A 69-Kv Compressed Air Circuit Breaker for 5,000,000 Kva [includes discussion]

This paper covers the development of a 5,000,000-kva compressed air circuit breaker rated 69,000 volts with 2,000-ampere continuous current-carrying capacity. The breaker is completely metal-enclosed for outdoor installation. It has six condenser bushings extending through the roof for connection to the customer's bus structure and for mounting of current transformers and potential devices. Verification tests included interrupting demonstrations at 66, 44 and 22 kv, to prove the breaker capable of handling the high currents required for 5,000,000 kva. Additional interrupting tests, with varying rates of rise of the recovery voltage, were made to prove further the ability of the breaker to interrupt and to indicate the factor of safety built into the breaker.