862 MIAILLOUX: SINGLE-PHASE ALTERNATORS. [June 14

DISCUSSION.MAlr Miailloix's Paper on Single-Phase A Iternators.

PRESIDENT STEINMETZ: Gentlemen: You hiave listened to avery interesting paper by Mr. Mailloux concerning some inter-esting experiments made by him in connection with the applica-tion and use of single-phase alternators, as I might say, to helpout the polyphase system. Not only to help out the polyphasesystem, but also to help out the polyphase system when it isnot there, that is, to produce it.

MR. POTTER:-I believe the author said the single-phase alter-nators were first synchronized with the three-phase current.

MR. MAILLOUX:-Yes.MR. POTTER:-Would it not be possible to start the system by

the steam station only, by synchronizing the two single-phasealteinators in quarter-phase relation, instead of synchronizingby the three-phase from the water power station, which I under-stand was done in the experiment referred to.

MR. MAILLOUX:-There is no difficulty in bringing the alter-nators into quarter-phase relation. The difficulty in followingIl'vr. Potter's plan, is to keep the alternators in quarter-phaserelation long enough to get the rotary converter started. Theexperiment might succeed and is worth trying if the hypothesiswhich I state is correct, namely, that we have a case where eachsingle-phase alternator is really coupled with one correspondingphase of the rotarv converter acting as a synchronous rnotor,then it would readily be seen that it makes no difference whetherboth phases are started. If we could start the rotary converterand run it at any speed at which it would excite itself, then themoment that it excited itself, we could couple one of the alter.nators in synchronism with it, by reducing the speed of thealternator to the correct frequency. When tlaat has been donewe could speed up the first engine, and of course the rotary con--verter, acting as a single-phase synchronous motor, would followit until the proper speed desired is attained. At that time the^second alternator could be coupled with it, or it could, in fact, beconnected with it at a lower frequency, and then by opening thethrottles of the two engines we could raise the speed to any pointdesired; if the hypothesis advanced is a correct one, it wouldseem possible to be able to start the outfit without the assistanceof the line current. In the experiments tried, the line currentwas alwavs used first to start the rotary converter, because that.was the easiest way of doing it. We had no other means ofstarting the rotary converter there. You can readily understandthat the arc light machines belted from it could not be used to.run the rotary converter and get it up to speed. We could onlydo it by starting the water power station and getting a certainamount of potential on the line, which we usually raised to thefull potential, and after the rotary converter was started. thereof course would be no difficulty whatever.

In the paper, I make the statement that the rotary converter

1902.] DISCUSSION AT GREAT BARRINGTON. 863

acts as an electromagnetic elastic couplinig. The word elastic isintended to allude to the fact, which is well understood, that nocorrection can take place unless there is a slight change in fre-quency, because, if the phase relations were maintained abso-lutelv perfect, there would be no possibility of any cross-currentor synchronizing current between any phase of the alternatingcurrent and the corresponding single-phase alternator; wetherefore conclude that there is a slight change or variation offrequency; and I believe if we had proper means of sufficientlyaccurate measurement of angular velocities, it would be clearlyshown that there is a slight change of frequency and variationback and forth in the frequency. That is what is intended bythe term elastic. It is the same thing as if we had a couplingwhich is somewhat yielding and which allows of a certain amountof motion between the two; and my reference to the effect of thedifference in frequency was intended to advert to the possibilitythat the amount of angular variation, that is to say the range ofelasticity in the electromagnetic coupling, would probably be,to some extent, a function of the freouency.

MR. H. E. HEATI:-In regard to this experiment, which ofcourse is very interesting, I notice thlat the rotary has a directcurrent, and it would be quite possible to excite its field from anoutside source. If that were done, and the alternator beforestarting was properly connected, would it not be possible to startthe engines together and make the rotary pick up as the enginestarted?

MR. MAILLOUX:-I believe that it would, and you will find itstated in the paper that the plant will eventually include astorage battery. When that is installed, which unfortunatelywas not the case at the time of the experiment, it would be possi-ble not only to excite the rotary transformer from the storagebattery-tnat would be in fact the normal way in which it wouldbe done-but it will also be possible to put it in motion. Underthose conditions the storage battery current would be used notonly as a means of keeping the rotary converter in motion, butit would also act as a " buffer " or as " ballast " capable of takingcare of any fluctuations occurring between the two phases.If we had had the storage battery we would not have hesi-tated in using the system practically, because we would not onlyhave a motor effect transfCered from one phase to the other,namely, from the phase which is increasing in frequency to thatwhich is lagging, but we might also have a motor effect due tocurrent taken out of the storage battery and tending to speed upthe rotary transformer, thiereby supplementing the correctingeffect taking place between the two alternators considered bythemselves. The addition of a storage battery will greatly addto the elasticity and the value of this method. I feel so wellsatisfied with the practical results that I would not hesitate atall under like condition to use a method of operation of that kind.

President Steinmetz then illustrated on the blackboard anexperiment made by himself some years ago.

864 MIAILLOUX: SINGLE-PHASE ALTERNA-TORS. [June 19

MR. JOTIN AJURP1Y:-Mr. Mailloux's diagram (Fig. 1) wouldrepresent exactly the conditions existing at Ottawa if a two-phase rotarv converter and two-phase generators weresuibstituted for the three-phase machines, and, if a 2,200-voltfour-wire line were drawn instead of the 25,000-volt line. Onmany occasions we have run the two-phase rotary from one ofour single-phase generators, starting it up by direct current fromour storage battery, synchronizing it and throwing it onto oneof our single-phase machines. Every evening we operate asingle-phase generator in parallel with one phase of our two-phase machines. We have a large ineandescent lighting loadand we transfer some circuits from one phase to the other inorder to load up the single-phase generator during peak houtrs.I intended to try the experiment which MAvr. Mailloux has shown*can be successfully carried out, because the single-phase gener-.ator works so nicely in parallel with the two-phase generators,and the rotary converter ran so well as a single-phaser that Ifelt certain the second single-phase generator could be connectedwith the other phase of the rotary converter all right. I am de-lighted to hear that it has been successfully done.

MR. MAILLOUX:-I consider the experiments related by Mr.Murphv to be a very satisfactory confirmation of the hypothesiswhich 1 advanced here to explain the operation under those con-ditions. As, stated in the paper, when there is a change inphases between the machines, such as occurred in this case, theonly complication that is introdluced is that the energy for cor-recting the phase relation, instead of being sent on one phase-*o-nly, is sent partly over two phases; in other words, if one ofthe single-phase alterna.tors tends to get out of step with tlheother single-phase alternator, the corrected impulse which itsends to or receives from the electromagnetic coupling or therotary converter, will be sent as a single-phase impulse as far asthe Scott transformer, but at that point it would divide in certainproportions so as to be sent beyond that point, partly throughtwo of the phases of the three-plhase system; so, really, theapparent complication introduced in this case by the change inphases from two-phase to three-phase does not affect the theorynor the operation. The problem remains still qluite as simpleas it would be if we were dealing with a t.wo-phase rotary con-verter and two single-phase alternators, or with a three-phaserotary transformer and three single-phase alternators.

PRESIDENT STEINMETZ:-If there is no further discussion onMr. Mailloux's paper, I call upon Mr. Arnold, to abstract hispaper on the " Method of Ascertaining from Dynamometer CarRecords the Power Required to Operate the Mott Haven Divi-sion of the N. Y. C. & H. R. R. R. and the Relative Costs ofOperation by Steam and Electricity."

[Mr. Arn.old then read his paper.]