GB738191A - Improvements in or relating to automatic electric circuit breakers - Google Patents

Abstract

738,191. Protective cut-out arrangements; automatic circuit-breakers. HENLEY'S TELEGRAPH WORKS CO., Ltd., W. T., and HOBAN, H. C. Feb. 23, 1954 [Feb. 25, 1953], No. 5297/53. Class 38 (5). In an automatic circuit-breaker wherein the controlled circuit is tripped open by a comparatively powerful electromagnet 2 under the control of a relay 10 sensitive to a light current, e.g. an earth leakage current, the armature 1 of the electromagnet is arranged to close a locking circuit immediately its movement is initiated so that the electromagnet is rendered independent of any subsequent action, e.g. chatter, of the relay. The relay 10 may be connected between an apparatus 15 and earth and in the event of earth leakage closes its contacts 20, 21 to energize the electromagnet 2. As the armature 1 starts to rise it releases a contact-carrying spring 24 which engages a fixed contact-carrying spring 25 to complete a circuit in parallel with the contacts 20, 21 to ensure the maintenance of the supply to the electromagnet 2. The further movement of the armature 1 breaks a toggle 3 to permit the opening of the main contacts 4.. 7 under the bias of a spring (not shown). The toggle 3 may be reset and the main contacts reclosed by downward and upward movements of a lever 25a. The circuit-breaker may be tested by depressing a push button 13d, which at contacts 13a, 13c disconnects the relay 10 from the apparatus 15 and at contacts 13c, 13b connects the relay to the supply through a resistor 28.