An overcurrent trip device that achieves reduction in tripping operation time against an accident current and a reduction in size is obtained. An overcurrent trip device for detecting an overcurrent flowing in a main circuit of a circuit breaker and operating a tripping mechanism of a circuit breaker in a closed state, comprising a trip conductor (5) connected to the main circuit; The tripping conductor (5) is penetrated inside, and the fixed iron core (4) excited by energization of the tripping conductor (5) and the fixed iron core (4) are opposed to each other through a magnetic gap, and the fixed iron core ( 4) Forming a magnetic circuit in cooperation with 4), a movable iron core (7) that is attracted and moved by the fixed iron core (4) when an overcurrent flows through the trip conductor (5), and a movable iron core (7) And a shaft (6) linked to the tripping mechanism of the circuit breaker and guided to the movement of the movable iron core (7), and the fixed iron core (4) crosses the magnetic circuit. A slit (4a) was formed in the direction, and magnetic saturation was suppressed by the slit (4a).
展开▼
