INSULATION MONITORING SYSTEM

摘要

An insulation monitoring system is provided to detect accurately a leakage current or an insulating resistance value of voltage supplied from a transformer regardless of a change of operational conditions of a VVVF(Variable Voltage Variable Frequency) like an inverter. An insulation monitoring system comprises followings. A voltage detector(311) is installed to detect a voltage component supplying to loads like a motor and to transform it to an uniform size. A zero-phase current transformer is installed to detect a leakage current of electric wire path. A current detector(331) is installed to extract frequency component by transforming the detected leakage current component to a voltage component. An analog/digital converter(32) is installed to transform an analog component of output values from the voltage detector and the current detector into a digital component. A programmable logic controller(35) and an input/output parts(361,362) are installed.