CHECK KEY DEVICE OF AUTOMATIC CIRCUIT BREAKER RESPONDING TO CURRENT LEAKAGE Russian patent published in 2003 - IPC

FIELD: circuit breakers operating in response to deviations of electrical parameters from normal values. SUBSTANCE: check key device has movable and fixed contacts and check key both mounted in circuit breaker housing; check key has L-shaped part protruding from housing and guide rod passed through contact holder hole. Check key is provided with reset spring and movable-contact actuating spring. Guide rod has head separated from its cylindrical part by annular drilling and made in the form of truncated cone whose base is smaller than diameter of cylindrical part of rod. Reset spring is fitted onto cylindrical part of rod and its diameter is larger than that of hole passing the rod. Movable-contact actuating spring is mounted on cylindrical rod head so that it abuts against butt-end of cylindrical part of rod and is rigidly fixed in position in annular drilling. L-shaped part of check key has steps on side edges of front surface and circuit breaker housing is provided with ridges coupled with steps to lock this part of check key in circuit breaker housing. Side of L-shaped part of check key parallel to side surface of circuit breaker covers housing bore accommodating check key. EFFECT: simplified design and enhanced operating reliability of check key device. 2 cl, 3 dwg