A 2-Cycle 138-Kv 10,000,000-Kva Air-Blast Circuit Breaker Design Considerations and Field Tests at Philip Sporn Station

A 2-cycle 138-kv 10,000-mva (megavolt-ampere) air-blast circuit breaker has been developed and field tested. Insofar as is known, this is the first 2-cycle breaker for transmission line voltages. The breaker interrupted both transmission line and bus faults while mounted on the trailer on which it was shipped. The maximum breaker duty was 10,230 mva. It is believed this is the highest fault duty ever imposed on a 138-kv breaker in a field test. The longest interrupting time was 1.85 cycles. The breaker rating is based on the proposed, symmetrical rating structure.