Time-lag measurement of void discharges and numerical simulation for clarification of the factor for partial discharge pattern

Partial discharge pattern has often been applied for diagnosing high voltage equipment. The pattern indicates the relation between the phase angle of applied voltage and the parameters such as discharge intensity and frequency. In the diagnosis, an acquired pattern from an equipment is compared with accumulated data base which provides the correlation between the pattern and the status like degradation or defects. However, clarification for generation of partial discharge pattern based on physics is yet not of satisfactory. The aim of this study is, therefore, to establish a physical model for partial discharge pattern generation based on statistical distribution of the discharge time-lag