| 摘要 |
PROBLEM TO BE SOLVED: To provide a ground directional relay which prevents unnecessary action in a sound phase more certainly, even if the invariable length of a cable is long, etc. SOLUTION: This ground directional relay, which detects a ground fault by zero-phase voltage and a zero-phase current accompanied with the ground fault, in a power receiving facility, is equipped with a means of determining the ground fault by the measurement of the frequency of the change of the polarity code of an input current signal from a zero-phase current transformer in addition to a means of detecting the ground fault by the magnitude of the zero-phase voltage and the zero-phase current and the mutual phase angle of these zero-phase voltage and zero-phase current, by a signal which is obtained by passing the input signal from a zero-phase transformer for detecting zero-phase voltage and the zero-phase current transformer for detecting a zero-phaser current, through a band-pass filter 3. COPYRIGHT: (C)2005,JPO&NCIPI
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