GB295772A - Improvements in and relating to systems of electric generator control - Google Patents

Abstract

295,772. British Thomson-Houston Co., Ltd., Peacock, J. V., and Nixon, L. R. May 27, 1927. Exciting - motor generators.-An electric generator driven by a machine having a falling speed-load characteristic, e.g. an induction motor, is designed to give substantially constant current over a wide range of voltage from zero and has an exciter mechanically driven therewith, the field of the exciter being varied in accordance with variations in the generator load. In Fig. 2, the generator 1 has a shunt field winding 2, a winding 4 fed from the exciter 5 and a differential series winding 3. The exciter has a shunt field winding 6, a series winding 7 and a winding 8 connected across the terminals of the generator 1. The windings 6, 7, 8 on the exciter all assist, and since the load on the generator is proportional to the voltage, decrease of speed due to increased load results in a greater current flow in the exciter field winding 8. The increase of ampere turns may be made proportional to the drop in speed of the main generator so that the exciter voltage is maintained constant or this voltage may be caused to increase. In a modification, the exciter winding 8 is connected in series with the generator shunt field winding 2. Fig. 4 shows another modification in which the additional winding of the exciter is dispensed with, but the circuit of the shunt winding 6 is extended to include a portion of a resistance 9 in series with the generator shunt field winding 2. If the driving machine be a continuous current motor, the exciter winding 8 may be connected so as to carry the whole or part of the motor current. Specification 281,009 is referred to.