GB264875A - - Google Patents

Abstract

264,875. British Thomson-Houston Co., Ltd., (Assignees of Jones, B. W.). Jan. 22, 1926, [Convention date]. Induction relays.-For starting and accelerating a motor, for example an induction motor 10 having rotor resistances 13, 14, 15, the resistance contactors 16, 17, 18 are controlled respectively by induction disc relays 19, 20, 21 subject to time and current retardation. Each relay normally stands open under the bias of a spring 25. A shunt magnet 28 with the customary shaded pole produces a torque tending to close the relay, and a similar series magnet 22 produces an opposing torque which prevents closure above ; a specified limit of stator current and prolongs the time required by the disc to turn through the closing angle. A piece of magnetic material 29 carried by the disc comes between the poles of the magnet 28 as the relay closes and thus terminates the movement quickly and forcibly. The first relay, in addition to closing the actuating circuit of the contactor 16, closes the circuit of the shunt magnet of the next relay, and so on in succession.