Measurement and analysis of partial discharge of high and medium voltage power equipment

The partial discharge measurement is gradually becoming an important preventing maintenance for power apparatuses with voltage level of higher than medium voltage. In practical, however, field measurement of partial discharge is easily suffered by interferences. The measurement compatible to the apparatuses and environmental features should be considered and different discharge models should be analyzed. This paper is aimed to measure partial discharge of medium voltage power equipment under use. Firstly, the measurement method by using high frequency current transformer (HFCT) is introduced, and then, the various partial discharges including internal discharge, along-surface discharge and tip discharge are modeled and energized to measurement. Furthermore, the discharge waveform features and phase distribution characteristics are analyzed for identifying the type of partial discharge. The measurement and analysis results for actual case are compared with the standard discharge pattern data of laboratory, which show that the proposed measurement and analysis have well representative. This can provide the basis for the establishment of the partial discharge database of medium voltage power equipment, which is also required for development of partial discharge automatic identification system.