 rs3 51 37 GD 37 514 51 G It] 129 oo 1$ 63 65 &S 05 05 51 oo 53 31 00 33 516 518 87 (33 87 518 520 12B (33 I 85 00 87 43 fa) 43 520 522 37 GO 3V 522 524 1 oo ffl 87 00 89 1 SB i 51 00 53 43 00 45 33 GD 33 52-1 526 87 GO 87 53 fE) 53 526 528 131 133 rT> 131 133 37 oo 39 528 530 89 GD 89 530 532 131 133 oo 133 135 87 00 89 i &S 61 07 43 00 45 33 (33 33 532 534 53 (S3 53 534 536 i fa) 133 135 89 00 91 53 oo 55 45 GD 45 37 oo 39 536 538 89 ra) 89 5i!8 540 i oo 136 137 07 67 SB i 33 00 35 540 542 91 fa) 91 39 GO 39 542 544" 135 137 (3) 135 137 89 00 91 53 00 55 45 fa) 45 544 54G 55 (33 55 540 518 135 137 oo 137 139 91 00 93 8 as 45 oo 47 33 oo 35 548 550 91 ra) 91 39 GO 39 55(1 552 i GD la: 552 554 93 CD 93 55 (33 55 554 556 ! 00 \8 91 oo 93 1 SB ?! 55 oo 57 45 oo 47 39 oo 41 35 GO 35 556 558 558 560 ffi GD ffl 93 00 95 47 fft3 47 560 562 93 (33 93 562 501 ffl 00 I B %8 a 55 oo 57 39 oo 41 35 GD 35 564 566 95 ra) 95 57 (33 57 5G6 568 i GD iU 93 00 95 47 fa3 47 5GS 570 41 GD 41 570 572 & CO 143 145 95 00 97 71 H ffl a 47 oo 49 35 oo 37 572 574 95 GD 95 57 r3 57 574 57G 143 145 ra) 143 n;> 57 oo 59 57G 578 1)7 fa) 97 41 ro) 41 578 580 143 146 00 145 147 95 00 97 i fig 78 73 47 oo 49 35 oo 37 580 582 582 584 145 147 (S3 145 147 97 00 99 57 00 59 49 fa3 49 41 oo 43 584 586 97 GD 97 59 (33 59 586 588 110 147 00 147 149 i SB ,S 37 GD 37 588 590 99 ra) 99 590 592 147 149 GD 147 149 97 00 99 49 (33 49 41 oo 43 592 594 59 (33 59 591 596 147 H9 00 149 151 99 00 101 ?S &S 7 7. 69 00 61 49 oo 51 37 (33 37 59G 598 99 GD 99 43 GD 43 598 600 161 GD 151 GOO 4 6 8 10 12 14 16 TWO-CIRCUIT, DOUBLE WINDINGS, FOR DRUM ARMATURES. No. OF CONDUCTORS FRONT AND BACK PITCHES a> cc o 1- 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES CONDUC F RE- ENTRANCV B F RE- EMTRAMO B F RE- ENTRANCY B F RE- ENTRANCY B F RE* ENTRANCY B F ENTRAMCY B F RE- ENTRANC B O 6 z 602 101 GO 101 602 604 $ oo m 99 oo 101 i SB i 59 OO 61 49 00 51 37 OO 39 604 MX; 61 (5) 61 43 OO 43 606 r.iis I GO is 101 oo 103 51 OO 51 608 roo 101 (5) 101 610 612 161 158 oo 18 i 48 43 00 45 37 oo 39 012 614 103 (S3 103 61 00 61 014 616 HI 165 GO S 101 oo 103 61 00 63 51 OO 51 616 618 618 620 m oo m 103 oo 105 77 77 & 77 79 51 oo 53 43 00 45 n GO 39 620 622 103 GO 103 622 624 m 167 (S3 1 61 oo 63 624 626 J05 CO) 105 63 GO 63 45 OO 45 626 628 HI oo 167 169 103 00 105 77 79 as 79 79 51 O 53 39 OO 39 628 630 630 632 167 16 (S3 167 169 105 oo 107 53 00 53 632 63"4 105 (S3 105 63 00 63 45 GO 45 634 0:10 I oo ffi S 79 81 63 oo 65 39 oo 41 636 638 107 00 107 638 (MO 16 101 (30 15V 101 105 oo 107 53 GO 53 45 00 47 640 642 642 644 ffi oo tt 107 oo 109 i as fl 63 00 65 53 oo 55 39 oo 41 644 040 107 oo 107 65 ro> 65 040 648 I (S3 i 45 oo 47 048 650 109 oo 109 050 652 ft oo 18 107 00 109 | Mj 1 53 oo 55 41 00 41 652 654 65 00 65 47 00 47 054 656 i GO $ 109 00 111 65 oo 67 55 OO 55 050 058 109 go 109 058 660 ',.'. oo at 3 as | 41 GO 41 660 662 111 (53 111 47 OO 47 662 664 i GO 106 107 109 oo 111 65 oo 67 55 GO 55 004 666 67 OO 67 666 668 B .0 167 1G 111 00 113 i ss ,: 55 57 47 00 49 41 00 43 008 670 111 OO 111 070 672 % (53 672 674 113 (S3 11:5 67 GO 67 074 676 1C7 1C9 oo i 111 00 118 B aj I 67 00 69 55 oo 57 47 oo 48 41 oo ,43 676 6V8 078 080 fi (SO 113 oo 115 57 GO 57 080 (182 113 GO 113 49 GO 49 082 <;s t 18 00 171 i,-; ; SB Si 67 oo 69 43 GO 43 084 G8C 115 CO 115 69 GO 69 686 68J a GO i 113 oo 115 57 00 57 088 C'.M) 49 OO 49 091) 092 a ;- lit 115 00 117 % &3 87 B 57 oo 59 43 (i) 43 092 094 115 GO 115 69 GO 69 094 696 in 176 GO 173 i 176 69 oo 71 49 00 51 090 6 ( J 117 OO 117 098 700 i oo 176 177 115 00 117 | W 1 57 00 51) 43 oo 45 700 4 6 8 10 12 14 16 TWO-CIRCUIT, DOUBLE WINDINGS, FOR DRUM ARMATURES. No. OF CONDUCTORS FRONT AND BACK PITCHES CO CE O 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES CONDUC" F RE- B F RE- ENTHArCV B F ENTRANCY B F RE- ENTRANCY B F tNTHANCY B F RE- ENTRANCV B F RE- ENTRANCV B o 6 Z 702 702 704 17o 177 GO ITS 177 117 OO 119 69 OO 71 59 CD 59 49 OO 51 704 706 117 rg) 117 71 C5) 71 706 708 I oo 177 179 i cS i 43 OO 45 708 710 119 CP 119 51 fa) 51 710 712 ffi fa) 177 179 117 119 59 CE> 59 712 714 71 52 71 714 716 iS oo IV'.' iai 119 oo 121 i S8 9 71 oo 73 59 oo 61 45 CO) 45 716 718 119 fp 119 51 (5) 51 718 720 m ffi) 119 720 722 121 CP 121 722 724 is oo 181 183 119 oo 121 i as i 71 00 73 59 oo M 51 oo 53 45 C 45 724 726 73 OD 73 726 728 181 183 CP 181 UP 121 00 123 61 nn 61 728 730 121 (V 121 730 732 181 183 oo 183 gj & 8 8 51 oo 53 45 oo 47 732 734 123 CP 123 73 OC 73 734 736 l$B ..:_-'>_ CP 188 1H1 121 00 123 73 oo 75 61 C9) 61 736 738 53 CD 53 738 740 183 '1H6 oo 186 '187 123 00 125 i 8 ^ 61 oo <;:>, 45 oo 47 740 742 123 fp 123 742 714 185 187 CP 186 187 73 oo 75 744 746 125 (V 125 75 rs? 75 53 fp 53 746 748 185 187 00 i 123 00 125 93 98 8 i 61 00 63 47 GD 47 748 750 750 752 187 18 fp ffi 125 oo 127 63 CP 63 53 oo 55 752 754 125 cp 125 75 2 75 754 756 J87 189 oo 189 191 93 95 %8 8 75 oo 77 47 CD 47 756 758 127 CP 127 758 760 .189 m CO) 189 191 125 00 127 63 fa) 63 53 oo 55 760 762 762 764 i>'j 191 oo .191 193 127 oo 129 95 95 ffl i 75 00 77 63 00 65 47 00 49 764 766 127 CP 127 77 rso 77 55 ca) 55 766 768 m m CP 191 193 768 770 125 fa) 129 770 772 00 193 195 127 00 129 95 97 ! 5i 63 oo 65 47 00 49 772 774 77 (ID 77 55 fp 55 774 776 g m 193 JOB 129 00 131 77 00 79 65 B 4,7 21 CM? 23 11 (55) 11 182 183 19 (98) 19 184 186 I ooo 46 49 1? %$ 31 33 23 ooo 25 17 ooo 19 16 15 ?^ 16 11 000 13 186 188 13 (55) 13 188 J90 8 Cas) 47 49 23 (9,9) 23 13 (55) 15 1 190 192 i CojQ OTTO 31 33 192 194 47 49 (sa) I 25 (9(0 25 19 (59) 2] 1 94 196 19 (55) 19 196 198 M ooo g 33 (W> 23 ooo 25 16 17 s U 17 11 000 13 198 200 200 4 6 8 10 12 14 16 TABLE OF TWO-CIRCUIT, TRIPLE WINDINGS, FOR DRUM ARMATURES. No. OF CONDUCTORS FRONT AND BACK. PITCHES CO E 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES CONDUC" F RE- ENTRANCI B F RE- B F HE- ENTRANCY B F RE- ENTRANCV B F RE- EHTRANCY B F RE- ENTRANC B F ET"NC B O d Z 202 I (55) 49 63 25 (55) 27 13 (55) 15 13 (aa> 13 202 204 is BBS 1 21 OOO 21 15 ooo 15 204 206 8 (55) I 25 (W> 25 19 r?5) 21 20(5 208 208 210 1 ooo 1 3 fSXi OTTO 86 37 27 ooo 27 {? S^ \i 210 212 212 214 B (as) If 25 (55) 27 21 (as) 23 13 (55) 13 214 216 35 37 (55) 86 37 21 ooo 21 15 ooo 15 216 218 1 (55) | 27 (55) 29 15 f9~) 17 13 ^55) 15 218 1220 220 222 1 ooo i % OOP G33 B 27 000 27 17 H ass u IV 222 224 23 (55) 23 224 226 u u (99") B 29 Coo) 29 21 (99) 23 226 22S XI 39 oVo ,-. so 228 230 1 (to g 27 17 232 '234 67 6 ooo i ! (55) i 29 ooo 31 23 ooo 25 i ^ B 15 000 15 234 236 23 f99) 23 236 238 i (99) 8? 29 (99) 29 238 240 I S? 1 240 242 B (99> 8 31 (55) 31 242 244 25 (95) 25 17 (55) 17 244 210 H ooo B 1 oVo 41 43 29 ooo 31 23 ooo 25 B trtfo | 17 000 19 15 000 15 240 -is 248 250 01 63 (98) 1 31 (99^ 33 15 (aa) 17 250 252 41 43 (55) 41 48 252 254 3 5 <5S) B 31 C99) 31 25 (aa) 27 254 250 25 (55) 25 256 258 ! ooo 1 41 43 g& 8 B8 ooo 33 21 |J aft? is 17 ooo 19 258 260 19 (99) 19 2(iO 262 62 n (aa) i 31 aiD 33 15 (aa) 17 262 2(14 B WTO B 27 000 27 2(5-1 26(3 I (55) 06 69 33 rofl) 35 25 (55) 27 17 (W) 17 2(i 1 21 000 21 288 290 B (55) 75 37 (98) 37 .".Ml 295 292 294 i ooo '7! 4B j3 49 61 35 ooo 37 29 ooo 31 23 W | 17 000 19 994 296 29 (55) 29 296 298 73 75 (55) B 37 (89) 39 19 J2)_ V) 998 300 B irVi 4U 61 21 ooo fll 300 4 6 8 10 12 14 16 TABLE OF TWO-CIRCUIT, TRIPLE WINDINGS, FOR DRUM ARMATURES. No. OF CONDUCTORS FRONT AND BACK PITCHES No.OF CONDUCTORS 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES F E i"rcv B F ENTHANCV B F RE- ENTRANCY B F EKTMNCY B F RE- B F RE- ENTRANCY B F ENTRANCY B 302 n 77 (55) 75 77 37 (55) 37 21 (22) 23 302 304 31 (55) 31 304 306 75 77 OOJ R 70 i (99) I 39 ooo 39 29 000 31 ::.. 26 ^S i 306 308 308 310 7 (55) i 37 (<39) 39 19 (99") 19 310 312 a u ^ 53 312 314 77 79 (29) 77 B 39 (82) 41 31 (55) 33 21 faa) 23 19 (89") 21 314 316 31 (99) 31 23 (99) 23 316 318 i ooo n u & se% R 39 ooo 39 25 'J7 SV? i 318 320 320 322 o jn f 79 H 41 (asD 41 322 324 8 (58) ^ 33 ooo 33 324 326 7 S3 (22) 81 S3 39 (2S) 41 31 (2S) 33 19 (22) 21 326 328 n (92) 23 328 330 1 ooo S g ^ S ' 41 ooo 43 :, 27 jDJiO E 23 ooo 25 21 ooo 21 330 332 332 334 i (99) n 86 41 (99) 41 33 (22) 35 334 336 | GTS ooo 56 67 33 000 33 336 338 "4 (99) 43 r?g) -13 338 340 340 342 B ooo B 56 57 (99) B 41 ooo 43 E ;-.:, ?';: 23 oor. 25 21 ooo 21 342 344 35 (99) 86 25 (55) 25 344 346 85 87 (5?) 8, r . B 43 (55) 45 33 (22) 35 21 (99) 23 346 348 n H ^ | 348 350 85 89 (5?) fl H 43 (9B) 43 350 352 352 354 87 H ooo 87 91 ;: 69 S,;-J 69 SI 4J 000 45 35 000 37 I S^J i 354 356 35 (55) 35 25 (55) 25 356 358 87 Ul (551 91 43 fas) 45 25 (5) 27 21 (92) 23 358 360 0? (aa) B el 360 362 8 (59) 89 98 45 (as) 47 23 (22) 23 362 364 37 (99) 37 364 366 89 93 000 91 H H 61 sag 01 03 45 ooo 45 35 ooo 37 t 8K i 366 368 368 370 91 '.'.; (55) 91 B 47 (29) 47 25 (99) 27 370 372 B S3 oVo 01 03 27 ooo 27 372 374 H '.... (55) 93 96 45 Caa) 47 37 (55) 39 23 (99) 23 374 376 37 (55) 37 370 37S 93 B ooo 93 97 I (90) S 47 000 49 i 81 88 23 000 25 378 380 380 382 93 87 (55) B 47 (as) 47 382 384 | SiS 1 39 ooo 39 27 ooo 27 381 386 95 97 (99) 95 99 49 (as) 49 37 (55) 39 27 (98) 29 386 388 388 390 96 9 ooo g B 05 CS/oD ooo 06 67 47 ooo 49 81 88 crtjo 88 88 23 000 25 390 392 392 394 97 Ut f99) f7 _ l"l 49 (99) 51 39 r?) 41 25 (99) 25 394 396 8? (22) 67 39 ooo 39 396 398 07 101 (58) 99 101 49 (99) 49 27 (99) 29 398 400 29 (99) 29 400 4 6 8 10 12 14 16 TABLE OF TWO-CIRCUIT, TRIPLE WINDINGS, FOR DRUM ARMATURES. No. OF CONDUCTORS FRONT AND BACK PITCHES No. OF CONDUCTORS 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES F RE- ENTRANCY B F RC- ENTRAHCY B F RE* ENTRANCV B F ENTR^Cr B F RE- ENTRANCY B F RE- CNTRANCY B F RE- ENTRANCY B 402 i 000 ,$ ?r ^ 61 51 OOO 51 as. OOO GS> S3 36 402 404 41 (99) 41 404 406 a (as) KJ 49 ( 51 39 (55) 41 25 (5a) 25 406 408 I CCQ OTJo Si 408 410 101 108 (99) us 51 (90) 53 25 iW) 27 410 412 29 (SS) 29 412 414 | ooo iisi w (aa) fl 51 ooo 51 41 ooo 43 a 3& @ i 29 ooo 31 414 416 41 29 470 4V 2 472 474 W ooo 77 79 &? B 59 ooo 61 47 ooo 49 30 &) BBg 8 29 ooo :>.i 474 476 47 r9) 47 476 4 ,8 i CM> 59 T99-) 59 178 480 79 l bV6 ft 480 482 i C99) ji 123 61 (oa) 61 33 (55) ;--,', -1S2 484 49 (98) 49 35 (So) 35 484 486 i 000 1" isj B (8) i 59 000 61 47 ooo 49 ^f as 29 oco 31 480 488 48,8 490 I (aa) J 61 (99) 63 31 ft?) 31 490 492 61 | ^S 81 83 492 494 121. (99) | 61 (SA) 01 49 (99) 51 404 496 49 (99) 49 35 (99) 35 496 4118 B B ooo $ | oVo S 63 000 63 i S^$ K 35 ooo 37 41)8 500 500 4 6 8 10 12 14 46 TASLE OF TWO-CIRCUIT, TRIPLE WINDINGS, FOR DRUM ARMATURES. No. OF CONDUCTORS FRONT AND BACK PITCHES CO tc o 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES CONDUC" F ETM^ B F RE- iNTRANCV B F RE- B F RE- ENTRANCY B F ENTRANCY B F RE- CNTRANC B F RE- EhTRANCY B 6 z. 502 ttB 1ST (99) ut 1-J7 61 (55) 63 31 (55) 31 502 504 83 S (55) 88 85 51 OOO 51 504 506 125 127 (9ft) 1-J5 129 63 (5s) 65 49 (as) 51 31 (55) 33 506 508 508 510 125 13 ooo 1-J7 12 9 t<6 cSS b5 bt 63 ooo 63 ! OOO QIS5 43 43 35 OOO 37 510 512 37 (as) 37 512 514 m m (sa) 121 131 65 (55) 65 51 (55) 53 514 510 85 H7 SvB 3 87 51 ooo 51 516 518 1-J7 131 (55) lift 131 63 (55) 65 31 (as) 33 518 520 520 522 1M 131 000 ttl I-IH 6? (55> 87 89 65 ooo 67 i S it 38 000 33 522 521 53 (9A> 53 37 (as) 37 524 526 i2 1 33 (90) i 65 r?^ 65 51 (SA> 53 37 (98) 39 526 528 5 8ft? 87 b9 528 530 131 133 r?tf) i 67 (5?) 67 530 532 532 534 131 135 000 133 135 87 89 CC3 OJJO 8 65 ooo 67 53 000 55 i l.'iT 67 (98) 67 542 544 55 (55) 55 544 546 i ooo 135 13V ft CG B H 69 ooo 69 53 ooo 55 i OOQ CFa5 45 47 546 548 548 550 130 law (99) 137 m 67 ^99) 69 33 (55) 35 550 552 93 Mfi I 39 000 39 552 554 137 13tt (55) 137 141 69 (M) 71 55 (55) 57 39 (55) 41 35 (as) 35 554 556 55 (55) 55 556 558 g 000 13? ("88) H 69 000 69 o 47 gg 47 47 558 560 560 562 i (as) 1 71 C9J!) VJ 5(32 564 6 8JS 43 96 57 000 57 564 566 ffl (as) 141 143 69 Czs) 7] 55 (as) 57 39 (as) 41 35 (55) 35 5I5G 568 41 (98) 41 568 57(1 HI 143 oou 145 M?S R 71 ooo 73 47 47 ^Ifo S 35 ooo 37 570 572 572 574 ill (55) 143 U5 71 (as) 71 57 (2.0) 69 574 57<) 7 ^BS) 7 57 ooo 57 57G 578 143 145 (as) 1*3 H7 73 SB) 73 578 580 41 (90) 41 580 582 113 H7 ooo 145 147 91 '.',- raS H n 71 ooo 73 47 | 8 i 41 ooo 43 35 ooo 37 582 68 t 59 (as) 59 584 58G 145 147 (as) n;> 14V 73 (2S) 75 57 (99) 59 37 (55) 37 586 588 7 W CCJ3 OOO V7 99 588 590 145 Htf (99-) 147 14*) 73 (99) 73 500 592 592 594 no 1 19 000 i 97 90 (20 W 1D1 75 ooo 75 59 000 61 i ig M u 41 ooo 43 594 596 59 (2S) 59 43 (55) 43 59(5 598 600 H7 (55) I 73 (55) 75 37 (55) 37 508 101 C^i> I 600 4 6 8 . 10 12 14 16 1 TABLE OF TWO-CIRCUIT, TRIPLE WINDINGS, FOR DRUM ARMATURES. No. OF CONDUCTORS FRONT AND BACK PITCHES CO 1C 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES CONDUC" F RE- ENTBANCY B F RC- ENTRANC1 B F RE- B F RE- B F E NTRANC B F RE- ENTRANC B F ENTHAUCY B o d Z 602 14V 161 (S> 14V 163 75 (92) 77 37 (55) 39 002 604 61 (55) 61 (i()4 ooo 148 m 000 IM 163 |V'i otfo m 7r, ooo 75 59 ooo 61 B JrtftS I i;oc, 111 IS ' 43 (55) 43 608 610 it) us (2JD 151 155 77 (55) 77 43 (5fi) 45 610 61*2 i (M) is 612 614 in 156 (55) 153 156 75 (SD 77 61 (9 63 37 (SD :i',) 614 616 61 (55) 61 616 618 163 166 ooo 158 157 101 H . S is 77 000 79 ..i 51 as 1 39 ooo 39 618 020 620 622 622 1ST (5 167 161 79 (55> 81 63 (55) 65 39 (55) 41 634 636 a ?ftS * 63 ooo 63 45 ooo 45 636 638 IB 161 (55) 159 1ft] 79 (55) 79 15 (W> 47 out 640 042 1&9 101 ooo i~uu m H oVS ?ffl 81 ooo 81 B 'V' .j S 042 M I 65 (55) 65 644 646 159 163 (M> I 79 (98) 81 63 (551 65 39 (55) 41 646 648 1% r9) B 048 650 161 183 O ! 81 (981 83 45 rflso 47 41 (55) 41 650 652 47 (991 47 052 654 101 16 ooo si I H 054 656 05 (9P) 65 656 658 i (55) 168 167 83 (2S) 83 658 <;r,o i oVo u* 660 002 163 167 (55) 166 167 81 (55) 83 41 (55) 41 662 664 67 (99) 67 47 (99) 47 664 666 166 167 000 165 169 109 111 C i 83 ooo 85 65 ooo 67 B ss H 47 000 49 41 ooo 43 000 668 008 670 166 169 (5s) 1(7 168 83 (55) 83 670 672 ffl s 115 672 674 i (55) I 85 &a) 85 67 (fifi) 69 074 676 67 (W) 67 070 678 i 000 ffl i SvJ 113 116 83 000 85 8? oVo B -IT 000 49 41 COO 43 078 080 49 (5 s ) 49 080 082 169 171 (98) 19 1J3 85 C2S) 87 43 (55) 43 082 68.1 i Cca) B 69 000 69 084 08C, (fliO i 85 (5JD 85 (17 69 680 088 08S li'.M) 1 ooo in 175 i 8K ffl 87 ooo 87 1? ;,';': B 690 692 49 r9ff) 49 692 694 i i 95 ooo 97 i sas i 53 ooo 55 47 ooo 49 762 764 77 rea) 77 55 (99) 55 764 766 768 10 .__ I 1 .'- fee') 191 193 95 (92) 95 75 (ea) 77 766 lit &V3 127 12 7G8 770 191 193 (22) .l 97 (as) 97 770 772 77?, 774 ffi ooo 48! 127 '129 raa) i 95 000 97 77 ooo 79 i 8 47 ooo 49 774 776 77 fee) 77 55 (98) 55 776 778 i (as) SJ 97 fee) 99 55 (95) 57 49 (55) 49 778 780 129 131 5gj IB 131 780 782 ID" (28) ( 197 97 (98) 97 782 784 79 real 79 784 786 195 197 000 196 "199 i crtft5 131 133 99 ooo 99 77 ooo 79 65 65 07^ 65 786 788 788 790 195 19U (?