TESTING DEVICE FOR INSULATION MONITORING DEVICE, INSULATION MONITORING DEVICE AND TESTING METHOD FOR INSULATION MONITORING DEVICE

PROBLEM TO BE SOLVED: To accurately grasp the operational state of an insulation monitoring device under a state that zero-phase currents flow in a zero-phase current detection sensor installed in the insulation monitoring device.SOLUTION: Currents for in-phase test having a phase the same as the phase of current components with resistance and currents for anti-phase test having a phase opposite to the phase of the current components with resistance are made to flow to a coil TL for test disposed at the detection object place of a zero-phase current detection sensor ZCT of an insulation monitoring device IO. From a current value Ihaving the in-phase components in the currents for in-phase test in a state that the currents for in-phase test are made to flow, and in a state that an abnormality detection signal is output in the insulation monitoring device IO and a current value Ihaving the anti-phase components in the currents for anti-phase test in a state that the currents for anti-phase test are made to flow, and in a state that the abnormality detection signal is output in the insulation monitoring device IO, a current value I in a state that the abnormality detection signal is output in the insulation monitoring device IO is calculated as I=(I+I)/2.