| 摘要 |
PROBLEM TO BE SOLVED: To grasp correct insulation deterioration state, even when connection is performed with wrong connection order for a voltage signal of a non-measurement electrical path, in a method of calculating the active component of leakage current, by taking the voltage signal of the non-measurement electrical path using a portable insulation monitoring device. SOLUTION: The insulation monitoring device includes a zero-phase current transformer 2 installed on a non-measurement circuit for detecting the leakage current, a plurality of zero-cross detection means 8, 9 for detecting a zero-cross point of the voltage signal of the non-measurement circuit and outputting a sampling start signal, a difference detection means 10 for detecting a time difference between the outputs of the plurality of zero-cross detection means, and a selection means 16 for discriminating the phase sequence of a three-phase power supply circuit from the result of the difference detection means 10. COPYRIGHT: (C)2008,JPO&INPIT
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