| 摘要 |
PURPOSE:To easily diagnose the deterioration of a thunder-resistant element, by leading out the terminal of the thunder-resistant element on the ground side thereof to the outside of a tank through an insulating bushing and connecting one end of a short-circuit piece for connecting CT to the led out external terminal. CONSTITUTION:A thunder-resistant element 4 having one terminal connected on the side of a primary bushing 3 is provided in the tank 1 of a transformer. The terminal of the thunder-resistant element 4 on the other ground side thereof is led out to the outside of the tank through an insulating bushing 5 and one end of a short-circuit piece 6 for connecting CT for measuring the leakage current of the thunder-resistant element 4 is connected to the led out external terminal and the other end of the short-circuit piece 6 is grounded to the tank 1. When the single leakage current of the thunder-resistant element 4 in measured, CT 8 is inserted in the short-circuit piece 6 and the leakage current is detected by a detection circuit 9 and, by the analysis of the magnitude thereof and frequency, the leakage current and the increase in the third and fifth higher harmonics accompanied by deterioration are investigated to make it possible to determine the deterioration degree of the thunder-resistant element 4.
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