Patent GB-516532-A (GB)
Title: Improvements in or relating to electric circuit-breaking devices of the gas-blast type
IPC: H01H33/74
Filed: 1938-06-21
Abstract: 516,532. Gas -blast switches. REYROLLE & CO., Ltd., A., and ALLAN, A. June 21, 1933, No. 18390. [Class 38 (v)] The blast of deionizing gas is produced by compressing the gas by two pistons or like members controlled by the relativelymovablecontact - members and respectively acting to produce an initial impulse blast at high pressure and a stream of gas at a somewhat lower pressure following the initial impulse blast. The gas may be air, nitrogen, carbon dioxide, argon, or a gaseous fluorinated alkyl chloride, such as difluoro - dichloro - methane. In Fig. 1, the hollow movable contact C carries a piston F. working in a cylinder E'which itself is slidable in a fixed cylinder E<2> against the action of a spring E<3>. When C is lowered to break circuit. air at high pressure is forced out of cylinder E<1> by way of a port C' into the hollow contact C, and after finishing its stroke, piston E drives the cylinder E<1> down to force a stream at slightly lower pressure from cylinder E' through the port C<4>, which is now below the cylinder E'. Alternatively the gas may be forced from the outer to the inner cylinder through a non - return valve and thence into the contacttube. The contact C passes with slight clearance into a series of apertures in a block B<2> and stack of plates B<3> arranged in an insulating cylinder B' containing the fixed contact A. One segment A<2> of the latter is longer than the others so as to draw an arc adjacent a lateral vent B', the blast emerging from the vent escaping through an outlet D<1> in the tubular insulating casing D. The lead C' to the contact C is arranged so that the current-loop drives the arc electrodynamically into the vents, which action may be replaced or supplemented by magnetic inserts in the unslotted plates of the stack constituting the enclosure. The movable contact is withdrawn clear of the enclosure in the fully-open position, and the arrangements described in Specification 516,529 may be employed in the present invention to prevent insulation-breakdown in the open position. In Fig. 3, the initial blast is forced through ports E<5>, E<6> in the inner and outer cylinders E<1>, E' respectively, into a separate supply pipe E<4>, the subsequent blast passing from E<2> through a non-return valve E'. The enclosure comprises blocks H held together by lateral bolts H<1>, and provided with registering grooves which form the vents H<2>, inlet port H<3> and central space for the solid contact C, which in this form may act as a blast-regulating valve by uncovering the ports and/or vents in succession. The pipe E<4> may, alternatively, Fig. 4, communicate with a pair of bellows by way of the ports J‹, J' in the hollow lower end of contact C. The latter carries the top plate J' of the upper bellows J, which is first compressed to provide the initial impulse, whereupon, the port J<6> having passed below the plate J<5>, the subsequent blast is produced by the lower bellows J<1>, J<2>, J<3> air controlling springs. A narrow slot H<4> is cut along the vent entrances H<2> to confine the arc thereto, the slot being of such size as to be filled by the arc as described in Specification 516,529. Successive uncovering of the vents can be effected by the arrangement described in that Specification. In Fig. 5 (not shown), the bellows arrangement of Fig. 4 is combined with the hollow movable contact of Fig. 1, and the enclosure comprises a stack of insulating plates which are held by longitudinal bolts shrouded with insulation to prevent flashover. Alternate plates are radially or otherwise slotted to provide vents, as in Specification 516,529. The invention is also adaptable to the arrangement of Fig. 7 of that Specification. The Specification states also that the arc may be drawn across vents in the wall of an open pressure-gas chamber, and that the enclosure may be moved instead of contact C to open the circuit, and refers to Specifications 516,530 and 516,531.