> 197 1P9 97 (eo) 99 66 (551 57 49 (55) 49 790 792 i (eel 131 133 57 ooo 57 792 794 197 UW (22) 197 2<)1 99 (55) 101 79 (aa) 81 49 (22) 51 794 758 79 (99) 79 796 798 JH m 000 199 2(11 m 133 fio DS> 133 133 99 ooo 99 65 cop CS3D R 798 800 800 4 6 8 10 12 14 16 O7 TUX ^ SI7IRSIT7] WINDING TABLES FOR MULTIPLE-CIRCUIT, SINGLE WINDINGS FOR DRUM ARMATURES. MULTIPLE-CIRCUIT, SINGLE WINDINGS, FOR DRUM ARMATURES. No. OF CONDUCTORS FRONT AND BACK PITCHES No. OF CONDUCTORS 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES F B F B F B F B F B F B F B 202 49 51 33 35 25 27 19 21 15 17 13 15 11 13 202 204 49 51 88 35 25 27 19 21 15 17 13 15 11 13 204 206 51 53 33 35 25 27 19 21 17 19 13 15 11 13 206 208 51 5:5 33 35 26 27 19 21 17 19 13 15 11 13 208 210 51 53 33 35 26 27 19 21 17 19 13 15 13 15 210 212 51 58 35 37 25 27 21 23 17 19 15 17 13 15 212 214 53 55 35 37 25 27 21 23 17 19 15 17 13 15 214 216 53 55 35 37 25 27 21 23 17 19 15 17 13 15 216 218 53 55 35 37 27 29 21 23 17 19 15 17 13 15 218 22i) 53 55 35 37 27 29 21 23 17 19 15 17 13 15 220 222 55 57 35 37 27 29 21 23 17 19 15 17 13 15 222 224 r>r> 57 37 39 27 29 21 23 17 19 15 17 13 15 224 226 55 57 37 39 27 29 21 23 17 19 15 17 13 15 226 228 55 57 37 39 27 29 21 23 17 19 15 17 13 15 228 230 57 59 37 39 27 29 21 23 19 21 15 17 13 15 230 232 57 59 37 39 27 29 23 25 19 21 15 17 13 15 232 234 57 59 37 39 29 31 23 25 19 21 15 17 13 15 234 236 57 59 39 41 29 31 23 25 19 21 15 17 13 15 236 238 59 61 39 41 29 31 23 25 19 21 15 17 13 15 238 240 r>;i 61 39 > 41 29 31 23- 25 19 2] 17 19 18 15 240 242 59 til 39 41 29 31 23 25 19 21 17 19 15 17 242 244 59 c,r 55 41 29 31 23 25 19 21 17 19 15 17 244 246 61 03" 39 41 29 31 23 25 19 21 17 19 15 17 246 24S m : o:; 41 43 29 31 23 25 19 21 17 19 15 17 248 250 61 03 41 43 :-',l 33 23 25 19 21 17 19 15 17 250 252 61 63 41 43 31 33 25 27 19 21 17 19 15 17 252 254 63 65 41 43 31 33 25 27 21 23 17 19 15 17 254 256 58 65 41 43 31 33 25 27 21 23 17 19 15 17 256 258 63 65 41 43 31 33 25 27 21 23 17 19 15 17 258 260 63 65 43 45 31 33 25 27 21 23 17 19 15 17 260 262 65 67 43 45 31 33 25 27 21 23 17 19 15 17 262 264 65 67 43 45 31 33 25 27 21 23 17 19 15 17 264 266 65 67 43 45 33 35 25 27 21 23 17 19 15 17 266 268 65 67 4)! 45 33 35 25 27 21 23 19 21 15 17 268 270 67 69 43 45 33 35 25 27 21 23 19 21 15 17 270 272 67 39 45 47 33 35 27 29 21 23 19 21 15 17 272 274 67 69 45 47 33 35 27 29 21 23 19 21 17 19 274 276 67 69 45 47 33 35 27 29 21 23 19 21 17 19 276 278 69 71 45 47 33 35 27 29 23 25 19 21 17 19 278 280 <;; 71 45 47 33 35 27 29 23 25 19 21 17 19 280 282 69 71 45 47 35 37 27 29 23 25 19 21 17 19 282 284 69 71 47 49 35 37 27 29 23 25 19 21 17 19 284 286 71 73 47 49 35 37 27 29 23 25 19 21 17 19 286 2SS 71 73 47 49 35 37 27 29 23 25 19 21 17 1!) 288 290 71 73 47 49 35 37 27 29 23 25 1',) 21 17 19 290 292 71 73 47 49 35 37 29 31 23 25 19 2] 17 19 292 294 73 75 47 49 35 37 29 31 23 25 19 21 17 19 294 296 73 75 49 51 35 37 29 31 28 25 21 23 17 19 296 298 73 75 49 51 37 39 29 31 23 25 21 23 17 19 298 300 73 75 49 51 37 39 29 31 23 25 21 23 17 19 300 Above choice of Pitches will prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch may be varied within reasonable limits. MULTIPLE-CIRCUIT, SINGLE WINDINGS, FOR DRUM ARMATURES. No. OF CONDUCTORS FRONT AND BACK PITCHES. No. OF CONDUCTORS 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES F B F B F B F B F B F B F B 302 75 77 49 51 37 39 29 31 25 27 21 23 17 19 302 304 75 77 49 51 37 39 29 31 25 27 21 23 17 19 304 306 7.-> 77 49 51 37 39 29 31 25 27 21 2:! 19 21 306 308 75 77 51 53 37 39 29 31 25 27 21 23 19 21 308 310 77 79 51 53 37 35 29 31 25 27 21 2:i 19 21 310 312 77 7',) 51 53 37 39 31 33 25 27 21 2:! 19 21 312 314 77 79 51 53 39 41 31 33 25 27 21 28 19 21 314 316 77 79 51 53 39 41 31 33 25 27 21 23 19 21 316 318 79 81 51 53 39 41 31 33 25 27 21 23 19 21 318 ;f2o 79 SI 53 55 39 41 31 33 25 27 21 23 19 21 320 322 79 81 53 55 39 41 31 m 25 27 21 23 19 21 322 324 79 SI 58 55 39 41 31 33 25 27 23 25 19 21 324 326 81 83 53 55 39 41 31 33 27 29 23 25 19 21 326 328 81 83 53 55 39 41 31 33 27 29 23 25 19 21 328 330 81 83 53 55 41 43 31 33 27 29 23 25 19 21 330 332 81 83 55 57 41 43 33 35 27 29 23 25 19 21 332 334 83 85 55 57 41 43 33 86 27 29 23 25 19 21 334 :;:; 83 85 55 57 41 48 33 35 27 29 23 25 19 21 336 338 83 85 55 57 41 43 33 35 27 29 23 25 21 23 338 ;J40 83 85 55 57 41 43 33 86 27 29 23 25 21 28 340 342 85 87 55 57 41 43 33 35 27 2!) 23 25 21 23 342 344 85 87 57 59 41 43 33 35 27 29 23 25 21 23 344 346 85 87 57 59 43 45 33 35 27 29 23 25 21 23 346 348 85 87 57 59 43 45 33 35 27 29 23 25 21 23 348 :J50 87 89 57 59 43 45 33 35 29 31 23 25 21 23 350 352 87 89 57 oil 43 45 35 37 29 31 25 27 21 23 352 354 87 80 57 59 43 45 35 37 29 31 25 27 21 23 354 :;.-,( ; 87 89 59 61 43 45 35 87 29 31 25 27 21 23 356 358 89 91 59 61 43 45 35 37 29 31 25 27 21 23 358 360 89 91 59 61 43 45 35 37 29 31 25 27 21 23 360 362 89 91 59 61 45 47 86 37 29 31 25 27 21 23 362 364 89 91 59 61 45 47 35 37 29 31 25 27 21 23 364 366 9] 93 59 61 45 47 35 37 29 31 25 27 21 23 366 368 91 93 61 63 45 47 35 37 29 31 25 27 21 23 368 370 91 93 61 63 45 47 35 37 29 31 25 27 23 25 370 372 91 93 61 63 45 47 37 39 29 31 25 27 23 25 372 374 93 95 61 63 45 47 37 39 31 33 25 27 23 25 374 376 93 95 61 63 45 47 37 39 31 33 25 27 23 25 376 378 93 95 61 63 47 49 37 39 31 33 25 27 23 25 378 380 93 95 63 65 47 49 37 39 31 33 27 29 23 25 380 382 95 97 63 65 47 49 37 39 31 33 27 29 23 25 382 384 95 97 63 65 47 49 37 39 31 33 27 29 23 25 384 386 95 97 63 65 47 49 37 39 31 33 27 29 23 25 386 388 95 97 63 65 47 49 37 39 31 33 27 29 23 25 388 390 97 99 63 65 47 49 37 89 31 33 27 29 23 25 390 392 97 99 65 67 47 49 39 41 31 33 27 29 23 25 392 394 97 99 65 67 49 51 39 41 31 33 27 29 23 25 394 396 97 99 65 67 49 51 39 41 31 33 27 29 23 25 39(1 398 99 101 65 67 49 51 39 41 33 35 27 29 23 25 398 400 99 101 65 67 49 51 39 41 33 35 27 29 23 25 400 Above choice of Pitches will prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch may be varied within reasonable limits. MULTIPLE-CIRCUIT, SINGLE WINDINGS, FOR DRUM ARMATURES. w o FRONT AND BACK PITCHES No. OF CON DOCTORS CONDUC1 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES o o z F B F B F B F B F B F B F B 402 99 101 65 67 49 51 39 41 33 35 27 29 25 27 402 404 99 101 67 69 49 51 3!) 41 33 35 27 29 25 27 404 406 101 103 07 69 49 51 39 11 33 35 27 29 25 27 406 408 101 103 67 69 49 51 39 41 33 35 29 31 25 27 40S 410 101 103 67 69 51 53 39 41 33 35 29 31 25 27 410 412 101 103 67 69 51 53 41 43 33 35 29 31 25 27 412 414 103 105 67 69 51 53 41 43 33 35 29 31 25 27 414 416 103 105 09 71 51 53 41 43 33 35 29 31 25 27 416 418 103 105 69 71 51 53 41 43 33 35 29 31 25 27 418 420 103 105 69 71 51 53 41 43 33 35 29 31 25 27 420 422 105 107 69 71 51 53 41 43 35 37 29 31 25 27 422 424 105 107 O'J 71 51 53 41 43 35 37 29 31 25 27 424 426 105 107 69 71 5:! 55 41 43 35 37 29 31 25 27 426 428 105 107 71 73 53 55 41 43 35 37 29 31 25 27 428 430 107 109 71 73 53 55 41 43 35 37 29 31 25 27 430 432 107 109 71 73 53 55 43 45 35 37 29 31 25 27 432 434 107 109 71 73 53 55 43 45 35 37 29 31 27 29 434 436 107 109 71 73 53 55 43 45 35 37 31 33 27 29 436 438 109 111 71 73 53 55 43 45 35 37 31 33 27 29 438 440 109 111 73 75 53 55 43 45 35 37 31 33 27 29 440 442 109 111 73 75 55 57 43 45 35 37 31 33 27 29 442 444 109 111 73 75 55 57 43 45 35 37 :-n 33 27 29 444 446 111 113 73 75 55 57 43 45 37 39 31 33 27 29 446 448 111 113 73 75 55 57 43 45 37 39 31 33 27 29 448 450 111 113 73 75 55 57 43 45 37 39 31 33 27 29 450 452 111 113 75 77 55 57 45 47 37 39 31 33 27 29 452 454 113 115 75 77 55 57 45 47 37 39 31 33 27 29 454 456 113 115 75 77 55 57 45 47 37 39 31 33 27 29 456 458 113 115 75 77 57 5'.) 45 47 37 39 31 33 27 29 458 460 113 115 75 77 57 59 45 47 37 39 31 33 27 29 460 462 115 117 75 77 57 59 45 47 37 39 31 33 27 29 462 464 115 117 77 79 57 59 45 47 37 39 33 35 27 29 464 466 115 117 77 7!) 57 59 45 47 37 39 33 35 29 31 466 468 115 117 77 79 57 59 45 47 37 39 33 35 29 31 468 470 117 119 77 7'J 57 59 45 47 39 41 33 35 29 31 470 472 117 119 77 79 57 59 47 49 89 41 33 35 29 31 472 474 117 119 77 79 59 61 47 49 39 41 33 35 29 31 474 476 117 119 79 81 59 61 47 49 39 41 33 35 29 31 476 478 119 121 79 81 59 Gl 47 49 39 41 33 35 29 31 478 480 11!) 121 79 81 59 61 47 49 39 41 33 35 29 31 480 482 119 121 79 81 59 61 47 49 39 41 33 35 29 31 482 484 119 121 79 81 5!) 01 47 49 39 41 33 86 29 31 484 486 121 123 79 81 59 61 47 49 39 41 33 35 29 31 486 488 121 123 81 83 59 61 47 1',) 39 41 33 35 29 31 488 490 121 123 81 83 61 63 47 49 39 41 33 35 29 31 490 492 121 123 81 83 61 63 49 51 39 41 35 37 29 31 492 494 123 125 81 83 61 63 49 51 41 43 35 37 29 31 494 496 123 125 81 83 61 63 49 51 41 43 35 37 29 31 496 498 123 125 81 83 61 63 49 51 41 43 35 37 31 33 498 500 123 125 83 85 61 63 49 51 41 43 35 37 31 33 500 Above choice of Pitches will prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch may be varied within reasonable limits. MULTIPLE-CIRCUIT, SINGLE WINDINGS, FOR DRUM ARMATURES. No. OF CONDUCTORS FRONT AND BACK PITCHES No. OF CONDUCTORS 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES F B F B F B F B F B F B F B 502 125 127 s: ; i 85 61 63 49 51 41 43 35 37 31 33 502 504 125 127 83 85 61 63 49 51 41 43 35 37 31 33 504 5(10 125 127 83 85 63 66 49 51 41 43 35 37 31 33 506 508 125 127 83 85 63 65 49 51 41 43 35 37 31 33 508 510 127 129 83 85 63 65 49 51 41 43 35 .87 ;-!i 33 510 ni2 127 129 85 87 63 65 51 53 41 43 35 37 31 33 512 514 127 129 85 87 63 65 51 53 41 43 35 82 31 33 514 516 127 129 85 87 63 65 51 53 41 43 35 37 31 33 516 518 1211 131 85 87 63 65 51 53 43 45 35 37 31 33 518 520 _1~29 131 85 87 63 65 51 53 43 45 37 39 31 33 520 522 121) 131 85 87 65 67 51 53 43 45 37 39 31 33 522 524 129 131 87 89 65 67 51 53 43 45 37 39 31 33 524 526 131 133 87 89 65 67 51 53 43 45 37 39 8J 33 526 528 131 133 87 89 65 67 51 53 43 45 37 39 31 33 528 530 131 133 87 89 65 67 51 53 43 45 37 39 33 35 530 532 131 133 87 89 65 67 53 55 43 45 37 39 33 35 532 534 133 135 87 89 65 67 53 55 43 45 o7 gg 33 35 534 536 133 135 89 91 65 67 53 55 I.", 45 37 39 :::! 35 536 538 133 135 9 91 67 69 53 55 43 45 37 39 38. 35 538 540 133 135 89 91 67 69 53 55 43 45 37 39 83 35 540 542 135 137 89 91 67 69 53 55 45 47 37 39 33 35 542 544 135 137 89 91 67 69 53 55 45 47 37 _39 : 33 35 544 546 135 137 89 91 67 69 53 55 45 47 37 39 33 35 546 548 135 137 91 93 67 69 53 55 45 17 39 41 33 35 548 550 137 139 91 93 07 69 53 55 45 47 39 41 33 35 550 552 137 139 91 93 R/J In 55 57 45 47 39 41 gg 35 652 554 137 139 91 93 6" , i 55 57 45 47 39 41 33 35 554 556 137 139 91 93 69 71 55 57 45 47 39 41 33 35 556 558 139 111 91 93 69 71 55 57 45 47 89 41 33 35 558 560 139 141 93 95 69 71 55 57 45 47 39 41 33 86 560 562 139 141 93 95 69 71 55 57 45 47 39 41 35 37 562 564 139 141 93 95 69 71 55 57 45 47 39 41 35 37 564 566 141 in 93 95 69 71 55 57 47 49 39 41 35 37 566 5IJS 141 143 93 95 69 71 55 57 47 49 39 41 86 37 568 570 141 143 93 95 71 73 55 57 47 49 89 41 35 37 570 572 141 143 95 97 71 73 57 59 47 49 39 -11 3.-> 37 572 574 143 145 95 97 71 73 57 59 47 49 39 41 35 37 574 576 143 145 95 97 71 73 57 59 47 49 41 43 35 37 576 578 M:i 145 95 97 71 73 57 59 17 49 41 43 35 37 578 580 143 145 95 97 71 73 57 59 47 49 41 43 35 37 580 582 145 147 95 97 71 73 57 59 47 49 Jl 43 86 37 682 5M 145 117 97 1)1) 71 73 57 59 47 49 -11 43 35 37 584 ggg 145 147 97 99 73 75 57 59 47 49 41 43 35 37 586 588 145 147 97 99 73 75 57 59 -17 49 41 43 35 37 588 C-!)() 147 149 97 99 73 75 57 69 49 51 41 43 35 37 590 592 147 Ml) 97 99 73 75 59 61 49 51 41 43 35 37 592 594 147 149 97 99 73 75 59 61 49 51 41 43 37 39 594 596 147 149 99 101 73 75 59 61 49 51 41 43 37 39 596 598 149 151 99 101 73 75 59 61 49 51 11 43 37 39 598 600 149 151 99 101 73 75 59 61 49 51 41 43 37 39 600 Above choice of Pitches will prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch may be varied within reasonable limits. MULTIPLE-CIRCUIT, SINGLE WINDINGS, FOR DRUM ARMATURES. No. OF CONDUCTORS FRONT AND BACK PITCHES No. OF CONDUCTORS 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES F B F B F B F B F B F B F B 602 149 151 99 101 75 77 59 61 49 51 41 43 37 39 602 604 149 151 99 101 75 77 59 61 49 51 43 45 37 39 604 606 101 153 99 101 75 77 59 61 49 51 43 45 37 39 60(i 608 151 153 101 103 75 77 59 61 49 51 43 45 37 39 608 610 151 153 101 103 75 77 59 61 49 51 43 45 37 39 610 612 151 153 101 103 75 77 61 63 49 51 43 45 37 39 612 614 153 155 101 103 75 77 61 63 51 53 43 45 37 39 614 616 153 155 101 103 76 77 61 63 51 53 43 45 37 39 616 618 153 155 101 103 77 71) 61 63 51 53 13 45 37 39 618 620 153 155 103 105 77 79 61 63 51 53 43 45 37 39 620 622 155 157 103 105 77 79 61 63 51 53 43 45 37 39 622 624 1 50 157 103 105 77 79 61 63 51 53 43 45 37 39 624 626 155 157 103 105 77 79 61 63 51 53 43 45 39 41 626 628 155 157 103 105 77 79 61 63 51 53 43 45 39 41 628 630 157 159 103 105 77 711 61 63 51 53 43 45 39 41 630 632 157 159 105 107 77 79 63 65 51 53 45 47 39 41 632 634 157 159 105 107 79 81 63 65 51 53 45 47 39 41 634 636 157 151) 105 107 7!) 81 63 65 51 53 45 47 39 41 636 638 159 161 105 107 79 81 63 65 53 55 45 47 3!) -11 638 640 159 161 105 107 79 81 63 65 53 55 45 47 31) 41 640 642 169 161 105 107 71) 81 63 65 53 55 45 17 39 41 642 644 159 161 ior 109 79 81 63 65 53 55 45 47 39 41 644 646 161 163 107 109 79 81 63 65 o:i 55 45 47 39 41 646 CIS Ifi'l 163 107 109 79 81 63 65 53 55 45 47 39 41 648 650 161 163 Tor: 109 81 83 I 63 65 53 55 45 47 39 41 650 652 161 163 107 109 81 83 68 67 53 55 45 47 39 41 652 654 163 165 107 109 81 83 65 67 53 55 45 47 39 41 654 656 163 165 10!) 