GB203772A - Improvements in and relating to the control of dynamo electric machines - Google Patents

Abstract

203,772. British Thomson-Houston Co., Ltd., Given, R. D., and Liddiard, H. W. C. June 12, 1922. Constant speed control systems.-The speed of an electric motor 2 fed by a controllable generator 1 is automatically maintained constant, irrespective of the speed at which the generator is driven, by arranging four exciter machines 3, 4, 5, 6, all of which are coupled to the shaft of the generator 1, so that 5 and 6 differentially excite 4, which excites the motor 2, and 4 and 5 differentially excite 3, which excite the generator 1, the characteristics of the machines being chosen so that a change in the speed of the generator shaft gives rise to a change of opposite sign in the differential excitations, thereby keeping approximately constant voltage applied to the armature and field of the motor 2. To change the motor speed as required, controlling means 8 are inserted in the field circuit of the exciter 3. A flywheel 7 is placed on the generator shaft, and an alternating current motor 9, automatically connected to mains 13 by a relay 12, is used to check the speed of the shaft when the motor 2 regenerates. In a simpler modification, the machine 4 is directly connected to the field of the generator 1, without employing the exciter 3, and the position of the controlling means 8 is correspondingly altered. The invention is intended for rolling- mill and winding motors.