| 摘要 |
Detection of degradation of the degree of vacuum in a vacuum interrupter suffers from poor sensibility because of mixed presence of various noises other than that due to discharge resulting from degradation. <??>The present invention allows accurate detection of degradation of the degree of vacuum by detecting the continuity of discharge produced between an electrode and a shield due to degradation of the degree of vacuum and the duration of discharge. The continuity of discharge is detected in accordance with a time slightly longer than 1 cycle time of a power-source voltage, and the duration of discharge is detected in accordance with a time sufficiently longer than 1 cycle time. <IMAGE> |
