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 THESIS 
 
 MULTIPHASE ALTERNATING 
 CURRENT TRANSMISSION 
 
 H. T, CORY 
 
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 Xtbrarp 
 
 |$ Ibarr^ ZL Cor^ 
 
 
 
 UNIVERSITY OF CALIFORNIA 
 AT LOS ANGELES

 
 xv
 
 # TK. 
 
 The transmission of power by multiphase alternating 
 currents is an outcome of the strenuous efforts of late 
 years made for the purpose of rendering inaccessible sourc^ 
 of power accessible. In other w rds the attempt has been 
 made to surpass Mohammed's great feat of bringing the 
 Mountains to him, by another feat of greater difficulty, ow 
 ing to the intangibility of the necessary components of it. 
 How well this has been carried out the amazing growth and 
 multiplication of power distribution plants will amply tes- 
 tify. Especially is meant those installations which derive 
 their power from remote sources where great quantities of 
 energy were previously being wasted in waterfalls and 
 rivers. 
 
 The necessity for transmission is quite apparent 
 
 when we consider the fact that manufacturing outers can- 
 
 . 
 
 not always be placed away off in the muuntains. 
 
 The necessity being realized the question becomes 
 how to obviate it. And in this case it has been f ounft that 
 the only way in which power can be efficiently transmitted 
 through long distances is by means of electricity. And at 
 the present time the most satisfactory method which has yet 
 presented itself is that of transmission by alternating cur- 
 rents differing in phase. 
 
 The economic transmission of power by electricity 
 demands primarily high potential, both to save expense in 
 copper and also at the same time to prevent excessive loss 
 in heating effect due to the large currents which become 
 
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 necessary with the use of low potential. 
 
 Since the power in watts of a current of electricity 
 depends upon two factory, current and electro-motive force 
 multiplied together, it follows that any given power may 
 be obtained with Tfidely varying values of the two factors 
 profiling their product is constant. Thus 1000 watts may 
 be transmitted by a current of 1000 amperes at a pressure 
 of 1 volt, or by a current of 1 ampere at 1000 volts, or by 
 500 amperes at 2 volts and so on ad infinitum, providing 
 that the product E C equals always 1000. Since the size of 
 a conductor depends upon the magnitude of the current flot- 
 ing through it, it is clear that to save copper the current 
 must be small and the pressure correspondingly *4ph. Fur- 
 thermore, since the loss by hart ting variea as the square 
 of the current another important reason for the use of 
 small currents, that is high potentials, is evident. Thus 
 we see the necessity for high tension transmission depends 
 upon important commercial considerations* 
 
 It becomes necessary in order to prevent great first 
 cost and to do away with excessive losses in operation. 
 
 Having established the important fact that hih 
 voltages are absolutely necessary, the reason - or the use 
 of alternating currents instead of direct currents will 
 bear explanation. 
 
 The reason in question is not so much a commercial 
 one as a practical one. The main consideration upon whcih 
 the use of alternating currents depends is that of the 
 wonderful flexibility of its applications* For instance,
 
 
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 if we have an alternator by the use of transformers con- 
 taining no moving parts whatever it is possible to use \\e 
 output of the generator at any potential whatever. And If 
 the machine is a two or three phase one it is possible, 
 and moreover practicable, to take from it currents of three 
 or two phase no matter what the original current may have 
 been. All of these transformations may be accomplished with 
 small losses* 
 
 The importance of being able to obtain a high volt- 
 age from a low voltage machine is at once evident when we 
 consider that the cost of transmission is lessened at high 
 pressures, the cost of copper varying inversely as the 
 square of the voltage, and moreover that it is practically 
 impossible to build a dynamo that will stand high enough 
 pressure to enable its output to be transmitted through 
 great distances. It has been found that it is practically 
 impossible to insulate the moving parts of generators giv- 
 ing en output at a potential of more than 3500 volts and 
 current greater than 30 to 50 amperes. This pressure is 
 bad enough t o deal with in an alternator where the moving 
 contacts are extremely simple; but when it comes to the 
 construction of a commutator to withstand this potential 
 the problem becomes impossible when the current is large. 
 The current simply jumps from tear to bar all around that 
 commutator forming an arc around it, with the result that 
 that important part is soon ruined. 
 
 Even suppose that it were possible to build direct 
 current generators of high voltage, say 10000 for example,
 
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 it would still b<3 impossible to run lights upon this cur- 
 rent, and the apparatus for reducing this potential down 
 
 to one not above the capacity of an incandescent lanip 
 
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 would involve the use of rotating parts requiring consider- 
 able attention and subject to continual wear. At the same 
 
 time the efficiency of such rotary converters is not equal 
 
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 to that of transformers. 
 
 Of course if all the light and power to be supplied 
 were situated immediately about the distribution center at 
 the end of the fcine only one rotary converter would be 
 needed. But in case the consumers wore scattered over a 
 considerable area the economical distribution of light and 
 power would demand high potentials, so high in fact as to 
 be prohibitive of the use of incandescent lamps without the 
 use of the apparatus Just mentioned. Exen then every con- 
 sumer cannot afford to have such an expensive and trouble- 
 some thing in his house as a rotary transformer, rotary con 
 verter, motor-generator, motor-dynamo or dynamotor as it 
 
 is variously called. 
 
 However this disagreeable necessity will be spared 
 him for a v/riile yet, since up to the present time no direct 
 
 current dynamos have been constructed to run on so high a 
 
 voltage of rijri| great power, 
 
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 Briefly, the superiority of the alternating current 
 for transmission of 11 - 1 ' and power depends upon the readi- 
 ness with which we can transform it up or down to any po- 
 tential whatever by means o^ inert apparatus which can be 
 insulated to withstand any pressure denired. This instru-
 
 
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 mont , the transformer, moreover, suffers no loss from wear 
 and ther3fore requires absolutely no attention whatever. 
 It can be put out in the rain on a pole and bo left there 
 for years without undergoing repair. 
 
 An alternating current power transmission plant 
 would in its chief essentials consist of the following 
 parts. First, at the source of power, say a waterfall, 
 there would bo an installation consisti|ngf of turbines or 
 impact wheels running one or more alternators wound for a 
 moderate difference of potential at the terminals. The cur 
 
 rent thus generated would be converted to one of high po- 
 
 curve. h& Q many 
 
 tential by menns of step up transformers, and then trans- 
 mitted to the distant point where it is to be utilized, 
 
 Which .".;1vs oTf t<iV 
 converted to a current of sufficiently lew potrnti?! by 
 
 sro values ~ 
 
 means of step down transformers, in order to render it ap- 
 plicable for use in lights or motors. 
 
 Until within f .he last few years it was impossible 
 
 A 
 to follow out the above scheme with any economy ojl account 
 
 of the inefficiency of alternating current motors. In fact 
 it has only been comparatively recently that they have had 
 any self starting alternating current motors at all that 
 would run successfully. But at the pr sent time the theory 
 of alternati! currents is much better understood, so that 
 now motors are made to run on them with Just as good re- 
 sults av obtained by the use of direct current motors. 
 still the use of alternating current motors is practically 
 a new thing > but fron what we havo soon of them already it 
 has been nnde evident that their use for the transmission
 
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 of power through long distances is far more efficient and 
 is attended with far better results than have ever been 
 realized by any other means. 
 
 In transmission work we have the choice of various 
 
 .or ; 
 systems, single phase, two phase and three phase. As is 
 
 we 
 well known, the simple alternating current is of a pultat- 
 
 r- 5 ' "* ' r ;~ f 
 ing character, the direction and intensity of the current 
 
 varying regularily according to a well determined law. So 
 that when we have a conductor moving in a magnetic field 
 on the periphery of an armature the fluctuations of current 
 and electro-motive force may be plotted in the form of a 
 curve. The curve in many cases is sinusoidal* 
 
 In a polyphase current generator we have a machine 
 
 . 1 -. , -, .,*< ; , ; . f r '-, $* & i \ **'** 
 
 which gives off several currents which pass through their 
 zero values and attain their maxima at different times but 
 still at regular intervals. 
 
 In a three phase dynamo for instance, we have an 
 armature with three windings each giving a current differ- 
 ing 120 degrees in phase from the other. It is evident 
 
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 that in an ordinary alternating current the power at times 
 
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 is zero, it being also of a pulsating character. But in a 
 polyphase current the power is prattically constant, as at 
 
 V 
 
 no time is the current flowingpO or anywhere near it. 
 
