GROUND FAULT DETECTION CIRCUIT FOR UNGROUNDED POWER SOURCE

摘要

An insulation state detection circuit includes a first charging circuit, a second charging circuit and a third charging circuit. A charging resistance value in the case that a capacitor is charged in the first charging circuit coincides with a charging resistance value in the case that the capacitor is charged in the second charging circuit when a resistance value of the ground fault resistor of a negative terminal side of a DC power source is a ground fault alarm threshold value for an insulation state of an alarm level. The charging resistance value of the first charging circuit coincides with a charging resistance value in the case that the capacitor is charged in the third charging circuit when a resistance value of the ground fault resistor of the positive terminal side is a ground fault alarm threshold value for an insulation state of an alarm level.