Examination of Longitudinal AC Breakdown Strength of Dielectric Surfaces as a function of Elastic Modulus

Abstract

This paper examines the influence of the elastic modulus of the polymer insulation on the tangential AC breakdown strength (BDS) of polymer interfaces theoretically and experimentally. In the experiments, four different materials with different elastic moduli, namely crosslinked polyethylene (XLPE), cured end product of epoxy resin (EPOXY), polyether ether ketone (PEEK) and silicone rubber (SiR) were employed under various contact pressures. The BDS of each interface increased as the contact pressure was augmented. As the contact pressure became threefold, the interfacial BDS rose by a factor of 2:4, 1:7, 1:8, and 1:4 in the case of the PEEK, EPOXY, XLPE and SiR interface, in a sequence following the decrease of the elastic modulus. Under the same contact pressure, it was observed that the lower the elastic modulus, the higher the BDS. The employed contact theory also suggested a decreasing BDS as the modulus was augmented; however, the experimental results tended to deviate widely from the estimated results as the pressure was significantly increased.