 These three classes of currents of course necessi- 
 tate different types of motors and generators. And the 
 c nstruction of a successful motor involves the application 
 of principles which were not understood for a long time. 
 
 The early attempts to operate motors on alternating
 
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 currents were naturally far from being successful on this 
 account. The first practical motors wre of the synchron- 
 ous type, the first one of which was experimented with at 
 North Foreland in 1884. All motors of any account whatever 
 were of this type until the discovery in 1888 of the pro- 
 perty of the rotating field as produced by two phase alter- 
 nating currents. We are indebted to Prof. Ferraris and to 
 Mr. Tesla for the first convincing experiments. These two 
 experimenters reached practically the same conclusion, 
 working independently and simultaneously. Since that time 
 the three phase motor has been developed upon the same liaes 
 and the two have been improved mechancially and theoretical- 
 ly until now, as Dr. Bell has pointed out in a recent arti- 
 cle, they are equal and in many points superior to the 
 best direct current motors. Dr. Bell believea thst they 
 will soon replace to a large extent the old direct cur- 
 rent motors in many important industrial applications. ( 
 ( E. W. XXIV, 124) 
 
 Transmission of power by alternating currents we 
 have seen may he accomplished by the use of three different 
 systems. (1) Single Phase, (2) Two Phase and (3) The Three 
 Phase system. The latter two are extremely similar, each 
 having its adherents and opponents^ It even seens that nost 
 controversies upon the relative merits of the two and three 
 phase currents are, in many respects due to commercial 
 question* rather than engineering det 'ils. We will now 
 consider the three methods of transmission or power by al- 
 ternating currents.
 
 
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 .
 
 SINGLE PHASE TRANSMISSION. 
 
 
 Single phase currents are practically limited to the 
 transmission of large units of pov/er. In such a case, at 
 the generating station there is an ordinary single phase 
 generator supplying current to step-up transformers per- 
 haps, transmitting power to a motor station where there 
 are step-down transformers to adapt the electro-motive 
 force to the requirements of one synchronous motor. This 
 motor is a machine exactly similar to the generator, being, 
 like it, separately excited. A synchronous motor on a 
 single phase circuit will not start itself, it being neces- 
 sary to bring it up by some auxiliary apparatus, usually a 
 self-starting motor running on the alternating current or 
 else a direct current motor actu^fed by storage batteries 
 
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 charged by the exciter. 
 
 This non-starting property of synchronous motors is 
 the great cause for their inability to be used in power 
 distribution. However, where it is desired simply to trans 
 mit one large unit of power from one locality to a more 
 favorable one the synchronous motor on account of its high 
 efficiency and perfect regulation for varying loads be- 
 comes a most valuable machine. 
 
 For power distribution in small ".nits the synchronous 
 motor possesses several serious defects other than the one 
 mentioned. Taking all together, the following obstacles 
 present themselves: (1) All synchronous motors must be 
 saparately excited, unless a part of the current be com- 
 atunicated; and this would necessitate ha addition of a 
 
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 trc ,')lesome commutator to all the oilier disadvantages. 
 Bven then (2} The machine must be started before it will 
 run. It must bo turned fast enough to approach the speed 
 of synchronism before the main current is switched on. Of 
 course this ^s of very small moment when a large plant is 
 to be operated as the additional expense of a small motor 
 would be insignificant; but such a necessary appendage pre- 
 cludes the use of synchrAnous motors being used by small 
 consumers. Moreover: (3) If the load exceeds a certain 
 amount the not or is thrown out of step and stops immediate- 
 ly | He ither will it start again when the overload is re- 
 moved: but, unlike a steam engine, waterwheel or any other 
 kind of motor the whole starting process must be repeated. 
 (4) The current la^s behind the electro-motive force by an 
 angle which is a maximum at no load and a minimum at full 
 load. Thus under favorable conditions the motor nay be re- 
 turning as much energy to the circuit alnost, as is being 
 ,^iven to it. Still the same current is flowing and al- 
 though it may not be doing any use full work all wires must 
 be made large enough to carry it and the C R losses are 
 ~:in on all the time. 
 
 (5) All synchronous motors require to be designed 
 not only for given voltage, speed -^nd output, but for a 
 given frequency and therefore van be worked only on ^iven 
 cirsv.its. (6) These motors all have dead points in each 
 
 thus necessitating their application in such a man- 
 
 ner that there will be no danger of stoppage at such points. 
 (7) Synchronous motors can be ran at one speed only and that
 
 
 
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 is the speed which would cause it n - ^ dynamo to ve 
 a current of the same frequency as that supplied it. This 
 of necessity limits its application to those cases v/here 
 constant speed is either necessary or at least unobjection- 
 able. 
 
 There are many other motors adapted to run on sin- 
 gle phase currents but few of them are efficient for moder- 
 ate powers such as would be required in distribution work. 
 There are, it is true, many cases v/here efficiency does 
 not count for much and it is in such crses that these mot- 
 ors find application. They are mostly, however, of minor 
 importance, being confined to umimpoHant duties such as 
 driving fans. 
 
 Ordinary direct current shunt and series ipotors have 
 been experimented with^with a view to their application!! 
 en alternating currents, but with small success. The fields 
 were carefully luminated to prevent loss by Poucault cur- 
 rents. Owing to the difference in the co-efficients of self 
 induction in armature and field of a shunt machine the two 
 cfjtfflpfts flowing through each differ in phase thus the 
 periods of minirrira and maximum magnetization in e ich do 
 not coincide, with the result that the motor runs in a 
 very unsatisfactory manner or even may not run at all. 
 The series machine acts somewhat better but it is also vory 
 unsatisfactory, the loss by hysteresis is sometimes con- 
 siderable, the current is made to lag considerably, and the 
 sparking at the brushes is distinctive owing to the self 
 induction in the armature coils. In both types the outrnit 
 per unit of weight is very mall.
 
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 11 
 
 In the shunt type condensers have been resorted to 
 to restore the difference in phase between the two cur- 
 rents but great difficulties have beem encountered. The a 
 action of the condenser is to cause the current tohave a 
 lead over the electro-mot iv: force. 
 
 In the first place the condenser must be designed 
 for one given frequency and for a certain angle of advance. 
 Just what angle of advance is necessary is very difficult, 
 one might say impossible, to determine on account of the 
 effect* of the armature reactions. Therefore it was found 
 impossible to counteract the effect of self induction. 
 Even could such a thing be done with entirely satisfactory 
 results, the fact still remains that a condenser is a 
 "white elephant" of considerable magnitude. In the first 
 place it is expensive, and in the second place it is liable 
 to get out of order and is susceptible to damaging effects 
 from climate etc. These things will change its capacity 
 and therefore at the same time will cause the angle ff ad- 
 vance which it gains to be an unknown quantity. 
 
 A more pratical motor than either of these is the 
 induction motor. This depends upon the principle that a 
 closed coil of wire when placed in an alternating field 
 tends to move LSO that the magnetic flux through it is a 
 minimum. If we take an ordinary armature and place in an 
 alternating magnetic field, short circuiting each coil at 
 the proper time, it will answer tho above conditions. 
 
 An ordinary to pole motor will, by exciting its 
 field with an alternating current and giving its brushes a 
 forward lead of about -1-5 degrees fulfill all of these re-
 
 
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 .
 
 18 
 
 quirenents. 
 
 Another way of doing it is to place tthortcircuited 
 armature coils unsymmetrically with reference to the field 
 That is, the number of poles in the field and the nuriber of 
 
 coils in the armature must not have a common factor. A 
 
 ,--,.-- 
 motor built on this plan will not start of its own accord 
 
 but will rotate in either direction in which it is started. 
 It can however be made self-starting by winding the field 
 coils in two sets of different windings, such that they 
 hall possess different coefficients of self induction; tbe 
 currents in each therefore differ in phase, and the machine 
 is virtually a two phase motor and self- starting. 
 
 The action of this motor is entirely similar to 
 that of the multiphase motors and depends upon the same 
 principle, that of the rotary field. A single phase cur- 
 rent may be divided into two branches in which the current 
 may be made to differ in phase by inserting capacity in 
 one branch and self induction in the other. This method, 
 however, leads to the use of the objectionable condenser 
 again. This is virtually an encroachment upon the domain 
 of multiphase currents, and having already alluded o the 
 rotary field and to the self-starting induction motor, it 
 will necessary in order to explain the principles of multi- 
 phase transmission and multiphase motors, that is trans- 
 mission by either two or three phase currents.
 
