Partial Discharge Measurement of Multi-void Inside Solid Insulation under AC and VLF Voltage Sources

Abstract

The problems of high voltage equipment usually come from the imperfection of solid insulation, which may be caused by poor workmanship during cable installation, leading to multi-void inside solid insulation and subsequently partial discharge when that cable is put in service. Therefore, this paper aims to investigate the discharge phenomena of multi-void inside solid insulation by creating artificial defects in epoxy resin and testing under AC and very low frequency voltage sources. The test object consists of a single void with different void diameters and multi-void created by injecting the air voids at atmospheric pressure into epoxy resin. The partial discharge inside a single void and multi-void is detected by using a conventional and unconventional sensor. The results of PD measurement are represented in the phase-resolved partial discharge (PRPD) and several partial discharge parameters, such as PD charge magnitude and PD repetition rate. In addition, the results are analyzed to observe the impact of the multi-void with different conditions such as variable void diameter, the thickness of epoxy resin, type of voltage source, and PD sensor. The test can specify trends toward breakdown and the severity of multi-void inside solid insulation.