Patent ID: 9030210
Filing Date: 2015-05-12
Classification: G01R

Abstract:
1. An insulation deterioration diagnostic apparatus for an electric path connected between an inverter device and an inverter-driven load device, comprising: a zero-phase current transformer having an annular magnetic core, a magnetizing coil wound around the magnetic core, and a detecting coil wound around the magnetic core, the transformer being for detecting a zero-phase current of an electric path; a magnetization control circuit for supplying an alternating current having a frequency at least twice as high as a drive frequency of the load device to the magnetizing coil to magnetize the magnetic core; and a frequency extracting circuit for extracting a predetermined frequency component from an output signal of the detecting coil; a detector for detecting one of a current waveform or a voltage waveform supplied to the load device, wherein the magnetization control circuit controls the current supplied to the magnetizing coil based on an output signal of the detector.