GROUNDING FAULT DETECTION DEVICE OF NON-GROUNDING SYSTEM LINE, AND GROUNDING PROTECTION RELAY AND GROUNDING FAULT DETECTION METHOD USING THE SAME

摘要

PPROBLEM TO BE SOLVED: To readily and surely determine whether grounding occurs in a premise or not based on not only a sine-wave zero-phase voltage and a zero-phase current but also a steep pulse-shaped or an intermittent-shaped zero-phase voltage and a zero-phase current. PSOLUTION: In the grounding fault detection device 20, a transformer 6 for measurement devices for detecting the zero-phase voltage Vo which appears on a non-grounding system line 1 due to a grounding fault occurred at a non-grounding system line 1 is connected to a zero-phase transformer 7, for detecting a zero-phase current Io flowing into the non-grounding system line 1 due to the generation of the grounding fault. The grounding fault detection device 20 is provided with a differentiating circuit 11 differentiating an instant value of the zero-phase voltage Vo obtained by the transformer 6 for measurement device with hour, a dividing circuit 12 dividing the zero- phase current Io detected by the zero-phase transformer 7 with the differentiated value of the zero-phase voltage Vo calculated by the differentiated circuit 11, and a determining circuit 17 determining whether the location of grounding fault occurred is in a hall or out of the premise based on the division value calculated by the division circuit 12. PCOPYRIGHT: (C)2003,JPO