GB760355A - Improvements in or relating to gas-blast electric circuit-breakers - Google Patents

Abstract

760,355. Gas-blast switches; actuation of switches. REYROLE & CO., Ltd., A. June 17, 1955 [March 17, 1954], No. 7765/54. Class 38(5) Each break in a double-break, gas-blast switch comprises an enclosure maintained filled with high-pressure gas in which the contacts separate, and a conducting nozzle through which the blast flows from the enclosure, the two nozzles having a common exhaust chamber by reduction of pressure in which, under control of a single exhaust valve, the flow through the nozzles is produced. The nozzles, exhaust valve, moving contacts and downstream fixed arcing electrodes are all electrically interconnected and insulated from earth. The nozzles may be fixed or movable and be either in a forward position when the breaker is closed flow through the nozzles is produced. The nozzles, exhaust valve, moving contacts, and downstream fixed arcing electrodes are all electrically inter-connected and insulated from earth. The nozzles may be fixed or movable and be either in a forward position when the breaker is closed and withdrawn when it is opened, or, as shown in the application of the invention to the breaker of Specification 748,225, may be moved forwards on the initial opening movement and withdrawn as the opening movement terminates. The breaks are housed in casings B, B' which are mounted, together with the exhaust chamber C containing pneumatic control means, on insuator groups A on a compressed-air reservoir, with insulating tubes A' supplying air and enclosing insulating rods for mechanical control of the valves. Each condenser insulator D, D<SP>1</SP> terminates in an upstream main contact and impedance arrangement generally similar to that of Specification 743,787, and incorporating a stress shield J<SP>2</SP>. Chamber C contains a rotary exhaust valve and operating motor generally similar to that of Specification 736,088, the valve comprising a disc-member F carried on a flexible diaphragm F<SP>2</SP> and having annular valve elements co-operating with rubber seatings C<SP>3</SP>., C<SP>4</SP>. Member F also has a pair of annular cam surfaces F<SP>6</SP>, F<SP>7</SP> co-operating with rollers N<SP>1</SP>, N<SP>2</SP> carried by the rotor N of a pneumatic motor. A further pair of rollers N<SP>4</SP>, N<SP>5</SP> on rotor N engage similar cam surfaces E<SP>4</SP>, E<SP>5</SP> on the respective nozzles E; E' to advance them against the action of springs E<SP>3</SP> into contact with the stress shields J<SP>2</SP>. The movable contacts L are driven by pistons L<SP>1</SP>, L<SP>2</SP> and geared together at L<SP>4</SP>, L<SP>5</SP> for simultaneous operation, opening-air being supplied through passages O<SP>2</SP>, K<SP>4</SP>, K<SP>5</SP> and closing- air through a passage (not shown), leading into a central space. Contacts L move within electrically-interconnected arcing electrodes K mounted on the ends of a tubular fitting K<SP>1</SP>. The rotor N is rotated through about 300 degrees by a vane in a casing O supported by arms 0<SP>1</SP>, two of which contain air ducts, as O<SP>4</SP>, to the valves controlling movement of the vanes, one being opened to admit air and the other being opened to atmosphere for the one operation, and the roles being reversed at the next operation. To open the breaker, the control valves are operated to operate rotor N, whereby the exhaust valve F is opened and the nozzles E, E<SP>1</SP> advanced against shields J<SP>2</SP>. A blast of air through the nozzles thus acts on the main arcs drawn between L and the respective fixed up-stream arcing contacts and shunted by the impedances. The nozzles are timed to retract after the main arcs are extinguished, the impedance arcs being then extinguished by the throttled blast through the nozzles restricted by contacts K. The breaker may be adapted for automatic reclosure and final isolation at a separate switch.