Pneumatic mechanisms for power circuit breakers

PNEUMATIC OPERATION of power circuit breakers, which started before 1900, was used very little until the last decade. The increasing energy required for closing circuit breakers of higher and higher rating, and the demand for quicker closing and reclosing, enhanced the advantages of the pneumatic mechanism and led to its present predominance in the operation of large power circuit breakers. Experience gained with the mechanisms which pioneered the applications and gained widespread use have guided the development of a new line of devices to meet modern requirements of circuit breakers over the voltage range of 230 to 14.4 kv, interrupting capacity range from the highest down to 500 megavolt-amperes, and interrupting times of 8, 5, and 3 cycles.