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 e"s noqjj sl)nsqs.u Bn^i aiojom yaBAqxtXum tW to $Rd3 
 
 .Jble 
 
 e-rijja srfu r-oiow ni af>i:; (Bid ow^ ojf.i bs&iviij ed Yarn ^ 
 
 > .tefiJt rfvl ai rol^o.Lriin.x llea fcmi lioiiBid eno 
 
 :iJ o' 0a.biflli J^3:!ft:-^.$^ 
 
 Ia erf^ ot bita Msil V^B^OT 

 
 13 
 
 MULTIPHASE TRANSMISSION. 
 
 Synchronous motors for multiphase transmission are 
 really synchronous induction motors but unlike single phase 
 synchronous motors they are to a certain extent self-~r 
 i**tiApg. However, what lends additional value to the 
 multiphase system is that all the motors, large and small, 
 are self starting and behave as well as, and often better, 
 than their direct current brethern. 
 
 For this we are indebted to the properties possessed 
 by the rotary field several times mentioned. Prof. Ferrar- 
 is in March 1888 discovered that when t\vo alternating cur* 
 rents, differing in phase from each other by 90 degrees, 
 were passed through two cur&ftts placed at right angles to 
 each other they set up a magnetic field which rotated cnce 
 for every cycle. Now if a closed coil be placed in this 
 magnetic field it will turn so as to keep the magnetic flux 
 through it a minimum as already stated. But since the 
 magnetic field Is also moving it follows that the enclosed 
 coil will revolve continually about its axis Just as long 
 as the magnetic field rotates. 
 
 The coil tries to move so that no currents will be 
 induced i-- it, in accordance v/ith the well established i<x>r 
 which states that a conductor moving in a magnetic field 
 v;ill have a crrrent set up in it in nuch a direction as to 
 oppose the motion. In the care under consideration it is 
 the magnetic fiold v; v ich moves primarily, thus inducing a 
 current in the conductor which causes the conductor to 
 3 so as *,o stop the current.
 
 . 
 
 : 
 
 :.-: otrvofve 
 Offl 
 
 ttie e^ifil BTOJom erf Lie $aA3 Bi mes^-a _ 
 
 ne.l'io bnr ,as IXev an- a-verted ^ns sn^^^- 8 ^^ Ha 
 
 HP 
 
 aet ;.-:.- --1 ( o.-^ oJ .be^'/.ebr:i' SIB w sirf^ to'? 
 t' 
 . -fU be^evcoi^Jb 88^1 iiDtBM 
 
 * h ' 
 
 ii^ .~f Brief av.o lol Ji gnlvarc oals ai Jblsil 
 ' vlove't 
 
 IX 
 
 ble 11 oiJrr^ij!S! B nt 5^ ' Q v*Bri* as^B^e 
 
 
 
 .
 
 "14 
 
 Therefore the conductor tries to become stationary 
 with reference to the magnetic field, which it can do only 
 by revolving as fast as the field and in the same direction. 
 
 It is plain enough to see why the conductor moves 
 if we grant that the magnetic field rotates as has been 
 said. The reason may be shown simply by means of a figure. 
 We will take the case of two currents which differ 90 de- 
 grees in phase. The figure represents an ordinary four 
 pole field with two separate windings. 
 
 The two windings are plac- 
 ed so that the wires con- 
 taining one current are 
 wound on opposite poles. 
 
 How since the two cur- 
 rents differ 90 degrees in 
 phase it follows that when 
 one is a maximum the other is a minimum. Suppose current 
 A 8 is a maximum at the time T, then at that instant there 
 is a north pole at N and a south pole at S, while the other 
 two possess no polarity whatever, but Just one quarter of 
 a cycle after, circuit A B is and C B is a maximum with 
 the resultf that the north pole has shifted to N 1 and the 
 south pole to S f . And so the action continues, the next 
 quarter cycle finds current A B a maximum but flowing in 
 the reverse direction, so that the north pole is at 3 and 
 the south pole at N. The final result is then a magnetic 
 field revolving in space about an axis perpindicular to 
 the plane of the diBgram. The closed coil in the practical
 
 .1 Oi$7 
 
 r. afc saivlo 
 ai |X 
 
 n*<> KB jrW J*'"- 
 
 latllfr rfblKtf w^norxiSfe ow* 'to eao riJ 
 
 rf-ilw il 
 
 t-.^o $nxfil& 
 
 > I)ri;:;o^ 
 '^ eon is ?/o/t 
 
 mu 
 
 
 IB H ^B tX^q .rl; 
 
 J a#t ctx;d v *xeve.jfw x- ^ 
 
 ^iw cur^iixjsn a al d D !>n fti 
 
 >^ i>aJtf{8 tad loq rf^* 3^"J *ri* 
 
 erf-t t ai/nJ:^noo not\?oa an' 1 A *8 oi aloq r 
 
 volt ^r s fl A ^ne-rtxrr 
 
 v 
 
 o 
 
 
 
 IlOt) f;
 
 machine becomes simply a series of closed coils on an ar- 
 mature core, revolving and trying to catch the magnetic 
 poles but never doing so. 
 
 The above machine is a rotarfr field two phase motor 
 and must be supplied by a two phase current. A three phase 
 motor is built on precisely the same principle. 
 
 Now in the two phase motor for example, the total 
 magnetizing force in the field, at any instant varies from 
 1 to 21 sin 46. (See Pig.) 
 
 At t sum of currents i 
 
 * * 1 sin 46 
 + 1 sin 40 
 -21 sin 46 
 
 - 1.4 i 
 
 j*^ 
 
 Showing that the magnetization varies from a function of i 
 
 to a function of 1.4 1. This is a variation of 40^> but on 
 account of armature reactions this figure is somewhat modi- 
 fied, it having been shown that the variation is somewhat 
 less than this figure. 
 
 Thtis it is shown that the motor has not only a rotat- 
 ing field but a pulsating one as well, therefore practice 
 has shown, that, as one would naturally sxpect from above 
 observations, the motor has a tendency to run synchronously. 
 
 Hence it follows that when the motor is not running 
 synchronously the power it is delivering must be the dif- 
 ference between the"positive" power of the rotating field 
 and the "negative" power of the pulsating field. It Is 
 "negative power in this case of non-synchronous action on
 
 , 
 
 . 
 
 r s eiff 
 Sliitt SSJSffq OWJ JE X<J feilu 
 
 0Iqjto 
 
 tsriq 'o-vi. d^ nJt wolf 
 arf^ ixt ' otol ^IsiJangflfli 
 
 i io nohfon-'/t i- aiort. 8el^i-.v f 5 o.t.tj9sl.tnailra drf JsrW 
 ras itrcf ',^0^ lo noiSel* alifT .1 *,I ' 
 
 -ibom ' ^sa'vrefiBOB ai i*-si;sil aiff^ snoiiijijjWpfX a'Xi^Bra*fa lo /m 
 ^aiiwaiot si n 
 
 a 
 
 aot^o^rtq ST otneitt ,IIew SB ^ .; Ei;q B 
 
 ;i . 
 
 
 
 to lv; 
 .
 
 ac count of the checking influence, which tends to atop the 
 machine.lt being a common observation that a synchronous 
 motor stops immediately on getting out of step. 
 
 The pulsating character of the field seems to be a 
 great drawback on the face of it, and so it is. It has 
 been found that the two phase motor does not run well on 
 full load, has a marked tendency to synchronism up to cer- 
 tain limits, and beyond those limits speed and torque rapid- 
 ly decrease. However this motor has the advantage over 
 all motors wave the three phase motor that it will start 
 on heavy load. 
 
 The three phase motor has a comparatively constant 
 field due to the use of three currents differing 120tn ph 
 phase, so that these objectionable features are almost en- 
 tirely eliminated. The amount of variation may be shown 
 
 in the same manner as in the previous case. 
 
 
 The figure re- 
 presents three cur- 
 rents differing in 
 phase by 120 
 
 At the time t current A + current C 2 1 sin 30 
 and B i. 
 
