| 摘要 |
PROBLEM TO BE SOLVED: To measure a grounding resistance without stopping power supply. SOLUTION: A superimposing current transformer 14 for superimposing an alternating voltage and a current value detecting current transformer 7 are inserted and arranged in a measuring object grounding conductor, and a frequency-variable alternating voltage is superimposed on the grounding conductor by a superimposing current transformer 13, and a current value in the case the frequency of the alternating voltage is changed in a prescribed range is detected by the current value detecting current transformer 7, and a quotient obtained by dividing the superimposed alternating voltage value by the detected current value is determined, and its minimum value is used as the grounding resistance value.
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