Circuit breaker

Abstract

A circuit breaker prevents adverse effects on an opening / closing mechanism by suppressing the large-scale outflow of arc gases, generated during a current-limiting opening operation of a movable contact piece, into a space in which the opening / closing mechanism is housed. In the circuit breaker, a first space in which a switching contact, a holder unit, and an arc-extinguishing device are housed is separated by a case inner wall from a second space in which an opening / closing mechanism are housed. The case inner wall has a lower toggle passage hole connecting the first space to the second space and extending along an operating range of a lower toggle of a toggle link mechanism coupled to the holder unit. A shutter section configured to block part of the lower toggle passage hole from the first space side in synchronization with the operation of the lower toggle during a current-limiting opening operation of a movable contact piece is provided.

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