TRIPPING APPARATUS OF CIRCUIT BREAKER

PROBLEM TO BE SOLVED: To make other sound branch circuits continue normal feeding, since a host breaker does not open its contact until a subordinate breaker breaks an excess current, and only the subordinate breaker directly relating to an accident occurrence spot opens its contact to break an accidental current, by materializing a selective breaking action with a simple structure. SOLUTION: The tripping apparatus TA of the host breaker is equipped with a movable iron piece 3 tripped by being displaced by magnetic attraction force due to the excess current, and a reset spring (b)6 giving deterrent force in accordance with the displacement of the movable iron piece 3 and stopping the movable iron piece 3 at a prescribed position in the first half cycle of the excess current to prevent it from being tripped, and when the excess current also continues in the next half cycle, the tripping apparatus is tripped by being displaced from the prescribed position where the movable iron piece 3 is deterred by the reset spring (b)6 by the magnetic attraction force due to the excess current. COPYRIGHT: (C)2006,JPO&NCIPI