GB419734A - Improvements in or relating to the control of electrically propelled vehicles - Google Patents

Abstract

419,734. Control of D.C. motors. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London, and CANSDALE, J. H., 40, Murray Road, Rugby. May 17, 1933, No. 14299. [Class 38 (iii).] In a control system for a traction motor employed regeneratively for braking, a contactor energized by the voltage across the series field winding of the motor operates to disconnect the motor from the supply when the regenerated current has fallen to a predetermined low value. Line contactors 1, 20, and series resistance contactors 2-5, having operating windings 1a, 20a, and 2a-5a, respectively, are controlled by contacts 21-25 on a master controller M ; shunt field resistance contactors 6-12 are similarly controlled by normally closed contacts 26-32 on the controller. The circuit of windings 1a, 20a includes the contacts 14 of a contactor 14a connected across the series field Y of the motor, auxiliary contacts 4x on resistance contactor 4, and normally closed auxiliary contacts 5y on resistance contactor 5. In starting, the energizing circuit of the line contactors is completed through contacts 5y, and subsequently through contacts 4x and 14, contacts 5y being opened when contacts 5 close. On returning the controller towards the " off " position for braking, contacts 5y remain open owing to the closure of maintainng contacts 5x on contactor 5, and after contacts 24 are opened, the circuit of windings 1a, 20a is maintained only by contacts 14, which are opened when the regenerated current falls to a low value, so that the motor is then disconnected. The controller must then be returned to the " off " position, to close contacts 5y in order to restart the motor.