Partial discharge characteristics of aged oil-impregnated paper under high humidity level

This paper presents a study on partial discharge (PD) characteristics of aged oil impregnated paper under high humidity level. The presence of the void in the impregnated paper with exposure to high relative humidity would induce partial discharge occurrences which eventually degrade the insulation performance of the paper. In this work, an artificial cylindrical void was created and the oil impregnated paper was aged up to 16 hours at 90% relative humidity. Moreover, partial discharge inception voltage (PDIV) and partial discharge extinction voltage (PDEV) were recorded. Based on the results, the longer aging time of kraft paper, the lower the PDIV and the PD magnitude. It is implied that the longer exposure to a high relative humidity, the more moisture being absorbed by the paper causes high repetition of PD at corona discharge level.