MOLDED-CASE CIRCUIT BREAKER WITH IMPROVED CONTACT ARM ASSEMBLY,TOGGLE LINK MEANS AND ARC SHIELD COMPONENT

摘要

The pivot shaft which couples the contact arm to the side support plates of a molded-case type circuit breaker is provided with a pair of spacer members that hold the contact arm in precise centered position relative to the support plates and prevent the contact arm from shifting laterally along the pivot shaft during trip and reset operations of the circuit breaker. The movable contact thus swings along a fixed predetermined arcuate path when the circuit breaker is tripped and subsequently reset. The toggle assembly is also simplified and reduced in size and cost by employing a single, upper toggle link and pivot shafts that are each anchored in place by an integrally-formed shoulder at one end and a force-fitted lock washer at the other end. The arc-quenching ability of the circuit breaker is also enhanced by providing a U-shaped arc shield within the breaker housing which defines an enlarged rectangular arc chamber that is centrally traversed by the movable contact as it swings along its fixed predetermined arcuate path when the circuit breaker has been tripped.