Circuits For Tesla Alternating Motors

Saturday, September 14, 1889
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THE ELECTRICAL WORLD. 178 [VoL. XIV. No. 11. Circuits fur Tesla Alternating llloturs. l\I. Leblanc, a French electrician, makes an ingenious suggestion in the London Elechiciun for the sulnpression of the double set of leads of the Tesla motor. He says that it is only necessary to take a transformer and equilibrate the self-induction of its secondary circuit (including in this, of course, the external circuit) hy interposing a suitable con- denser. The current in this circuit will then he displaced in phase by precisely one-quarter wave length over that of the primary. The primary coil of the transformer is placed in circuit with one set of the Tesla field coils. the ends of tht; circuit being connected directly tothe twfo main leads: the second- ary is connected with the other field circuit, a suitable con- denser being interposed between secondary and set of field coils, and the ends of the circuit are connected to- gether. We can also, if desired, go a. step further and balance the self-induction of the primary also, so as to suppress the ap- parent increase of resistance of the system with respect to the generator. Another highly novel suggestion is as follows: Having an alternating current of given pedod, to obtain It current of any other required period. To do this, take a Gramlne ring and divide the coils into three circuits zz, Ir, c, in such a way that every alternate coil all round the ring is in circuit c, while the remaining coils in each alternate quadrant belong to circuits u and I1 respectively. In fact, so far as a and b are concerned. the circuits are placed exactly as in the Tesla motor, while a coil of circuit c intervenes between every pair of coils all round, Through circuits a and (J two independent alter- nating currents are sent, which differ in phase by 90 de- grees again as in the Tesla motor. The coils of circuit c are connected to the bars of a Gramine commutator, and upon this, according to M. Leblancls solution,a pair of brushes is caused to rotate. Now, while the brushesare at rest, the Icoils 1: are the seat of an induced E. BI. F. equal in period and midway in phase to that of the currents in a and b; but now, if the brushes rotate upon the commutator, it is easy to see that the period may be eithe diminished or in- creased according to the relative velocity of the brushes as compared with that of the virtual ,rotation of the poles in the ring caused by the current a and b.