Linkage-based off-stop apparatus and methods for circuit breakers

A circuit breaker, comprising:

• first and second side frames;
• an operating handle pivotally mounted to the side frames, the operating handle moveable to an OFF configuration provided main contacts of the circuit breaker are not fused together, the operating handle including a first leg and a second leg, and a blocking engagement portion on one of the first and second legs;
• a cross bar housing;
• a blocking member pivotally coupled to one of the first and second side frames at a pivot location and rotatable between an unblocked orientation and a blocked orientation, the blocking member including a linkage attachment location and a blocking contact portion;
• and
• a linkage coupled between the cross bar housing at a first end and the linkage attachment location on the blocking member at a second end, the linkage being configured to:
• position the blocking member in the unblocked orientation provided that the main contacts are not fused together, and
• configure the blocking member to the blocked orientation if the main contacts are fused together, wherein the blocking member in the blocked orientation is configured to engage the blocking engagement portion as the operating handle is moved to the OFF configuration and the engagement places the blocking member under a compressive force between the pivot location and the blocking contact portion.

A method of operating a circuit breaker including an off-stop mechanism, the method comprising:

• providing an operating handle moveable towards an OFF configuration to separate main contacts, the operating handle including a blocking engagement portion;
• providing a blocking member including a blocking contact portion, the blocking member pivotally mounted at a pivot location, a cross bar housing, and a linkage pivotally coupled between the cross bar housing and the blocking member, the blocking member moveable between a blocked configuration and an unblocked configuration by the linkage dependent upon whether main contacts are fused;
• moving the operating handle towards the OFF configuration;
• and
• positioning the blocking member in the blocked configuration with the linkage as the cross bar housing fails to rotate due to the main contacts being fused;
• and
• blocking further motion to the OFF configuration by contact between the blocking engagement portion of the operating handle and the blocking contact portion of the blocking member, wherein the blocking compresses the blocking member between the blocking contact portion and the pivot location.