Examination of Impulse PD Inception Location by Electric Field Analysis in Ester Oil/Pressboard Composite Insulation System

This paper investigates partial discharge (PD) starting point under impulse voltage application in the ester oil /press-board (PB) composite insulation system. Experimental results are compared with those in the mineral oil and PB composite system to discuss the difference of the discharge characteristics and its mechanism. For ester oil, unlike mineral oil, when the gap length was increased from 0.8 to 1.6 mm, there was no change in the distribution of the PD starting points.