INSULATION MONITORING SYSTEM amp; INSULATION DETECTING METHOD FOR ELECTRIC POWER SUPPLY SYSTEM

摘要

An insulation detecting apparatus of the present invention comprises a voltage detecting means for detecting a voltage component of each of three phases, a zero-phase current transformer for detecting zero-phase leakage current flowing between the power line and ground, a leakage current detecting means for converting a leakage current component detected by the zero-phase current transformer into a voltage component and extracting a frequency component lower than a certain frequency or a frequency component of a commercial frequency band, a phase comparing means for detecting a phase difference between an output value of each of the three phases of the voltage detecting means and an output value of the leakage current detecting means, an analog-to-digital conversion unit for converting the output value of the leakage current detecting means into a digital component, an operation controller for reading and outputting a variety of data, and an input-output unit. According to the present invention, the insulation state of a power line can be detected by calculating active component leakage current between a power line including a load and the ground that is directly related to an insulation state or reactive component leakage current that is not directly related to the insulation state, but generated by ever-existing electrostatic capacitance, and the insulation detecting apparatus can be remotely controlled.