GB761923A - Improvements in and relating to apparatus for the control of electric circuit breakers - Google Patents

Abstract

761,923. Protective cut-out arrangements. ENGLISH ELECTRIC CO., Ltd. July 1. 1955 [July 6, 1954], No. 19723/54. Class 38(5) In a control arrangement for an electric circuit-breaker of the type having tripping mechanism which if the circuitbreaker is closed on to a fault overrides the closing mechanism and allows the circuit-breaker to open, an electrically-aotuable means C for initiating a circuitbreaker closing operation is connected in series with a pair of normally open contacts B-3 of an "anti-hunting" relay B and with contacts A-3 of a control relay A. In Fig. 1, when a control switch CS is moved to its "close" position the control relay A is energized over contacts B-1, LS and closes contacts A-1, A-2, A-3. Relay B is now energized and opens contacts B-1 and closes contacts B-2, B-3, the last completing the circuit for the means C which may be the coil of a contactor, a closing solenoid or electrically operated blast valve. As the circuit-breaker closes, the contacts LS of a limit switch are opened to de-energize the control relay A to open contacts A-1, A-2, A-3, the coil C being de-energized but the relay B remaining energized over its contacts B-2 so long as the control switch is maintained closed. Hence if the circuitbreaker trips out before the control switch is restored, the open contacts B-1 prevent the re-energizing of the relay A when the contacts LS reclose and so prevent any further attempt at reclosing, i.e. "hunting." In a modified arrangement, Fig. 2 (not shown) the opening of the contacts of the relay A are delayed, the relay A being deenergized on the closing of the relay B. Fig. 3 (not shown) illustrates an arrangement for a circuit-breaker having independently-operated closing mechanisms for each pole. The limit switch may be provided with additional contacts to maintain the relay B energized when the circuitbreaker is closed and the control switch is restored to its "neutral" position (Figs. 4 and 5, not shown). A warning device may be controlled through further contacts on relay B and through contacts on the circuit-breaker to give warning of faulty closing or tripping.