Intermediate latch for a molded case circuit breaker

Abstract

A molded case circuit breaker includes a generally 'Z' shaped intermediate latch structure which has upper and lower substantially planar sections that are each bent at an angle with respect to a center pivot section. The upper portion of the intermediate latch includes one or two latch surfaces. One of these latch surfaces engages the cradle of the operating mechanism of the circuit breaker, to latch the operating mechanism when the circuit breaker is closed. The other latch surface engages a trip bar or an intermediate latch bar, which is rotated by the trip unit when an overcurrent condition occurs. The lower portion of the intermediate latch structure also includes a latch surface which may engage a trip bar. This latch surface is sloped such that when the latch surface of the trip bar is moved along this sloped latch surface, the trip bar rotates. This rotation of the trip bar adjusts the spacing between the trip bar and a bimetallic strip or magnetic armature of a thermal and magnetic trip unit to allow the rating of the circuit breaker to be changed in the field. The pivot portion of the intermediate latch structure includes two mounting tabs, one on either side of the latch. The mounting tabs have a generally rectangular cross-section and, due to the angled relationship between the pivot portion and the upper and lower portions of the intermediate latch, the latch pivots on an edge of the mounting tabs. This edge is aligned with an angular opening in the mechanical frame to mount the intermediate latch. The mounting tabs also retain a biasing spring which biases the intermediate latch toward the cradle and biases the trip bar or latch bar toward the intermediate latch.