INSULATION MONITORING METHOD

PURPOSE:To provide an insulation monitoring method by which the insulating state of a high-voltage power receiving equipment and substation can be always monitored. CONSTITUTION:The porous bottom section of a reference electrode 1 which outputs a constant DC voltage depending upon the kind of the electrode solution corresponding to the material of a grounding electrode 2 buried in the ground near a high-voltage power receiving equipment and substation is buried in the ground near the electrode 2 so that a leakage current from the electrode 2 can be superimposed upon the DC voltage of the reference electrode 1. The filter 3a of a measuring section 3 extracts signals of commercial frequency components from the superimposed signals and a measuring unit 3b measures the level of the extracted signals and discriminates the insulating state of the power receiving equipment and substation based on the measured results of the unit 3b.