Patent GB-526429-A (GB)
Title: Improvements in and relating to electrical switches of the air or gas blast type
IPC: H01H33/70
Filed: 1939-03-10
Abstract: 526,429. Gas - blast switches; switchgear structures. DAVIES, D. R., and METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. March 10, 1939, Nos. 7862, 9348 and 23432. [Class 38 (v)] , The casing of a horizontally-withdrawable, gas-blast cixcuit-breaker is divided at 1 into a large lower part 2 containing the breaker proper and an upper part 3 containing an arc chute which is removable with the upper part. The busbars and cable are connected by plugging contacts respectively to lead-in conductors 4, 5 in insulators 6, the fixed contact 8 being attached to 4 and mounted in a refractory insulating mass 12 locating the arc chute. The contact 9 on conductor 5 has pivoted to it an arm 10 carrying an arcuate contact 11 working in a passage 13 in mass 12, and connected by links 25, 26 with operating mechanism 28 incorporating a pneumatic cylinder 29. A compressed-air container 33 connected by pipe 59 with a common header, leads over pipe 35 to a control valve 30, a further pipe 31 leading to a header 32 from which pipes 15 are taken to the individual phases. Each pipe is clamped at 16 to contact 9 and leads to a transverse passage 14 for arc-quenching, the arc being subdivided by insulating barriers 22 and cooled by nests 37 of vertical plates. An insulating sleeve 24 and nozzle 23 extending from the chute co-operate with a fixed discharge passage 55 containing metal wool for further cooling the gases. Alternatively the nozzles 23 may discharge into a common conduit on the fixed part of the gear, Fig. 4 (not shown). The individual phases in the casing 2, 3 are separated by vertical insulating barriers and an inspection plate 38 is provided on the casing- front. The fixed contact preferably comprises a pair of fingers which are centrally pivoted and the ends opposite to the movable contact are urged apart by a spring, Fig. 3 (not shown). A circuit-breaker unit similar to the above, but having a modified gas-discharge device, may form part'of a cubicle-type of switchgear, the unit being mounted in front of the outer side of a front wall of a closed compartment housing hand conductor and busbar isolating switches, Fig. 5 (not shown). Fig. 6 shows an arrangement of a unit which is adapted to be raised for isolation purposes and is adapted for 33 kV. circuits by the provision of two series breaks, each with blast-supply and separate arc chute in a common arc chute structure. The blast-supply pipe 110 divides into two parts leading to separate transverse passages in blocks 12, 12<1> supported on insulator 102. The arcuate contacts 11, 11' are secured to conducting arms 10, 10<1> pivoted on conductors 104, 105 which pass through insulating bushings 106 and have lower socket contacts 108. The arms 10, 10<1> are operated simultaneously by linkage 25, 25' from the mechanism 28. A pair of plates 120 divide the chute into two similar parts vented at 121, 122 at which point cooling means additional or alternative to that 37 may be provided. For maintaining the insulation in a dry state, nozzles in a hot-air pipe 124 register with openings 125 in the compartment 127 through which air may pass into the breaker-enclosure. The Figure shows an arrangement similar to that of Specification 345,303, in which the cable 132 enters a teeing- chamber 134 from which connections 135, 138 lead in opposite directions to conductors 137 which co-operate with the socket contacts 108. Corresponding busbar connections are shown at 139, 142 for the left-hand one of the two breakers. The enclosure carries hooks 144 for lifting the unit by a crane, and locating shafts 145 engage guide pillars on the frame 130, as in Specification 341,188. The Specification refers also to separate casings for the individual phases, and to two or more parallel-connected sets of contacts, one opening after the others and provided with the gas-blast and arc chute.