| 摘要 |
PURPOSE:To detect the partial electric discharge of electric equipment in a ground metallic container by providing a parallel resonance circuit of a variable inductance made of ferromagnetic body and variable capacity to the leg part of the container and connecting it to an oscillograph. CONSTITUTION:The variable self-inductance 6 made of ferromagnetic body is fitted to the leg 5 of the metallic container 3 of a gas breaker 2 while interlinking with the leg 5, and the variable capacitor 7 is fitted to the leg 5 and inductance 6 in parallel. The industance 6 is varied by a variable gap. When this parallel resonance circuit resonates, a resonating current of specific frequency does not flow to the resonance circuit, but is sent to the oscillograph 9 by a lead 8 connected between the metallic container 3 and resonance circuit and the rest flows from the leg 5 to the ground. An induced voltage pattern due to external noise is measured separately without the parallel resonance circuit and both patterns are compared with each other to identify an induced voltage due to partial electric discharge caused in the metallic container.
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