111 81 83 65 67 53 55 45 47 39 41 6JMi 608 163 165 109 111 SI 83 65 67 68 55 45 47 41 43 608 660 163 165 109 111 SI 83 65 67 53 55 47 49 41 43 600 662 165 167 109 111 jIH ; s;r 65 67 55 57 47 49 41 43 662 664 165 167 109 111 81 83 65 67 55 57 47 49 41 43 664 666 165 167 109 111 83 85 65 67 55 57 47 49 41 43 666 668 165 167 111 113 83 85 65 67 55 57 47 49 41 43 668 670 167 169_| 111 113 S3 85 65 67 55 57 47 49 41 43 670 672 167 169 111 113 53 85 67 69 55 57 47 49 41 43 672 674 167 169 111 113 83 85 67 69 55 57 47 49 41 43 674 676 167 169 111 113 85 85 67 69 55 57 47 49 41 43 676 678 169 171 111 113 83 6 67 69 66 57 47 49 41 43 678 680 169 171 113 115 83 SB 67 69 55 57 47 49 41 43 680 682 169 171 113 115 85 87 67 69 55 57 47 49 41 43 682 684 169 171 113 115 85 87 67 69 55 57 47 49 41 43 684 686 171 173 113 115 85 87 67 69 57 59 47 49 41 43 686 688 171 173 113 115 85 87 67 69 57 59 49 51 41 43 688 690 171 173 113 115 85 87 67 69 57 59 49 51 43 45 690 692 171 173 115 117 85 87 69 71 57 69 49 51 43 45 692 694 173 175 115 117 85 87 69 71 57 59 49 51 43 45 694 696 173 175 115 117 85 87 69 71 57 59 49 51 43 45 696 698 173 175 115 117 87 89 69 71 57 59 49 51 43 45 698 700 173 175 115 117 87 89 69 71 57 59 49 51 43 45 700 Above choice of Pitches will prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch may be varied with n reasonable limits. UKI7BRSIT7 MULTIPLE-CIRCUIT, SINGLE WINDINGS, FOR DRUM ARMATURES. CO o FRONT AND BACK PITCHES No. OF CON DOCTORS CONDUC" 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES O 6 z F B F B F B F B F B F B F B 702 175 177 115 117 87 89 69 71 57 59 49 51 13 45 702 704 175 177 117 119 87 89 69 71 57 59 49 51 43 45 704 700 175 177 117 119 87 89 69 71 57 59 49 51 13 45 706 708 175 177 117 119 87 89 69 71 57 59 49 51 13 45 708 710 177 179 117 119 8f 89 69 71 59 61 49 51 43 45 710 712 177 179 117 119 87 89 71 73 59 61 49 51 43 45 712 714 177 179 117 119 89 91 71 73 59 61 49 51 43 45 714 716 177 179 119 121 89 91 71 73 59 61 51 53 43 45 716 718 179 181 119 121 89 91 71 73 59 61 51 53 43 45 718 720 179 181 119 121 89 91 71 73 59 61 51 53 43 45 720 722 179 181 119 121 89 91 71 73 59 61 51 53 45 47 722 724 179 181 119 121 89 91 71 73 59 61 51 53 45 47 721 720 181 183 119 121 89 91 71 73 59 61 51 53 46 47 726 728 181 183 121 123 89 91 71 73 59 61 51 53 45 47 728 730 181 183 121 123 91 93 71 73 59 61 51 53 45 47 73(1 732 181 183 121 1 23 91 93 73 75 59 61 51 53 45 47 732 734 183 185 121 12:', 91 93 73 75 61 68 51 53 45 47 734 736 183 185 121 123 91 93 73 75 61 63 51 53 45 47 736 738 183 185 121 123 91 93 73 75 61 68 51 53 45 47 738 740 183 185 123 125 91 93 73 75 61 68 51 53 45 47 740 742 185 187 123 125 91 93 73 75 61 03 51 53 45 47 742 _744 185 187 123 125 91 93 73 75 61 63 53 55 45 47 744 746 185 187 123 125 93 95 73 75 61 63 53 55 . 45 47 740 748 isr, . 187 123 125 93 95 73 75 61 63 53 55 45 47 748 750 187 189 123 125 93 95 73 75 61 63 53 65 45 47 750 752 187 189 125 127 93 95 75 77 61 03 53 55 45 47 752 754 187 189 125 127 93 95 75 77 61 68 53 55 47 49 754 756 187 189 125 127 93 95 75 77 (il 63 53 55 47 49 756 758 189 191 125 127 93 95 75 77 63 65 53 55 47 49 758 760 189 191 125 127 93 95 75 77 63 65 53 55 47 49 700 762 189 191 125 127 95 97 75 77 63 65 53 55 47 49 762 764 189 191 127 1 29 95 97 75 77 63 65 53 55 47 49 764 766 191 193 127 129 95 97 75 77 63 65 53 55 47 49 766 768 191 193 127 129 95 97 75 77 63 65 53 55 47 49 708 770 191 193 127 129 95 97 75 77 63 65 53 55 47 49 770 772 191 193 127 129 95 97 77 79 63 65 55 57 47 49 772 774 193 195 127 129 95 97 77 79 63 65 55 57 47 49 774 776 193 195 129 131 95 97 77 79 63 65 55 57 47 49 776 778 193 195 129 131 97 99 77 79 63 65 55 57 47 49 778 780 193 195 129 131 97 99 77 79 63 65 55 57 47 49 780 782 195 197 129 131 97 99 77 79 65 67 55 57 47 49 782 784 195 197 129 131 97 99 77 79 65 67 55 57 47 49 784 __780 195 197 129 131 97 99 77 79 65 67 55 57 49 51 786 788 195 197 131 133 97 99 77 79 65 67 55 57 49 51 788 790 197 199 131 133 97 99 77 79 65 67 55 57 49 51 790 792 197 199 131 133 ] 153 113 115 8!) 91 75 77 63 65 55 57 910 912 227 229 151 153 113 115 91 93 75 77 65 67 55 57 932 914 227 229 151 153 113 115 91 93 75 77 65 67 57 69 914 916 '2-27 229 151 lf,3 113 115 91 93 75 77 65 67 57 69 916 918 229 231 151 153 113 115 91 93 75 77 65 67 57 59 918 920 229 231 153 155 113 115 91 93 75 77 65 67 57 59 920 922 229 231 153 155 115 117 91 93 75 77 65 67 57 59 922 924 229 231 153 155 115 117 91 93 75 77 65 67 57 59 924 926 231 '233 153 155 115 117 91 93 77 79 65 67 57 69 926 928 231 233 153 155 115 117 91 93 77 79 65 67 57 59 928 930 231 233 153 155 115 117 91 93 77 79 65 67 57 65 930 932 231 233 155 157 115 117 93 95 77 79 65 67 57 59 932 934 233 235 155 157 115 117 93 95 77 79 65 67 57 59 1)34 936 233 235 155 157 115 117 93 95 77 79 65 67 57 59 936 938 233 235 155 157 117 119 93 95 77 79 65 67 57 59 938 940 233 235 155 157 117 119 93 95 77 79 67 69 57 59 940 942 235 237 155 157 117 119 93 95 77 79 67 69 57 59 942 944 235 237 157 159 117 119 93 95 77 79 67 69 57 59 944 946 235 237 157 159 117 119 93 95 77 79 67 69 59 01 946 948 235 237 157 159 117 119 93 95 77 79 67 69 59 01 948 950 237 239 157 159 117 ] 1 '.) 93 95 79 81 67 69 59 61 950 952 237 23!) j 157 159 117 119 95 97 79 81 07 69 59 61 952 954 237 239 157 159 119 121 95 97 79 81 67 69 59 61 954 956 237 239 159 161 119 121 95 97 79 81 67 0!) 59 61 956 958 239 241 159 161 119 121 95 97 79 81 67 0!) 59 01 958 960 239 241 159 161 119 121 96 97 79 81 67 69 59 01 960 962 239 241 159 101 119 121 95 97 79 81 67 69 59 61 962 964 239 241 159 161 119 121 95 97 79 81 67 69 59 61 964 966 241 243 159 161 119 121 95 97 79 81 67 69 59 61 966 968 241 243 IB; 163 119 121 95 97 79 81 69 71 59 61 968 970 241 243 161 163 121 123 95 97 79 81 69 71 59 61 970 972 241 243 161 163 121 123 97 99 79 81 69 71 59 61 972 974 243 245 161 163 121 123 97 99 81 83 69 71 59 61 974 976 243 245 161 163 121 123 97 99 81 83 69 71 59 61 976 978 243 245 161 163 121 123 97 99 81 83 69 71 61 63 978 980 243 245 163 165 121 123 97 99 81 83 69 71 61 03 98(1 982 _245 247 163 165 121 123 97 99 81 83 69 71 61 03 982 984 245 247 163 165 121 123 97 99 81 83 69 71 61 63 984 986 245 247 163 165 123 125 97 99 81 83 69 71 61 63 986 988 245 247 163 165 123 125 97 99 81 83 69 71 61 63 988 990 247 24!) 163 165 123 125 97 99 81 83 69 71 61 63 990 992 247 249 165 167 123 125 99 101 81 83 69 71 61 63 992 994 247 249 165 167 123 125 99 101 81 83 69 71 61 63 994 996 247 249 165 167 123 125 99 101 81 83 71 73 61 63 990 998 249 251 165 167 123 125 99 101 83 85 71 73 61 63 998 1000 249 251 165 107 123 125 99 101 83 85 71 73 61 63 1000 Above choice of Pitches wfll prove most satisfactory, although, as stated in text, the absolute magnitude of average pltcb may be varied within reasonable thrifts. MULTIPLE CIRCUIT, SINGLE WINDINGS, FOR DRUM ARMATURES. No. OFCONDUCTORS FRONT AND BACK PITCHES No. OFCONDUCTORS 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES F B F B F B F B F B F B F B 1002 249 251 165 167 125 127 99 101 83 85 71 73 61 63 1002 1004 249 251 167_ 169 125 127 99 101 83 85 71 73 61 63 1004 100(5 251 253 107 169 m 127 99 101 83 85 71 73 61 63 1006 1008 251 253 167 169 125 127 99 101 83 85 71 73 61 63 1008 1010 251 253 167 169 125 127 99 101 83 85 71 73 63 65 1010 1012 251 253 167 169 125 127 101 103 83 85 71 . 73 63 65 1012 1014 253 255 167 169 125 127 101 103 83 85 71 73 63 65 1014 1016 253 255 169 171 125 127 101 103 83 85 71 73 63 65 1016 1018 253 255 169 171 127 129 101 103 83 85 71 73 63 65 1018 1020 253 255 169 171 127 129 101 103 83 85 71 73 63 65 1020 1022 255 257 169 171 127 129 101 103 85 87 71 7:1 63 65 1022 1024 255 257 169 171 127 129 101 103 85 87 73 75 63 65 1024 1026 255 257 169 171 127 129 101 103 85 87 73 75 63 65 1026 1028 255 257 171 173 127 129 101 103 85 87 73 75 63 65 1028 1030 257 259 171 173 127 129 101 103 85 87 73 75 63 65 1030 1032 257 259 171 173 127 129 103 105 85 87 73 75 63 65 1032 1034 257 259 171 173 129 18J 103 105 85 87 73 75 63 65 1034 1_036 257 259 171 173 129 131 103 105 85 87 73 75 63 65 1036 1038_j 259 261 171 173 129 131 103 105 85 87 73 75 63 65 1038 1040 259 2lU 173 175 129 131 103 105 85 87 73 75 63 65 1040 10-12 259 261 173 175 129 131 103 105 85 87 73 75 65 07 1042 1044 259 2<>1 178 J 175 129 131 103 105 85 87 73 75 65 67 1044 104(3 261 263 173 175 129 131 103 105 87 89 73 75 65 67 1046 1048 261 263 173 175 129 131 103 105 87 89 73 75 65 67 1048 1 050 261 263 173 175 131 133 103 105 87 89 73 75 65 67 1050 1052 261 263 175 177 131 133 105 107 87 89 75 77 65 67 1052 1054 263 265 175 177 131 133 105 107 7 89 75 77 65 67 1054 1056 263 265 175 177 131 133 105 107 87 89 75 77 65 67 1056 _1058_ 263 265 175 177 "13.1 I 133 105 107 87 89 75 77 65 67 1058 101)0 263 265 175 177 131 133 105 107 87 89 75 77 65 67 ioi;o 1062 265 267 175 177 131 133 105 107 87 89 75 77 65 67 1062 1064 265 267 177 179 131 133 105 107 87 89 75 77 65 67 1064 1066 265 267 177 179 133 135 105 107 87 89 75 77 65 67 1066 1068 265 267 177 179 133 135 105 107 87 89 75 77 66 67 1068 1070 267 269 177 1 79 188 185 105 107 89 1)1 75 77 (55 67 1070 1072 267 269 177 179 133 135 107 109 89 91 75 77 66 67 1072 1074 267 269 177 179 133 135 107 109 89 91 75 77 67 I','.) 1074 1070 267 269 179 181 133 135 107 109 89 91 75 77 67 69 107(1 1078 269 271 179 181 133 135 107 109 89 91 75 77 67 69 1078 1080 269 271 179 181 133 135 107 109 89 91 77 79 67 69 1080 1082 269 271 179 181 135 137 107 109 89 91 77 79 67 69 1082 1084 269 271 179 181 135 137 107 109 89 91 77 79 67 <;'.) 1084 1086 271 273 17!) 181 135 137 107 109 89 91 77 79 67 69 1086 1088 271 273 LSI 183 135 137 107 109 89 91 77 79 67 69 1088 1090 271 273 181 183 186 137 107 109 89 91 77 7! 67 69 1090 1092 271 27:) 181 183 135 137 109 111 89 91 77 79 67 69 1092 1094 273 275 181 183 135 137 109 111 91 93 77 79 67 69 1094 1096 273 275 1.81 183 135 137 109 111 91 93 77 79 67 69 1096 10!>8_[ 273 275 181 183 137 139 109 111 91 93 77 7!) 67 69 1098 1100 273 275 183 185 137 139 109 111 91 93 77 7',) 67 69 1100 Above choice of Pitches will prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch may be varied within reasonable limits. MULTIPLE-CIRCUIT, SINGLE WINDINGS, FOR DRUM ARMATURES. No. OF CONDUCTORS FRONT AND BACK PITCHES CO DC O 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES o 3 z o F B F B F B F B F B F B F B o o z 1102 275 277 183 185 137 139 109 111 91 93 77 79 67 69 1102 1104 i-:> 277 183 185 137 139 109 111 91 93 77 79 67 69 1104 1106 275 277 183 185 137 139 109 111 91 93 77 79 69 71 1106 1108 275 277 183 185 137 139 109 111 91 93 79 81 69 71 1108 1110 277 279 183 185 137 139 109 111 91 93 79 81 69 71 1110 1112 J77 279 185 187 137 139 111 113 91 93 79 81 69 71 1112 1114 277 279 185 187 139 141 111 113 91 93 79 81 69 71 1114 1J1 6 277 279 185 187 139 141 111 113 91 93 79 81 68 71 1116 1118 279 281 185 187 139 141 111 113 93 95 79 81 69 71 1118 1120 279 281 185 187 139 141 111 113 93 95 79 81 69 71 1120 1122 279 281 185 187 139 141 111 113 93 95 79 81 69 71 1122 1124 279 281 187 189 139 141 111 113 93 95 79 81 69 71 1124 1126 281 283 187 189 139 141 111 113 93 95 79 81 69 71 1126 1128 281 283 1S7 189 139 141 111 113 93 95 79 81 69 71 1128 1130 281 283 187 189 141 143 111 113 93 95 79 81 69 71 1130 1132 281 283 187 189 141 143 113 115 93 95 79 81 69 71 11 32 1134 2S3 285 187 189 141 143 113 115 93 95 79 81 69 71 1184 1136 283 285 189 191 141 143 113 115 93 95 81 83 69 71 1136 1138 283 285 189 191 141 143 113 115 93 95 81 83 71 73 1138 1140 283 285 189 191 1 11 143 113 115 93 95 81 83 71 73 1140 111:2 285 287 189 191 141 113 113 115 95 97 SI 83 71 73 114.2 1111 285 287 189 191 141 143 113 115 95 97 81 83 71 73 1144 1146 285 287 189 191 1 13 145 113 115 95 97 81 83 71 73 1146 HIS 285 287 191 193 143 145 113 115 95 97 81 S3 71 73 1148 1.150 287 289 191 193 143 145 113 115 95 97 81 83 71 73 1150 1152 li-Si 289 191 193 143 145 115 117 95 97 81 83 71 73 1152 1151 287 2S9 191 193 143 145 115 117 95 97 81 83 71 73 1 1 54 1156 287 289 191 193 143 145 115 117 95 97 81 83 71 73 1 1 56 1158 289 291 191 193 1 13 145 115 117 95 97 SI 83 71 73 1 1 58 1160 289 291 193 195 143 145 115 117 95 97 81 83 71 73 1160 1.162 289 291 193 195 1 15 m 115 117 95 97 81 S3 71 73 1~162 lli;i 289 291 193 195 145 147 115 117 95 97 83 85 71 73 11 (it 1166 291 293 193 195 145 14T 115 117 97 99 83 85 71 73 lliilj 1168 291 293 193 195 145 147 115 117 97 99 83 85 71 73 1168 1170 291 293 193 195 145 147 115 117 97 99 83 85 73 75 1170 1172 291 293 195 197 145 147 117 119 97 99 83 85 73 75 1172 1171 293 295 195 197 145 147 117 119 97 99 83 85 73 75 1174 1176 293 295 195 197 145 147 117 119 97 99 83 85 73 75 1176 1178 293 295 195 197 147 149 117 119 97 99 83 85 73 75 1178 1180 293 295 195 197 147 149 117 119 97 99 83 85 73 75 1180 1182 295 297 195 197 147 149 117 119 97 99 . 83 85 73 75 1182 11M 295 297 197 199 147 149 117 119 97 99 83 85 73 75 list 1186 295 297 197 199 117 149 117 119 97 99 83 85 73 75 rise, 1188 295 297 197 199 117 149 117 119 97 99 83 H5 73 75 1188 1190 297 29!) 197 199 147 149 117 119 99 101 83 85 73 75 1190 lli2 297 299 197 199 147 149 119 121 99 101 85 87 73 75 1192 11'.) 1 297 299 197 199 149 151 119 121 99 101 85 87 73 75 1194 11!)6 297 299 199 201 149 151 119 121 99 101 85 87 73 75 1196 1198 29!l 301 199 201 149 151 119 121 99 101 85 87 73 75 1198 1200 299 301 191) 201 1 19 151 119 121 99 101 85 87 73 75 1200 Above choice of Pitches will prove most satisfactory, although as stated in text, the absdute magnitude of average pitch may be varied within reasonable limits. MULTIPLE-CIRCUIT, SINGLE WINDINGS, FOR DRUM ARMATURES. No. OF CONDUCTORS FRONT AND BACK PITCHES CO IT D 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES O 3 p F B F B F B F B F B F B F B d Z 1202 299 301 199 201 149 151 119 121 99 101 85 87 75 77 1202 1204 299 301 199 201 149 151 119 121 99 101 85 87 75 77 1204 1206 301 303 199 201 149 151 119 121 99 101 85 ~_$7 75 77 12(>i; 1208 301 303 201 203 U9 151 119 121 99 101 85 87 75 77 1208 1210 301 303 201 203 151 153 119 121 99 101 85 87 75 77 1210 1212 301 303 201 203 151 153 121 123 99 101 85 87 75 77 1212 1214 803 305 201 203 151 153 121 123 101 103 85 87 75 77 1214 1216 303 305 201 203 151 153 121 123 101 103 85 87 75 77 1216 1218 303 305 201 203 151 153 121 123 101 103 85 87 75 77 1218 1220 303 305 203 205 151 153 121 123 101 103 87 89 75 77 1220 1222 305 307 203 205 151 153 121 123 101 103 87 89 75 77 1222 1224 305 307 203 205 151 153 121 123 101 103 87 89 75 77 1224 1226 305 307 203 205 153 155 121 123 101 103 87 89 75 77 1226 1228 305 307 2(13 205 153 155 121 123 J01 103 87 89 75 77 1228 1230 307 309 203 205 153 155 121 123 101 103 87 89 75 77 1230 1232 307 309 205 207 153 155 123 125 101 103 87 89 75 77 1232 1234 307 309 205 207 153 155 123 125 101 103 87 89 77 79 1234 1236 07 309 205 207 153 155 123 125 101 103 87 89 77 79 1236 1238 309 311 205 207 153 155 123 125 103 105 87 89 77 79 1238 1240 309 311 205 207 153 155 123 125 103 105 87 89 77 79 1210 1242 309 311 205 207 155 157 123 125 103 ] 05 87 89 77 79 1242 1244 309 311 207 209 155 157 123 125 103 105 87 89 77 79 1244 1246 311 313 207 209 155 157 123 12.". 103 105 87 89 77 79 1246 1248 311 313 207 209 155 157 123 i'i:, 103 105 89 91 77 79 1 24H 1250 311 313 207 209 155 157 123 12.-, 103 105 89 91 77 79 1250 1252 311 313 207 209 155 157 125 127 103 105 89 91 77 79 1252 1254 818 315 207 209 155 157 125 127 103 105 89 91 77 79 1254 1256 318 315 209 211 155 157 125 127 103 105 89 91 77 79 1256 1258 313 315 209 211 157 159 125 127 103 105 89 91 77 79 1258 1260 313 315 209 211 157 159 125 127 103 105 89 91 77 79 1260 1262 315 317 209 211 157 159 125 127 105 107 89 91 77 79 1262 1264 315 317 209 211 157 159 125 127 105 107 89 91 77 79 1264 126G 315 317 209 211 157 159 125 127 105 107 gg 91 79 81 1266 1208 815 317 211 213 157 159 125 127 105 107 89 91 79 81 1268 1270 317 319 211 213 157 159 125 127 105 107 89 91 79 81 1270 1272 317 319 211 213 157 159 127 129 105 107 89 91 79 81 1272 1274 317 319 211 213 159 161 127 129 105 107 89 91 79 81 1274 127G 317 819 211 213 159 161 127 129 105 107 91 93 79 81 1276 1278 319 321 211 213 15!) 