Patent GB-454186-A (GB)
Title: Improvements in or relating to electrical circuit interrupters
IPC: H01H33/18
Filed: 1935-08-22
Abstract: 454,186. Fluid-blast switches; arcrupturing in switches. WESTINGHOUSE ELECTRIC & MANUFACTURING CO., East Pittsburgh, U.S.A.-(Assignees of Lingal, H. J. ; 613, Cascade Road, and Dickinson, R. C. ; 1412, Penn Avenue, both in Wilkinsburg, Pennsylvania, U.S.A.) Aug. 22, 1935, No. 23548. Convention date, Sept. 12, 1934. [Class 38 (v)] A circuit interrupter has means for establishing an arc incident to the circuit-opening operation of the interrupter within a body of arc-extinguishing fluid and in a predetermined localized zone in the length of an endless passage along which the arc is bodily moved laterally of itself during each opening operation, so as to cause a flowing stream of the fluid to be moved around the said passage and laterally between the arc-establishing means. The structure is mounted on the lower end of the lead-in 25 by means of a clamp 23 which is connected by a U-shaped part 27 with a base 21, to which is pivoted a contact 29 biassed by a spring into engagement with the part 35 of the movable bridge 15. The plate structure is housed within a pair of magnetic cap members 41, from which it is insulated by members 42 of moulded insulation, the whole being secured by means of an insulating central bolt 39 and apertured to admit the contacts. In order to produce a radial field, a coil 38 is assembled at each end of the structure, the upper coil being connected at one end to the frame and at the other to a plate 55. Within the upper coil are located two pairs of plates, each pair comprising an annular iron plate 47 and an insulating outer plate 49, alternating with a pair of insulating plates 53, below the lower of which is arranged the plate 55 with an annular insulating plate 57. The lower coil is connected between a pair of similar plates 55 and contains a set of plates similar to that of the upper coil, but in inverted order. The remaining elements in the stack comprises two groups of plates defining the outline of the arc passage 37, sandwiched between three groups of plates having openings forming pockets for retaining fluid near the arc. The latter groups each comprise a pair of insulating plates 59, 65 sandwiched between a pair of sets which each comprise, Fig. 13, an iron plate 47 and an insulating plate 69, a second iron plate 71 and an insulating liner 73. The plates 59, 65, 69, 73 are provided with cut-out parts, as shown in Fig. 13, to serve as the pockets. The passage-defining plates comprise (1) iron plates 47, 71 insulated from the passage 37 by liners 75, 77, Fig. 9, and (2) insulating plates 79, 81, Fig. 11, the latter being adjacent the middle group of pocket-forming plates. The whole passage-defining structure is held in alignment by means of insulating pins passing through openings 83 into the plates 55. When 15 is lowered to open the circuit, contact 29 follows until its shoulder 87 is arrested by the cap 41, so that an arc is formed between 29, 35 and drawn down into the structure. When the arc engages the upper plate 55, the upper part of it is short-circuited by the upper coil 38 which is thereby energized in series with the arc. On further downward movement, an arc is drawn between the upper and middle plates 55 in the arc passage 37, and subsequently the part 35 moves out of the structure altogether, whereby the arc between the middle and lower plates 55 is shorted by the lower coil 38 which is thus energized. The part of the arc in the passage 37 is rapidly moved laterally by the radial field of the coils 38 into un-ionized fluid which mixes turbulently with the arc to extinguish it at the zero of the cycle. At the same time the arc acting as a piston drives the fluid in front of it round the passage 37 so that the flow of fluid is prolonged after the currentzero to prevent restriking of the arc. In the modification shown in Fig. 19, the coil 115 is connected between the plate 103 and the annular contact 117 in a magnetic cap 107 which is threaded to receive an insulating liner 111. A stack of insulating plates 121, 123, alternately of different diameters to provide pockets, are mounted on a magnetic bolt 125 to define, with insulator 111, the arc passage 113. The tubular movable contact 119 has a flattened contact part 127 and a helical part which is so arranged that, under the influence of the field, the arc is moved along it and progressively lengthened independently of the lengthening produced by the downward movement of the contact. When the latter leaves the passage 113, the arc products flow expulsively through the arc stream and out of the lower end of the passage. In both forms the insulating plates may be of fibre or other material evolving arc-extinguishing gas when in proximity to an arc.