 Therefore since sin 30 * 1/2 it follows that A + B 
 -B. At the time t, C 0, A 1 sin 60 and B i sin 120 
 So C * A +(-B) again. This relation holds good at any time 
 Therefore at any time any one of the three currents 
 equals minus the sum of the other two.
 
 it* ,eo 
 
 . 
 
 a-CTl 8- ios 
 
 't to is^oBtBi I 3rf? 
 
 aarf *I .Jt ;< 
 no He*' nan .ton aeofc icd--;in easf'q owtf cr:" tedtf JMUJO! nos-' 
 
 'us^a II rv l/r.iij soJoa osarfq eetri^ erft eva* *IO^OEJ XI* 
 
 baol 
 
 iB^co j3 sar 
 
 cb sJfieTHTo e0^^i^ lo eau er'^ QJ exffe Me 11 
 
 r:o;ia erf VJSEI noi*r>J:*Xy "o 
 
 & 
 
 ~$i ei;/Titt edf 
 -100 
 
 ^ _ _ _ . . \ / \ / \ / v / i 
 
 021 \;rf sasnq Y , 
 
 / \ : 
 
 05 rUa 1 S = ^ne^tirb 4- A ^ns*iTi?o 4 
 
 > j .1 A . 8 
 
 , 3B I^oos at . ;+ A o^. 
 
 ,-xaxfT 
 o fioua edj airni al.
 
 At t the absolute sum is 2 1 and at t'^the ab- 
 solute sum is 1.7321. This is the maximum fluctuation, 21 
 and 1.7321 being the extreme limits. Therefore neglecting 
 armature reactions the magnetization varies (2.00-1.73) 
 4 2. 14X> as againsfc 40$ for the two phase motor. As 
 has already been stated the influence of the armature re- 
 actions is to decrease somewhat the range of the pulsations 
 but both motors are effected practically to the flame extent. 
 Thus It appears that the two phase field pulsates almost 
 three times more than the three phase field. The effect 
 of this has already been described. 
 
 It has been shown that In th ease of the three 
 
 
 phase current differing 120 in phase the algebraic sum of 
 
 the three currents Is always 0, therefore according to Kirch 
 hoff's law, on current can be connected in series with or 
 in parallel to the other two; this at once suggests a 
 method of winding three phase generator armatures. The 
 windings can be grouped into three series of coils in 
 either of the two following manners. 
 
 This method is called 
 
 the open connection, 
 HH 0* 1, E*nft 1$ 
 
 while the other one is known as the closed connection, 
 life 
 
 The armature of a Thomson-Houston Arc machine can
 
 IS :v* ai 3.trfT 
 
 3A . X diraiuxe 
 
 '%^ ) '> erf* 8. / 
 
 fo 
 Tysons erf* 'to eo.ne.ellni erf* b:te*a rtted vfcsailB MBf 
 
 rf* to e^n^i e/f* ^rtwemoa 8Bfis-xo*A o^ el 
 smsa e-^ o^ xUs^^-oBiq be^oBll n* eto^oai if^ocf 
 
 ^ erf* serf* eiom 
 .f)etfXToef> rtasrf vbeetla asr? 8lrf 4 i to 
 
 nv f.n"? ":o eefj >i^ rJt Jaxfct rworia need a*rf 
 
 "o .JLS oistue^Ifi arf^ ficBifq ni OSI anilettib ^ndiiiro eaariq 
 
 t O 
 TO K^iw ReiTos ni fca^oen^oc ed JTBO ^n9*ni/o no t wal a'llorf 
 
 a 
 6ffT .aerirtfaipia to.tjrranoa sesrfq enrtt gni&niw lo 
 
 ni alioo lo if eetr:* o*nl bqjjcn^ ed nso a^nifeniw 
 
 erf* to te. 
 
 si borf* 
 
 O C 
 neqo erf^ i_- .... 
 
 noli- 3 mv -ano ta^o erf* 
 
 "l (\ 
 
 
 31 
 
 nlrl oa0 OTA :
 
 by the addition of three collecting rings be made into a 
 three phase armature. In the same manner any armature may 
 be altered to give three phase currents with but little 
 trouble 
 
 ,. notary fir; 
 Rotary field motors are extremely simple, there be- 
 ing no sliding contacts, and the armature being wound with 
 
 heavy bars of copper connected across the ends, making a 
 
 of a rotary fi$ld " 
 
 good mechanical structure, far excelling direct current 
 
 armatures in point of durability and freedon from liabil- 
 ity to heat. 
 
 Dabrowalsky made careful and exhaustive tests with 
 a three phase motor and found it absolutely devoid of syn- 
 chronous ac 4 ion, and when compared with a good direct cur- 
 natle slip is Oc 
 rent motor os similar output, actually showed higher ef- 
 
 fioience. He also f ound t hat they gave greater output for 
 the same weight than ordinary motors, and this despite the 
 lag produced in the exciting current and the "magnetic slip" 
 
 When the current lags behind the electro-motive 
 force the power in it expressed in watts is: 
 
 E I* cos <J> 
 
 where (Ms the angle of lag. Cos f is what is called the 
 ffpwer factor, the maximum value of which is 1. This cor- 
 fesponds to an angle of 0for cos 1. Hence it becomes 
 evident that the greater the power factor becomes the 
 smaller the useless idle current becomes. That is we 
 do not have to use large wire for a large current when on- 
 ly a small part of it is useful. 
 
 The maximum value of the power factor being unity, 
 the cosine of the angle of lag expresses when multiplied
 
 Cv 
 
 
 
 el :Jxe & . om &I$ :t -<; 
 
 tB eri* I&lla on 
 
 t afcn9 ert aiio*OB M^Oennoo 
 ctoe'iife ^nxllaoxa tfit *&*' 
 
 mo^l noMttt isns ^ilidstifl) lo ^n;oq ni 
 
 .+B0ii 
 
 ri'iw acfaecf evltfeizsrlxa .bna IcteiSD dlUH 
 -HVQ lo biovob vle-rfx-IoedB ^i IwuioTr' 51 biw "to^om ee^lq 
 
 -s erg in b 
 
 tellma so 
 3 f>njjo"i eels eK , one i oil 
 
 actiqeeb alrf^ Ijna ,8"ioJofn 
 
 fenlrfeci 
 
 rtf 
 
 iswoq 
 
 ^> add I f 
 
 bellao ai crrfw i 4 .gal te elsnfl erf* 
 -too irft *I e ixn arfct ^ 
 
 seciooecf *i an9H .1 aoo tot0 to 
 
 erfiT s s&t te 
 
 0w si JarfT . :d ^ne* '.Jt aselss; 
 
 ntrfw
 
 by 10, percent directly. The power factor is therefore 
 generally spoken of as so much per cent. As the load in- 
 creases the la# decreases so that the power factor in- 
 creases, a very good characteristic. Rotary field motors 
 
 are now built v/ith power factors as high as 9(>X 
 
 . 
 Magnetic slip. It has bean shown that the armature 
 
 of a rotary field tends to rotate fast enough to catch the 
 magnetic field. As a matter of fact it never does. There 
 is always a difference in the frequency of the dynamo. 
 This difference is the "magnetic slip". 
 
 Polyphase motors have a tendency to run in phase 
 with the generator and when they are in step *&k the mag- 
 netic slip is 0. 
 
 flail ing *frwquency of generator ng 
 
 and w " motor nri 
 
 The slip becomes ng- nm, and the per cent of slip is: 
 
 (ng- nni) 4 ng. 
 
 The frequency and the magnitude of the armature cur- 
 rent evidently depends upon the magnetic slip, for the rate 
 of cutting of the lines of force in the field depends upon 
 the difference betv^eon the speed of the fiold and the 
 speed of the armature. 
 
 Slip increases both the frequency and the current tin 
 the armature, thereby weakening the resultant magnetic 
 field and the counter electro-motive-force of the field 
 winding, allowing more current to flow through it. 
 
 The total magnetization decreases as the armature 
 VA.T. Co>-
 
 ,01 Yd 
 
 . 
 
