A spring mechanism for circuit breakers

FOR APPLICATIONS where neither storage batteries nor control power transformers are practical, some type of mechanism has been needed to close oilless circuit breakers at the necessary speed without requiring an external source of electric control power. In addition to the correct closing speed, such a mechanism should supply sufficient energy to close and latch the circuit-breaker contacts under the maximum short-circuit conditions. The mechanism should be sufficiently compact for front mounting on a magne-blast oilless circuit breaker when applied in the vertical lift metal-clad switchgear enclosure. Tripping of the mechanism should be possible from either current transformers, a-c or d-c sources, or manual means. For safety reasons, both closing or tripping operations of the circuit breaker should be possible with the door of the metal-clad unit closed. In order to eliminate the necessity for auxiliary apparatus, such a mechanism should receive its energy from manual motion. To obtain sufficient closing speed, the manual energy supplied by the attendant must be stored and released instantaneously. Manual operation of the mechanism should require a minimum of time and effort from the station attendant.