GB557517A - Improvements in and relating to electric motor control systems - Google Patents

Abstract

557,517. Automatic control systems. BRITISH THOMSON-HOUSTON CO., Ltd. Feb. 20, 1942, No. 2268. Convention date, Feb. 20, 1941. [Class 38 (iv)] [Also in Group XXXVII] Series traction motors 17, 18 are connected in 8-connection as described in Specification 400,416, [Group XXXVII], to a Metadyne machine 12 and are accelerated and regeneratively braked under the control of a controller 19 through the medium of an exciter 66, " composing " metadyne exciters 56, 57 and the fields of the machine 12, the motors also have separately excited fields 128, 129 supplied from a metadyne exciter 130. During regenerative braking, if the voltage across the motors rises above that across the primary brushes of the machine 12, a polarized relay 35 reverses and causes resistors 174, 175 to be inserted in series with the motors. The dropping of an undervolt relay 118 or the lifting of an overvolt relay 181 causes a load absorbing resistor 176 to be connected across the primary brushes of the machine 12. An " overload " relay 27, responsive to the field current of the exciters 56, 57, when lifted causes a main line contactor 25 to drop. Constant speed of the machine 12 and the various exciters driven thereby is maintained by applying the difference of voltage of machines 98 and 99 to fields on the " composing " exciters 56, 37 ; the machine 98 being regulated to constant volts by a relay 106 and the machine 99 being self excited with an unsaturated field. The machine 98 is also used for charging a battery 20 over a cut-in reverse current cut-out relay 112.