 -rr ' >1 iewc - ;,33se*io 
 
 L 
 
 > \;ifi*oH .oJt Jailed -tev & af; 
 
 ss err dlitfd won eta 
 
 erf* 3riJ aworie need sBr r il 
 
 n"o3o o^ rf^uonQ .taal e^fltca o3 abne^ 1)1611 ^tj 
 0isrfT .aeof, isvsn ^i cfss3: ' lo^^sni B A .Mall 
 
 eri^ nl eonetetlif) B ayawlB si 
 
 -r B 
 
 B 
 
 neriw 
 
 .0 si gila 
 lo von 
 
 in lo^ora " 
 
 :GJL qjila "io ^nao t^q srl-i -bna t mn -gn aemoodd 
 
 lei t qila oijanaiBm iid' nc-qu 
 
 l)XJtl dn.' nl eo^o^ to aaaJtl sri,i lo siii^4^ to 
 e-rf^ I)B blei'i eru 1 lo &-eqe s -vJeQ' er. B ' b srid" 
 
 ' ^^ 
 
 mi 
 
 engsir. 
 
 wo II 
 
 ...I ell 
 
 f 

 
 20 
 
 current increases there is therefore SCT.G condition^ of af- 
 fairs during which the torque is a maximum, this condition 
 is evidently not the one where the armature current is a m 
 maximum, that is when the machine i& start ingt| Therefore 
 we see it is impossible dfor these motors to exert their 
 maximum torque on starting. 
 
 middle of the &s*.. 
 third collecting r: 
 
 It ii* ablr. 
 
 *.'V; . .'- .' - ,- v " prc 
 
 "vor<ki *w* "have- tbre current* 
 
 *^ 
 ^ntl ceil as ordim f ad him no effect upon 
 
 \ 
 
 > are inserts
 
 t to fnol 
 
 tjBl 
 
 i ftj . : ffW ' 1: :-:.' ... : ' .-." , .. ' 
 
 ^ ai ^Briv t t!0mJ:3Uira 
 
 ?iex o^ i 21 eel 
 
 tumlxarn
 
 21 
 
 MONOCYOLIC SYSTEM. 
 
 Within the last few months there has been intro- 
 duced a new (?) system of power distribution called by the 
 
 inventors "Mono cyclic System* The generator is wound like 
 
 . 
 an ordinary single phase machine with the exception that a 
 
 supplementary winding or "teaser* coil, connected In the 
 
 middle of the main winding and the terminal brought to the 
 rsist flown Ir it* i?o> thu- 5. t ^Mte bs J* 
 third collecting ring. Prom this third collecting ring a 
 
 Th* aMaf 
 wire is run to those points, and those points only, whers 
 
 power is needed. This system it is claimed possesses all 
 
 $& wall * motor* *?':. -.d. ' 
 of the advantages of a single phase system with regard to 
 
 facility of regulation, with the additional advantage that 
 
 
 
 it is able to carry polyphase motor loads. 
 > rtntft 3*0 DIM y as they 
 
 This third winding is so proportioned that the r- 
 ' mieh wirt &i * pbaa* phas* and 
 
 sultant e. m. f. is composed of the electfco-motive-forces 
 
 differing 60 in ph^se. 
 
 ill mtHni* di ' v /-.' ; ', -rsR* S'- 
 
 Now if in the apparatus for transformation one of 
 
 bution irtrolYir . tiro 
 
 these e. m. f.s is reversed we have three currents differ- 
 ing in phase by 120 ! However, it ic claimed that this sup- 
 plemental coil as ordinarily used has no effect upon the 
 voltage of the two outside wires, so that they may be used 
 for lighting in the ordinary way. But when it is desired 
 to run a motor two transformers are inserted between the 
 power v/ire and each of the two cipher nnes, with the second- 
 ary of one reversed so as to give throe currents 120apart. 
 In this circuit may be inserted an ordinary three phase 
 motor.
 
 . 
 
 - 
 
 } 
 
 [ Jbnuov 8i ro^s'jf 
 / 
 B f ta ^tisnifyia rus 
 
 erf;! Hi, fti^osnnoo ,Iioo "neajs* .isalqqjLra 
 
 srtt c3 tfrfsjjoid iBnimed ertt fins $nlfeniw $i&iH a*# to %ffcf*tfT 
 
 B an.hr j}ii-^3olloo .oii.-ij MOPI^ .gnli $xxjt.to.tJUL6t> firfJW^ 
 
 terfw t Yino a^n?">q aaoif^ bits ,is4 i nlq eaoxfl o^ nxrt 1 otlw 
 
 ,= i .11 rnfcSe^a aiiiT ,l>6^esn al ttwoq 
 
 oj b'SB;e^ -i,tiw .^tva^s sasiiq slgnis s lo 83fi^fiBvl>jB dri^ to 
 -^n.'itxno^ 9 rf^ ji^iv; t noi^sJj/seT to 
 .acsol ic^oic ssarfq^Io 1 *r^^^o o? elds ai 
 jTo-icnq[ 03 ai gnlJaniw f>ilri-j airif 
 to beooqmoo ai .1 .m .e 
 
 .OBBiiq nl 00 
 lo dno not^ar.nOiSnBt;? -ro'i arjus*XBqqa 8-i^ ni t 
 
 l)02iovi>t ai s.1 .in .e 
 
 que elrf^ ^Brfct JbsmxBlo ai ^i ,-xevewoH !021 '^d easxlq ni 
 arfl noqir ^o0tl0 oa jsui besif vliisniino 3fi lioo 
 d XB2I ^D/l^ ifarfr o f a*tiw ef)ia^jjo owct eriJ 
 sab ai ^i ner^r iuH ,\;aw ^jsni^o eri^ ni 
 
 ndewted i)t^i88ni eis aterr rwt 
 
 Imooea erlt 
 
 ^H9-t*tiro i l 
 
 lq e*t ;, bd^teani ec ni
 
 .28 
 
 W Where the subsidary e. m. f. 4 generated is of small 
 moment 5 ^ower may be generated by single phase generators 
 and at the point where a motor is required the displaced 
 e. m. f. may be generated by a synchronous motor, thus doing 
 away with the third wire for great distances. 
 
 The motors are designed so as to cause a counter 
 $ ^ M. f. in the powr wire of such magnitxide tht no cur- 
 rent flows in it, so that it fAy be disconnected entirely. 
 
 The chief advantage of this system appears to be in 
 central station distribution where a great many light* 
 as well as motors are required. 
 
 Z&wtOIl & '- 
 
 It would seem from what has been said that for tran- 
 mission of power through long distances three phase cur- 
 rents are best particularly as they only require 15% as 
 ach wire as the single phase phase and the two complete 
 
 [\ i iP* ' '- w Vf 
 
 circuit two phase system. The three phase system however 
 
 
 
 is rather difficult to handlt in lighting, so for distri- 
 bution involving lighting and power the two phase and mono- 
 * !> is gr$at 
 
 cyclic systems are superior. 
 
 , . *.,:& awv^i- t i .tr 
 
 By mean* of transformers with suitably proportioned 
 
 alA- i.;; 
 
 windings it is practicable to convert from two phase and 
 
 " 
 
 vice versa. Consequently a Judicious admixture of the 
 
 two systems would seem to offer an ideal solution of the 
 
 i 
 
 problem! 
 
 The copper used by each system is easily calculated. 
 Dr. Bell has secured the following results. Taking single 
 phase system as the base: 
 
 Single phase two wire- Copper 100.0 
 
 3 * 31.25
 
 
 Iltes to si &e;t.8reft9 fe& .t ,ra ,0 .-ta&*<toB &ttt ttSiit 
 efQJirrsnjvs P?*F.f:q elan i a ^d freest snag ecf \'ast 
 
 . om e etariw 4 nloq erfct * 
 : l>*lB-t*fl6?i <* MH t .ffl * 
 
 rtafvts r iot silw bildcf 
 ^.aoo B asyf;o o* BS oa f0n^t89i> et 
 -mo on ^.^rf. 4 eb^t-trnoBm A&an lo *ilw tttwog &jf 4 Hi .t ,HI 
 .^l9Ti.-.:j:o be -yanno?>jsitl> ed ^1$ rtJt ^jrf* :oa f *l ni 
 ri ed Oc 'siseqq.o n!1aYS slrf 4 to 8:^B-tnjRv6*t .%0JtffO 
 
 nis no^om as Haw 
 
 rq PSI.I;> KftOfEBitaib ^itol 
 
 ftrf,* 8S 
 
 f bna es^rfq e* 
 
 -itrUib -io*i OB t gniirfsll it.t 
 Offptm BrtB aajs-fq owe? sd 4 ^9WO(I 
 
 iiro<| lo 
 
 b re o i 4 rc o q ot Q v I < ^ 1' we ri ^ I. w 
 
 ess/iq ow 4 m6^t 4 ivnoo o 4 
 to eit:.txJt!Ut 
 nol^ifloa Isebi n 
 
 noJ: 4 iid 
 
 eta amoa^a oxlo^o 
 1 o 
 
 al 
 
 o,- 
 
 ainaifa^a 
 
 
 bfteu -xa^qoo 

 
 23 
 
 Two Phase 4 wire Copper 100.0 
 
 Thret 3 " 75.0 
 
 Two i<?t 1 3 "(using sane voltagel45.5 
 
 Three 4 2 23.2 
 
 Monocyclic as ordinarily used 1 >0-125 
 
 The three pnase system is therefore the most econom- 
 ical of tfire for all of the practical systems. 
 
