Circuit Interruption by Air Blast

By using the prestored energy of compressed air for the twofold function of circuit interruption and circuit-breaker operation, a new and original oilless circuit interrupter has been evolved. This air- blast circuit breaker has a guillotine-like arc- interrupting characteristic and can be made practically immune to the adverse effects of circuit recovery voltage. The historical background of oilless circuit breakers is discussed with particular reference to European designs. The electrical and mechanical design of air-blast circuit breakers for indoor use and the factors affecting that design, are described in some detail.