INSULATION DETECTOR AND ELECTRICAL DEVICE

摘要

An insulation detector (30) that is connected to an electrical device provided with a device capacitor and/or battery for detecting or measuring, with a high degree of precision and a simple architecture, insulation resistance with respect to a housing or ground for a device or a load. Said insulation detector (30) is provided with an insulation-detector capacitor (31), a voltage detection unit (33) that detects the voltage across said insulation-detector capacitor (31), and a current-path-forming switch (32) for forming a current path that includes the insulation resistance of the electrical device. Said current-path-forming switch (32) connects the following in series: ground or a housing, the device capacitor (22), and the insulation-detector capacitor (31). The voltage detection unit (33) measures the aforementioned insulation resistance by measuring the time constant of changes in the voltage across the insulation-detector capacitor (31). Relative to the magnitude of the capacitance of the device capacitor (22), the magnitude of the capacitance of the insulation-detector capacitor (31) is such that said capacitance can be disregarded when measuring the insulation resistance.