| 摘要 |
PROBLEM TO BE SOLVED: To lessen the contact resistance and improve a large current breaking property, withstand voltage, and melting and depositing resistance by adjusting surface roughness of a contact material to have specified values as the maxi mum height and the mathematical average roughness, respectively. SOLUTION: Respective contact materials 13a, 13b are vacuum-brazed in the center parts of the end faces of electrodes 7, 8, respectively. The roughness of the contact materials is controlled to be 12μm or lower as the maximum height Ry defined as JIS B0601 and 4μm or lower as the mathematical average roughness Ra. In the case the surface roughness exceeds 12μm (Ry) or 4μm (Ra), the contact resistance of the contact points increases and due to excess Joule heat generation, the large current breaking property is deteriorated. Moreover, an electric field is concentrated on a part where a projected part is formed and withstand voltage is therefore decreased and at the same time, partial melting and deposition easily occur and thus the melting and depositing resistance of the contact points is deteriorated and a vacuum circuit breaker having excellent durability is obtained.
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