| 摘要 |
PURPOSE:To simultaneously measure a leak current and partial discharge, by providing a DC leakage detection impedance Z1 wherein DC high voltage is applied to one terminal thereof and a cable to be measured is connected to the other terminal thereof and connecting HPF and a partial discharge detection impedance Z2 to Z1 in parallel. CONSTITUTION:A DC high voltage generator 60 is connected to a case 21 and a high voltage is applied between the conductor of a cable 10 to be measured and the sheath 10a thereof through a DC leakage detection impedance (Z1) 22. When the cable 10 generates insulating deterioration, leak current flows and terminal voltage is generated in Z1 22 and the magnitude of the leak current is displayed on a display device 43 through an optical fiber 50B. When discharge is generated by the insulating deterioration of the cable 10, a pulse is generated and the first wave thereof flows in the path of the head part of the cable 10, HPF 27, a partial descharge detection impedance (Z'2) 23, a case 21 and a cable sheath 70a. The second wave reflected from the remote end of the cable 19 and reflected therefrom to reach the heat part thereof and a third wave, generated when the first wave is reflected from the head part to reach the remove end where reflected to be returned to the head part, are flowed in the same path. The first-third wave signals generated at both terminals of Z2 23 are displayed on a pulse number display device 48 through an optical fiber 50A and the measure ment of partial discharge is performed from display content.
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