GB295045A - Improvements in and relating to electric control systems and apparatus therefor - Google Patents

Abstract

295,045. British Thomson-Houston Co., Ltd., (Assignees of Townsend, G. R.). Aug. 5, 1927, [Convention date]. Controllers with no-volt release, electromagnetic.-A motor 10 which is started under the control of any of the push-button switches 13, and stopped by operating any of the pushes 19, is disconnected from the supply on occurrence of low-voltage and is re-connected automatically if the normal voltage is restored within a given time period of such a duration that the motor would not have come to rest. Upon operation of any switch 13 of the contactor 12 picks up and at contacts 22 completes the circuits of coils 15 which cause series connected contacts 17 to close immediately, the racks 20 moving freely over ratchet pinions 21, and thereby establish a maintaining circuit for the contactor 12. Upon the occurrence of low-voltage, the contactor 12 immediately opens, and the coils 15 are de-energized, the racks 20 fall slowly, being retarded by escapement wheels 18. If normal voltage is restored before the contacts 17 open, the contactor 12 recloses, but if the contacts 17 have opened, then the contactor can only be re-closed by pressing one of the switches 13. Upon operating any push 19, the corresponding contacts 17 is opened and the rack 20 is moved out of engagement with the ratchet pinion 21 so that this rack falls without any time delay and thus the motor is stopped. One of the time delay switches is located adjacent each starting push button 13. In a modification, the push buttons 13 are in series with the coils 15 and the contacts 17 are in series with the coil of the contactor 12, the contacts 22 closing a maintaining circuit for the coils 15. The mode of action is similar to that of the first system.