Patent GB-622162-A (GB)
Title: Improvements in or relating to electric circuit interrupters
IPC: H01H33/32
Filed: 1947-03-03
Abstract: 622,162. Gas-blast switches. WESTING- HOUSE ELECTRIC INTERNATIONAL CO. March 3, 1947, No. 5980. Convention date, Nov. 23, 1945. [Class 38(v)] In a pressurized - container, gas blast circuit-breaker such as that described in Specification 621,452, the operating mechanism comprises a piston 21 exposed on one side to container pressure which closes the circuit-breaker against a spring 49 when the top of the piston is vented to atmosphere. Pressure is equalized above the piston to allow the spring to open the circuit-breaker when the piston is unlatched. The operating cylinder 1 is bevelled at its lower end to the container, Fig. 1, (not shown), and the cross-bar bridging the two arcing units is reciprocally operated by an insulating rod 10 screwed to the piston 21. To move the circuit-breaker mechanism to the closed position, as shown in Fig. 2, magnet-valve 89 is energized to admit pressure from the conduit 91 through passages 115, 116 to a spring-biased piston 97 operating the double-acting valve 93 to close the pressure inlet port 94 and open the exhaust port 95 venting the space above the operating piston 21 to atmosphere through ports 119. Pressure in the operating cylinder 17 forces the piston up, and in the latter part of its stroke a latching-head 25 formed on an extension of the piston rod engages a block 30 screwed to a spring-loaded rod 32 movable in a gas-tight bellows 34, and secured at its upper end to a spring-loaded plate 53. The rod is forced up until a roller 63 carried between two lugs 65 on the plate 53, is latched by an arm 61. Latch-rods 26 carried between two pairs of levers 28 pivoted to the block 31 engage the latch-head 25 to hold the piston 21 in the closed position. Towards the end of the latching stroke the roller 63 engages a lever 106 pivoted at 107 to move a connecting rod 104 down and open a " dumpvalve " 103 venting the space above the spring-loaded piston 97 to atmosphere so that the double-acting valve 93 moves up to admit pressure gas above the operating piston ready for opening. At the same time, lever 84 pivoted at 85 is carried up to rock a pivoted bell-crank 79 operating an auxiliary switch 78 which de-energizes the magnet-valve 89 and lights a " closed " indicating lamp. To open the circuitbreaker, relay 68 is energized to operate a spring-biased trip-lever 66 pivoted at 67, and release the latch arm 61. Springs 54, 55 force the rod 32 down so that the latchrods 26 are forced apart by the cam surfaces 123 releasing the piston 21 which is forced down by spring 49 to open the circuit-breaker, pressure being equalized above and below the piston through conduit 91. The auxiliary switch 78 is operated in the reverse direction to de-energize the opening relay 68 and light an " open " indicating lamp. When the trip-lever 66 is in the opening position it engages a pin 111 on the rod 104 to hold the dumpvalve 103 open so that the double-acting valve 93 will not be operated to start a closing movement if the magnet-valve 89 is energized at the same time. A control circuit for tripping by overload relay or pushbutton, Fig. 5 (not shown), comprises an interlock relay to disconnect the closing- relay, and a "stick-circuit" to ensure completion of a tripping movement once it is initiated. A closing push-button is similarly provided with a stick-relay and an anti-pumping relay.