INSULATION MONITORING DEVICE AND METHOD OF ELECTRIC INSTALLATION

摘要

PROBLEM TO BE SOLVED: To extract accurately a leakage current component only by measurement of a current and a voltage with a simple constitution without requiring exclusive supplementary equipment such as a transformer for injection. SOLUTION: In this insulation monitoring device 10, a current measuring means 11 samples and measures at prescribed time intervals a zero-phase current from ZCT 4 bonded to a grounding wire 3 of a receiving transformer 1, to thereby acquire a zero-phase current sampling value. A voltage measuring means 12 samples and measures at prescribed time intervals a supply voltage supplied from a cable 2, to thereby acquire a voltage sampling value. A simulated vector generation means 13 generates a charging current simulated vector having an approximately the same phase as a charging current to ground of an electric installation by using the voltage sampling value. An orthogonal component operation means 14 calculates an orthogonal component to the charging current simulated vector of the zero-phase current sampling value. An insulation monitoring means 15 determines existence of an insulation failure of the electric installation based on the orthogonal component. An alarm output means 16 outputs an alarm in the case of the insulation failure. COPYRIGHT: (C)2006,JPO&NCIPI