 & - . . j. 
 
 . 
 
 With regard to the frequency of alternating currents 
 we find in machines as now made quita a largo raage. In as 
 much as the old standard of single phase system was 133 
 some companies manufacture motors still to run on that fre- 
 quency. Now, however, the tendency is to lower this. 
 
 Impedance depends upon raqu2rtcy^/R%(27rn A 'L) v where 
 is the frequency. Thus we see that it is desirable to 
 have the frequency as low as possible to make the impedance 
 of the motors small, '^iien the impedance is great the an- 
 gle of lag between a. in. f . and current is great, causing 
 a large idle current to flow in the motor fialds. In other 
 words the power factor is made small. 
 
 But there is a limit to the lowness of the frequency 
 and that is the minimum at which electtic lights will burn 
 steadily. This minimum is about 35; below this lamps flick 
 r noticeably. The usual practic no.v is to adopt a fre- 
 quency of about 60, this being a^plicabla to both power and 
 light. In plants where the transmission of power is the 
 prim* factor and lighting is a minor consideration, n is 
 often as low as 25.
 
 3~~ 
 
 * 
 
 .: . 
 
 ac. ?oi e . 
 
 v io ^onoirpeil -erf* 6' tiW 
 
 i.I. .eg: in ! votf an adi: ! ew 
 
 n:c;o: ,.3 esprit: el^nia lc fc^fibiUi^tt bio aria a rioum 
 
 ; JBA ilii-c 
 
 .fc 
 
 noqxr afcneq 
 01* clos'ilasi) si ^i .'fiiW ee v/ ai/flT . v;oni;psil erf^ ai xx 
 
 or-J s^ferr? o^ I -Jieaoq GB wol C ^<oxreup*t 
 ant ^sei?. ri aonsbaqm* rfc it^rfW" .IlAffiB rro-tom 
 
 * 
 
 l .sMeil, 
 
 IISLiQ dluttc ai ' 1 
 
 ^on^upetl orfj lo . . 
 
 m.^'i I 
 
 ; 
 
 I Xsi/B.^ .^lJB80^: 
 
 to 
 
 al 
 
 no
 
 34 ~ 
 
 In order to carry en some experiments in alternat- 
 ing currents of different numbers of phases and different 
 frequencies a 16 horse power multipolar Orooker-Wheeler mot- 
 or was so connected as to give three phase alternating 
 currents. This result was accomplished by connecting the 
 commutator parts of the ordinary armature three collect- 
 ing rings in such a way that the three currents were taken off 
 as alternating currents . After a little experimentation 
 it was clearly demonstrated that the curves of the electro- 
 motive- force of these three phase alternating currents 
 were very Tar from true sinusoidal curves. Subsequently 
 some experiments were tried upon a Thomson-Houston epen coil 
 arc machine, three connecting rings having been placed 
 Just outside the three bar commutator. Finding this on 
 the whole unsatisfactory it was decided to stfcJtifctuct an "Ex- 
 perimental Generator", the idea being to so arrange" the 
 \vinding on t e armature that it could be used as a 500 volt 
 constant potential generator or m 
 
 In the case of the dynamo we added thsl^ effect to 
 the shunt turns and in the case of the motor would be s 
 connected that the ampere turns in series would tend to 
 counteract the ampere tarns of the shunt winding. 
 
 In making the armature it as decided to use a 
 toothed core and in winding the connections were so left 
 that any of the following combinations could be used. 
 
 1. A constant potential continuous current dynamo. 
 
 2. A constant potential continuous motor. 
 
 3. A single phase constant potential alternating current
 
 X 38K 
 
 ?lttia IKIB : s ^lil> 10 itr 
 
 SI a 
 IB f*rfq 1 o* a* fee;; 
 
 tf ftfrriaJiqaK; .*3ft 
 
 % 
 
 it* t*. jfoxm 61 agfiit **! 
 
 B 5^1A . a^navitfo snijjsn*ie*jta 911 
 e v lo a^v-ruo 8f\ r ^ ^eri^ i>* --tjrt *8H oos>^ vXtis&Io a^r ^i 
 
 rfq *e"t;itf o6rf^ ^: votolt -ev 
 adug .a 
 
 froanrOJfT & 
 neerf anlTs 
 
 .-jofa^/jmjtioo tsd 
 
 X 
 
 HB uO';HiiG|a^'o^ be^-trvefe asw li 
 sri* Ssstfciifi ca ot 
 
 sd ^Xi/ow ^o^o 0tft m e9o ^rfj 01 biui tirii/f 
 bns^ fclifot* ac j adif 
 
 a i? o^ bdbiae:) a^ 3i eT^^Bimtfl e: ^i 01 
 
 r 
 
 . 
 . 
 
 .
 
 dynamo hav ng frequency of 40, which it was possible to 
 increase and having an elect ro-rootive force of 1000 volts. 
 
 4. k two phase alternating current dynamo of 5250 volts 
 difference of potential. 
 
 5. A three phase alterriatirsg dynamo of 133 volts dif- 
 ference of potential. 
 
 The details of the armature are shown in the blue prints. 
 The reason for making a machine of this character was that 
 it was possible to combine in one machine a generator 
 which could be used for a large nuribar of different purposes 
 and it is believed that it will be a valuable adjunct to 
 our electrical laboratory here. The machine is now in 
 course of construction and will be completed within a very 
 
 short time. The design of this machine will now be given. 
 
 th& 
 By reference to the blue prints *&& general dimensions and 
 
 characteristic feature f tbe generator will be easily seem* 
 
 
 

 
 . 
 
 fen* e8gtc 
 eaurCg ow* A , 
 ^ soneiellifc 
 
 f CI 3 oii!inJ> >aci^ setrfS A .$ 
 
 laictrtetoe! to 
 ; e^ia 9tir^8Art8 4^ lo 
 
 ai--;:; lo ealiiaaal a ^.iaCBm iot 
 if!ji'it a *'ii:iojR/i eo ni 
 
 oqi^q -te'i ill io -f scf ; :>.;n s^^^ fi TO^ b8if *o bltio ifoi/lw 
 
 .a* v^>.t 
 ;v 3 ni.iJi 
 
 ai 
 
 *d JIlw to.-tBt^ri f^. to
 
 ASSUMPTIONS. 
 
 The dynamo is designed to ive 40 amperes at a po- 
 tential of 500 volts at- the brushes. The peripheral veloc- 
 ity is to be rather high, 3600 ft per sec., because the 
 machine i to be rather small for its output in volts. The 
 
 deei^n is tc resemble a IS horse power Crocker-Wheeler raot- 
 
 / 
 or. 
 
 ftAJkfttfr t> ' ' 
 
 i-^wlll bf assumed as 72. 2$, thin i that of the 
 0-W machine, any two peles covering 130 on the armature. 
 
 ' t> fei& V' v d?t ' ttV^f*-?li 
 
 The armature will/ have a toothed core practically the ame 
 
 rf teeth ' ' > ' ' - 'tf* 
 
 size ad the C-W Aotor. That is 12" diameter and 8 long. 
 
 The thickness of-' the ring will be 3". 
 
 For high speed, multipolar, toothed ring armature 
 
 / -i 
 of 20 K. W. capacity an allowance of 6400 lines of force 
 
 per fit-pnasc -cm. in the field is good practice (A. 8. Wiener, 
 
 Blectric^al World) 
 
 T & machine of thif ty?* a* mil*r 
 / * . 
 
 f ' mi ttet a different* * 
 
 COMPUTATIONS. 
 f 80 TOltl 
 
 Total current 40 10 amperes = current 
 
 
 4 T 
 
 
 / 
 
 differ 
 
 
 / 
 
 in each conductor, since armature is 
 
 divided t 
 
 / 
 
 
 
 
 / 
 
 / 
 
 into four parallel circuits. 
 
