| 摘要 |
PROBLEM TO BE SOLVED: To provide a ground fault detector which has a simple and small circuitry with an insulation resistance measuring feature, and a ground fault remote monitoring system using the ground fault detector. SOLUTION: A current transformer CT2 in a detector circuit 20 detects ground current I<SB>O</SB>which refluxes an earthing conductor L<SB>E</SB>by receiving a signal voltage E of a power supply circuit 10. Only low frequency components of the ground fault current I<SB>O</SB>goes through a low-pass filter circuit LF. The ground current I<SB>O</SB>is diverted at the low-pass filter circuit LF to flow into a compensation resistance (r) and a compensation condenser (q). The current (i<SB>r</SB>) flowing into the compensation resistance (r) is transmitted to a phase difference detecting part 2. The phase difference detecting part 2 detects a phase difference between the current (i<SB>r</SB>) flowing into the compensation resistance (r) and the signal voltage E of a power supply circuit 10. A controlling part 3 sends a control signal to make the phase difference to be 0 to the compensation resistance (r) when receiving a detection result signal. As a result, influence of capacitance to the earth is compensated by adjusting the resistance. COPYRIGHT: (C)2005,JPO&NCIPI
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