| 摘要 |
PROBLEM TO BE SOLVED: To provide a vacuum circuit breaker having an excellent breaking characteristics and an excellent reignition characteristics by optimizing various metallurgic conditions of Cu-W alloy or Cu-WC alloy. SOLUTION: Each contact of this vacuum circuit breaker is formed of a contact material containing 10-50 wt.% of a conductive constituent phase formed of Cu, and 50-90 wt.% of an arc-resisting constituent formed of W (or WC). The ratio of the difference (T1-T2) value between a fusion start temperature T1 obtained by measuring the conductive constituent phase formed of Cu in the contact material on the Celsius basis in a heating process and a coagulation start temperature T2 obtained by measuring the conductive constituent phase formed of Cu on the Celsius basis in a cooling process after heating it to at least 1,200°C to the temperature T1, that is, [(T1-T2)×100/T1] is set less than 2.8%. Thereby, both the breaking characteristics and the reignition characteristics can be satisfied. COPYRIGHT: (C)2004,JPO
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