GB677441A - Electrodynamic braking systems for electric motors - Google Patents

Abstract

677,441. Control of D.C. motors. TELEMECANIQUE ELECTRIQUE. Sept. 19, 1949. [Oct. 7, 1948] No. 24082/49. Class 38 (iii). When a reversing controller is moved to a forward-running position, contactors AV and L are energized, together with a relay F which closes contact F<SP>1</SP> and opens contact F, the motor starting with its armature shunted by resistors RF<SP>1</SP>, RF<SP>2</SP>. Further movement of the controller opens contact SH to disconnect the armature shunt circuit, contacts D<SP>1</SP>, D<SP>2</SP>, D<SP>3</SP>, then being closed in sequence to remove armature resistors R<SP>1</SP>, R<SP>2</SP>, R<SP>3</SP>. Return of the controller to the "off" position disconnects the motor from the line and completes a braking circuit through contacts AV, F, and SH. The energization of reversing contactor coil AV and relay coil F<SP>2</SP> is maintained by the dynamic operation of the motor. At about a quarter of the line voltage contact F<SP>2</SP> closes to remove resistor RF<SP>2</SP> from the braking circuit, the contactor AV releasing at about a tenth of the line voltage when the motor is practically stationary. The contacts F, F<SP>1</SP>, operate so that there is no interruption of exciting current. Braking as described will take place in the event of supply voltage failure, the relays F and SH. being adjusted to release at about half the normal supply voltage.