METHOD FOR DIAGNOSING ABNORMAL CONDITION OF ISOLATION TRANSFORMER AND DEVICE THEREFOR

摘要

An abnormal diagnosing device (20) mounted on an isolation transformer has an operation controller (27) for receiving a mutual induction signal generated in a primary coil (11) of the isolation transformer when a DC power from DC power supply (21) and an AC signal from an oscillator (22) are applied to a capacitor (C) constituting a resonance circuit along with the primary coil (11) through a differential amplifier (24), a signal smoothing circuit (25), and a voltage sensing section (26). The mutual induction signals are supplied in order while the frequency of the AC signal outputted from the oscillator is varying. The operation controller judges the frequency characteristic of the mutual induction signals based on the mutual induction signals, compares the frequency characteristic with those during normal operation, line breakage, and short circuit stored in a memory (28) and detects line breakage or short circuit in the secondary-side closed circuit of the isolation transformer.