| 摘要 |
PROBLEM TO BE SOLVED: To grasp the aspects of a grounding fault that vary with time, when the fault occurs in correspondence with individual concrete electrical events that differ according to the causes of faults, and thereby makes it possible to accurately infer the causes of the fault in detail. SOLUTION: A zero-phase current classifying means 12 carries out frequency analysis to grasp temporal changes in zero-phase current, computes the rate of harmonic content of each representative order, each time to classify the waveform of zero-phase current into multiple waveform patterns, and computes the selected time occurrence ratio of each waveform pattern. A coincidence-determining means 13 determines the coincidence between the selected time occurrence ratio of each waveform pattern and the sample data of zero-phase current prepared, beforehand, in correspondence with individual different electrical events with respect to each fault cause. A zero-phase voltage classifying means 14 classifies the waveform of zero-phase voltage, according to the magnitude of zero-phase voltage. A fault cause final determination means 15 estimates the ultimate determined fault cause, based on the result of zero-phase current waveform classification and on the result of the coincidence determination thereof and the result of the zero-phase voltage waveform classification. COPYRIGHT: (C)2009,JPO&INPIT
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