Patent ID: 8618813
Filing Date: 2013-12-31
Classification: F24D,G01R,H02H,Y02B

Abstract:
1. A circuit fault detecting device for detecting a fault in a load circuit that is supplied power from a power supply line through two relay contact points that are provided respectively in each of a pair of power supply lines, the circuit fault detecting device comprising: a detecting portion, connected between power supply lines and a load circuit, detecting a detected value in accordance with a magnitude of a leakage current that flows through a ground between the power supply line and the load circuit; and an evaluating portion evaluating whether or not there is a breakdown of the insulation of the load circuit, relative to ground, based on the detected value obtained when the relay contact points are open, wherein: the evaluating portion calculates a difference value between a detected value that is obtained when the relay contact points are open and a detected value that is obtained when the relay contact points are closed, compares to a difference threshold value that indicates a difference value between a detected value when the relay contact points are open, obtained when the insulation resistance of the load circuit, relative to a ground, has fallen to a lower limit value of a normal range, and a detected value obtained when the relay contact points are closed, and evaluates whether or not there is a breakdown of insulation in a load circuit in accordance with the comparison results.