DETECTION DEVICE FOR ELECTRIC LEAKAGE STATE AND DETECTION METHOD

PROBLEM TO BE SOLVED: To provide a detection device capable of determining a resistance value of an insulation resistor, and a detection method.SOLUTION: A detection device detects electric leakage in a DC power supply of which a positive electrode terminal is connected through an insulation resistor to a case that houses the DC power supply, and includes an AC power supply, an additional resistor, a voltage detection circuit and an arithmetic unit. The AC power supply is connected to the case as well as the negative electrode terminal of the DC power supply through a detection resistor and a coupling capacitor, and outputs AC signals. The additional resistor is connected in parallel to the insulation resistor. The voltage detection circuit detects the voltage of the detection resistor and outputs detection information to the arithmetic unit. Using the detection result of the voltage detection circuit, the arithmetic unit determines a combined resistance value for the insulation resistor and the additional resistor, and from the combined resistance value, determines a resistance value of the insulation resistor.