GB610765A - Improvements in or relating to electric motor control systems - Google Patents

Abstract

610,765. Control of motors. WESTING- HOUSE ELECTRIC INTERNATIONAL CO. April 16, 1946, No. 11643. Convention date, April 3, 1945. [Class 38 (iii)] Non-regenerative braking.-In a control system in which a dynamic braking circuit is established where power is cut-off from the motor and including resistance controlling the motor contact which is shunted in steps during acceleration, the shunting means is only effective to shunt a portion of the resistance during dynamic braking. In the Figure, the series motors 10 and 11 driving a vehicle such as a mining locomotive can be reversed by contacts 19 and 20 on the manual controller MC. Closure of the line switch L1, which is energized on the first step of the controller, connects the motors and their starting resistances R1 and R2, in parallel, to the supply, Further movement of the controller reduces and finally short-circuits resistances R1 and R2, but the reduction of R2 is done in part by one or more electric or electro-pneumatic contactors such as 24, the operating coils of these contactors or of their operating valves being,controlled by the controller MC and the contacts 25 of switch L1. On failure of the supply the motors can be electrically braked by reversing the controller, but not all of resistance R2 can be cutout of the braking circuit, because contacts 25 will be open and the contactor or contactors 24 will not be operated. Switch L1 cannot be reclosed, on restoration of the supply, until the controller is brought to the " off " position to close contacts 22 and energize the no-volt relay 21, which maintains itself by its contacts 23.