GB936798A - Improvements in and relating to air or gas blast electric circuit breakers - Google Patents

Abstract

936,798. Gas-blast switches. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. March 7, 1960 [March 9, 1959], No. 8103/59. Class 38 (5). In a gas-blast circuitbreaker having at least two sets of serially-connected contacts per phase available for automatic operation, operation of less than the full number of series contact sets may be initiated manually. In Fig. 1, a pressure gas reservoir 40 is provided with two blast valves 41, 42 similar to those described in Specification 936,797 which admit gas to pipes 43, 44 leading to support insulators and series-connected interrupter heads of the "seal-in" type. The operating rods 47, 47a of the valves are coupled to a shaft 49 by arms 48, but the rod 47 is indirectly connected to the valve slide 46 by means of a tube 103 surrounding rod 47 and normally retained relative thereto by latch links 104, 107 and lever 110 (Fig. 2). A normal tripping operation is initiated by energization of a trip coil 78 to release a latch 77 allowing linkage 74, 72, 70, 68, 67, 65 to move as a crank arm 63 is turned anticlockwise by a spring 56 which also turns an arm 53 on the shaft 49 to open the blast valves 41, 42. To initiate opening of the circuit-breaker manually under highly-inductive light load conditions, a coil 135 is energized by means of a push-button (not shown) to operate a valve 126<SP>1</SP>, admitting pressure gas to a pipe 125 so that a piston 116 is moved to the left, rotating lever 110 anticlockwise to unlatch parts 103, 104 and move the tube 103 downward so as to open the blastvalve 41 and thereby its associated interrupter heads. Pressure gas from the pipe 125 also enters a restricted pipe 136 for delayed operation of a piston 138 which closes contacts 141 ... 143 to energize the coil 78 so as to effect operation of valve 42 by rotation of shaft 49 and consequent resetting of the latch 104. Normally -closed contacts 147 . . . 149 and 151, 93, 152 in series with contacts 141 . . . 143 are opened respectively by anticlockwise rotation of the lever 63 and by movement of a piston 93 by pressure gas admitted during a closing operation to a piston 89 acting on a flange 84 of a link 82. In an alternative arrangement (Fig. 3, not shown), the rod 47 is directly coupled to the blast valve 41 and the tube 103 and its control means are omitted, the individual operating blast to the tube 43 being provided through an auxiliary valve, which blast, after a time-delay operates a pneumatic switch to effect energization of the coil 78. In Fig. 4, the blast-valves 1, 2 are operated from linked coaxial shafts 3, 4 and energization of a coil 19a releases the shaft 3 alone for initial operation of the blast valve 1 and thereafter blast valve 2 is operated by shaft 4 when a latch 29 is released by energization of a trip coil 30 through a circuit controlled by the movement of a blast-actuated piston 31. Specification 882,816 also is referred to.