GB595217A - Improvements in or relating to gas-blast electric circuit interrupters - Google Patents

Abstract

595,217. Gas-blast switches. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. May 24, 1945, No. 13012. Convention date, May 24, 1944. [Class 38(v)] [Also in Group XXIX] A gas-blast circuit-breaker has a pneumatically-actuated isolator and a signalling- device which is pneumatically-interconnected with the isolator for indicating the fully open and closed positions thereof. Momentary depression of the opening-button 112 completes a circuit through coils 116, 118, 120, thereby opening valves 91, 70 and operating a contactor 122 having maintaining contacts 123 and contacts 124 which break a circuit to closing-coils 125, 126. Compressed-air from a tank 87, passes via a conduit 94 and the valve 91, to open a valve 89, and thus allow switch-opening-air to flow through a conduit 97 into a cylinder 102. The valves 89, 90 are pneumaticallyinterlocked by part of the air, which acts, through a conduit 129, on a piston 130 of closing- valve 90, so that opening will always take precedence over closing. In the cylinder 102, a dump-valve 100 closes an exhaust aperture 104, and the air passes through a column 2 and a conduit 44, to close a dump-valve 40 and open first a main breaking gap 23, 24, then a parallelconnected impedance breaking- gap 46, 47, and finally the disconnect-contact 9. When the disconnect - piston 62 reaches the end of its travel, it opens a spring-returned valve 60, whereupon air flows through an aperture 63, conduit 64, and valve 70 to a piston 71, which moves a switch-arm 75, to the position 131, thereby completing a circuit from a segment 132 over a line 82 to the indicator-lamp 83, and breaking a circuit at a segment 79 to de-energise coils 116, 118, 120, and cut off the supply of switch-opening air. When the pressure within the column 6 is lowered by leakage, the valve 40 opens and thereby allows springs 28, 50 to reclose contacts 24, 47. Momentary depression of the closing-button 133, operates a contactor 135, the contacts 127, 128 of which complete a circuit through coils 125, 126, and thus open valves 92, 68. Compressed-air from the tank 87, passes via a conduit 94 and the valve 92, to open the valve 90 and allow closing-air for the disconnect-contact 9 to flow through a conduit 98, to a piston 107, which actuates the dump-valve 100 so as to open the exhaust-aperture 104 and thereby allow high-speed reclosure. Air is conducted from the cylinder 108, via an aperture 110, a column 3, and a valve 33, to the piston 62 which closes the disconnect-contact 9. When the piston 62 reaches the end of its travel, it opens a spring- returned valve 61, whereupon closing-air flows through the aperture 63, conduit 65, and valve 68 to the piston 71, which moves the switch-arm 75 back to the position shown, thereby extinguishing the lamp 83, and making a circuit from the segment 79, over coils 120, 118, 116, segment 81 and line 82, to the indicator-lamp 84, but the current through the circuit is insufficient effectively to energise these coils. The air supply is cut off when the arm 75 engages a segment 80, and energises a contactor 137, which opens contacts 136 and deenergises the contactor 135, the contactor 137 then being itself de-energised by the opening of contacts 138. When the closing- valve 90 opens, it moves a rod 143 which moves the arm 75 back on to the end of the segment 79, so that in the event of the closing-button 133 being depressed during fault-conditions, a current transformer 54 energises an overload contactor 58 and makes a circuit over contacts 59 and coils 116, 118, 120, thus opening the closing- circuit at contacts 124. Pumping of the interrupter when the button 133 is maintained closed during fault-conditions, is avoided by contacts 153 of the contactor 122, closing a circuit to contactor 137, which opens contacts 136 to de-energise the contactor 135, and is held closed by its own contacts 152 so long as the button 133 is held closed.