| 摘要 |
PURPOSE:To take a measurement without providing any neutral point circuit while placing the insulation resistance of an isolated system AC circuit in a hot line state by detecting a leak current which flows through the insulation resistance of an AC circuit by the application of a DC voltage by a DC amplifier. CONSTITUTION:When a DC voltage is applied form a DC power source E to the hot line AC circuit 12 of an isolated system through a current limiting resistance R1, the DC leak current i3 flows through the insulation resistance Rx that the AC circuit 12 has. An AC voltage multiplied by the voltage between terminals A and B is removed by a filter circuit 11 and only the DC voltage is applied to a DC amplifier Tr through series resistances R2, R3, and R4 to drive an indicator instrument M, thereby indicating the value of the insulation resistance Rx. Further, an AC by-pass capacitor C1 prevents the AC voltage of the AC circuit 12 from leaking and being applied to the DC power source E through the current limiting resistance R1.
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