| 摘要 |
PURPOSE:To enable diagnosis of a highly accurate analysis of deterioration in the insulation, by applying an AC voltage as external energy in the release of the residual charge to ensure the release thereof sufficiently and in a short time. CONSTITUTION:After a switch 2 is set to the DC power source position to apply a DC voltage of 10-20kV to a sample cable 1 for about 10 minute and then, set to the ground position to discharge the residual charge for one minute. Then, the switch 2 is changed over to the test transformer 5 position to adjust a slide transformer 6 so that the voltage will boost to the maximum from zero at a fixed speed. Then, a fine direct current flowing through a cable 1 is detected with a detection resistance 7 and after the removal of AC components with a reduction filter 8, it is inputted into a Y terminal of an X-Y recorder 9 while a tertiary voltage of the transformer 5 is inputted into the X terminal of the recorder 9 through an AC transducer 10. Then, the output voltage of the transformer 5 is raised to the maximum from zero by adjusting the slide transformer 6 and then, lowered to zero to measure the released current value of an AC electric field. This enables simple diagnosis of the deterioration in the water tree at a high accuracy and in a short time. |
