A conserved-pressure air-blast circuit breaker for high-voltage service

This paper describes the design and construction of a 138-kv, 1,500,000-kva air-blast circuit breaker. The construction is made possible by the use of a new interrupting device which utilizes the axial blast nozzle together with a “conserved pressure” chamber. The chamber receives the exhaust from the interrupting nozzle and contains the movable contact of the breaker in its open position. By means of a spring-loaded relief valve the pressure and dielectric strength of the air in the chamber are maintained at a high level.