A New 138-Kv 10,000-Mva Air-Blast Circuit Breaker

A new air-blast circuit breaker rated at 138 kv, 1,600 amperes, 10,000 mva (megavolt-amperes) has been developed for outdoor service on the lines of a large metropolitan utility. Designed as individual, double-break interrupter units mounted above conventional outdoor current transformers, the several columns of the breaker are mounted on a supporting framework and provided with a central control housing. Each interrupter is mounted inside its individual air storage tank for maximum interrupter efficiency. The use of porcelain for air tubes or interrupter housings to contain high-pressure air has been avoided in order to gain high safety factors in design. Dry air bleed for insulation protection is not required. The breaker is designed to handle a recovery voltage rate of 1,000 volts/¿sec (per microsecond) at rated current interrupting value.