| 摘要 |
PROBLEM TO BE SOLVED: To provide a fine ground fault detector for narrowing down an occurrence part of fine ground fault by easily detecting the fine ground fault being an omen before a ground fault accident occurs. SOLUTION: A current waveform generated on a neutral point of a transformer 11 is detected with a fine ground fault current sensor 16 to be input to a waveform diagnosing device 21. The waveform diagnosing device 21 does not observe steep pulse waveforms of several nsec to several msec, observes current waveforms in a smaller range than 30% sensitivity of zero phase current in entire ground fault, and estimates an occurrence part or aspect of fine ground fault based on a comparison result of current waveform obtained on an equivalent circuit leading to a neutral point of the transformer 11 through a power cable from a fine ground fault occurrence point and current waveform in fine ground fault detected with the fine ground fault current sensor 16. COPYRIGHT: (C)2009,JPO&INPIT
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