GB302466A - Improvements in or relating to electric motor-generators - Google Patents

Abstract

302,466. Fletcher, G. H., Tustin, A., and Metropolitan-Vickers Electrical Co., Ltd. Nov. 9, 1927. Motor - generators. - In continuous-curreut motor generator sets of the kind employing a mechanically-coupled exciter for the purpose of maintaining constant the voltage of the generator when the speed varies, the exciter is self-excited and auxiliary field windings are provided on the motor and generator in addition to and separate from the main field windings, the exciter being connected directly across the auxiliary winding of the motor and in series with that of the generator. In Fig. 1 the motor 2 of a motorgenerator forming part of the equipment of an electric traction system, is provided with a main series field winding 4 and an assisting winding 10 supplied by the shunt-wound exciter 12. The generator 3 has a shunt field winding 5 and an opposing winding 11 connected across the exciter armature. In a modification, the exciter armature and auxiliary field winding 11 are in series across the terminals of the generator 3 so that the voltage across the winding 11 is the resultant of the output voltages of the exciter and generator. The exciter is so designed that in normal conditions, its voltage is slightly less than that of the generator and varies more rapidly with change of speed. The generator may be provided with an additional series winding to provide voltage compensation for variation in the generator load. According to the Provisional Specification, the generator may have an additional field coil in series with the motor, and the shunt field winding of the exciter may be connected in series with the auxiliary field winding of the motor.