| 摘要 |
PROBLEM TO BE SOLVED: To provide a vacuum circuit breaker equipped with a vacuum valve of excellent current breaking characteristics through stabilization of restriking characteristics of a contact point alloy. SOLUTION: With the vacuum circuit breaker equipped with a detachable pair of conductive shafts penetrated into a vacuum vessel, a detachable pair of opposing contacts with one end bonded to the conductive shaft, and a vacuum valve having, as is needed, an arc shield, when accumulative amount of discharge gas discharged from the contact points in heating process from normal temperature up to 1,600 deg.C is (VL), accumulated amount of discharge gas discharged during heating process between above 1,600 deg.C and at least 2,600 deg.C is (VH), and accumulated amount of discharge gas discharged in heating process from normal temperature to at least 2,600 deg.C is (VL+VH)=(VO), (VL/VO) ratio of the contact points is set at not more than 80 vol%, or preferably, not more than 50 vol% (including 0%), so that it is possible to provide a vacuum circuit breaker equipped with a vacuum valve of excellent current breaking characteristics by stabilizing restriking characteristics of a contact point alloy.
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