161 127 129 105 107 91 93 79 si 1278 1280 319 321 213 215 159 161 127 129 105 107 91 93 79 81 I -280 1282 319 321 213 215 159 161 127 129 105 107 91 93 79 81 1282 1284 319 321 213 215 159 161 127 129 105 107 91 93 79 81 128-1 1286 321 323 213 215 159 161 127 129 107 109 91 93 79 81 1286 1288 321 323 213 215 159 161 127 129 107 109 91 93 79 81 1288 1290 321 323 213 215 161 163 127 129 107 109 91 93 79 81 1290 1292 321 323 215 217 161 163 129 131 107 109 91 93 79 81 1292 1294 323 325 215 217 161 163 129 131 107 109 91 93 79 81 1294 1296 323 325 215 217 161 163 129 131 107 109 91 93 79 SI 1296 1298 323 325 215 217 161 163 129 131 107 109 91 93 SI 83 1298 1300 323 325 215 217 1(11 163 129 131 107 109 91 93 81 83 1300 Above choice of Pitches will prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch may be varied within reasonable limits. MULTIPLE-CIRCUIT, SINGLE WINDINGS, FOR DRUM ARMATURES. No. OF CONDUCTORS FRONT AND BACK PITCHES No. OF CONDUCTORS 4 POLES 6 POLES 8 POLES 10 POLES 12 , POLES 14 POLES 16 POLES F B F B F B F B F B F B F B 1302 325 327 215 217 161 163 129 131 107 109 91 93 81 83 13(12 1304 325 327 217 219 161 163 129 131 107 109 93 95 81 83 1304 i:;o6 325 327 217 219 163 165 1 29 131 107 109 93 95 81 83 1306 1308 325 327 217 219 163 165 129 131 107 109 93 95 81 83 1308 1310 327 329 217 219 163 165 129 131 109 111 93 95 81 83 13.1.0 1312 327 329 217 219 163 165 131 133 109 111 98 95 81 83 1.312 1314 327 329 217 219 163 ] 65 131 133 109 11 1 93 95 81 83 i:m 1316 327 329 219 221 163 165 131 133 109 111 93 95 81 83 1316 1318 329 331 219 221 163 165 131 133 109 111 93 95 81 83 1318 1320 329 331 219 221 163 165 131 133 109 111 93 95 81 83 1320 1322 329 331 219 2-21 165 167 131 133 109 111 98 95 81 83 1322 1324 329 331 219 221 165 167 131 133 109 111 93 95 81 83 1324 1326 331 333 219 221 165 167 l:U 133 109 111 93 55 81 83 132(5 1328 331 333 221 223 165 167 131 133 109 111 93 95 81 83 132.8 1330 331 333 221 22:! 165 167 131 133 109 111 93 95 83 85 1330 l :;:(_' 331 883 221 223 165 167 133 135 109 111 95 97 83 85 1332 1334 333 335 2-2} 223 1 65 167 133 135 111 U3 95 97 83 85 1334 1336 333 335 221 223 165 167 133 135 111 113 95 97 83 85 1386 1338 333 335 221 223 167 169 133 135 111 113 95 97 83 85 1388 1340 333 335 223 225 167 169 133 135 111 113 95 1)7 83 85 1340 1342 335 337 223 225 167 169 133 135 111 113 95 97 83 85 1342 13.fl 335 337 223 225 167 169 133 135 111 113 95 97 83 85 1344 1346 335 337 223 225 167 169 133 135 111 113 96 97 83 85 1346 13_48 335 337 223 225 167 169 133 135 111 113 95 97 83 85 1348 1350 337 339 223 225 167 169 133 135 111 113 95 97 83 85 1350 1352 337 339 225 227 167 169 135 137 111 113 95 97 83 85' 1352 1354 337 339 225 227 169 171 135 137 111 113 95 97 88 85 1354 K{5G 337 339 225 227 169 171 135 137 111 113 95 97 83 85 1356 1358 339 341 '2 2r, 227 169 171 135 137 113 115 95 97 83 85 1358 1360 339 341 225 227 169 171 135 137 113 115 97 99 83 85 1360 1362 339 341 225 227 169 171 135 137 113 115 97 99 85 87 1362 1364 339 341 227 229 169 171 135 137 113 115 97 99 85 87 13(14 1366 341 343 227 229 169 171 135 137 113 115 97 99 85 87 1366 1368 341 343 227 229 169 171 135 137 1.13 115 97 99 85 87 1368 1370 341 343 227 229 171 173 135 137 113 115 97 99 85 87 1370 1372 341 343 227 229 171 173 137 139 113 115 97 8S 85 87 1372 1374 343 345 227 229 171 173 137 139 113 115 97 99 85 87 1374 1376 343 345 229 231 171 173 137 139 113 115 97 99 85 87 1376 1378 343 345 22!) 231 171 173 137 139 113 115 97 99 85 87 1378 l.-sso 343 345 22!) 231 .171 173 182 139 113 115 97 99 86 87 1380 1382 345 347 229 231 171 17:! 137 139 115 117 97 99 85 87 1382 1384 345 3~47 '2-2'.) 231 171 173 137 139 115 117 97 99 85 87 1384 1386 345 347 229 231 173 175 137 139 115 117 97 99 85 87 1380 1388 345 347 231 233 173 175 137 139 115 117 99 101 85 87 1388 1390 347 349 231 233 173 175 137 139 115 117 99 101 85 87 1390 1392 347 349 231 233 173 175 139 141 115 117 99 101 85 87 1392 1.39.4 347 349 231 233 173 175 139 141 115 117 99 101 87 89 1394 1396 347 349 231 233 173 175 139 141 115 117 99 101 87 89 1396 1398 349 351 231 233 173 175 139 141 115 117 99 101 87 89 1398 1400 849 861 233 235 173 175 139 Ml 115 117 99 101 87 89 1400 Above choice of P tches will prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch may be varied within reasonable limits. MULTIPLE-CIRCUIT, SINGLE WINDINGS, FOR DRUM ARMATURES. No.OF CONDUCTORS FRONT AND BACK PITCHES CO c o 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES No.OF CONDUC" F B F B F B F B F B F B F B 1402 349 351 233 235 175 177 139 14] 115 117 99 101 87 89 1402 1104 349 351 233 235 175 177 139 141 115 117 99 101 87 89 1404 1400 351 353 233 235 175 177 139 141 117 119 99 101 87 89 1406 1408 351 353 233 235 175 177 139 141 117 119 ',)!) 101 87 89 1408 1 lit) 351 353 233 235 175 177 139 141 117 119 99 101 87 89 1410 1 112 351 353 235 237 175 177 141 143 117 119 99 101 87 89 1412 1414 353 355 235 237 175 177 141 143 117 119 99 101 87 89 1414 1416 353 355 235 237 175 177 141 143 117 119 101 103 87 89 1410 i us 353 355 235 237 177 179 141 143 117 119 101 103 87 89 1418 1420 353 _35_5 235 2:!7 177 179 141 143 117 119 1.01 103 87 89 1420 14-22 355 357 235 237 177 179 141 143 117 119 101 103 87 89 1422 1424 355 357 237 239 177 179 141 143 117 119 101 103 87 89 1424 1120 355 357 237 '239 177 179 141 143 117 119 101 103 89 91 1420 1428 355 357 237 239 177 179 141 143 117 119 101 103 89 91 1428 1430 357 359 237 239 177 179 141 143 119 121 101 103 89 91 1430 1432 357 359 237 239 177 179 143 145 119 121 101 103 89 91 1432 1434 357 359 237 239 179 181 143 145 111) 121 101 103 89 91 1434 1 130 357 359 239 241 179 181 143 145 119 121 101 103 89 91 1436 1438 359 861 239 241 179 181 143 145 119 121 101 103 89 91 1438 1440 359 361 239 241 179 181 143 145 119 121 101 103 89 91 1440 1442 359 301 239 241 179 181 143 145 119 121 101 103 89 91 1442 1444 359 301 239 241 17'.) 181 143 145 119 121 103 105 89 91 1444 1446 301 363 239 241 179 181 143 145 119 121 103 105 89 91 1440 1448 301 363 241 243 179 181 143 145 119 121 103 105 89 91 1448 1450 301 363 241 243 181 1 83 143 145 11!) 121 103 105 89 91 1450 ! 152 301 363 241 243 LSI 183 145 147 119 121 103 105 89 91 1452 1454 303 365 241 243 181 183 145 147 121 123 103 105 89 91 1454 1450 303 365 241 243 181 183 145 147 121 123 103 105 89 91 1450 ] I'M 363 365 241 243 181 183 145 147 121 123 103 105 91 93 1458 1400 363 305 243 245 181 183 145 147 121 123 103 105 91 93 1400 1462 365 367 243 245 181 183 145 147 121 123 103 105 91 93 1402 HG4 305 307 243 245 181 183 145 147 121 123 103 105 91 93 1404 1460 305 307 243 245 183 185 145 147 121 123 103 105 91 93 1466 1408 365 367 243 245 183 185 145 147 121 123 103 105 91 93 1468 1470 307 369 243 245 183 185 145 147 121 123 103 105 91 93 1470 1472 367 ISO'.) 245 247 183 185 147 149 121 123 105 107 91 93 1472 1474 367 369 245 247 183 185 147 149 121 123 105 107 91 93 1474 1470 367 369 245 247 183 185 147 149 121 123 105 107 91 93 1476 1478 369 371 245 247 183 185 147 149 123 125 105 107 91 93 1478 1480 369 371 245 247 183 185 147 149 123 125 105 107 91 93 1480 1482 309 371 245 247 185 187 147 149 123 125 105 107 1)1 93 1482 1484 369 371 247 249 185 187 147 149 123 125 105 107 91 93 1484 1480 371 373 247 249 185 187 147 149 123 125 105 107 91 93 1486 1488 371 373 247 249 1S5 187 147 149 123 125 105 107 1)1 93 1488 Tl'.H) 371 373 247 249 185 187 147 149 123 125 105 107 93 96 141)0 14112 371 373 247 249 185 187 149 151 123 125 105 107 93 95 14D2 1494 373 375 247 249 185 187 149 151 123 125 105 107 93 95 1494 14110 373 375 249 251 185 187 149 151 123 125 105 107 93 95 1496 141(8 373 375 249 251 187 189 149 151 123 125 105 107 93 95 1498 1500 373 375 249 251 187 189 149 151 123 125 107 109 93 95 1500 Above choice of Pitches will prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch may be varied within reasonable limits. MULTIPLE-CIRCUIT, SINGLE WINDINGS, FOR DRUM ARMATURES. No.OF CONDUCTORS FRONT AND BACK PITCHES No.OF CONDUCTORS 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES F B F B F B F B F B F B F B 1502 375 377 249 251 187 189 119 151 125 127 107 109 93 95 1502 1504 375 :;77 21'.) 251 187 189 119 151 125 127 107 109 93 95 1501 i:,u<; 375 :;77 219 251 187 1 si) 149 151 125 127 1(17 109 93 95 1506 150.8 375 :i77 251 253 1X7 18!) 149 151 125 127 107 109 22 95 1508 1510 :;77 379 251 253 1M7 189 149 151 125 127 107 109 93 95 1510 1 :, I 2 377 :!7!) 251 25.5 187 1 89 151 153 125 127 107 109 93 95 1512 1511 :!77 :i7'.l 251 253 1 Ml) 191 151 153 125 127 107 109 93 95 1511 1510 ::77 :!7lt 251 25:; ] SI) 191 151 153 125 127 11(7 109 93 95 1510 1518 :!7D 381 25 1 253 1.H9 191 151 153 125 127 107 109 93 95 1518 1520 379 38| 253 255 189 191 151 153 125 127 1(17 109 93 95 1520 1522 379 381 253 255 189 191 151 153 125 127 107 109 95 97 1522 1521 :!7'. 38i 25:', 255 189 191 151 153 125 127 1(17 109 95 97 1 52 1 152 3()G 75 79 49 53 37 41 29 33 23 27 19 23 17 21 306 oo 308 75 79 49 53 37 41 29 33 23 27 19 23 17 21 308 GZ> 310 75 79 49 53 37 41 29 33 23 27 21 25 17 21 310 oo 312 75 79 49 53 37 41 29 33 23 27 21 25 17 21 312 GD 314 77 81 51 55 37 41 29 33 25 29 21 25 17 21 314 00 316 77 81 51 55 37 41 29 33 25 29 21 25 17 21 316 GD 318 77 81 " 51 55 37 41 29 33 25 29 21 25 J7 21 318 oo 320 77 81 51 55 37 41 29 33 25 29 21 h 25 17 21 320 GD 322 79 83 51 55 39 43 31 35 25 29 21 25 19 23 322 oo 324 79 83 51 55 39 43 31 35 25 2 21 25 19 23 324 GD 320 79 83 53 57 39 43 31 35 25 29 21 25 19 23 326 oo 328 79 83 53 57 39 43 31 35 25 29 21 25 19 23 328 GD 330 81 85 53 57 39 43 31 35 25 29 21 25 19 23 330 332 oo 332 81 85 53 57 39 43 31 35 25 29 21 25 19 23 GD 334 81 85 53 57 39 43 31 35 25 29 21 25 19 23 33i oo 336 81 85 53 57 39 43 31 35 25 29 21 25 19 23 336 GD 338 83 87 55 59 41 -15 31 35 27 31 23 27 19 23 338 00 340 83 87 55 59 41 45 31 35 27 31 23 27 19 23 340 go 342 83 87 55 59 41 45 33 37 27 31 23 27 19 23 342 00 344 83 87 55 59 41 45 33 37 27 31 23 27 19 23 344 GD 310 85 89 55 59 41 45 33 37 27 31 23 27 19 23 13-16 oo 348 85 89 55 59 41 45 33 37 27 31 23 27 19 23 348 GD 350 85 89 5T 61 41 45 33 37 27 31 23 27 19 23 350 oo 352 85 89 57 61 41 45 33 37 27 31 23 27 19 23 352 GD 354 87 91 57 61 43 47 33 37 27 31 23 27 21 25 351 oo 350 87 91 57 61 43 47 33 37 27 31 23 27 21 25 356 GD 358 87 91 57 " ol 43 47 33 37 27 31 23 27 21 25 358 oo 360 87 91 57 61 43 47 33 37 27 31 r~23 27 21 25 3<;o GD 362 89 93 59 63 43 47 35 39 29 33 23 27 21 25 362 00 364 89 93 59 63 43 47 35 39 29 33 23 27 21 25 304 GD 300 89 93 59 63 43 47 35 39 29 33 25 29 21 25 366 oo 38 89 93 59 63 43 47 35 39 29 33 25 29 21 25 368 GD 370 91 95 59 63 45 49 35 39 29 33 25 29 21 25 370 oo 372 91 95 59 63 45 49 35 39 29 33 25 29 21 25 372 O 374 91 95 61 65 45 49 35 39 29 33 25 29 21 25 374 00 376 91 95 61 65 45 -1!) 35 39 29 33 25 29 21 25 370 GD 378 93 97 61 65 45 49 35 39 29 33 25 29 21 25 378 00 380 93 97 61 65 45 49 35 39 29 33 25 29 21 25 3Sli GD 382 93 97 61 65 45 49 37 41 29 33 25 29 21 25 382 oo 384 93 97 61 65 45 49 37 41 29 33 25 29 21 25 381 (2) 386 95 99 63 67 47 51 37 41 31 35 25 29 23 27 386 oo 388 95 99 63 67 47 51 37 41 31 35 25 29 23 27 388 GD 390 95 99 58 67 47 51 37 41 31 35 25 29 23 27 390 oo 392 95 99 63 67 47 51 37 41 31 35 25 29 23 27 392 GD 394 97' fioi- 63 67 47 51 37 41 31 35 27 31 23 27 394 oo 396 97 ng 63 67 47 51 37 41 31 35 27 31 23 27 396 CS) 398 97 101 65 69 47 51 37 41 31 35 27 31 23 27 398 oo -KKI 97 101 G5 69 47 51 37 41 31 35 27 31 23 27 400 Above choice of Pitches will prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch may be varied within reasonable limits. MULTIPLE-CIRCUIT, DOUBLE WINDINGS, FOR DRUM ARMATURES. RE-ENTRANCY No.OF CONDUCTORS FRONT AND BACK PITCHES No. OF CONDUCTORS 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES F B F B F B F B F B F B F B CD 402 99 103 65 69 49 53 39 43 31 35 27 31 23 27 402 00 404 '.)'.) 103 65 69 49 53 39 43- 31 35 27 31 23 27 404 CD 406 99 103 65 69 49 53 39 43 31 35 27 31 23 27 406 00 408 99 103 65 69 49 53 39 43 31 35 27 31 23 27 408 22 410 101 105 67 71 49 53 39 43 88 37 27 31 23 27 410 oo 412 101 105 67 71 49 53 39 43 33 37 27 31 23 27 412 CD 414 101 105 67 71 49 53 39 43 33 37 27 31 23 27 414 00 416 101 105 67 71 49 68 39 43 33 37 27 31 23 27 416 go 418 103 107 67 71 51 55 39 43 33 37 27 31 25 29 418 00 420 103 107 67 71 51 55 39 43 33 37 27 31 25 29 420 CD 422 103 107 69 73 51 55 41 45 33 37 29 33 25 29 422 oo 424 103 107 69 73 51 55 41 45 33 37 29 33 25 29 424 CD 426 105 109 69 73 51 55 41 45 33 37 22 33 25 29 426 oo 428 105 109 69 73 51 55 41 45 33 37 29 33 25 29 428 CD 430 105 109 69 73 51 55 41 45 33 37 29 33 25 29 430 00 432 105 109 69 73 51 55 41 45 33 37 29 33 25 29 432 CD 434 107 111 71 75 53 57 41 45 35 39 29 33 25 29 434 oo 436 107 111 71 75 53 57 41 45 35 39 29 33 25 29 436 CD 438 107 111 71 75 53 57 41 45 35 39 29 33 25 29 438 00 440 107 111 71 75 53 57 41 45 35 39 29 33 25 29 440 CD 442 109 113 71 75 53 57 43 47 35 39 29 33 25 29 442 00 444 109 113 71 75 53 57 43 47 35 39 29 33 25 29 444 CD 446 10'.) 