| 摘要 |
<p>PURPOSE:To estimate the degradation position of a power cable, by obtaining the resistance of a cable shielding layer between the cable degradation position and the other end of the cable. CONSTITUTION:A DC high voltage Hv is applied between a conductor 1 of one end E1 of a power cable and a grounded shielding layer 2, and the leakage current from a degradation position X is read on the first ammeter A1. In this case, switches S1 and S2 are opened and a variable DC power source E0 is set to zero for the purpose of stopping the shunt of the leakage current. Then, the switch S1 is closed, the variable DC power source E0 is regulated, and the deflection of the ammeter A1 is set to zero. Since a current is not flowed to a shielding resistance R1 of a section from one end E1 of the power cable to the position X when this circuit is balanced, a shielding resistance R2 of a section from the position X to the other end E2 is obtained. When the DC high voltage Hv is not applied, switches S1 and S2 are closed to read values on an ammeter A2 and a voltmeter V1, and a resistance R1+R2 of the shielding layer of the overall length of the cable is calculated, and the position X is estimated on a basis of the ratio of the overall resistance R1+R2 to the shielding resistance R2 of the section from the position X to the other end E2.</p> |
