Effects of Solid Dielectric Material and Compressive Force on Interfacial AC Breakdown Voltage between Two Solid Dielectrics

Abstract

One of the weak points of all solid insulation system is the breakdown strength along the interface between two solid dielectrics. The low breakdown voltage is considered to be due to the small cavities formed in the interface due to surface morphology. In this paper, we investigated the effects of dielectric material and compressive force on interfacial breakdown voltages. The results that we obtained are as follows: (1) most of the interfacial breakdowns between two solid dielectrics were developed by avoiding the contact area for high-pressure region, (2) in cases of polymethyl methacrylate (PMMA) and high-density polyethylene (HDPE), the breakdown voltages increased with increasing the compressive force, (3) mechanically soft insulating material was found to be better than hard material, because cavities existed between two solid dielectrics by compressive force become small, and (4) although the same compressive force was applied to the interface, the breakdown voltages increased with increasing uniformity of the surface.