113 73 77 53 57 43 47 35 39 29 33 25 29 446 oo 448 109 113 73 77 53 57 43 47 35 39 29 33 25 29 448 oa 450 111 115 73 77 55 59 43 47 35 39 31 35 27 31 450 oo 452 111 115 73 77 55 59 43 47 35 39 31 35 27 31 452 CD 454 111 115 73 77 55 59 43 47 35 39 31 35 27 31 454 00 J456 111 115 73 77 55 59 43 47 35 39 31 35 27 31 456 02 458 113 117 75 79 55 69 43 47 37 41 31 35 27 31 458 00 460 113 117 75 79 55 59 43 47 37 41 31 35 27 31 460 CD 462 113 117 75 79 55 59 45 49 37 41 31 35 27 31 462 oo 464 113 117 75 79 55 59 45 49 37 41 31 35 27 31 464 CD 466 115 119 75 79 57 61 45 49 37 41 31 35 27 31 460 oo 468 115 119 75 79 57 61 45 49 37 41 31 35 27 31 468 CD 470 115 119 77 81 57 61 45 49 37 41 31 35 27 31 470 oo 472 115 119 77 81 57 61 45 49 37 41 31 35 27 31 472 CD 474 117 121 77 81 57 61 45 49 37 41 31 86 27 31 474 oo 476 117 121 77 81 57 61 45 49 37 41 31 35 27 31 476 CD 478 117 121 77 81 57 61 45 49 37 41 33 37 27 31 478 00 480 117 121 77 81 57 61 45 49 37 41 33 37 27 31 480 CD 482 119 123 79 83 59 63 47 51 39 43 33 37 29 33 482 00 484 119 123 79 83 59 63 47 51 39 43 33 37 29 33 484 CD 486 119 123 79 83 59 63 47 51 39 43 88 37 29 33 486 oo 488 119 123 79 83 59 63 47 51 39 43 88 37 29 33 488 CD 490 121 125 79 83 59 63 47 51 89 43 33 37 29 33 490 00 492 121 125 79 83 59 63 47 51 39 43 33 37 29 33 492 CD 494 121 125 81 85 59 63 47 51 39 43 33 37 29 33 494 oo 4% 121 125 81 85 59 63 47 51 39 43 BJ 37 29 33 496 CD 498 123 127 81 85 61 65 47 51 39 43 33 37 29 33 498 oo 500 123 127 81 85 61 65 47 51 39 43 33 37 29 33 500 Above choice of Pitches will prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch may be varied within reasonable limits. MULTIPLE-CIRCUIT, DOUBLE WINDINGS, FOR DRUM ARMATURES. RE-ENTRANCY No.OF CONDUCTORS FRONT AND BACK PITCHES CO O 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES CONDUCT F B F B F B F B F B F B F B o o Z CE) 502 123 127 81 85 61 65 49 53 39 43 33 37 29 33 502 00 504 123 127 81 85 61 65 49 53 39 43 33 37 29 33 504 SO 506 125 129 83 87 61 65 49 53 41 45 35 39 29 33 506 oo 508 125 121) 815 87 61 65 49 53 41 45 35 39 29 33 5 OS CE> 510 125 129 83 87 61 65 49 53 41 45 35 39 29 33 510 oo 512 125 129 83 87 61 65 49 53 41 45 35 39 29 33 512 CE> 514 127 131 83 87 63 67 49 53 41 45 35 39 31 35 514 oo 516 127 131 83 87 63 67 49 BJ 41 45 35 31) __ 31 35 516 CE> 518 127 131 85 89 63 67 49 53 41 45 35 39 31 35 518 oo 520 127 131 85 89 63 67 49 53 41 45 35 aa_ 31 35 520 (5) 522 129 133 85 89 63 67 51 55 41 45 35 39 31 35 522 00 524 129 133 85 89 63 67 51 55 41 45 35 39 31 85 r.;i i CE> 526 129 133 85 89 63 67 51 55 41 45 35 39 31 35 526 oo 528 129 133 85 89 63 67 51 55 41 45 35 39 31 35 528 O 530 131 135 87 91 65 69 51 55 43 47 35 39 31 35 530 00 532 131 135 87 91 65 69 51 55 43 47 35 39 31 35 532 CE> 534 131 135 87 91 65 69 51 55 43 47 37 41 31 35 534 oo 536 131 135 87 91 65 69 51 55 43 47 37 41 31 35 536 CE> 538 133 137 87 91 65 69 51 55 43 47 37 41 31 35 538 00 540 133 137 87 91 65 69 51 55 43 47 37 41 31 35 540 CD 542 133 137 89 93 65 69 53 57 43 47 37 41 31 35 542 oo 544 133 137 89 93 65 69 53 57 43 47 37 41 31 35 544 CE> 546 135 139 89 93 67 71 53 57 43 47 37 41 33 37 546 00 548 135 139 89 93 67 71 53 57 43 47 37 41 33 37 548 CE> 550 135 139 89 93 67 71 53 57 43 47 37 41 33 37 550 00 552 135 139 89 93 67 71 53 57 43 47 37 41 33 37 552 CE) 554 137 141 91 95 67 71 53 57 45 49 37 41 33 37 554 00 556 137 141 91 95 (',7 71 53 57 45 49 37 41 33 37 556 CE) 558 137 141 91 95 67 71 53 57 45 49 37 41 33 37 558 oo 560 137 141 91 95 67 71 53 57 45 49 37 41 33 37 560 CE) 562 139 143 91 95 69 73 55 59 45 49 39 43 33 37 662 00 564 139 143 91 95 69 73 55 59 45 49 39 43 33 37 504 CE) 566 139 143 93 97 69 73 55 59 45 49 39 43 33 37 566 oo 568 139 143 93 97 69 73 55 59 45 49 39 43 33 37 508 CE) 570 141 145 93 97 69 73 55 59 45 49 39 43 33 37 570 00 572 141 145 93 97 69 73 55 59 45 49 39 43 33 37 572 CE) 574 141 145 93 97 69 73 55 59 45 49 39 43 83 37 574 oo 576 141 145 93 97 69 73 55 59 45 49 39 43 33 37 570 CE) 578 143 147 95 99 71 75 55 59 47 51 39 43 35 39 578 oo 580 143 147 95 99 71 75 55 59 47 51 39 43 35 39 580 CE) 582 143 147 95 99 71 75 57 61 47 51 39 43 35 39 582 00 584 143 147 95 99 71 75 57 61 47 51 39 43 35 89 584 CE) 580 145 149 95 99 71 75 57 61 47 51 39 43 35 39 586 00 588 1 15 149 95 99 71 75 57 61 47 51 39 43 35 39 588 CE> 5 'JO 145 149 97 101 71 75 57 61 47 51 41 45 35 39 590 00 592 145 149 97 101 71 75 57 61 47 51 41 45 35 39 592 CE) 594 147 151 97 101 73 77 57 61 47 51 41 45 35 31) 51)4 oo 596 147 151 97 101 73 77 57 61 47 51 41 45 35 39 596 CE> 51)8 147 151 97 101 73 77 57 61 47 51 41 45 35 39 598 oo 000 147 151 97 1U1 73 77 57 61 47 51 41 45 35 39 600 Above choice of Pitches will prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch ma'y be varied within reasonable limits. MULTIPLE-CIRCUIT, DOUBLE WINDINGS, FOR DRUM ARMATURES. RE-ENTRANCY No.OF CONDUCTORS FRONT AND BACK PITCHES No.OF CONDUCTORS 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES F B F B F B F B F B F B F B GD r,02 149 153 99 103 73 77 59 63 49 53 41 45 35 39 602 oo 604 149 153 99 103 73 77 59 63 49 53 41 45 35 39 604 GD 606 149 153 99 103 73 77 55 63 49 53 41 45 35 39 606 oo 608 149 153 9SJ 103 73 77 59 63 49 53 41 45 35 39 608 GD 610 151 155 99 103 75 79 59 63 49 53 41 45 37 41 610 oo 612 151 155 99 103 75 79 59 68 49 53 41 45 37 41 612 GO 614 151 155 101 105 75 79 59 63 49 53 41 45 37 41 614 00 616 151 155 101 105 75 79 59 63 49 53 41 45 37 41 616 CD 618 153 157 101 105 75 79 59 63 49 53 43 47 37 41 618 00 620 153 157 101 105 75 79 5'.) 63 49 53 43 47 37 41 620 (5) 622 153 157 fill 105 75 79 61 65 49 53 43 47 37 41 622 00 624 153 157 101 105 75 79 61 65 49 53 43 47 37 41 624 GD 626 155 159 ll):5 107 77 81 61 65 51 55 43 47 37 41 626 oo 628 155 159 103 107 77 81 61 65 51 55 43 47 37 41 628 GD 630 155 159 103 107 77 81 61 65 51 55 43 47 37 41 630 oo <;:i2 155 159 103 107 77 81 (11 65 51 55 43 47 37 41 632 QD. 634 157 161 103 107 77 81 61 65 51 55 43 47 37 41 634 00 636 157 161 103 107 77 81 61 65 51 55 43 47 37 41 636 GJB 638 157 161 105 109 77 81 61 65 51 55 43 47 37 41 638 oo 640 157 161 105 109 77 81 61 65 51 55 43 47 37 41 640 PJ3 642 159 163 105 109 79 83 63 67 51 55 43 47 39 43 642 00 644 159 i'6_3 105 109 79 83 63 67 51 55 43 47 39 43 644 646 159 163 105 109 79 83 63 67 51 55 45 49 39 43 646 00 648 159 163 105 109 79 83 63 67 51 55 45 49 39 43 648 GD 650 161 165 107 111 79 83 63 67 53 57 45 49 39 43 650 00 652 161 165 107 111 79 83 63 67 53 57 45 49 39 43 652 GD 654 161 165 107 111 79 83 63 67 53 57 45 49 39 43 654 00 656_ 161 165 107 111 79 83 63 (57 53 57 45 49 39 43 656 SSL- 658 163 167 107 111 81 85 63 67 53 57 45 49 39 43 658 00 660 168 167 107 111 81 85 63 67 53 57 45 49 39 43 660 GD 662 163 167 11)9 113 81 85 65 69 53 57 45 49 39 43 662 oo 664 163 167 109 113 81 85 65 69 53 57 45 49 39 43 664 GD 666 " 165 161) 10!) ] 1 3 81 85 65 69 53 57 45 49 39 43 666 00 668 165 169 109 113 81 85 65 69 53 57 45 49 39 43 668 GD 670 165 169 109 113 81 85 65 69 53 57 45 49 39 43 670 oo 672 165 169 109 113 81 85 65 69 53 57 45 49 39 43 672 ua 674 167 171 111 115 83 87 65 69 55 59 47 51 41 45 674 00 070 167 171 111 115 88 87 65 69 55 59 47 51 41 45 676 OQ 678 167 171 111 115 83 87 65 69 55 59 47 51 41 45 678 00 <;so 167 171 111 115 83 87 65 69 55 59 47 51 41 45 680 GD 682 169 173 111 115 83 87 67 71 55 59 47 51 41 45 682 oo 684 169 173 111 115 83 87 67 7i 55 59 47 51 41 45 684 GD 686 169 173 113 117 83 87 67 71 55 59 47 51 41 45 686 oo 688 169 173 113 117 83 87 67 71 55 59 47 51 41 45 688 GD 690 171 175 113 117 85 89 67 71 55 59 47 51 41 45 690 oo 692 171 175 113 117 85 89 67 71 55 59 47 51 41 45 692 GD 694 171 175 113 117 85 89 67 71 55 59 47 51 41 45 694 oo 096 171 175 113 117 85 89 67 71 55 5!) 47 51 41 45 696 GD Baa 173 177 115 119 85 89 67 71 57 61 47 51 41 45 698 oo 700 173 177 115 119 85 89 67 71 57 61 47 51 41 45 700 Above choice of Pitches will prove most satisfactory, although, as stated in text, the absolute magnitude of average p tch may be varied within reasonable limits. 5SI7BRSIT7 MULTIPLE-CIRCUIT, DOUBLE WINDINGS, FOR DRUM ARMATURES. RE-ENTRANCY No.OF CONDUCTORS FRONT AND BACK PITCHES No. OF CONDUCTORS 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES F B F B F B F B F B F B F B GD 702 173 177 115 119 85 89 69 73 57 61 49 53 41 45 702 oo 704 173 177 115 119 85 89 69 73 57 61 49 53 41 45 704 GD 706 175 170 115 119 87 91 CO 73 57 61 49 53 13 47 706 oo 708 175 179 115 119 87 91 69 73 57 61 40 53 43 47 708 GD 710 175 179 117 121 87 91 69 73 57 61 49 53 43 47 710 oo 712 175 179 117 121 87 91 69 73 57 61 49 53 43 47 712 GD 714 177 181 117 121 87 91 69 73 57 61 49 53 43 47 714 oo 716 177 181 117 121 87 91 69 73 57 61 49 53 43 47 716 GD 718 177 181 117 121 87 91 69 73 57 61 49 53 43 47 718 720 oo 721) 177 LSI 117 121 87 91 69 73 57 61 49 53 43 47 GD 722 179 183 119 123 89 93 71 75 59 63 49 53 43 47 722 00 724 179 183 11!) 123 89 93 71 75 59 63 49 53 43 47 724 GD 726 179 183 119 123 89 93 71 75 59 63 49 53 43 47 720 oo 728 179 183 119 123 89 93 71 75 59 63 49 53 43 47 728 GD 730 181 185 119 123 89 93 71 75 59 63 51 55 43 47 730 oo 732 181 185 119 123 89 93 71 75 59 63 51 55 43 47 732 GD 734 181 185 121 125 SO 93 71 75 59 63 51 55 43 47 734 00 736 181 185 121 125 89 93 71 75 59 63 51 66 43 47 736 GD 738 183 187 121 125 91 95 71 75 59 63 51 55 45 49 738 00 740 183 187 121 125 91 95 71 75 . 59 63 51 55 45 49 740 fflj 742 ]83__ 187 121 125 91 JBfi_ 73 77 59 63 51 55 45 49 742 oo 744 183 187 121 125 91 95 73 77 59 63 51 55 45 49 744 GD 746 185 189 123 127 91 95 73 77 61 65 51 55 45 49 74i; 00 748 185 189 123 127 91 95 73 77 61 65 51 55 45 49 748 GD 750 185 189 123 127 91 95 73 77 61 65 51 55 45 49 750 oo 752 185 189 123 127 91 95 73 77 61 65 51 55 45 49 752 GD 754 187 191 123 127 93 97 73 77 61 65 51 55 45 49 754 oo 756 187 191 123 127 93 97 73 77 61 65 51 55 45 49 J5JS GD 758 187 191 125 129 93 97 73 77 61 65 53 57 45 49 758 00 760 187 191 125 129 93 97 73 77 61 65 53 57 45 49 760 CD 762 189 193 125 129 93 97 75 79 61 65 53 57 45 49 762 oo 764 189 193 125 129 93 97 75 79 61 65 53 57 45 49 764 GD 766 ISO 193 125 129 93 97 75 79 61 65 53 57 45 49 766 oo 768 189 193 125 129 93 97 75 79 61 65 53 57 45 49 768 GD 770 191 195 127 131 95 99 75 79 63 67 53 57 47 51 770 oo _772 191 195 127 131 95 99 75 79 63 67 53 57 47 51 772 GO 774 191 195 127 131 95 99 75 79 88 67 53 57 47 51 774 oo 776 191 195 127 131 95 99 75 79 68 67 53 57 47 5J 776 GD 778 193 197 127 131 95 99 75 79 63 67 53 57 47 51 778 oo 780 193 197 127 131 95 99 75 79 63 67 53 57 47 61 780 GD 782 193 197 129 133 95 99 77 81 63 67 53 57 47 51 782 00 784 193 197 129 133 95 99 77 81 63 67 53 57 47 51 784 GD 786 195 199 129 133 97 101 77 81 63 67 55 59 47 51 786 oo 788 195 199 129 133 07 101 77 81 63 67 55 59 47 51 788 GD 790 195 199 129 133 97 101 77 81 63 67 55 59 47 51 790 00 792 195 199 120 133 97 101 77 81 63 67 55 59 47 51 792 GD 794 197 201 131 135 97 101 77 81 65 69 55 59 47 51 794 oo 796 197 201 131 135 97 101 77 81 65 (10 55 _jsa 47 51 796 GD 798 197 201 131 135 97 101 77 81 65 69 55 59 47 51 798 00 800 197 201 131 135 97 101 77 81 65 69 55 59 47 51 800 Above choice of Pitches will prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch may be varied within reasonable limits, MULTIPLE-CIRCUIT, DOUBLE WINDINGS, FOR DRUM ARMATURES. RE-ENTRANCY No. OF CONDUCTORS FRONT AND BACK PITCHES CO 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES F B F B F B F B F .B F B F B o d z GD 802 199 203 131 135 99 103 79 83 65 69 55 59 49 53 802 00 804 199 203 131 135 99 103 79 83 65 69 55 59 49 53 804 GD. 806 199 203 133 137 99 103 79 83 65 69 55 59 49 53 806 oo 808 199 203 133 137 99 103 79 83 65 69 55 59 49 53 808 GD 810 201 205 133 137 99 103 79 83 65 69 55 59 49 53 810 oo 812 201 205 133 137 99 103 79 83 65 69 55 59 49 53 812 GO 814 201 205 133 137 99 103 79 83 65 69 57 61 49 53 814 oo 16 201 205 133 137 99 103 79 83 65 69 57 61 49 53 816 GO 818 203 207 135 139 101 105 79 83 67 71 57 61 49 53 818 oo 820 203 207 135 139 101 105 79 83 67 71 57 81 49 53 820 GD 822 203 207 135 139 101 105 81 85 67 71 57 61 49 53 822 00 824 203 207 135 139 Jfoi 105 81 85 67 71 57 61 49 53 824 GD 826 205 209 135 139 101 105 81 85 67 71 57 61 49 53 826 00 828 205 209 135 139 101 105 81 85 67 71 57 (11 49 53 828 GD 830 205 209 137 141 101 105 81 85 67 71 57 61 49 53 830 00 832 200 209 137 141 101 105 81 85 67 71 57 61 -49 53 832 GD 834 207 211 137 141 103 107 81 85 67 71 57 61 51 55 834 oo 836 207 211 137 141 103 107 81 85 67 71 57 61 51 55 836 GD 838 207 211 137 141 103 107 81 85 67 71 57 61 51 55 838 oo 840 207 211 137 141 103 107 81 85 67 71 57 61 51 55 840 GD 842 209 213 139 143 103 107 83 87 69 73 59 63 51 55 842 oo 844 209 213 139 143 103 107 83 87 69 73 59 63 51 55 844 GD 846 209 213 139 143 103 107 83 87 69 73 59 (13 51 55 846 oo 848 209 213 139 143 103 107 83 87 69 73 59 63 51 55 848 GD 850 211 215 139 143 105 109 83 87 69 73 59 63 51 55 850 00 852 211 215 139 143 105 109 83 87 69 73 59 63 51 55 852 GD 854 211 215 141 145 105 109 83 87 69 73 59 63 51 55 854 00 856 211 215 111 145 105 109 83 87 69 73 59 63 51 55 856 GD 858 213 217 141 145 105 109 83 87 69 73 69 63 51 55 858 oo 860 213 217 141 145 105 109 83 87 69 73 59 63 51 55 860 GD 862 213 217 141 145 105 109 85 89 69 73 59 63 51 55 862 oo 864 213 217 141. 145 105 109 85 89 69 73 59 63 51 55 864 GD 8liG 215 219 143 147 107 111 85 89 71 75 59 63 53 57 866 00 8(>8 215 219 143 147 107 111 85 89 71 75 59 63 53 57 868 (S3 870 215 219 143 147 107 111 85 89 71 75 61 65 53 57 870 00 872 215 219 143 147 107 111 85 89 71 75 61 65 53 57 872 GD 874 217 221 143 147 107 111 85 89 71 75 61 65 53 57 874 00 876 217 221 143 147 107 111 85 89 71 75 61 65 53 57 876 GD 878 217 221 145 149 107 111 85 89 71 75 61 65 53 57 878 00 880 217 221 145 149 107 111 85 89 71 75 61 65 53 57 880 GD 882 219 223 145 149 109 113 87 91 71 75 61 65 53 57 882 oo 884 219 223 115 149 109 113 87 91 71 75 61 65 53 57 884 GD 88(3 219 223 145 149 _109 113 87 91 71 75 61 G5 53 57 886 oo 888 219 223 115 149 109 113 87 91 71 75 61 65 53 57 888 GD 890 221 225 147 151 109 113 87 91 73 77 61 65 53 57 890 oo 892 221 225 147 151 109 113 87 91 73 77 61 65 53 57 892 GD 894 221 225 147 151 1 09 113 87 91 73 77 61 65 53 57 894 00 896 221 225 147 151 109 113 87 91 73 77 61 65 53 57 896 GD 898 223 227 147 151 111 115 87 . 91 73 77 63 67 55 59 898 oo 900 223 227 147 151 111 115 | 87 91 73 77 63 67 55 59 900 Above choice of Pitches will prove most satisfactory, although;, as stated in text, the absolute magnitude of average pitch may be varied within reasonable limits. - MULTIPLE-CIRCUIT, DOUBLE WINDINGS, FOR DRUM ARMATURES. RE-ENTRANCY No.OF CONDUCTORS FRONT AND BACK PITCHES CO cc o 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES CON DUG! F B F B F B F B F B F B F B O o Z CE> 902 223 227 149 153 in 115 89 93 73 77 63 67 55 59 902 oo 904 223 227 149 153 in 115 89 93 73 77 63 67 55 59 904 CS3 906 225 229 149 153 in 115 89 1)3 73 77 63 67 55 59 906 00 908 225 229 149 153 in 115 89 93 73 77 63 67 55 59 908 (33 910 225 229 149 153 in 115 89 93 73 77 63 67 55 59 910 oo 912 225 229 149 153 in 115 89 93 73 77 63 67 55 59 912 Cfl) 911 227 231 151 155 113 117 89 93 75 79 63 67 55 59 914 oo 916 227 231 151 155 113 117 89 93 75 79 63 67 55 59 916 QD 918 227 231 151 155 113 11.7 89 93 75 79 63 67 55 59 918 oo 920 227 231 151 155 113 117 1 89 93 75 79 63 67 55 59 920 922 229 233 151 155 113 117 91 95 75 79 03 67 55 59 922 oo 924 221) 233 151 155 113 117 91 95 75 79 63 67 55 59 924 O 926 229 233 153 157 ,113 11.7 91 95 75 79 65 69 55 59 926 00 928 229 233 153 157 113 117 91 95 75 79 65 69 55 59 928 C5> 930 231 235 153 157 115 119 91 95 75 79 65 69 57 61 930 oo 932 231 235 153 157 115 119 91 95 75 79 65 69 57 61 932 C5D 934 231 235 153 157 115 119 91 95 75 79 65 69 57 61 934 oo 936 231 235 153 157 115 119 91 95 75 79 65 69 57 01 930 CE> 938 233 237 155 159 115 119 91 95 77 81 65 01) 57 61 938 oo 940 233 237 155 159 115 119 91 95 77 81 65 69 57 61 940 (2) 942 233 _237 155 159 115 .119 93 97 77 81 65 69 57 61 942 oo 944 233 _237 155 159 115 119 93 97 77 81 65 69 57 61 944 CE> 940 235 239 155 159 117 121 93 97 77 81 65 69 57 61 946 oo 948 235 239 155 159 117 121 93 97 77 81 65 Oil 57 61 948 CS) 950 235 239 157 161 117 121 93 97 77 81 65 0!) 57 61 950 oo 952 235 239 157 161 117 121 _tt 97 77 81 65 01) 57 61 952 CE> 954 237 241 157 161 117 121 1)3 97 77 81 67 71 57 61 954 oo 956 237 241 157 161 117 121 1)3 97 77 81 67 71 57 61 956 C5) 958 237 241 157 161 117 121 93 97 77 81 67 71 57 61 958 oo 960 237 241 157 161 117 121 1)3 97 77 81 67 71 57 61. 