GB982012A - Improvements relating to gas-blast electric circuit interrupters - Google Patents

Abstract

982,012. Gas-blast circuit-breakers; pneumatic actuation of switches; fusible cut-outs. A. REYROLLE CO. Ltd. July 6, 1961 [July 12, 1960], No. 24313/60. Headings H2B and H2G. A gas-blast circuit-breaker or cut-out has a supply of compressed gas at high pressure sealed in a pressure vessel 11 by a frangible diaphragm 15 and means operating automatically on the occurrence of a fault for rupturing the diaphragm 15 to initiate an arc extinguishing blast of gas directed over the contacts or electrodes, the blast being exhausted into a receiver 12 containing gas initially at much lower pressure than that in the pressure vessel 11, whereby shortly after rupture of the diaphragm the gas pressures in the receiver and pressure vessel will be equalized at an intermediate superatmospheric pressure sufficient to withstand the recovery voltage across the gap between the opened contacts. In the circuit-breaker of Fig. 4, a striker 26 is released or operated by a solenoid 27 when an overload occurs, the striker causing the rupture of the diaphragm 15. The resulting differential pressure acting on the nozzle contact 20 opens the contact against the bias of a spring 22 and a blast of gas flows through the nozzle contact. A latch 33 retains the contact 20 in its open position when the pressures in the vessel 11 and receiver 12 are equalized. As shown the contact 60 may be movable so that the circuit-breaker can also be used as a " load-break " switch. In this case the contact 60 is tubular and is mechanically operated by a rod 61 carrying a piston 64 which causes a gas-blast when the contact 60 is opened. A fixed arcing electrode 23 may be provided. In the cut-out of Fig. 2, a fuse 46 melts under overload conditions and releases a spring-loaded striker pin 26A which ruptures the diaphragm 15 causing a blast of gas to flow through a nozzle 42 to extinguish the arc formed between a fixed electrode 18 and the end of the striker pin. In a modified arrangement, Fig. 3, not shown, the fuse is directly attached to the diaphragm which is ruptured by the arc formed when the fuse melts. In this case the receiver 12 may be provided with a restricted outlet to permit the loss of pressure from the pressure vessel and receiver after the arc has been extinguished and a series isolator has been opened.