GB442561A - Improvements in starting means for capacitor type single-phase induction motors - Google Patents

Abstract

442,561. Control of A.C. motors. ENGLISH ELECTRIC CO., Ltd., 28, Kingsway, London, and BALL, R. D., and ROBERTS, L., Phoenix Works, Bradford. Sept. 24, 1934, No. 27391. [Class 38 (iii)] The capacity in the starting, winding circuit of a single-phase capacitor type induction motor is reduced, as the motor speeds up, by means comprising a condenser 3 in series with the starting winding 2, a normally open single-pole switch 4 in series with the winding and the condenser, an operating coil 4a connected in circuit with the running winding 1 or both the running and starting windings, which operating coil closes the switch 4 in response to the normal starting current and allows it to open again when the motor current falls below a predetermined value, and a further condenser 5 in parallel with the switch contacts alone or both the switch and the condenser 3, providing an alternative circuit for the starting winding when the switch is open. Discharge resistance 6 may be connected across the condenser 3. In order to protect the motor from continuous excessive starting current in the event that the motor fails to start properly, the coil 4a may operate a further switch which closes after a time interval, and effects the disconnection of the motor from the supply.