 
 Size of 
 
 Allow SOO circular nils per ampere, 
 
 will re- 
 
 Armature 
 
 quire wire of cross section of 
 
 
 
 
 
 Qenduo/fcor 
 
 000 circular mils 13 B <* S (5179) 
 
 
 i 
 
 Diam bare ^13 0.^72 
 
 
 
 Insulation 0,02 

 
 
 33Xov 005 "Jo 
 
 _ ^ _ j .1 ^_ . ,* W .r* > * V %*>& 
 
 u O.J c. i 
 
 ^1 IIJ3.3IB 
 ) I 
 
 .10 
 
 aeiegma 01 0^ 
 . IT - 
 
 dt &f>ivJ:b <1 eiij^smB sonia ^ic^oubiioo rfo.se ni 
 
 ax Birl* ( S.SY 3B bemnfe't* fd 
 
 ,9-xi/; no Ool nitevco a.I<r. o^ x^ui nirfiWMi W-0 
 
 eioo 0fttoo* * evarf IlJtw ^i/^BCfia srff 
 w iii. ax ctjjrf'i' .to-^on W-0 
 
 lf -S erf II iw snlt r 
 
 
 Iliw , tell/olio OOc: woJ to 
 
 to ,3 eeorro to eiiv nii/p 
 
 ,i ei'' aliffl iBli/oiio 0003 T0 
 
 ^.0 fc 
 
 SO.
 
 Total Diameter - O."092 
 Length of 
 
 Volts per om active wire 
 actioe wire 
 
 B^X Peripheral vel.X 30,6 X v% 
 
 10* x 5<r^ wirt 
 
 3600 X 50.5 X .732 
 
 1Q* X 
 
 = .033 (volts per om active wire 
 
 500 X 4 - 24096 om wire for 500 volts 
 055 
 
 24096 790 feet active wire. 
 30.5 
 
 '"-' - - - '{MvjMjkW "?**.;' T" f*"** A* 
 
 Dimensions It has been determined by practice that a 
 
 of teeth toothed armature with rectangular slots and trap 
 and slots, ezoidal teeth the width of a slot should be 
 
 that of the top of a tooth. To get the proper 
 number of teeth the allowable difference in po- 
 tential between adjacent commutator bars must 
 be considered. 
 
 In a machine of this type and of similar 
 output practice has shown that a difference of 
 
 
 potential of 20 volts may be allowed. 
 
 In this machine between bars 90apart the 
 difference of potential is 500 volts, therefore 
 500 25 gives number of bars in 1/4 of ar- 
 mature 100 bars for the whole 100 teeth 
 100 slots. 
 
 12* X TT m 37.49 circum. of Armature. 
 
 37'l49 * OU87 width of slot 
 2 X 100 
 width slot 3 /16
 
 80", 
 
 to 
 eilir avisos o is<! ai 
 
 3.0S K 
 
 x. 00*3 
 
 mo fe^ ailor) 
 -r^t W^Nr no *36t ^ X 000 
 
 to bna a* ** rf;J ^ nirfom s al 
 
 to eonetetti.b B ^ait^ nworfa BJ. ojstf 
 
 ed ^am acf^oir 02 to 
 
 no^w^ecf euirioera airf^ nl 
 t aulov COS ai XaJc^ne^oq to soa 
 to *\X ni a-xad to' ledmirn B&vts 3S 
 
 OX sXorlw eriu tot BTBd'OOX SIT.: 
 
 . >la OOX 
 fxA to ,J : --VS * TT X 
 
 3 ta li^foiw V8-x;o g>j!'vj5 
 oonrs 
 
 dX\ $ 
 
 TS Iirrs Svtola Tsljj^riB^Dsi rijftw <ii^JBBtii JNif^o^ rlcTae^ to 
 3(.f Mirarfe ^ols B lo tefclir er{^ rfcteeJ Xylose 8c?ola iflB 
 iW J08 of .fiifobr a to qo^ erl^ to 
 
 oq n ftit-netlJtfc elcfawoIXji erfJT xf^seit to 
 
 *. | ti'-.- > v : 
 
 -t^jjiH atecf
 
 " 
 
 and 0.184 diameter 2 15 wires. 
 
 Can therefore wind two 2 No. 15 wires side by 
 
 side. 
 
 . 
 
 790 7'.9 a 94'.8 necessary length of wire in 
 TOT 
 each slot. 
 
 94,6 11+ say 12 wires in every 
 
 5T1 of arm. ) 
 
 *ne* f ' ad jHMaftvfeftt <?** 
 
 slot. This gives then 2 wires wide and 6 deep 
 
 0.092 width of 1* 12 
 ; _ 6 
 Depth slot 75S2 9/U depth of slot 
 
 Check for 1. of active wire 
 
 Ife "" 800 feet 
 
 for 
 
 Calculated 790 
 
 Actual 800 1 
 
 From large drawing width of tooth at bot- 
 
 , a 2 Cffi / 
 
 torn was found to be 11/16 being only 1/64 
 
 Iron tfire. ;JN i^ 99 g& 
 
 less than top. 
 
 Armature will be "bar wound" every conductor 
 
 will be connected with another 90* away. 
 Ratio total To^al wire 
 
 Then from drawing to scale * * 3 
 to active Active 
 
 R 10 8 !>' 
 
 Resisteuice Cir. Mils 
 
 Of 10.6 X 3 X 800 X L 
 
 5180 Ie (Four il circuits) 
 Armature 
 
 = 0.311 ohms 
 
 
 
 Drop in potential C R 
 
 ln * 40 X .311 
 
 Potential , 12 . 4 Volt8
 
 aeilw SI ,otf a owJ f>niw 
 
 ni aiiw to rf*anai ?iBa&6dn 8. 9. % V o 
 
 nJt ae*riw SI 
 
 ' 
 
 ! ht sa^iw S narf.t awts a 
 
 StX I to ffjbw&*0. 
 
 . a 
 
 >ola to H^qaJb dl\6 Sc . 
 
 to ,1 
 
 008 * 
 
 '008 * 
 
 to rf^fclw s^^^s^^ a^iBl mot 1 ? 
 
 so el 
 w l>njiow iad w ed lllw 
 
 *09 lerf^onfi nJlw ba^oejsnoo ed lllw 
 Ia;,,og 
 S elfioa Qtf 3niwfi*jJb 
 
 'a 8,01 H 
 
 elf?^ / 
 
 X ' - to 
 
 661^ 
 
 ciario !!*( 
 
 . X
 
 
 Heat loss Loss ) B C V K 12.4 X 40 
 
 497.6 watts 
 
 X * 497 2.48X loss 
 200OO 
 
 ft 
 
 Magnetic Circuit 
 
 Air space By drawing to scale, allowing l/16"for clear- 
 ance, 1/32 "for binding wires and somewhat over 1/2 (5/9) of 
 
 length of tooth for space taken up by conduc- 
 ts tors, A= 0*42 1.07 cm for one pole 
 
 - 
 
 Si H* 
 
 17*6 
 5400 X 2.14 
 
 Amp. turns 1.26 
 
 for 
 Air space 9172 amp. turns for Air space 
 
 From the sane drawing. 
 Length of L. of mag. circuit is in wtt Fe 52 cm 
 Iron Oirc. * * * "Ji " " ca>t Fe 86 cm 
 Allowing Y 1.4 i.e. 40^ leakage 
 
 ^c<rrvte, * 5400 9000 = 
 
 For B 9000 in wtt Fe H 4 
 
 si = Hi 
 
 ^0}>. . ; vSlS p t '' - Of 
 
 m 58- X 4 
 Amp. turns 1,26 
 
 for Wrt Fe 155 amp. turns for wtt iron 
 
 Between each wrt iron core there is a cast iron 
 yoke 3"X 8".5 through which 1/2 of &,*<+, goes 
 1/2 area core TT d v 5.5 V f 
 
 12.6 8q. inches. 
 
 t^4 sir* mils)
 
 0* X .KI H a C'fN ; 
 
 BO. . 7t aeol X 
 
 ' 
 
 t el&oa o* ani^rafiU? soaqe ilA 
 
 to ($\3) S\I ^rero tBi*vao i>nB 8*ii*r j.d 
 
 -oii>noo Yd 5# n^fBd' eaeq 
 no -id sis V0, 
 
 tot 
 sf.^B tJtA -sot sm/j* .qmfif' SYl^ ' i' eofiqt 
 
 eras eri^ 
 
 a? Jiw nl ai jii/oiio .asw to .-I to 
 mo ae e^ ^610 * 
 
 I Y 
 
 t 
 
 . 
 
