Investigation of Partial Discharges in Epoxy Resin with Horizontally and Vertically Aligned Two Voids

Partial discharge (PD) activity significantly affects the reliability of insulation systems, with void positioning in epoxy resin playing a critical role in molded transformers. This study investigates the influence of PD in epoxy resin containing two artificial voids (1 mm in diameter) arranged in horizontal and vertical alignments, focusing on PD characteristics, electrical treeing behavior, and breakdown mechanisms. PD activity and electrical tree were monitored using a high-frequency current transformer (HF-CT) sensor and a transient earth voltage (TEV) sensor. The results indicate that void alignment strongly influences PD inception, discharge intensity, and propagation patterns. FFT (Fast Fourier Transform) spectrum analysis revealed distinct differences between the two configurations in vertically and horizontally aligned voids. Furthermore, electrical treeing was observed in the horizontally aligned voids, leading to breakdown. However, in vertically aligned voids, electrical treeing was difficult to detect, and a breakdown occurred suddenly. These findings highlight that void alignment significantly influences PD behavior and breakdown progression, providing valuable insights for improving insulation design and diagnostic techniques in high-voltage applications, contributing to the development of more reliable insulation systems.