Field tests and performance of heavy-duty high-speed 138-kv circuit breakers — Oil and air-blast

The heavy expansion brought about on the Central System of the American Gas and Electric Company in response to demands for power during the defense and war periods has produced a requirement for circuit-breaker rupturing duties close to 3,500 megavolt-amperes. In order to test the interrupting performance and reliability of two types of 138-kv 3,500-megavolt-ampere circuit breakers, the first an oil, the second an air-blast design, and also to explore faster reclosing cycles than now offered by the most improved oil circuit breakers, high-capacity, field tests were carried out at the Philo Plant of The Ohio Power Company. In these tests, involving 20 interruptions on each breaker, there has been accomplished for the first time successful interruption of a full three-phase short circuit of 3,500 megavolt-amperes with three-cycle interruption and with 13-cycle reclosure. The results of these tests, it is believed, indicate that a goal of 5,000 megavolt-amperes with 12-cycle reclosure definitely is attainable.