960 CE> 962 239 243 159 163 119 123 95 99 79 83 67 71 59 63 962 00 964 239 243 159 163 119 123 95 99 79 83 67 71 59 63 964 CE> 966 239 243 .159 103 119 123 95 99 79 83 67 71 59 63 966 oo 968 ^239 243 159 163 119 123 95 99 79 83 67 71 59 63 968 CE> 970 241 245 159 163 119 123 95 99 79 83 67 71 59 63 970 oo 972 241 245 159 163 119 123 95 99 79 83 67 71 59 63 972 974 241 245 161 165 119 123 95 99 79 83 67 71 59 63 974 oo 970 241 245 161 165 119 123 95 99 79 83 67 71 59 63 976 CE> 978 243 247 101 165 121 125 95 99 79 83 67 71 51) 03 978 oo 980 243 247 J01 165 121 125 95 99 79 S3 67 71 59 63 980 C5J 982 243 247 161 165 121 125 97 101 79 83 69 73 59 63 982 00 984 243 247 161 165 121 125 97 101 79 83 69 73 59 63 984 O 980 245 249 163 167 121 125 97 101 81 85 01) 73 51) 63 980 oo 988 245 249 103 167 121 125 97 101 81 85 01) 73 59 63 988 00 990 245 249 163 167 1 121 125 97 101 81 85 69 73 59 63 990 oo 992 245 .249 163 167 121 125 97 101 81 85 69 73 59 63 992 CE> 994 247 251 163 167 123 :27 97 101 81 85 69 73 61 65 994 oo 996 247 251 J63 167 .123 :27 97 101 81 85 69 73 61 65 990 CD 998 247. 251 165 169 123 {27 97 101 81 85 69 73 01 65 998 oo 1000 247 251 165 169 123 127 97 101 81 85 69 73 61 65 1000 Above choice of PHches will prove roost satisfactory, although, as stated in text, the absolute rnagnttouda of average. pHjch may be varied within reasonable Emits. MULTIPLE-CIRCUIT, DOUBLE WINDINGS, FOR DRUM ARMATURES. RE-ENTRANCY No. OF CONDUCTORS FRONT AND BACK PITCHES CO o 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES CON'DUC" F B F B F B F B F B F B F B o d Z GO 1002 249 253 165 169 123 127 99 103 81 85 69 73 61 65 1002 00 1004 249 253 165 169 123 127 99 103 81 85 69 73 61 65 1004 go 1006 249 253 165 169 123 127 99 103 81 85 69 73 61 6 1000 oo 1008 249 253 165 169 123 127 99 103 81 85 69 73 <;i 65 1008 GD 1010 251 255 167 171 125 129 99 103 83 87 71 75 61 65 1010 oo 1012 ~55l 255 167 171 125 129 99 103 S3 87 71 75 61 65 ! 1012 GD 1014 251 255 167 171 125 129 99 103 83 87 71 75 61 65 i 1014 oo 1016 251 255 167 171 125 129 99 103 83 87 71 75 61 65 1016 GO 1018 253 257 167 171 125 129 99 103 83 87 71 75 61 65 1018 oo 1020 253 257 167 171 125 129 99 103 83 87 71 75 61 65 1020 GD 1022 253 257 169 173 125 129 101 105 83 87 71 75 61 65 1022 oo 1024 253 257 169 173 125 129 101 105 83 87 71 75 61 65 | 1024 GO 1020 255 259 169 173 127 131 101 105 83 87 71 75 63 67 1026 oo 1028 255 259 169 173 127 131 101 105 83 87 71 75 63 67 1028 GD 1030 255 259 169 173 127 131 101 105 83 87 71 75 63 67 1030 oo 1032 255 259 169 173 127 131 101 105 83 87 71 75 68 67 1032 GD 10:54 257 261 171 175 127 131 101 105 85 89 71 75 63 67 1034 00 1036 257 261 171 175 127 131 101 105 85 89 71 75 63 67 10.36 GD 1038 257 261 171 175 127 131 101 105 85 89 73 77 63 67 1038 00 1010 257 261 171 175 127 131 101 105 85 89 73 77 63 67 1040 GD 1042 259 263 171 175 129 133 103 107 85 89 73 77 BJ 67 1042 oo 1044 259 263 171 175 129 133 103 107 85 89 73 77 63 67 1044 GD 1046 259 263 173 177 129 133 103 107 85 89 73 77 63 67 1046 00 1048 259 263 173 177 129 133 103 107 85 89 73 77 63 67 1048 GD 1050 261 265 173 177 129 133 103 107 85 89 73 77 63 67 1050 00 ] 052 261 265 173 177 129 133 103 107 85 89 73 77 63 67 1052 GD 1054 261 265 173 177 129 133 103 107 85 89 73 77 63 67 1054 oo 1056 261 265 173 177 129 133 103 107 85 89 73 77 63 67 1056 GD 1058 263 267 175 179 131 135 103 107 87 91 73 77 65 69 1058 00 ]()60 263 267 175 179 131 186 103 107 87 91 73 77 65 69 1060 GD 1062 263 267 175 179 131 135 105 109 87 91 73 77 65 69 10I12 oo 1064 263 267 175 179 131 135 105 109 87 91 73 77 65 69 1064 GD 1066 265 269 175 179 131 135 105 109 87 91 75 79 65 69 1066 oo 1068 265 269 175 179 131 135 105 109 87 91 75 79 65 69 1068 GD 1070 265 269 177 181 131 135 105 109 87 91 75 79 65 69 1070 00 1072 265 269 177 181 131 135 105 109 ' 87 1)1 75 79 65 69 1072 GD 1074 267 271 177 181 133 137 105 109 87 91 75 79 65 69 1074 00 1076 267 271 177 181 133 137 105 109 87 91 75 79 65 69 1076 GO 1 078 267 271 177 181 133 137 105 109 87 91 75 79 65 69 1078 00 1080 267 271 177 181 133 137 105 109 87 91 75 79 65 69 1080 GO 1 082 269 273 179 183 133 137 107 111 89 93 75 79 65 69 1082 00 1084 269 273 179 183 133 137 107 111 81) 93 75 79 65 69 1084 GD lose, 269 273 171) 183 133 137 107 111 89 93 75 79 65 69 1086 00 108H 269 273 179 183 133 137 107 111 82 93 75 79 65 69 loss GD 101)0 271 275 179 183 135 139 107 111 89 93 75 79 67 71 1090 oo 101)2 271 275 179 183 135 139 107 111 89 93 75 79 67 71 1092 GO 1094 271 275 181 185 135 139 107 111 89 93 77 81 67 71 1094 oo 1096 271 275 181 185 135 139 107 111 89 93 77 81 67 71 1096 GD 1098 273 277 181 185 135 139 107 111 89 93 77 81 67 71 109S O 1100 273 277 181 185 135 139 107 111 89 93 77 81 67 71 1100 Above choice of Pitches will prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch may be varied within reasonable limits. MULTIPLE-CIRCUIT, DOUBLE WINDINGS, FOR DRUM ARMATURES. RE-ENTRANCY No.OF CONDUCTORS FRONT AND BACK PITCHES No.OF CONDUCTORS 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES F B F B F B F B F B F B F B (53 1102 273 277 181 185 135 139 109 113 89 93 77 81 67 71 1102 oo not 273 277 181 185 135 139 109 113 89 93 77 81 67 71 1104 1106 275 279 183 187 137 141 109 113 91 95 77 81 67 71 1106 oo 1108 275 279 183 187 137 141 109 113 91 95 77 81 67 71 1108 C2> 1110 275 279 183 187 137 141 109 113 91 95 77 81 67 71 1110 00 1112 275 279 183 187 137 141 109 113 91 95 77 81 67 71 1112 CE> 1114 277 281 183 187 137 141 109 113 91 95 77 . 81 67 71 1114 oo 1116 277 281 is:', 187 137 141 109 113 91 95 77 81 67 71 1116 CE> 1118 277 281 185 189 137 141 109 113 91 95 77 81 67 71 1118 oo 1 120 277 281 185 189 137 141 109 113 91 95 77 81 67 71 1120 CE> 1122 279 283 185 189 139 143 111 115 91 95 79 83 69 73 1122 00 1124 279 283 185 189 139 143 111 115 91 95 79 83 69 73 1124 C53 1126 279 283 isr, 1 89 139 113 111 115 91 95 79 83 69 73 1126 oo 1128 279 283 185 189 139 143 111 115 91 95 79 83 69 73 1128 (5) i i:jo 281 285 187 191 139 143 111 115 93 97 79 83 69 73 1130 00 L132 281 285 187 191 139 143 111 115 93 97 79 88 69 73 1132 (33 1134 281 285 187 191 139 143 1 111 115 93 97 79 83 69 73 1134 o o USfi 281 ass 187 191 139_ 143 111 115 93 97 79 83 _fia _ 73 1136 Co) 1138 288 287 187 191 141 145 111 115 93 97 79 83 69 73 1138 oo UK) 288 287 187 191 141 145 111 115 93 97 79 83 69 73 1140 C53 1142 283 287 189 193 141 145 113 117 93 97 79 83 69 73 1142 oo 1 Hi 283 287 189 193 141 145 113 117 93 97 79 83 69 73 1144 CE> 1146 285 289 1S9 193 141 145 113 117 93 97 79 83 . 82_ 73 1146 oo IMS 285 289 189 193 141 145 113 117 93 97 79 S3 69 73 1148 C53 1150 285 289 189 193 141 145 113 117 93 97 81 85 69 73 1150 O 1152 285 289 189 193 141 145 113 117 93 97 81 85 69 73 1152 o 1154 287 291 191 195 143 147 113 117 95 99 81 85 71 75 1154 oo 1156 287 291 191 195 143 147 113 117 95 99 81 85 71 75 1156 CE> 1158 287 291 191 195 143 147 113 117 95 99 81 85 71 75 1158 oo 1160 287 291 191 195 143 147 113 117 95 99 81 85 71 75 1160 (5) 1162 289 293 191 195 143 147 115 119 95 99 81 85 71 75 1162 oo 1164 289 293 191 195 143 147 115 119 95 99 81 85 71 75 1164 CE> 1166 289 29:', 193 197 143 147 115 119 95 99 81 85 71 75 1166 oo 1168 289 293 193 197 143 147 115 119 95 99 81 85 71 75 1168 CE> 1170 291 295 193 197 145 149 115 119 95 99 81 85 71 75 1170 oo 1172 291 295 193 197 145 149 115 119 95 99 81 85 71 75 1172 (5) 1174 291 295 193 197 145 149 115 119 95 99 81 85 71 75 1174 oo 1176 291 295 193 197 145 149 115 119 95 99 81 85 71 75 1176 1178 293 297 195 199 145 149 115 119 97 101 83 87 71 75 1.178 00 USD 293 297 195 199 145 149 115 119 97 101 83 87 71 75 1180 1182 293 297 195 199 145 149 117 121 97 101 83 K7 71 75 1182 1 1 Si 293 297 195 199 145 149 117 121 97 101 83 87 71 75 1184 1186 295 299 195 199 147 151 117 121 97 101 83 87 73 77 1186 00 1188 295 299 195 199 147 151 117 m 97 101 83 87 73 77 1188 GO 1190 295 299 197 201 147 151 117 121 97 101 83 87 73 77 1190 oo 11112 295 299 197 201 147 151 117 121 97 101 83 87 73 77 1192 CD 111 )! I'M 301 197 21)1 147 151 117 121 97 101 83 87 73 77 1194 oo 11 IK; 297 301 197 201 147 151 117 121 97 101 83 87 73 77 1196 3D 11!S 297 301 197 201 147 151 117 121 97 101 83 87 73 77 1198 oo 1200 297 301 197 201 147 151 117 121 97 101 83 87 73 77 1200 Above choice of Pitches will prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch may be varied wfthin reasonable limits. MULTIPLE-CIRCUIT, DOUBLE WINDINGS, FOR DRUM ARMATURES. RE-FNTRANCY No.OF CONDUCTORS FRONT AND BACK PITCHES CO cc o 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES CONDUCl F B F B F B F B F B F B F B IL O 6 Z GD 1202 299 303 199 203 149 153 119 123 99 103 83 87 73 77 1202 oo 1204 299 303 199 203 149 153 119 123 99 103 3 87 73 77 1204 so 1206 299 308 199 203 149 153 119 123 99 103 85 89 73 77 1206 oo 1208 299 303 199 203 149 153 119 123 9!) 103 85 89 73 77 1208 CD 1210 301 305 199 203 149 153 119 123 99 108 85 89 73 77 1210 00 1212 301 305 199 203 149 153 119 123 99 103 85 89 73 77 1212 GD 1214 301 305 201 205 149 153 119 123 99 103 85 89 73 77 1214 00 1216 301 305 201 205 149 153 119 123 99 103 85 89 73 77 1216 GD 1218 303 307 201 205 151 155 119 123 99 103 85 89 75 79 1218 00 1220 : ; n.; 307 201 205 151 155 119 123 99 103 85 89 75 79 1220 GD 1222 303 307 201 205 151 155 121 125 99 103 85 89 75 79 1222 oo 1224 81):! 307 201 205 151 155 121 125 99 103 85 89 75 79 1221 GD 1226 305 309 203 207 151 155 121 125 101 105 85 89 75 79 1226 oo 1228 805 30'.) 203 207 151 155 , 121 125 101 105 85 89 75 79 1228 32 1230 305 809 203 207 151 155 121 125 101 105 85 89 75 79 1230 . 00 1232 305 309 203 207 151 155 121 _125 101 105 85 89 75 79 1232 GD 1234 307 311 203 207 153 157 121 125 101 105 87 91 75 79 1234 00 1236 307 311 203 207 153 157 121 125 101 105 87 91 75 79 1236 GD 1238 307 311 205 209 153 157 121 125 101 105 87 91 75 79 1238 00 1240 307 311 205 209 153 157 121 125 101 105 87 91 75 79 1240 _GD_ 00 1242 309 313 205 209 153 157 123 127 101 105 87 91 75 79 1242 1244 8Q2 313 205 209 153 157 123 .1 2i_ 101 105 . 87. 91 75 79 1244 52 124fi 309 313 205 209 153 157 123 127 101 105 87 91 75 79 12 tO oo 1248 309 313 205 209 153 157 123 127 101 105 87 91 75 79 1248 GD 1250 311 315 207 211 155 159 123 127 103 107 87 91 77 81 1250 00 1252 311 315 207 211 155 159 123 127 103 107 87 91 77 81 1252 GD 1254 311 315 207 211 155 159 123 127 103 107 87 91 77 81 1254 00 1256 311 315 207 211 155 159 123 127 103 107 87 91 77 81 1250 GD 1258 313 317 207 211 155 159 123 127 103 107 87 91 77 81 1258 00 1260 313 317 207 211 155 159 123 127 103 107 87 91 77 81 1260 GD 12(12 313 317 209 213 155 159 125 129 103 107 89 93 77 81 1262 00 12G4 313 317 209 213 155 159 125 122 103 107 89 93 77 81 1264 GD 1266 315 319 209 213 157 161 125 129 103 107 89 93 77 ' 81 1266 00 126S 815 319 209 213 157 161 125 129 103 107 89 93 77 81 1268 GD 1270 315 319 209 213 157 161 125 129 103 107 89 93 77 81 1270 00 1272 315 319 209 213 157 161 125 129 103 107 89 93 77 81 1272 GD 1274 317 321 211 215 157 161 125 129 105 109 89 93 77 81 1274 oo 1270 317 321 211 215 157 161 125 129 105 109 89 93 77 81 1276 GD 1278 317 321 211 215 157 161 125 129 105 109 89 93 77 81 1278 00 1280 317 321 211 215 157 161 125 129 105 109 89 93 77 81 1 280 GD 1282 319 323 211 215 159 163 127 131 105 109 89 93 79 83 1282 00 1284 319 323 211 215 159 163 127 131 105 109 89 93 79 88 1284 GD 1286 319 323 213 217 159 163 127 131 105 109 89 93 79 83 1286 00 I 288 319 323 213 217 159 163 127 131 105 109 89 93 79 83 1288 GD 1290 321 325 213 217 159 163 127 131 105 109 91 95 79 83 1290 00 1292 321 325 213 217 159 163 127 131 105 109 91 95 79 83 1292 GD 1294 321 325 213 217 159 163 127 131 105 109 91 95 79 83 1294 oo 1296 32! 325 I 213 217 159 163 127 131 105 109 91 95 79 83 1296 GD 1298 323 327 215 219 161 1 65 127 131 107 111 91 95 79 83 1298 00 1300 323 327 215 219 161 165 127 131 107 111 91 95 79 83 1300 Above choice of Pitches will prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch may be varied within reasonable limits. MULTIPLE-CIRCUIT, DOUBLE WINDINGS, FOR DRUM ARMATURES. RE-ENTRANCY No.OF CONDUCTORS FRONT AND BACK PITCHES en K O 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES CONDUCl F B F B F B F B F B F B F B d T. CD 1302 323 327 215 219 161 165 129 133 107 111 91 95 79 83 1302 00 f;Yo4 323 327 215 219 161 165 129 133 107 111 91 95 79 83 1301 GD 1306 1 ;!25 329 215 219 161 165 129 133 107 in 91 95 79 83 1300 oo 1308 r~:!25 329 215 219 161 165 129 138 107 111 !)1 95 79 83 1308 GD 1310 325 525 217 221 161 165 129 133 107 111 91 95 79 83 1310 oo 1312 325 32!) 217 221 161 165 12!) 133 107 111 91 95 79 83 1312 GD 1314 327 331 217 221 163 167 129 133 107 in 91 96 81 85 1314 00 1316 327 331 217 221 163 167 129 133 107 111 91 95 81 ' 85 1316 GD 1318 327 331 217 221 163 167 129 133 107 111 93 97 81 85 1 3 18 oo 1320 327 331 217 221 163 167 129 133 107 111 93 97 81 85 1320 GD 1322 329 333 219 223 163 167 131 135 109 113 98 97 81 85 1322 oo 1324 32!) 333 219 223 163 167 131 135 109 113 98 97 81 85 1324 GD 1326 329 333 219 223 163 167 131 135 109 113 95 97 81 85 1320 oo 1328 329 333 219 223 163 167 131 135 109 113 93 97 81 85 1328 eg 1330 331 335 219 223 165 169 131 135 109 113 93 97 81 85 1330 00 1332 331 335 219 223 165 169 131 135 109 113 93 97 81 85 1 332 GD 1334 331 335 221 225 165 169 131 135 109 113 93 97 81 85 133-1 oo 1336 331 335 221 225 165 169 131 135 109 113 93 97 81 85 1 336 (2) 1338 333 337 221 i 225 165 169 131 135 109 113 93 97 81 85 1 338 oo 1340 333 337 ~2"2~1 225 165 169 131 135 109 113 93 97 81 85 1310 GD 1342 333 337 221 225 165 169 133 137 10!) 113 93 97 81 85 1342 oo 1344 838 337 221 225 165 169 133 137 109 113 93 97 81 85 1344 GD 1346 335 339 223 227 167 171 133 137 111 115 95 99 83 87 1346 00 1348 335 339 223 227 167 171 133 137 111 115 '..-> 99 83 87 1318 E 1 350 335 339 223 227 1C. 7 171 133 137 111 115 95 99 83 87 1350 oo 11552 335 33!) 223 227 167 171 133 137 111 115 95 99 83 87 1352 GD 1354 337 341 223 227 167 171 133 137 111 115 95 99 83 87 1 354 oo 1356 337 341 223 227 167 171 133 137 111 115 !)5 99 83 87 1 356 GD 1358 337 341 225 229 167 171 133 137 111 115 95 99 83 87 1 358 oo I3<;o 337 341 225 229 167 171 133 137 111 115 95 99 83 87 1360 GD 1362 339 343 225 229 169 173 135 139 111 115 95 99 83 87 1362 oo 1361 339 343 225 229 169 173 135 139 111 115 95 99 83 87 1364 GD 1366 339 343 225 229 169 173 135 139 111 115 95 99 83 S7 1366 oo 1368 339 343 225 229 169 173 135 139 111 115 95 '.)!) 83 87 1368 GD 1370 341 345 227 231 1 69 173 135 139 113 117 95 9;i 83 87 1370 oo 1:572 341 345 227 231 169 173 135 13!) 113 117 95 99 88 87 1372 . OB 1374 341 345 227 231 169 173 135 139 113 117 97 101 83 87 1374 oo 1376 :;tl 345 227 231 169 173 135 139 113 117 97 101 83 87 1376 GD 1378 343 347 227 231 171 175 135 139 113 117 97 101 85 89 1378 oo .1:580 343 347 227 231 171 175 135 139 113 117 97 101 85 so 1381) CD 1 3S2 343 347 229 233 171 175 137 141 113 117 97 101 85 S!