Circuit breaker with latch preventing rebound of blow open contact arm

摘要

The movable contact arm (37)s of a circuit breaker (1) are latched in the blow open position to prevent rebound and possible restrike of the arc in response to the very high magnetic repulsion forces generated by a short circuit in the protected electrical system. Each movable contact arm (37) is mounted on a secondary carrier (57) coupled to a main carrier by a spring loaded cam mechanism (93) which allows the movable contact arm (37) to blow open before the main carrier (55) is rotated to the open position by the spring driven circuit breaker operating mechanism (27). In one embodiment of the invention, the movable contact arm (37) is latched in the blow open position by a latching detent (121) in the cam surface (113) of the cam mechanism (93). In a preferred embodiment, the secondary carrier (57) is latched by a detent (127) formed by a leaf spring (123) cantilevered from a fixed support (63). Subsequent rotation of the main carrier (55) by the operating mechanism (27) releases the latch (1'19 ) by rotating the secondary carrier (57) clear of the detent (127) formed by the leaf spring (123). <IMAGE>