| 摘要 |
PROBLEM TO BE SOLVED: To improve a slit arc-extinguishing plate, such that excessive internal pressure rise of a breaker case is suppressed by reducing a total generation amount of a pyrolysis gas generated from the slit arc-extinguishing plate at current interruption, while ensuring high breaking performance by effectively exerting slit effect throughout the opening movement region of a moving contact. SOLUTION: This circuit breaker is so structured that a pair of the slit arc-extinguishing plates 9, formed of an insulation material, are arranged along an opening/closing movement path of a moving contact shoe 3 forming a pair with a fixed contact shoe 2 by facing them to both sides of the movement path; and a slit arc-extinguishing space is formed between facing wall surfaces thereof. The slit arc-extinguishing plates are arranged along the total length area of the opening movement path of the moving contact 3a; a step part 9a is formed at a longitudinal middle position on the inside surface of each slit arc-extinguishing plate; and a narrow slit distance d1 and an expanded slit distance d2 (d2>d1) are set, in an area close to the fixed contact 2a and in an area on the opening end side of the moving contact 3a, respectively. COPYRIGHT: (C)2006,JPO&NCIPI
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