A New 69-Kv Compressed-Air Circuit Breaker

A metal-enclosed 3-phase 69-kv 3,500,000-kva 2,000-ampere compressed-air circuit breaker of the orifice type has been developed for outdoor service. The metal enclosure has six condenser bushings extending through the roof for connecting the circuit breaker terminals to the metalclad bus structure. Each pole of the circuit breaker consists of an air reservoir, blast valve, isolating switch, and an interrupter. The interrupter assembly includes a moving-contact assembly, two orifice-type stationary contacts, and two exhaust gas receiving chamber, all clamped together by four spring-loaded wood Micarta rods. The isolating switches of the three poles are gang-operated by a single pneumatic mechanism mounted on the air reservoir of the center pole. This circuit breaker has successfully passed all its commercial tests and has interrupted 37,500 amperes with 44 kv across a single pole.