| 摘要 |
PROBLEM TO BE SOLVED: To provide a most appropriate method for diagnosis of insulation deterioration in a hot-line of a high voltage power cable. SOLUTION: In this diagnosis method, an alternating voltage is applied from an AC power E to a cable 1, a passing band region of a band-pass filter 7 is adjusted to a frequency (fundamental frequency) of the power source E and a frequency component of the AC power E outputted from the filter 7 is canceled by a resistance adjustment of a variable resistance R1, and a capacity adjustment of a variable capacitor C1 and is adjusted to be a minimum. The size of a harmonic current with respect to a basic frequency of the current released at the time is measured. The measurement of the harmonic current is carried out regarding the AC voltage having a different voltage value, and a deterioration degree of the cable is decided by a ratio of the harmonic current detected in an application of each voltage. Since correlation exists between the ration of the harmonic current and the rupture voltage of the cable, the degree of deterioration for the cable can be diagnosed.
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