GB966110A - Circuit interrupter - Google Patents

Abstract

966,110. High-voltage switches. S. & C. ELECTRIC CO. Dec.11, 1961 [May 23, 1961], No. 44181/61. Heading H2B. A circuit interrupter comprises a cylindrical insulating casing 33 containing gas at superatmospheric pressure, hermetic seals at the ends of the casing, terminal assemblies 34, 35 including annular flanges 57 cemented at the ends of the casing, separable contacts in the housing interconnecting the terminal assemblies and operating means 90 for the contacts extending out of the housing through one of the seals. In the arrangement shown, the contacts comprise a main moving contact 86 which bridges fixed slotted tubular contacts 80 and a movable auxiliary contact 144 which co-operates with a resiliently mounted fixed contact 140. The contacts are operated by respective operating rods 90 extending through bellows 98 providing seals between the rods 90 and contact-carrying tubes 75, 149 brazed to a plate 53. This plate has a flange 55 which is soldered at 56 to an annular diaphragm 47 which is soldered at 50 to a metallic band, e.g. of platinum, on the end of the casing. The seal at the left-hand end of the casing is provided by a diaphragm 40 similarly soldered to the casing and provided with a tubular extension 44 having a closure plate 179. A filling tube 182 secured to a bellows 177 extends through an aperture in the plate 179 and carries a latch 188. When the pressure in the casing falls, a spring 184 moves the bellows, tube and latch sufficiently to release a spring-loaded indicator drum 193 from the latch. The movable auxiliary contact 144 is tubular and is carried within a nozzle assembly 145 so that when this assembly is drawn into the tube 149 on opening of the contacts a gas-blast is formed through and around the moving contact 144. The gas may be at pressure of the order of two atmospheres and consist of sulphur hexafluoride or other gas. Decomposition products of the gas due to arcing may be removed by cylinders 167 of activated alumina with or without sodium hydroxide, or of calcium carbonate. The contact assemblies are additionally supported by plates 112 interconnected by insulating rods (not shown), which in an arrangement having multiple series-connected main and auxiliary contacts, are provided with high resistance coatings for voltage distributing purposes. The Specification describes the interrupter as forming part of a load-break disconnecting switch which also includes an air-break isolator and a common operating mechanism as described in Specifications 898,462 and 898,463.