INSULATION RESISTANCE DECREASE DETECTOR AND ITS SELF-DIAGNOSTIC METHOD

摘要

PROBLEM TO BE SOLVED: To provide an insulation resistance decrease detector and its self-diagnostic method capable of self-diagnosing whether or not functions of the detector itself are normally working. SOLUTION: The insulation resistance decrease detector detects the decrease of insulation resistance in a vehicle including a direct current power source system electrically insulated from the vehicle body and an alternate current circuit connected with the direct current power source system comprises a resistor Rs for self-diagnosis and a switch element Q directly connected between a connection point of a detection resistor Rd and an insulation resistor Ri and the ground. It also comprises a control means 52 for controlling the switch element Q to be off for insulation resistance decrease detection functioning and to be on for self diagnosis functioning, and a judgment means 52 for judging a degradation in failure of the detection resistor Rd when the switch element Q is turned on and the voltage Vx value of connection point appearing in the connection point of the detection resistor Rd and the insulation resistor Ri is detected to be different from a reference value. COPYRIGHT: (C)2005,JPO&NCIPI