MULTI-POLE CIRCUIT BREAKER WITH ADJUSTABLE THERMAL TRIP UNIT

摘要

A multi-pole circuit breaker with adjustable thermal trip unit characterized by a circuit breaker mechanism having a plurality of pole units, means releasable hen released from a latched position to effect simultaneous opening of the circuit breaker contacts, a multi-pole trip device including trip means for each of said pole units, each of said trip means being constructed to operate upon the occurrence of certain current conditions to effect release of said releasable means, and each pole unit comprising a bimetal element responsive to current flow to effect heating thereof. The circuit breaker also comprises a first trip bar and a second trip bar, the first trip bar being mounted to oscillate between latched and unlatched positions and being biased in the latched position, the second trip bar being pivotally mounted on the first trip bar at spaced locations between the ends of the first trip bar and being pivotally adjustable to varying spacings from the bimetal elements, and an adjusting cam mounted on the first trip bar and engageable with the second trip bar for adjusting the second trip bar with respect to the bimetal elements.