GB593575A - Improvements in or relating to electric circuit interrupters having arc-extinguishing arrangements - Google Patents

Abstract

593,575. Fluid-blast switches; automatic circuit-breakers. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. April 25, 1944, No. 7725. Convention date, March 19, 1942. [Class 38(v)] A fluid-blast circuit-breaker has an insulating blast conduit 11 which includes an electromagnetically operated control valve 13 and is closed by valve 35 when the pressure inside the arcing chamber 17 exceeds that in the conduit. A cylinder 19 is closed by metal plate 21, the central contact aperture 23 of which co-operates with contact 73 fitted to piston 83. The movable contact 33 is opened by the downward movement of spring-urged piston 43 when the latch 51 is actuated by electromagnet 53, which also operates valve 13. The breaker is closed by passing fluid through valve 45 to actuate piston 43. Arcing horn 65 is connected to contact 33 through cable 59 and is placed diametrically opposite to arcing horn 67 which, extends upwards inside the cylinder and is connected to contact 73. The fixed contact 31 is connected through rod 95 to the plate 21. When the contacts 31, 33 are parted, the arc is blown by a fluid blast from conduit 11 onto gas-evolving insulating plates 85. The pressure in the chamber 17 is increased by the gas produced until piston 83 is lowered, thereby drawing another arc, which is in series with arc 90. This second arc is extinguished by the glas blast, thus breaking the circuit. Spring 75 recloses contacts 23, 73 when the pressure subsides. Fig. 4 shows a modification in which the arc is moved onto the gas-evolving plates 147 by magnetic plates 145 disposed between them. The second arc is formed between contact 123 and nozzle 141. A piston 127, fitted to the contact 123 and moving in a cylinder 129 provided with limiting stops 139, is biased out of the cylinder by pivoted spring guides 137 which engage pins 133 secured to piston 127. The nozzle 141 is connected to the fixed contact 105 by rod 143. In a further modification, Fig. 6 (not shown), the magnetic plates 145 are replaced by an external blow-out coil. In this modification, only one arc is formed, this being moved against the gas-evolving plates by the coil and then being extinguished by the rush of gas which occurs when the vent is opened. Fig. 9 (not shown) incorporates this modification with the contact and fluid blast mechanism of Fig. 1. The invention is also stated to be applicable to liquid blast extinguishing means in which case liquid is placed in the pressure chamber and the gas-evolving plates dispensed with.