CIRCUIT BREAKER

摘要

A circuit breaker comprises an adjustable trip unit having electronic circuitry for initiating a tripping command upon detection of overcurrent conditions. The trip unit includes an externally accessible interchangeable plug-in rating adjuster removably supported on the housing of the circuit breaker by a threaded rod and tube. An interlock mechanism cooperates with the trip bar of the circuit breaker and secured mechanism to insure that only when a compatible rating adjuster is properly seated in the housing and the threaded rod is completely engaged within the threaded tube will the circuit breaker mechanism be removed from the trip-free condition. Coordination of a proper rating adjuster with a corresponding trip unit and circuit breaker is achieved by coordinating the lengths of the rod and tube and the position of the threaded portions thereof such that only a rating adjuster which is electrically compatible with a particular circuit breaker and trip unit will properly engage the threads of the tube to remove the circuit breaker from the trip-free condition.