Effect of pressure and elastic modulus on tangential breakdown strength of solid-solid interfaces

Breakdown strength (BDS) of the interface between the two solid dielectrics is much lower than the BDS of the bulk materials due to formation of microscopic cavities at the interface. The main motivation of this paper is to explore the impact of the applied contact pressure and composite elastic modulus on the AC tangential BDS of dry-mate, wet-mate and oil-mate solid-solid interfaces experimentally. In the experiments, two different contact pressures were applied using different mechanical loads with two different materials having different elastic moduli, i.e. cross-linked polyethylene (XLPE) and silicon rubber (SiR). Two rectangular prism shaped samples were placed between two vertical Rogowski shaped electrodes in air, water or oil. Field simulations were also performed on the test objects to assess the electric field distribution and they show a good agreement with the experiments. The experiments show that the elastic modulus, contact pressure and void-filling medium (air/water/oil) have a significant impact on the tangential BDS.