GB936797A - Improvements in "seal-off" air or gas blast electric circuit breakers - Google Patents

Abstract

936,797. Gas-blast switches. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. Feb. 26, 1960 [Feb. 27, 1959], No. 6978/59. Class 38 (5). In a gas-blast circuit-breaker such as that described in Specification 821,069, wherein the contacts are maintained open by the gas pressure, the valve which exhausts the contact chamber for contact closing is pressure operated through a restricted passage so that it can be sealed off from the contact chamber by the final opening movement of the blast valve and it does not operate until the closing movement of the blast valve is completed. As shown, downward movement of the operating rod 18 moves the blast valve 11 to open ports 8, allowing pressure gas to flow from the receiver 1 into the contact chamber or chambers through an insulator 2. Gas also flows to a valve piston 23, but this is not operated since the flow is restricted by a passage 28 and the lower end of the valve 11 seats on an annular ring 27 to cut off this flow. When the rod 18 is moved upward the restriction of pressure build-up in the space 30 due to the passage 28 allows the ports 8 to be closed and sealed at 17 before the valve piston 23 is moved downward to open ports 9 to the atmosphere and discharge the interior of the valve 11 and the contact chamber. A spring 26 recloses the valve 23 as the pressure falls. A space 31 and passage 32 act as a dashpot for the valve 11.