The combination of two solid dielectrics (interface) increases the risk of formation ofmicroscopic cavities reducing the breakdown strength (BDS) of the interfaceconsiderably, particularly when the electric field has a tangential component. The mainpurpose of this paper is to investigate the impact of the applied contact pressure andcomposite elastic modulus on the tangential ac BDS of the solid-solid interfacesexperimentally. In the experiments, three different contact pressures were applied usingdifferent mechanical loads with two different materials having different elastic moduli,i.e. cross-linked polyethylene (XLPE) and silicon rubber (SiR). Two rectangular prismshaped samples were placed between two vertical Rogowski shaped electrodes either inair or oil. The type of the interface (air/oil) is highlighted duly upon showing the results.Increase in contact pressure caused relatively higher increase in the tangential BDS ofdry SiR-SiR (assembled in air) than that of XLPE-XLPE, revealing that elastic modulusfacilitated significantly to reduce the mean void size in SiR that in turn improved thetangential BDS. Likewise, the tangential BDS of hybrid interfaces formed by XLPE-SiRspecimens increased by 43% compared to that of XLPE-XLPE interface at the samepressure. Additionally, the same set of experiments assembled in oil reveals that thepresence of oil enhanced the tangential BDSs around 2-3 times for all three-interfacecases. Moreover, with the increase of applied pressure the tangential BDS of air-filledand oil-filled cavities tended to get significantly higher.
展开▼
