| 摘要 |
PROBLEM TO BE SOLVED: To improve assemblage, cutoff performance of a circuit breaker, and to reduce the cost of a circuit breaker case by improving an assembling structure of a current cutoff part. SOLUTION: This circuit breaker incorporates the current cutoff part, a switch mechanism, an overcurrent tripping device in a circuit breaker body case 1, and the current cutoff part comprises fixed contacts 8 and 9, a bridging movable contact 10, a press-contact spring 11, a pushing rod 12 opening and closing the movable contact interlocked with the switch mechanism, a pair of right and left arc-extinguishing devices 13, and an arc guide 14. All components 8-14 of the current cutoff part are all incorporated in a single body cylindrical unit case 17 for every other phase so as to be formed into a single polar cutoff unit 16, and the cutoff unit is incorporated in a lower part case of the cutoff body case. Then, the unit case 17 is so constituted as to have gas exhaust ports 17a opened in its left/right both ends and the gas emitted during cutting off the current is forcedly passed through the arc- extinguishing device to stretchingly drive the arc.
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