New Design Oil Circuit Breakers for 7,500,000-Kva 230-Kv Service

As a logical step in the trend toward achieving a minimum oil content but still retaining the advantages of the time-proved dead-tank construction a new 230- kv circuit breaker built around a novel design of tank has been developed. The extra volume of oil which contributes nothing to the insulation nor to the efficiency of the circuit breaker in interrupting performance has been eliminated and the required amount of oil reduced to the point where simplified methods of oil handling and maintenance procedures are possible. Design tests on the circuit breaker prove its adequacy in meeting design standards and extensive High Power Laboratory tests reveal a superior performance in interrupting fault and line-charging currents. The quantity of oil used and the design of the contacts is such as to permit a number of fault interruptions without maintenance operation.