Molded case circuit breaker with an apertured molded cross bar for supporting a movable electrical contact arm

摘要

A molded case circuit breaker includes an operating mechanism having an integral or one-piece, rotatable, molded cross bar. The cross bar includes an enlarged section, associated with each phase or pole of the circuit breaker, having a window, pocket or enclosed opening formed therein for the receipt of a base portion of an upper movable electrical contact of a pair of separable electrical contacts. Also disposed in the opening is a compression spring and an associated spring follower positioned between the compression spring and the base portion of the upper electrical contact. The compressive spring force biases the upper electrical contact for movement in unison with the cross bar. Upon the occurrence of a high level short circuit or fault current condition, the spring follower may be downwardly deflected to enable the upper electrical contact to move independently of the cross bar. The downwardly deflected spring follower is designed to then retain the upper electrical contact spaced apart from the other separable electrical contact. The opening in the enlarged section also enables a flexible current carrying shunt to be received therein and to be fixedly secured to the base portion of the upper electrical contact.