Patent GB-191016763-A (GB)
Title: Improvements in Alternating Current and Alternating and Direct Current Machines.
Inventor: KLEIN LEOPOLD
IPC: H02K47/08
Filed: 1910-07-13
Granted: 1911-07-13
Abstract: 16,763. Klein, L. July 13. Exciting, dynamos, regulating; motors, controlling.-Consists in the use of a uniformly distributed low-resistance auxiliary coil called an " up-help " coil to assist the starting and paralleling of alternating-current converters or synchronous motors, and for compounding these machines or alternating-current generators, and compensating their armature fields at any power-factor. For starting, the auxiliary and armature coils of the machine act as an asynchronous motor; for compounding, they act magnetically in opposition. Being uniformly distributed, they can be interchangeably used as primary and secondary in function. The application to a double-current generator is shown in Fig. 3, the armature and field windings being omitted. The auxiliary conductors 10 form a drum winding embedded in the field poles. For starting the machine from the alternating-current side s, the switch 13 is closed and the resistance 11 gradually cut out of the auxiliary circuit, so that the machine runs up as an induction motor. The synchronizing-lamps 12 indicate when the direct-current switches 8 may be closed. The machine is compounded by introducing direct current between the points a, b and b, c. A single-phase machine is started by supplying alternating-current to the auxiliary coils, the main field coils being used, in parallel or independently short-circuited. as a starting- winding. To reduce the time of starting and give hyper-synchronous speeds, the number of alternating poles may be reduced to increase the speed of the rotary field, such reduction being made in the winding that is acting as primary for the asynchronus starting. In the form shown in Fig. 4 for this purpose, a', b<1> are the coils of two poles and a<2>, b<2> those of the remaining four poles of a six-pole machine, the current in the former being reversible by a switch 13<b>, to give the polarity N, N, N, S, S, S instead of N, S, N, S, N, S. For starting the machine as an induction motor, the auxiliary coil C, Fig. 5, receives alternating current from the terminals s', and a resistance in the armature circuit B is gradually cut out. Polyphase currents, or currents of higher periodicity than those supplied to the coil C, may be supplied to the armature for bringing the machine up to speed quickly, the switch 13<a> being in its upper position so as to connect the coils B to the supply s for this. Armature compensation may be effected by supplying alternating or direct current to the auxiliary coils, in the latter case the coils preferably being arranged in two groups to give field components at right-angles to each other and at forty-five degrees to the main field. Any drum winding scheme may be used for the auxiliary coils 10, such as that shown in Fig. 7 in which the alternating-current is introduced at the points a, b, c, and the compensating direct current at the points marked + and -. In the case of cascade converters and other synchronous combinations, the auxiliary coils are applied to the element of the combination which gives it its synchronous character.