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

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.