GB975825A - Improvements relating to an electric circuit breaker - Google Patents

Abstract

975,825. Gas blast switches. LONDON ELECTRICITY BOARD, and H. LLOYDWILLIAMS. Dec. 16, 1960 [Sept. 16, 1959], No. 31618/59. Heading H2B. A pneumatically-operated interrupter comprises bridging contacts 25, 26 movable on insulated rails 16 into and out of engagement with a pair of fixed contacts 2, 3 each comprising three pairs of upstanding tongues arranged on three sides of a hollow square. Mounted between the bridging contacts is the gas actuating unit 32, 34. One end 32 is externally threaded to receive 34 and is formed with a blind bore 37 whilst the other end is internally threaded to receive a plug 41 and is formed with a blind bore 39, the two bores being joined by an aperture 43. Mounted in bore 39 is a piston 45 and rod 46 which normally extends from bore 37 to the end of bore 39. The piston is held in this position by a spring-retracted latch 53 itself retained by a latch 58. Separating the bores 37 and 39 is an aluminium diaphragm 49 held in place by a plug 48 which also holds a hollow needle 51 in place. A cylinder of gas contained in cylinder 34 is, when applied to cylinder 32, pierced by the hollow needle and the pressure obtaining in the cylinder 34 is indicated on a pressure indicator 63. When the latch 53 is tripped by an electromagnet 59 with the contacts closed, the diaphragm 49 is ruptured and the piston is forced by the gas pressure to the right, so engaging the base 4 between the fixed contacts and forcing the moving contacts to the left. When the piston has passed the ports 60 in the cylinder 32 the gas is ejected through them and extinguishes the arc and reacts against the fixed contact casing to force the contacts apart. Specification 767,205 is referred to.