GB868000A - Improvements in or relating to circuit breakers - Google Patents

Abstract

868,000. Gas-blast switches; protective arrangements. I-T-E CIRCUIT BREAKER CO. April 21, 1958 [Oct. 11, 1957], No. 12602/58. Class 38 (5). A gas-blast switch has a hollow contactcarrying member 14 through which blast gas passes into an arc-chute 30 where it acts on an arc extending between arc-runners 36, 37, the member 14 also having an opening 50 intermediate its ends to direct a small portion of the blast gas into the region occupied by the switch contacts 16. . . 19 when closed to scavenge that region and assist transfer of the arc to the arc-runners 36. The blast gas is supplied under the control of a solenoid-operated valve 150 from a reservoir 99 which also supplies gas for opening and closing operations. To open the switch an opening valve 111 is operated to apply gas to a piston 126 which moves to the left to release a latch 130 and to move a valve piston 125 so that gas is supplied to a cylinder 102 on the right of a piston 103. When the valve 111 is permitted to close, a spring 143 restores the valve pistons to the positions shown, so that a subsequent opening of the closing valve 110 results in the return movement of the piston 103 to close the switch. Fig. 3 illustrates an " anti-pumping " control circuit in which the operation of the contacts 204 of a closing switch causes the energization of the solenoid 210 of the closing valve 110 from a supply source 203, the solenoid 210 being de-energized by the opening of contacts 206 which are opened when the member 14 reaches its closed position. Should a fault exist, overload relay contacts 215 close to energize the solenoid 211 of the closing valve 111 and the resulting pressure in the pipe-line 112 operates a pressure switch 220 to change-over contacts 205, 217 and 214. The opening of contacts 205 causes the de-energization of the closing solenoid 210 should the contacts 204 remain closed, and contacts 217, 214 complete a holding circuit for the solenoid 211 so that the member 14 is opened and the contacts 204 must be opened before any attempt at reclosure can be effected. Contacts 216 in series with the operating solenoid 250 of the blast valve 150 open when the member 14 has completed twothirds of its opening stroke. Specification 804,660 is referred to.