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In this paper a comparative study of cavity defects partial discharge in single and double cavities was performed at different applied voltages. The variation of the PD magnitudes and phase-resolved-patterns (PDPRP) are studied as a function of increasing supply voltage magnitude. The study is conducted on polymer insulation discs. Two test samples were prepared. Sample 1 consist of a cavity of 0.1 mm thickness and sample 2 with 2 of 0.1 mm cavities positioned 0.1 mm apart in the middle of the insulation. The PD magnitude of the double voids are affected significantly by the increase in applied voltage compared to the single cavity magnitude. The PDPRP however are invariant. An electric field simulation model was created using QuickField Software to investigate the electric field distribution profiles in the insulation model. The simulation results correlated with the measurement results.

This study presents the simulation of the electrical field distribution in voids encapsulated in epoxy insulation material using QuickField™ software. The significance of this study is to further understand how electric field distribution influences partial discharge activity in insulation material containing air voids. The insulation model consists of single and double voids located in the middle of the insulation. The simulation results indicate that the electric field in the single void is higher than in the case of two voids adjacent to each other. However, despite the voids being identical to the enhancements of the electric fields in the voids is not to the same extent.

Electrical insulation is one of the most critical parts of most of high voltage power system equipment, and its quality plays a significant role in determining the reliability of the equipment. Most common problems of power equipment are associated with insulation failure. Partial discharges are common problems in electrical insulation. Measurement of partial discharge is therefore widely used to diagnose the condition of the insulation system. Hence, it is imperative to study how partial discharge activity can be analyzed in insulation material containing multiple cavities. The objective of this paper is to apply the Phase-Resolved Partial Discharge Analysis (PRPDA) technique to insulation with single and two cavities close to each other in order to investigate the behavior of the partial discharge activity. Through the analysis of the experimental results, it was established that phase-resolved partial discharge pattern for two cavities is different from that of the single cavity pattern.