METHOD OF JUDGING THE CAUSE OF THE GROUND FAULT OF HIGH-VOLTAGE DISTRIBUTION LINE

摘要

PURPOSE:To simplify and secure maintenance and inspection work by specifying the cause of a ground fault to a cable when the waveform of zero-phase voltage is a step form wave or in a rectangular wave and the pulse of 0.1-1mS in width appears in a zero-phase current. CONSTITUTION:If a ground fault occurs in one or two lines of nongrounded three-phase AC type high-voltage distribution lines 22, zero-phase voltage V0, through a GPT10, and zero-phase current I0, through the ZCT 18 of a corresponding feeder, are detected respectively. And the zero-phase voltage V0 and the zero-phase current I0 are inputted into a waveform recording and analyzing device 20, and there the waveform is recorded, and also the frequency is analyzed. Moreover, recorded each phase is displayed on the CRT screen of the waveform recording and analyzing device 20. Hereupon, making it a judgment condition that the waveform of the zero-phase voltage V0 is a step form wave or a rectangular wave, and that the pulse 0.1-1mS in width appears in the zero- phase current I0, the cause of the ground fault is specified to a feeder 14.