DIAGNOZING METHOD OF VOID DEFECT OF ELECTRIC APPARATUS ON THE BASIS OF PARTIAL DISCHARGING PHASE CHARACTERISTICS

PURPOSE:To diagnoze rapidly and precisely the kind of a void defect and its generating position by finding out the partial discharging phase characteristics of a partial discharging pulse to applied voltage and detecting similarity of the found partial discharging phase characteristics to previously found diagnozing reference partial discharging phase characteristics. CONSTITUTION:Polarity discriminators 4, 5 for separating a partial discharging pulse into positive and negative polarity pulses, detectors 6, 7 for detecting generated phase angle phi for the level of the partial discharging pulse, i.e. apparent discharged charge (q), and an AC applied voltage and phi-q pattern detectors 8, 9 are formed. In addition, storage devices 10, 11 for storing a diagnozing reference phi-q distribution pattern and similar pattern detectors 12, 13 are also formed. The diagnozing reference cycle average phi-q distribution pattern read out from the storage devices 10, 11 are compared with a pattern obtained from a diagnozed apparatus. Consequently, the diagnosis of the kind of the void defect and its generating position and the forecasting diagnosis of deterioration can be performed rapidly and precisely.