| 摘要 |
PROBLEM TO BE SOLVED: To make electromagnetic trip operation having little dispersion in a breaking time by lowering an electromagnetic trip current, as for a compact circuit breaker having many restricted conditions on a storage space. SOLUTION: In this circuit breaker having a switch mechanism part 71 to switch a two pole switch part and an overcurrent trip part 21 provided on one or both of the current passages to both switch parts to interrupt the switch part by actuating the switch mechanism part 71 in response to the overcurrent, the overcurrent trip part provided on the one current passage is equipped with a fixed iron piece 70 excited by a current in the passage and a movable iron piece 72 provided face to face with the fixed iron piece 70 to actuate the switch mechanism part 71 when attracted by the fixed iron piece 70, and the confronting part 72b of the movable iron piece 72 facing the fixed iron piece 70 is made thicker than other parts in order to have a big mass.
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