> 1 382 oo 1384 343 347 229 233 171 175 137 141 113 117 97 101 85 89 1384 03 i:i8i; 345 349 229 233 171 175 137 141 113 117 97 101 85 89 1386 oo 1388 345 34!) 229 233 171 175 137 141 113 117 97 101 85 89 1388 GD l :t'.io 345 34!) 229 233 171 175 137 141 113 J17 97 101 85 89 1390 oo i:i'.2 345 349 229 233 171 175 137 141 113 117 !>7 101 85 89 131)2 22 1394 317 351 231 235 173 177 137 141 115 119 97 101 85 89 1394 oo 1396 347 351 231 2:55 173 177 137 141 115 119 97 101 85 89 1396 GD 1398 347 351 231 235 173 177 137 141 115 119 !)7 1(11 85 89 1398 oo 1400 347 351 231 235 173 177 137 14.1 115 119 97 101 85 89 1400 Above choice of Pitches will prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch may be varied within reasonable limits, MULTIPLE-CIRCUIT, DOUBLE WINDINGS, FOR DRUM ARMATURES. RE-ENTRANCY No. OF CONDUCTORS FRONT AND BACK PITCHES ' CONDUCTORS 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES F B F B F B F B F B F B F B O 6 Z CD 1402 349 353 231 235 173 177 139 143 115 119 99 103 85 89 1402 00 1404 349 353 231 235 173 177 188 143 115 119 99 103 85 89 1404 C5) MOO 349 353 233 237 173 177 139 143 115 119 99 103 85 89 1406 00 1408 349 353 233 237 173 177 139 143 115 119 99 103 85 89 1408 go 1410 _861 355 2:',:', 237 175 179 139 143 115 119 99 103 87 91 1410 00 1412 351 355 2:i3 237 175 179 189 143 115 119 99 103 87 91 1412 OD 1414 351 355 233 237 175 179 139 143 115 119 99 103 87 91 1414 oo 1416 351 355 233 2:i7 175 179 139 143 115 119 99 103 87 91 1410 CE> 1418 353 357 235 239 175 179 139 143 117 121 99 103 87 91 1418 oo 1420 353 357 235 239 175 179 139 143 117 121 99 103 87 91 1420 <3D 1422 353 357 23| 239 175 179 141 145 117 121 99 103 87 91 1422 oo 1424 353 357 235 239 175 179 141 145 117 121 99 103 87 91 1424 CE> 1426 355 359 235 239 177 181 141 145 117 121 99 103 87 91 1426 oo 1428 355 3.',!) 235 239 177 181 141 145 117 121 99 103 87 91 1428 C> 1430 355 359 237 241 177 181 141 145 117 121 101 105 87 91 1480 oo 1432 355 359 237 241 177 181 141 145 117 121 101 105 87 91 1432 (S3 1434 357 361 237 241 177 181 141 145 117 121 101 105 87 91 1434 00 1436 357 361 237 241 177 181 141 145 117 121 101 105 87 91 1436 CE> 1438 357 361 237 241 177 181 141 145 117 121 101 105 87 91 1438 oo 1440 357 361 237 241 177 181 141 145 117 121 101 105 87 91 1440 CE> 1442 359 363 239 243 179 183 143 147 119 123 101 105 89 93 1442 oo 1444 359 363 239 243 179 183 143 147 119 123 101 105 89 93 1444 C> 1446 359 363 239 243 179 183 143 147 119 123 101 105 89 93 1446 00 1448 359 363 239 243 179 183 143 147 119 123 101 105 89 93 1448 CO) 1450 361 365 239 243 179 183 143 147 119 123 101 105 89 93 1450 oo 1452 361 365 239 243 179 183 143 147 119 123 101 105 89 93 1452 O 1454 361 365 241 245 179 183 143 147 119 123 101 105 89 93 1454 oo 1456 361 305 241 245 179 183 143 147 119 123 101 105 89 93 1456 (33 1458 363 367 241 245 181 185 143 147 119 123 103 107 89 93 1458 oo 1460 363 367 241 245 181 185 143 147 119 123 103 107 89 93 1460 1402 363 367 241 245 181 185 145 149 119 123 103 107 89 93 1462 oo 1464 363 367 241 245 181 185 145 149 119 123 103 107 89 93 1464 C53 1466 30,) 369 243 247 181 185 145 149 121 125 103 107 89 93 1466 oo 1468 365 369 243 247 181 185 145 149 121 125 103 107 89 93 1468 CD 1470 365 369 243 247 181 185 145 149 121 125 103 107 89 93 1470 00 1472 365 369 243 247 181 185 145 149 121 125 103 107 8!) 93 1472 CD 1474 367 371 243 247 183 1S7 145 149 121 125 103 107 91 95 1474 00 1470 367 371 243 247 183 187 145 149 121 125 103 107 91 95 1476 O> 1478 367 371 245 249 183 187 145 149 121 125 103 107 91 95 1478 00 14,80 367 371 245 249 183 187 145 149 121 125 103 107 91 95 1480 Cfl) 1482 309 373 245 249 183 187 147 151 121 125 103 107 91 95 1482 oo 1484 369 373 245 249 183 187 147 151 121 125 103 107 91 95 1484 C53 1486 369 373 245 249 183 187 147 151 121 125 105 109 91 95 1486 oo 1488 369 373 245 2411 183 187 147 151 121 125 105 109 91 95 1488 Ca) 1490 371 375 247 251 185 189 117 151 123 127 105 109 91 95 1490 oo 1492 371 375 247 251 185 189 147 151 123 127 105 109 91 95 1492 C2) 1494 371 375 247 251 185 189 147 151 123 127 105 109 91 95 1494 oo 1496 371 375 247 251 185 189 147 151 123 127 105 109 91 95 1496 CE> 1498 373 377 247 251 185 189 147 151 12:! 127 105 109 91 95 1498 00 1500 373 377 247 251 185 189 147 151 123 127 105 109 91 95 1500 Above choice of Pitches will prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch may be varied within reasonable limits. or ran UHIVBRSIT7 MULTIPLE-CIRCUIT, DOUBLE WINDINGS, FOR DRUM ARMATURES. RE-ENTRANCY No.OF CONDUCTORS FRONT AND BACK PITCHES CO cc. o 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES CONDUC' F B F B F B F B F B F B F B O o Z go 1502 373 377 249 253 185 189 149 153 123 127 105 109 91 95 1502 00 1504 373 377 249 253 185 189 149 153 123 127 105 ' 109 91 95 1504 go 1506 375 379 249 253 187 191 149 153 123 127 105 109 93 97 1506 oo 1508 375 379 249 253 187 191 149 153 123 127 105 109 93 97 1508 GD 1510 375 379 249 253 187 191 149 153 123 127 105 109 93 97 1510 oo 1512 375 379 249 253 187 191 149 153 123 127 105 109 93 97 1512 GD 1514 377 381 251 255 187 191 149 153 125 129 107 111 93 97 1514 oo 1516 377 381 251 255 187 191 149 153 125 129 107 111 93 97 1516 GD 1518 377 381 251 255 187 191 149 153 125 129 107 111 93 97 lf> IS 00 1520 377 381 251 255 187 191 149 153 125 129 107 111 93 97 1520 35 1522 379 383 251 255 189 193 151 155 125 129 107 111 93 97 1522 oo 1524 1579 383 251 255 189 193 151 155 125 129 107 111 93 97 1524 05 1 :,26 379 383 253 257 189 193 151 155 125 129 107 111 93 97 1526 oo 1528 379 383 253 257 189 193 151 155 125 129 107 111 93 97 1628 GD 1530 381 385 253 257 189 193 151 155 125 129 107 111 93 97 1530 oo 1532 381 385 253 2:, - 189 193 151 155 125 129 107 111 93 97 1532 GD 1534 381 385 253 257 189 193 151 155 125 129 107 111 93 97 1534 oo 15:56 ;>,si 385 253 257 ls:i 193 151 155 125 129 107 111 93 97 1536 GO 1538 :;s;>, :;s, 255 259 191 195 151 155 127 131 107 111 95 99 1538 oo 1540 383 3S7 255 259 191 195 151 155 127 131 107 111 95 99 1540 GD 1542 383 387 255 259 191 195 153 157 127 131 109 113 95 99 1 542 00 1544 383 387 255 259 191 195 153 157 127 131 109 113 95 99 1544 GD 1546 3S5 389 255 259 191 195 153 157 127 131 109 113 95 99 1 546 oo 1548 385 389 255 259 191 195 153 157 127 131 109 113 95 99 1548 GD 1550 385 389 257 261 191 195 153 157 127 131 ID'.) 113 95 99 1550 oo 1552 385 389 257 261 191 195 153 157 127 131 109 113 95 99 1552 CD 1554 387 391 257 261 193 197 153 157 127 131 109 113 95 99 1554 oo 1556 3H7 391 257 261 193 197 153 157 127 131 109 113 95 99 1556 GD ]558 387 391 257 261 193 197 153 157 127 131 109 113 95 99 1558 oo 1560 387 391 257 261 193 197 153 157 127 131 109 113 95 99 1560 GD 1562 389 393 259 263 193 197 155 159 129 133 109 113 95 99 1562 oo 1564 389 393 259 263 193 197 155 159 129 133 109 113 95 99 1564 GD 1566 389 393 259 263 193 197 155 159 129 133 109 113 95 99 1566 oo 1568 389 393 259 263 193 197 155 159 129 133 109 113 95 99 1568 GD 1570 391 395 259 263 195 199 155 159 129 138 111 115 97 101 1570 00 1572 391 395 259 263 195 199 155 159 129 133 111 115 97 101 1572 GD 1 57 1 391 395 261 265 195 199 155 159 129 133 111 115 97 101 1574 oo 1576 391 395 261 265 195 199 155 159 129 133 111 115 97 101 1576 GD 1.5 7S 393 397 261 265 195 199 155 159 129 133 111 115 97 101 157S oo 1580 393 397 261 265 195 199 155 159 129 133 111 115 1 97 101 1580 GD 15H2 393 397 261 265 195 199 157 161 129 133 111 115 97 101 1582 00 1584 393 397 261 265 195 199 157 161 129 133 111 115 97 101 1584 GD i:>si; 395 399 263 267 197 201 157 161 131 135 111 115 97 101 1586 00 1588 395 399 263 267 197 201 157 161 131 135 111 115 97 101 1588 GD 1590 395 :',',)'.! 263 267 197 201 157 161 131 135 111 115 97 101 1590 oo 1592 i 395 399 263 267 197 201 157 161 131 135 111 115 97 101 1592 GD 1594 397 401 263 267 197 201 157 161 131 135 111 115 97 101 1594 oo 1596 397 401 263 267 197 201 157 161 131 135 111 115 97 101 15% GD J.V.IS 397 mi 265 269 197 201 157 161 131 135 113 117 97 101 1598 oo 1600 397 401 265 269 197 201 157 161 131 135 113 117 97 101 1600 Above choice of Pitches will prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch may be varied within, reasonable limits. WINDING TABLES FOR MULTIPLE-CIRCUIT, TRIPLE WINDINGS FOR DRUM ARMATURES. MULTIPLE-CIRCUIT, TRIPLE WINDINGS, FOR DRUM ARMATURES. RE-ENTRANCY No.OF CONDUCTORS FRONT AND BACK PITCHES No.OF CONDUCTORS 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES F B F B F B F B F B F B F B 202 47 53 31 37 23 29 17 23 13 19 11 17 9 15 202 ooo 204 47 53 31 37 23 29 17 23 13 19 11 17 9 15 204 m 206 49 55 31 37 23 29 17 23 15 21 11 17 9 15 206 8$) 203 19 55 31 37 23 29 17 23 15 21 11 17 9 15 208 000 210 49 55 31 37 23 29 17 23 15 21 11 17 11 17 210 m 212 49 55 33 39 23 29 19 25 15 21 13 19 11 17 212 (as) 214 51 57 33 39 23 29 19 25 15 21 13 19 11 17 214 ooo 216 51 57 33 39 23 29 19 25 15 21 13 19 11 17 216 (aa) 218 51 57 33 39 25 31 19 25 15 21 13 19 11 17 218 (as) 220 51 57 33 39 125 31 19 25 15 21 13 19 11 17 220 ooo 222 63 59 33 39 25 31 19 25 15 21 13 19 11 17 222 (5s) 224 53 59 35 41 25 31 19 25 15 21 13 19 11 17 224 (22) 226 53 59 35 41 25 31 19 25 15 21 13 19 11 17 226 ooo 228 53 59 35 41 25 31 19 25 15 21 13 19 11 17 228 Gfi) 230 55 61 35 41 25 31 19 25 17 2:5 13 19 11 17 230 55 232 55 61 35 41 25 31 21 27 17 23 13 19 11 17 232 ooo 2:u 55 61 35 41 27 33 21 27 17 23 13 19 11 17 234 (52) 236 55 61 37 43 27 33 21 27 17 23 13 19 11 17 236 (ca) 238 57 63 37 43 27 ;!:>, 21 27 17 23 13 19 11 17 238 ooo 240 57 63 37 43 27 33 21 27 17 23 15 21 11 17 240 > 242 57 03 37 43 27 33 21 27 17 23 15 21 13 19 242 (S) 244 57 63 37 43 27 33 21 27 17 23 15 21 13 19 244 000 246 59 65 37 43 27 33 21 27 17 28 15 21 13 19 246 (55) 248 59 65 39 45 27 n 21 27 17 23 15 21 13 19 248 35 250 59 65 I 39 45 29 35 21 27 17 23 15 21 13 19 250 ooo 252 59 65 39 45 29 35 23 29 17 23 15 21 13 19 252 (Sa) 254 61 67 39 45 29 35 23 29 19 25 15 21 13 19 254 400 99 105 65 71 47 53 37 43 31 37 25 31 23 29 406 ooo 408 99 105 65 71 47 5 37 43 31 37 27 33 23 29 408 488 119 125 79 85 57 63 45 51 37 43 31 37 27 33 488 > 490 119 125 79 85 59 65 45 51 37 43 31 37 27 33 490 ooo 492 119 125 79 85 59 65 47 53 37 43 33 39 27 33 492 <3> 494 121 127 79 85 59 65 47 53 39 45 33 39 27 33 494 (55) 496 121 127 79 85 59 65 47 53 39 45 33 39 27 33 496 000 498 121 127 79 S5 59 65 47 53 39 45 33 39 29 35 41)8 OS) 500 121 127 81 87 59 65 47 53 39 45 33 39 29 35 500 Above choice of Pitches will prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch may be varied within reasonable limits. MULTIPLE-CIRCUIT, TRIPLE WINDINGS, FOR DRUM ARMATURES. RE-ENTRANCY No. OF CONDUCTORS FRONT AND BACK PITCHES No. OF CONDUCTORS 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES F B F B F B F B F B F B F B (as) 502 123 129 81 87 59 65 47 53 3'.t 45 33 39 29 35 502 ooo 504 123 12',) 81 87 59 65 47 53 39 45 33 39 29 35 504 (2ft) 506 123 129 81 S7 61 67 47 53 39 45 33 39 29 35 506 ($$) 508 123 129 81 87 61 67 47 53 39 45 33 89 2'.) 35 508 000 510 125 131 M 87 61 67 47 53 39 45 33 39 29 35 510 512 125 131 83 89 61 67 49 55 39 45 33 39 29 35 512 514 125 131 83 89 61 67 49 55 39 45 33 89 29 35 514 000 516 125 131 83 89 61 67 49 55 39 45 33 39 29 35 516 (as) 518 127 133 83 89 61 67 49 55 41 47 88 39 29 35 518 (55) 520 127 133 83 89 61 67 49 55 41 47 35 41 29 35 520 ooo 522 127 133 83 89 63 69 49 55 41 47 35 41 29 35 522 (ft) 524 127 133 85 91 63 69 49 55 41 47 35 41 29 35 52 1 m 526 12!) 135 85 91 58 69 49 55 41 47 35 41 29 35 526 000 528 129 135 85 91 63 69 49 55 41 47 35 41 29 35 528 (2ft) 530 129 135 85 91 63 69 49 55 41 47 35 41 31 37 530 (as) 532 129 135 85 91 63 69 51 57 41 47 35 41 31 37 532 ooo 534 131 137 85 91 63 69 51 57 41 47 35 41 31 37 534 (2ft) 536 131 137 87 93 63 69 51 57 41 47 35 41 31 37 536 (2ft) 538 131 137 87 93 65 71 51 57 41 47 35 41 31 37 53 H 000 540 131 137 87 93 65 71 51 57 41 47 35 41 31 37 540 (2ft) 542 133 139 87 93 65 71 51 57 43 49 35 41 31 37 542 (2ft) 544 133 139 87 93 65 71 51 57 43 49 35 41 31 37 544 ooo 546 133 139 87 93 65 71 51 57 43 49 35 41 31 37 546 _6 139 145 91 97 67 73 53 59 45 51 37 43 33 39 5Ji6 (2ft) 568 139 145 91 97 67 73 53 59 45 51 37 43 33 39 568 ooo 570 139 145 91 97 69 75 53 59 45 51 37 43 33 39 570 as) 572 139 145 93 99 69 75 55 61 45 51 37 43 33 39 572 <15) 574 141 147 93 99 69 75 55 61 45 51 37 43 33 39 574 ooo 57(1 141 147 93 99 69 75 55 61 45 51 3!) 45 33 39 576 (2ft) 578 141 11, 93 99 69 75 55 61 45 51 39 45 33 39 578 (2fl) 580 141 147 93 99 69 75 55 61 45 51 3!) 45 33 39 580 ooo 582 143 149 93 99 69 75 56 61 45 51 39 45 33 39 582 (2ft) 584 113 149 95 101 69 75 55 61 45 51 39 45 33 39 584 28 586 143 149 95 101 71 77 55 61 45 51 39 45 33 39 586 000 588 113 149 95 101 71 77 55 61 45 51 39 45 33 39 588 (2fi) 590 145 151 95 101 71 77 55 (11 47 53 39 45 33 39 590 > 592 145 151 95 101 71 77 57 63 47 53 39 45 33 39 592 ooo 594 145 151 95 101 71 77 57 63 47 53 39 45 35 41 594 (2ft) 596 115 151 97 103 71 77 57 63 47 68 39 45 35 41 596 (2ft) 598 147 153 97 103 VI 77 57 63 47 53 39 45 35 41 598 000 600 147 153 '.)7 103 71 77 57 63 47 53 39 45 35 41 600 Above choice of Pitches will prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch may be varied within reasonable limits. MULTIPLE-CIRCUIT, TRIPLE WINDINGS, FOR DRUM ARMATURES. RE-ENTRANCY No. OF CONDUCTORS FRONT AND BACK PITCHES CO K o 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES CON DUG' F B F B F B F B F B F B F B o d Z (SS) 002 147 153 97 103 73 79 57 63 47 53 39 45 35 41 602 (aa) 604 147 153 97 103 73 79 57 63 47 53 41 47 35 41 604 ooo 006 149 155 97 103 73 79 57 63 47 53 41 47 35 41 606 SB) 008 149 155 99 105 73 79 57 63 47 53 41 47 35 41 608 (5) 610 149 155 99 105 73 79 57 63 47 53 41 47 35 41 610 ooo 612 _ 149 155 99 105 73 79 59 65 47 53 41 47 35 41 012 752 185 191 123 129 91 97 73 79 59 65 51 57 43 49 752 (aa) 754 185 191 123 129 91 97 73 79 59 65 51 57 45 51 754 000 756 185 191 123 129 91 97 73 79 59 65 51 57 45 51 756 (5a) 758 187 193 123 129 91 97 73 79 61 67 51 57 45 51 758 25 760 187 193 123 129 91 97 73 79 61 67 51 57 45 51 760 ooo 762 187 193 123 129 93 99 73 79 61 67 51 57 45 51 762 (aa) 764 187 193 125 131 93 99 73 79 61 67 51 57 45 51 764 (22) 766 189 195 125 131 93 99 73 79 61 67 51 57 45 51 766 ooo 768 189 195 125 131 93 99 73 79 61 67 51 57 45 51 768 (aa) 770 189 195 125 131 93 90 73 79 61 67 51 57. 45 51 770 (aa) 772 189 195 125 131 93 99 75 81 61 67 53 59 45 51 . 