| 摘要 |
PROBLEM TO BE SOLVED: To automatically measure the earth resistance with high accuracy in a short time. SOLUTION: The earth resistance is determined while applying a center frequency, a first high frequency side-frequency and a first low frequency-side frequency respectively positioned at a high frequency side and a low frequency side by the first frequency with respect to the center frequency, and a second high frequency side-frequency and a second low frequency-side frequency respectively positioned at a high frequency side and a low frequency side larger than the first frequency with respect to the center frequency, as measurement frequencies, measuring processes (steps 52-54) for determining a minimum value are executed, the measuring processes (steps 55, 53) are executed while applying the measurement frequency corresponding to the minimum value as the new center frequency when the measurement frequency corresponding to the minimum value is the frequency except for the center frequency, and the minimum value is determined as the earth resistance when the measurement frequency corresponding to the minimum value is the center frequency, and the first frequency is less than a reference frequency (steps 56, 58).
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