A New 69-Kv Oil-Blast Circuit Breaker

All recent circuit breaker developments in the higher voltage transmission field have included such features as faster fault clearing, faster reclosing after faults, reduced oil requirements, and reduced maintenance. This paper describes the development of an improved line of oil-blast circuit breakers incorporating these features at 69 kv. The new circuit breakers as compared with superseded designs are smaller, require less oil, have improved oil-blast interrupters, use sealed bushings without gaskets, have a simplified top frame and linkage design, and use air operators. Complete laboratory tests have been made to check the electrical and mechanical characterstics of these new circuit breakers. These tests then were supplemented by actual field tests at 66-kv interrupting staged short circuits over a wide range of currents as well as switching the capacitance current of long unloaded 66-kv lines.