GB313665A - Improvements in or relating to regulating systems for dynamo electric machines - Google Patents

Abstract

313,665. Filmer, C., and Associated Electrical Industries, Ltd. March 20, 1928. Motor-generators. - The generator of a motorgenerator set particularly for use in electric traction systems has both series and separate excitation, and field control means are provided for varying simultaneously the motor speed and the generator excitation so as to maintain the generator voltage characteristic substantially unaltered at varying speeds of the set. The characteristic of the generator is defined by a set of curves each connecting generator voltage and generator load at a particular value of the supply voltage or other variable feature such as motor field connections. The motor 1 driving the generator 2 has a series field winding in two parts 7, 8, and the generator has a field winding 9 in series with the motor, and a compounding winding 10 in series with its own load. In addition to driving the generator for supplying power for control circuits, train lighting and supplying exciting current for the axle-driven exciters used during regenerative braking, for example as described in Specification 313,427, [Class 38 (iii), Electric motor control systems &c.], the motor may be used to drive an exhauster 4 for the brakes. To release the brakes, the speed of the exhauster is increased by short-circuiting the part 8 of the motor series field winding by means of the switch 12 which also short-circuits a part 11 of the generator field winding 9 whereby the excitation of the generator is reduced to compensate for the increase of speed. In order to compensate for variation in the point of operation in the saturation curve of the generator with variation in speed, a second switch 14 interlocked with the switch 12 is arranged to short-circuit a part 13 of the generator compounding winding 10. The brake control lever may be arranged to operate the motor field control means.