GB517447A - Improvements in and relating to electric switches with arc-extinguishing means - Google Patents

Abstract

517,447. Gas-blast switches. BRITISH THOMSON-HOUSTON CO., Ltd. July 28, 1938. Nos. 22481, 22482, 22483 and 22484. Convention dates, July 29, 1937, Aug. 5, 1937, Aug. 5, 1937, and Aug. 7, 1937. Addition to 467,809. [Class 38 (v)] The invention of the parent Specification is modified in that the tubular member communicates with the blow-out chamber only at a part or parts located intermediately of the ends of the member. Fig. 1 shows the gas-evolving tube 1, the chamber 2 housing the fixed contact, the movable contact 4, and filling member 3 which may also be of gas-evolving material. The tube 1 consists of an inner carbamide-resin tube, reinforced by an outer hard-fabric tube screwed at 9, 10 into the blow-out chamber 6. This tube is further reinforced by a tube 11 made of non- carbonizing material, such as the polymerized acrylic acid derivatives described in Specification 483,128. The evolved gas passes through openings 5 into the chamber 6 and thence through a metal gauze cooler 7 and vents 8. In another embodiment, the oval blow-out chamber 22, Fig. 2, is formed of parts 25, 26, 27 braced together by an insulating tube 29 provided with opposite threads 15, 16 The evolved gas thus passes through the openings 5 into an intermediate chamber 20 within tube 29 and then through apertures 21 and preferably through a metallic gauze cooler 14 wound or otherwise mounted on the tube 29, into the blow-out chamber 22. A second cooler 13 may be located over the vents 8. To minimise the gas pressure impact on the walls of the blow-out chamber when the latter is oval, Figs. 4, 5 (not shown), the tube 1 is surrounded by a spaced concentric cylinder for taking up the first shock, this cylinder being, e.g., of metal and apertured so that the gas passes readily therethrough. A gauze cooler is provided on the inside of the cylinder and may itself be constructed to function as the " shock " cylinder. The " shock " cylinder may be made of springy material. e.g., of steel, Fig. 6 (not shown), with overlapping longitudinal edges controlled by a compression spring to vary the opening between these edges according to the gas pressure. In a further embodiment, the oval blow-out chamber 44, Fig. 7, has the tube 1 arranged at one focus, and at the other focus the chamber is provided with a dome 46 and if desired a similar lower dome 40 in which the vents 47 are provided. A cooler 49 is provided coaxial with the dome 46 which is braced by a bolt 48.