 H e n: iilf ni 0009 ff 10^ 
 
 
 . 
 
 a i e f 
 
 to . 
 
 V | IT 6'tOO B; 
 
 ~T"1T* 
 
 . ;
 
 Area 
 
 5 
 
 Area yoke - 3 X 8.6 25.5 Sq. In. 
 Hence Bc*s\fc 85*5 2 
 
 Bv.Kt SB 126 T 
 
 Ampere turns 
 
 Then B in oast iron will be 4500 
 For B 4500 in. oast iron H 7.5 
 And si= Hi 
 
 7-.5 X 55 
 
 for 
 
 RO J,y0rg 
 
 Cast Pe 
 
 Size of 
 Wire 
 
 
 1.26 
 
 a 340 Ampere* turns oast Fe 
 Then total ampere turns on field will be : 
 9172 for air space 
 166 wrt iron circuit 
 
 340 for oast iron circuit 
 TO7T total. 
 
 It is now necessary to determine the size ef 
 
 wire on the field 
 
 Circular mils 10.8 si X 1' of average turn 
 
 125 
 
 In this formula 125 represents 1/4 of the 
 total voltage as the four field coils are in 
 series. 
 
 Wire may be easily wound to the depth of 
 3 1/2 inches 
 
 Hence diameter average turn is: 
 9" length is 28 "27 2135 
 
 Then: 
 
 Circular milg 10.S X 9677 X 2.35 
 "lifts 
 
 
 * 1965 
 
 *L7 B&S wire(2048 oir. mils)
 
 
 l .p8 ci.eSi 8.8 X 6 
 
 . ' * 
 
 :i ^aflo ni S 
 
 to-ii J&60 .ni 006* a to'S 
 JK Rie JboA 
 
 ae x .L 
 
 erf j 1 177 bls-t'l rto arrrj^ s*ieqm IB^O^ nerfT 
 
 ncni 
 no-rJt ^ao 10! 
 
 OKI 
 
 to \.i" 
 
 ni ei alioo fcleit iirot e/tt 86 
 
 asitea 
 to rftqei) eri^ o^ f>niiow ^11 BBS ed YRt sti 
 
 ae^onx S\I 5 
 
 :ai n*x 
 
 JS VS?82 si 
 
 a.a x vvae Y a.oi 
 
 tot 
 
 es.ti- ftrf^ t>r! :.crfeitel> o ^Beaeoen won ai dl to eslB 
 
 bit? 11 erU o eiiw 
 lo X X ia 3 01 * aliia 

 
 Turns on 
 Cores 
 
 No. layers 
 etc. 
 
 Series 
 Ooil 
 40 amperes 
 
 Allowing 1000 circular mils per ampere this 
 will carry 2 amperes. 
 Then no. turns on each core is: 
 9677 4832 
 
 Diam bare 17 = OS045 
 
 Insulation 0*02 
 Total 
 
 3.5 53.8 m 54 No. layers of wire 
 
 .065 
 
 4832 89.5 90 No. wires in layer 
 
 JWK 
 
 Hysteresis 
 
 0.065 X 90 5.8 length of core winding. 
 
 The compounding coil will be wound out- 
 side of this in a space 6 rt long. It must carry 
 Allowing 10000 circular mils per ampere will 
 require 40000 circular mils *4(4i743) 
 Diam. bare* 4 0^20 
 
 Insulation0y02 
 Total Diam. 
 
 
 6 27 turns, This win give 1080 ampere 
 turns to compensate for drop in potential in 
 armature. 
 
 Losses. 
 (1) Armature 
 
 (a) 0*R,. 497.6 watts (page S-4) 
 
 (b) Hystersis 
 
 Watts lst fcHcJ X vol. ou. cm Xcyc per sec 
 
 Vol. ef armature. 
 
 Mean depth ring- 3',' mean diam. 9", length * 8''
 
 
 ft* no 
 
 no wrxc/f 
 6OSO v an0 
 
 20*0 *" fl0-!<tlt!8nl 
 
 GW.6'. la. 1 
 
 B19v;fil .OK 
 
 }c fe^fil .oK >d" S.SS a. -5 
 
 iS 
 
 1*4 al 
 
 )80I evjtg III .snii^ VU 
 
 " ! 
 ni I*lj06^oq nl qtnb tol 
 
 nWNdl (i) 
 
 o u) 
 
 Eie (d) 
 
 i_ee leg . 
 
 .pi ? 4^*ti 
 
 -t^nel 8S W,"3 SBO.O 
 
 .^.ol"< i a I aldl to 0AJt 
 
 ^q el'iiff- TBitf&Tto 00001 
 
 TOT^ 
 
 . 
 . 
 
 .
 
 Vol. *3X7XrX9 676.48 
 
 This neglects the preoLiae of the slots, so 
 is too large; but the increased hysteresis in 
 Hysteresis the teeth has also been neglected 
 
 678.48 X 2.64 3 11127 Cu. c. 
 But 90 f> of this is iron on account of the 
 lamination, paper etc. 
 
 11127 X .9 10014 
 Induction in armature 
 ^"* Ay. w 1/2 tr (dlam. polej v 12.6 
 
 B? Xt^aKkfe m a 24 
 
 Hysteresis 24 
 
 practically 1 to 2 /. B^ 4500 
 
 Cycles per eec. Rev per min. 4 
 
 50 X 
 
 ^ :,'-,- . *fr?, r -- 
 
 " 1^00 2 40 
 -WT X 
 
 For B = 4500, fnA m 1465 
 Hence Watts lost 
 
 1465 X 10000 X 40 = r 58>6 
 
 107 :> * l!!r 
 
 Poucault (6) Poucault Currents 
 
 Currents W lost - x^X B^X n v X 10*' W X vol. 
 
 where x thickness of disc in mils 50 
 n cycles per sec if^.J^t - 40 
 Watts lost 2600 X 20250000 X 10000 X 1600 
 
 10'* 
 
 * 61 watts 
 Priction (d) Friction 2^ output 20000 X .02 
 
 400 watts 
 (2) Field Loss
 
 . 
 
 
 oc , -*s=i**t - 
 
 at 
 
 .nwecf OR Is 
 
 ; . 
 
 oJ ai 
 * ertt 
 
 to 
 
 
 I^-iiT- 1 - 
 
 w^ ft .*. ^ oj" 1 
 
 . irj teq vH ", 
 ST" 
 
 S 00&J K 
 
 * f ^A *lf 
 
 
 .5-1 * lib I | t OO^ 
 
 > '^-. v.- v*".^:^ 
 
 B< 
 
 
 .Jov X 01 X n X'S X^x P ^aol W 
 nl oaif) to S8x)r;>fsiriJ * x eteriw 
 
 0051 X OfXXJJ 7 
 
 so. x ooc 
 
 a 
 
 . . 
 
 
 (i>) 

 
 (2) Field Loss. 
 Field IOBB (a) Shunt coll loss is S C 500 X 2* 1000 watts 
 
 $b) Series coil I/ Of turn * ir X 12.75 * 3'.2 
 Loss in 12 
 
 Series 3.2 X 27 X 4 total aeries coil In ft 34s'.6 
 Coil R of 345 7 .6 .006 ohm 
 
 Then C^R* 1600 X .086 m 137.6 watts 
 
 OOMJAERCIAL 1PPICI8NCY 
 
 Useful output M 38 amperes at 487.6 volts 
 Total looses are: 
 
 O!R 497.6 watts 
 
 Hysteresis* $6.6 * 
 
 fouoault Cur. 81.0 * 
 
 Friction 400.0 
 
 Shunt PieldlOOO.O 
 
 Series " 137.6 
 ' 
 
 Efficiency 
 
 "~X 
 
 Efficiency 
 
 89.
 
 . 
 
 r - >e 
 
 8.7SX * $&O, X 
 
 d7- i 
 
 d.7* i 
 
 - f 0.1 -.t, 
 
 0.00^ 
 O.OOOIMei* 
 
 , . ; fs.r 
 
 6 v 4.^ v F* 
 
 " nl 
 
 ; T X SU 
 
 HIT* . . .to a: xioo

 
 R
 
 '' TK 
 
 I nfii cory - 
 
 C81m 
 
 Multiphase 
 alternating 
 
 current 
 
 snii s s x 011 
 
 L^ 
 
 This book is DUE on the last date stamped below