GB904160A - Improvements in gas-blast electric circuit interrupters - Google Patents

Abstract

904,160. Fluid-blast switches. WESTINGHOUSE ELECTRIC CORPORATION. Oct. 10, 1960 [Nov. 18, 1959], No. 34698/60. Class 38 (5). A fluid switch compris clue hou ate stat tending through one of the hou assembly carrying the coope: within the earthed housing 45, and 13, wall of the earthed housing 45 for actuating the assembly. The contact rod 30 is fixe whi mounting boss 33 for adjustment purposes. The puffer assembly comprises an insulating cylinder 17 movable over a fixed piston 18 carried at the end of a fixed tubular insulating guide 19. The movable contact, comprising contact fingers 27 and arcing contact 28, is carried at the end of the cylinder and is connected to a movable guide rod 36 which engages conducting fingers 37. An insulating nozzle 88 is also carried by the end of the cylinder 17 to guide the fluid-blast from the cylinder on to the arc drawn when the contacts are opened. The casing may be sealed and contain sulphur hexafluoride at several atmospheres pressure. Activated alumina may be provided (at 110) to absorb moisture and decomposed arc products. When the switch is used in an overlapping differential protective arrangement, Fig. 6, current transformers 43, 44 are arranged on the earthed casing 45 and may be provided with insulating outer casings 43a, 44a so that fault current to earth, due to a flash-over on an insulator 34 or to a fault occurring within the housing 45, passes between the current transformers 43, 44 and causes the operation of both differential relays 54, 55 and the opening of the switch together with the switches 46, 47 on both sides of the system. A fault 83 or 84 on a feeder 48 or 49 causes the opening of the switch and the appropriate switch 46 or 47 only. In an alternative arrangement, Fig. 7 (not shown), the current transformers may have an outer conducting shield so that a flashover on an insulator 34 only results in the opening of the two switches.