772 000 774 191 197 125 131 93 99 75 81 61 67 53 59 45 51 774 (aa) 776 191 197 127 133 93 99 75 81 61 67 53 59 45 51 776 (ss) 778 191 197 127 133 95 101 75 81 61 67 53 59 45 51 778 ooo 780 191 197 127 133 95 101 75 81 61 67 53 59 45 51 780 (22) 782 193 199 127 133 95 101 75 81 63 69 53 59 45 51 782 (2fi) 784 193 199 127 133 95 101 75 81 63 69 53 59 45 51 784 ooo 786 193 199 127 133 96 101 75 81 03 69 53 59 47 53 786 (52) 788 193 199 129 135 95 101 75 81 63 69 53 59 47 53 788 55 790 195 201 129 135 95 101 75 81 63 69 53 59 47 53 790 000 792 195 201 129 135 95 101 77 83 63 69 53 59 47 53 792 (22) 71)4 195 201 129 135 97 103 77 83 63 69 53 59 47 53 794 (22) 796 195 201 129 135 97 103 77 83 63 69 53 59 47 53 796 ooo 798 197 203 129 135 97 103 77 83 63 69 53 59 47 53 798 (22) 800 197 203 131 137 97 103 77 83 63 69 55 61 47 53 800 Above choice of Pitches will prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch may be varied within reasonable limits. MULTIPLE-CIRCUIT, TRIPLE WINDINGS, FOR DRUM ARMATURES. RE-ENTRANCY No. OF CONDUCTORS FRONT AND BACK PITCHES o 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES CONDUC1 F B F B F B F B F B F B F B O 6 z (SS) 802 197 203 131 137 97 103 77 83 63 69 55 61 47 53 802 ooo 804 197 203 131 137 97 103 77 83 63 69 55 61 47 53 804 (ss) 806 199 205 131 137 97 103 77 83 65 71 55 61 47 53 806 (ss) 808 199 205 131 137 97 103 77 83 65 71 55 61 47 53 808 ooo 810 199 205 131 137 99 105 77 83 65 71 55 61 47 53 810 (8) 812 199 205 133 139 99 105 79 85 65 71 55 61 47 53 812 m 814 201 207 133 139 99 105 79 85 65 71 55 61 47 53 814 ooo 816 201 207 133 139 99 105 79 85 65 71 55 61 47 53 816 (55) 818 201 207 133 139 99 105 71) 85 65 71 55 61 49 55 818 CM) 820 201 207 133 139 99 105 79 85 65 71 55 61 49 55 820 ooo 822 203 209 133 139 99 105 79 85 65 71 55 61 49 55 822 SaJ 824 203 209 135 141 99 105 79 85 65 71 55 61 49 55 824 Ss) 826 203 209 135 141 101 107 79 85 65 71 55 61 49 55 826 ooo 828 203 209 135 141 .101 107 79 85 65 71 57 63 49 55 828 (Sfl) 830 205 211 135 141 101 107 79 85 67 73 57 63 49 55 830 (&) 832 205 211 135 141 101 107 81 87 67 73 57 63 49 55 832 ooo 834 205 211 135 141 101 107 81 87 67 73 57 63 49 55 834 (M) 836 205 211 137 143 101 107 81 87 67 ' 73 57 63 49 55 836 (2SJ 838 207 213 137 143 101 107 81 87 67 73 57 63 49 55 838 ooo 840 207 213 137 143 101 107 81 87 67 73 57 63 49 55 840 (SS) 842 207 213 137 143 103 109 81 87 67 73 57 63 49 55 842 (SS) 844 207 213 137 143 103 109 81 87 67 73 57 63 49 55 844 ooo 84l> 209 215 137 143 103 109 81 87 67 73 57 63 49 55 846 ) 848 209 215 139 145 103 109 81 87 67 73 57 63 49 55 848 (as) 850 209 215 139 145 103 109 81 87 67 73 57 63 51 57 850 ooo 852 209 215 139 145 103 109 83 89 67 73 57 63 51 57 852 (M) 854 211 217 139 145 103 109 83 89 69 75 57 63 51 57 854 ) 856 211 217 139 145 103 109 83 89 69 75 59 65 51 57 856 ooo 858 211 217 139 145 105 111 83 89 69 75 59 65 51 57 858 (SS) 860 211 217 141 147 105 111 83 89 69 75 59 65 51 57 860 (S3) 862 213 219 141 147 105 111 83 89 69 75 59 65 51 57 862 ooo 864 213 219 141 147 105 111 83 89 69 75 59 65 51 57 864 (52) 860 213 219 141 147 105 111 83 89 69 75 59 65 51 57 866 (SS) 868 213 219 141 147 105 111 83 89 69 75 59 65 51 57 868 ooo 870 215 221 141 147 105 111 83 89 69 75 59 65 51 57 870 (33) 872 215 221 143 149 105 111 85 91 69 75 59 65 51 57 872 (S3) 874 215 221 143 149 107 113 85 91 69 75 59 65 51 57 874 ooo 876 215 221 143 149 107 113 85 91 69 75 59 65 51 57 876 GOD 878 217 223 143 149 107 113 85 91 71 77 59 65 51 57 878 (S3) 880 217 223 143 149 107 113 85 91 71 77 59 65 51 57 880 ooo 882 217 223 143 149 107 113 85 91 71 77 59 65 53 59 882 1078 267 273 177 183 131 137 105 111 87 93 73 79 65 71 1078 ooo 10HO 267 273 177 183 131 137 105 111 87 93 75 81 65 71 10SO CM) 1082 267 273 177 183 133 139 105 111 87 93 75 81 65 71 1082 cas) 1084 267 273 177 183 133 139 105 111 87 93 75 81 65 71 1084 ooo 1086 269 275 177 183 133 139 105 111 87 93 75 81 65 71 1086 CM) 1088 269 275 179 185 133 139 105 111 87 93 75 81 65 71 1088 CM) 1090 269 275 179 185 133 139 105 111 87 93 75 81 65 71 1090 000 1092 269 275 171) 185 133 139 107 113 87 93 75 81 65 71 1092 (Sa) 1094 271 277 179 185 133 189 107 113 89 1)5 75 81 65 71 1094 CM) 1096 271 277 179 185 133 139 107 113 89 95 75 81 65 71 1096 ooo 1098 271 277 179 185 135 141 107 113 89 95 75 81 65 71 1098 (M) 1100 271 277 181 187 135 141 107 113 89 95 75 81 65 71 1100 Above choice of Pitches wjll prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch may be varied within reasonable limits. MULTIPLE-CIRCUIT, TRIPLE WINDINGS, FOR DRUM ARMATURES. RE-ENTRANCY No OF CONDUCTORS FRONT AND BACK PITCHES en DC o 4. POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES CONDUCl F B F B F B F B F B F B F B h. o Z fSSt 1102 273 279 181 187 135 141 107 113 89 95 75 81 65 71 1102 ooo 11D1 273 279 181 187 135 141 107 113 89 95 75 81 65 71 1104 (3D 1106 273 279 181 187 135 141 107 113 89 95 75 SI 07 73 1106 (2a) 1108 273 279 181 187 135 141 107 113 89 95 77 83 67 73 1108 ooo 1110 275 281 181 187 135 141 107 113 89 95 77 83 67 73 1110 (&&) 1112 275 281 183 189 135 141 109 115 89 95 77 83 67 73 1112 <3a) 1114 275 281 183 189 137 143 109 115 89 95 77 83 67 73 1114 ooo 1116 275 281 183 189 137 143 109 115 89 95 77 83 67 73 1116 (ss) 1118 277 283 183 ISO 137 143 109 115 91 97 77 83 67 73 1118 (so) 1120 277 283 183 18!) 137 143 10!) 115 91 1)7 77 83 67 7;! 1120 ooo 1122 277 283 183 189 137 143 109 115 91 97 77 83 1 67 73 1 122 (SA) 1124 277 2S3 185 191 137 143 109 115 91 97 77 83 67 73 1124 (fifl) 1126 279 285 185 191 137 143 109 115 91 97 77 83 67 73 1126 ooo 1128 271) 285 185 191 137 143 109 115 91 97 77 83 67 73 1128 (S) 1130 279 285 185 191 139 145 109 115 91 97 77 83 67 73 1130 (SS) 1132 279 285 185 191 139 145 111 117 91 97 77 83 67 73 1132 ooo ll:tl 281 287 185 191 139 145 111 117 1)1 97 77 83 67 73 1134 (aa) 1136 281 287 187 193 139 145 111 117 91 97 79 85 67 73 1136 (S) ll:!8 281 287 187 193 139 145 111 117 91 97 79 85 69 75 1138 ooo 1140 281 287 187 193 139 145 111 117 91 1)7 79 85 69 75 1140 (Si 1142 283 289 187 193 139 145 111 117 93 99 79 85 69 75 1142 GOD 1144 283 289 187 193 139 145 111 117 93 99 79 85 69 75 1111 ooo 1146 283 289 187 193 141 147 111 117 93 99 79 86 01) 75 1 140 (3D 1148 283 2S1J 189 195 141 147 111 117 93 99 79 s.-) 69 75 1148 (5e) 115H 2S5 291 189 195 141 147 111 117 93 99 79 85 69 75 1150 ooo 1 1 52 285 291 189 195 141 147 113 119 93 99 79 85 69 75 1152 (3D 1154 285 291 189 11)5 141 147 113 119 93 99 79 85 69 75 1154 GOD 1156 285 291 189 195 141 147 113 119 93 99 79 85 69 75 1156 ooo 1158 287 293 189 195 Ml 147 113 119 93 99 79 85 69 75 1158 GOD 1160 2S7 293 191 197 141 147 113 119 93 99 79 85 69 75 1160 GOD 11IJ2 287 293 191 197 143 149 113 119 93 99 7!) 85 69 75 1162 ooo i Hvi 287 293 191 11)7 143 149 113 119 93 99 81 87 69 75 1164 GOD 1 Kill 289 295 191 197 111! 149 113 119 95 101 81 87 69 75 1100 GOD 1108 289 295 191 197 143 149 113 119 95 101 81 87 69 75 1168 ooo 1170 2S!> 295 191 197 143 149 113 119 95 101 81 87 71 77 1170 CM) 1172 289 295 193 199 143 149 115 121 95 101 81 87 71 77 1172 (9?) 1171 291 21)7 193 1 1)1) 143 149 115 121 95 101 81 87 71 77 1174 ooo 1170 291 297 193 11)1) 143 149 115 121 95 101 81 87 71 77 1176 GOD 1178 21)1 297 193 199 145 151 115 121 95 101 81 87 71 77 1178 293 299 193 199 145 151 115 121 95 101 81 87 71 77 1182 GOD 3184 293 21)1) 195 201 145 151 115 121 95 101 81 87 71 77 1 ] SI (aa) 1186 293 299 195 201 145 151 115 121 1)5 101 81 87 71 77 1186 OOO 1188 21)3 29!) 195 201 145 151 115 121 95 101 81 87 71 77 1188 SR) 1190 21)5 301 195 201 145 151 115 121 97 103 81 87 71 77 1190 Sa) 1192 2!>5 301 195 201 145 151 117 123 97 103 83 89 71 77 1192 ooo 11'.) 1 21)5 301 195 201 147 153 117 123 97 103 83 89 71 77 1194 (Sa) ll'.IO 295 301 197 203 147 153 117 123 97 103 83 89 71 77 1196 fiS 1198 2'.7 :jo:s 197 203 147 153 117 123 97 103 83 89 71 77 1198 ooo 1200 297 303 197 203 147 153 117 123 97 103 83 89 71 77 1200 Above choice of Pitches will prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch may be Varied within reasonable limits. MULTIPLE-CIRCUIT, TRIPLE WINDINGS, FOR DRUM ARMATURES. RE-ENTRANCY No. OF CONDUCTORS FRONT AND BACK PITCHES No.OF CONDUCTORS 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES F B F B F B F B F B F B F B _ (55) 12(18 313 319 209 215 155 161 123 129 103 109 87 93 77 83 1268 1270 315 321 209 215 155 161 123 129 108 109 87 98 77 83 1270 000 1272 315 321 209 215 155 161 125 131 103 109 87 93 77 83 1272 (55) 1274 315 321 209 215 157 163 125 131 103 109 87 93 77 83 1274 (52) 1276 315 32 1. 209 215 157 163 125 131 103 109 89 95 77 83 1216 ooo 1278 317 323 209 215 157 163 125 131 103 109 89 95 77 83 1278 (55) 1280 317 323 211 217 157 163 125 131 103 109 89 95 77 83 1280 (55) 1282 317 323 211 217 157 163 125 131 103 109 89 95 77 83 1282 000 1284 317 323 211 217 157 163 125 131 103 109 89 95 77 83 1284 1472 365 371 243 249 181 187 145 151 119 125 103 109 89 95 1472 CM) 1474 365 371 243 219 181 187 145 151 119 125 103 109 89 95 1474 ooo 1476 365 371 243 249 181 187 145 151 119 125 103 109 89 95 1476 Caa) 1478 367 373 243 U?49 181 187 145 151 121 127 103 109 89 95 1478 CM) 14SO 367 373 243 249 181 187 145 151 121 127 103 109 89 95 1480 ooo 1482 367 373 243 249 183 189 145 151 121 127 103 109 89 95 1482 CM) 1484 367 373 245 251 183 189 145 151 121 127 103 109 89 95 1484 CM) 1486 369 375 245 251 183 189 145 151 121 127 103 109 89 95 1486 ooo 1488 369 375 245 251 183 189 145 151 121 127 103 109 89 95 1488 CM) 1490 369 375 245 251 183 189 145 151 121 127 103 109 91 97 1490 CM) 1492 369 375 215 251 183 189 147 153 121 127 103 109 91 97 1492 ooo 1494 371 377 245 251 183 189 147 153 121 127 103 109 91 97 1494 (9> 1496 371 377 247 253 183 189 147 153 121 127 103 109 91 97 1496 C5a> 1498 371 377 247 253 isr, 191 147 153 121 127 103 109 91 97 1498 ooo 1500 371 377 247 253 185 191 147 153 121 127 105 111 91 97 1500 Above choice of Pitches will prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch may be varied within reasonable limits. MULTIPLE-CIRCUIT, TRIPLE WINDINGS, FOR DRUM ARMATURES. RE-ENTRANCY No. OF CONDUCTORS FRONT AND BACK PITCHES CO o: 4 POLES 6 POLES 8 POLES 10 POLES 12 POLES 14 POLES 16 POLES CONDUC^ F B F B F B F B F B F B F B O 6 Z (22) 1502 373 379 247 253 185 191 147 1 5:< 123 129 105 111 91 97 1502 (22) 1504 373 379 247 253 185 191 147 153 123 129 105 111 91 1)7 1501 ooo 151 10 373 379 247 253 185 11)1 147 153 123 129 105 111 91 97 1506 (sa) 1508 373 379 249 255 185 191 147 153 123 129 105 111 91 97 1508 (22) 1510 375 381 249 255 185 11)1 147 153 123 12!) 105 111 91 97 1510 ooo 1512 375 381 249 255 185 191 149 155 123 42!) 105 111 91 97 1512 (22) 1514 375 381 249 255 187 193 149 155 123 129 105 111 91 97 1514 m 1516 375 381 249 255 187 193 149 155 123 129 105 111 91 97 1516 ooo 1518 377 383 249 255 187 193 149 155 123 129 105 111 91 97 1518 (55) 1520 377 383 251 257 1S7 193 1 49 155 123 129 105 111 91 97 1520 (22) 1522 377 383 251 257 187 193 149 155 123 129 105 111 93 99 1522 000 1524 377 383 251 257 187 193 149 155 123 129 105 111 93 99 1524 (22) 1526 379 385 251 257 187 193 149 155 125 131 105 111 93 99 1526 (22) 1528 379 385 251 257 187 193 149 155 125 131 107 113 93 99 1528 ooo 1530 379 385 251 257 189 195 149 155 125 131 107 113 93 99 1530 m 1532 379 385 253 259 189 195 151 157 125 131 107 113 93 99 1532 (sa) 1534 381 387 253 259 189 11)5 151 157 125 131 107 113 93 99 1534 ooo 1536 381 387 258 259 189 195 151 157 125 131 107 113 93 99 1536 (22) 1538 381 :is7 253 259 189 11)5 151 157 125 131 107 113 93 99 1538 (22) 1540 381 387 253 251) 189 195 151 157 125 131 107 113 93 99 1540 ooo 1542 383 389 253 259 IS!) 195 151 157 125 131 107 113 1)3 99 1542 MI 1544 383 389 255 261 1 81) 195 151 157 125 131 107 113 93 !)!) 1544 m 1546 383 389 255 261 191 197 151 157 125 131 107 113 !)3 99 1546 000 15 IS 383 389 255 261 191 197 151 157 125 131 107 113 !)3 99 1548 _ 1550 385 391 255 261 191 197 151 157 127 133 107 113 93 99 1550 m 1552 .385 391 255 261 191 197 153 159 127 133 107 n;; 93 99 1552 000 1554 385 391 255 261 191 197 153 159 127 133 107 113 95 101 1554 (22) 1556 :;sr, 391 257 263 11)1 197 153 159 127 133 109 115 95 101 1556 155H 387 393 257 263 191 197 153 159 127 133 109 115 95 101 1568 ooo 1500 387 393 257 263 191 197 153 159 127 133 109 115 95 101 15(50 (sa) 1562 387 393 1 257 263 193 199 153 159 127 133 109 115 95 101 1562 (22) 1564 387 393 257 263 193 199 153 159 127 133 109 115 95 101 1504 000 1566 381) 395 257 263 193 199 153 159 127 133 109 115 95 101 1506 (22) 1568 389 395 259 265 193 199 153 159 127 133 109 115 95 101 1508 Sa) 1570 389 3D5 259 265 193 199 153 159 127 133 109 115 95 101 1570 000 1572 389 : ;i)5 259 265 11)3 ID!) 155 161 127 133 109 115 95 101 1572 (22) 1574 391 397 259 266 193 I!)!) 155 161 129 135 109 115 95 101 1574 m 1570 391 397 259 266 193 11)1) 155 161 129 135 109 115 95 101 1576 000 1578 391 397 259 20,5 195 201 155 161 129 135 109 115 !)5 101 157S 5s~ 15SO 391 397 261 267 11)5 201 155 101 i 129 135 109 115 95 101 1580 (28) 1582 393 399 261 267 1 1)5 201 155 161 129 135 109 115 95 101 1 5S2 000 1 5H 1 393 399 261 267 195 201 155 161 129 135 111 117 95 101 1584 122 1586 393 399 261 267 195 201 155 161 129 135 111 117 97 103 1 5S6 (22) 1588 393 399 261 267 11)5 201 155 161 129 135 111 117 97 103 15S8 ooo 151)0 395 401 261 267 11)5 201 155 161 129 135 111 117 97 ]03 151)0 (80 1 .7 11! 395 401 263 269 195 201 157 163 129 135 111 117 97 J03 1592 (22) 151(4 :ili5 401 21.3 269 11)7 21)1! 157 163 129 135 111 117 97 103 1594 ooo 1596 395 401 203 J.r.'.i 197 2(K! ! 157 163 129 135 111 117 97 J03 1500 (22) 151)8 397 403 263 20'.) 197 203 157 163 131 137 111 117 97 103 151)8 (22) 1600 397 403 263 20',l 197 203 157 163 131 137 111 117 97 103 1600 Above choice of Pitches will prove most satisfactory, although, as stated in text, the absolute magnitude of average pitch may be varied within reasonable limfts. LIST OF WORKS ON ELECTRICAL SCIENCE, PUBLISHED AND FOR SALE BY D. VAN NOSTRAND COMPANY, 23 Murray and 27 Warren Streets, New York. ABBOTT, A. V. The Electrical Transmission of Energy. A Manual for the Design of Electrical Circuits. 8vo, cloth. (/ press.") AKNOLD, E. Armature Windings of Direct Current Dynamos. Extension and application of a general winding rule. Translated from the original German by Francis B. DeGress, M. B. ( In press ) ATKINSON, PHILIP. Elements of Static Electricity, with full description of the Holtz and Topler Machines, and their mode of operating. Illustrated. 12mo, cloth. $1.50. The Elements of Dynamic Electricity and Magnetism. Second Edition. Illustrated. 12mo, cloth. $2.00. Elements of Electric Lighting, including Electric Generation, Measurement, Storage, and Distribution. Seventh Edition. Fully revised and new matter added. Illustrated. 8vo, cloth, fl.50. 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(5) UNIVERSITY OF CALIFORNIA LIBRARY BERKELEY Return to desk from which borrowed. This book is DUE on the last date stamped below. OCT 2 1 1950 LD 21-:OOm-9,'48(B399sl6)476