Low Voltage On-Line Insulation Monitoring System

摘要

A low voltage on-line insulation monitoring system is provided to detect and monitor an effective leakage current value corresponding to an insulation resistance value or a resistance component, accurately. A low voltage on-line insulation monitoring system comprises a low frequency overlapping device, a zero-phase current transformer(9,11), a current/voltage converter(61), an amplifier(62,64), a filter(63), a frequency detector(66), an analog/digital converter(65), and a control device(70). The low frequency overlapping device overlaps two kinds of low frequency signal voltages(f1 Hz, f2 Hz) to a low voltage line, separately. The zero-phase current transformer detects a leakage current flowing between the low voltage line and ground. The frequency detector determines whether the frequency of the low frequency signal is f1 Hz or f2 Hz using a leakage current component.