Fundamental research on dielectric breakdown between XLPE and silicon rubber interface in HV cable joint

The effect of interfacial pressure on the insulation breakdown of the interface between a piece of XLPE and a piece of silicon rubber was investigated. A pair of plate-needle electrodes was sandwiched at the interface. A uniformly distributed weight was put on the sample with the interfacial pressure from 20 kN/cm2 to 300 kN/cm2. The breakdown voltage and the discharge current were recorded; the light distribution at the interface were visually recorded and then analyzed. Results demonstrate that correlation exists between the discharge light and discharge current; breakdown voltage decreases with the decrease of interfacial pressure; both the distributions of light and current depend on the interfacial pressure. Therefore, sufficient interfacial pressure between cable and joint should be met to lengthen the cable joint's life expectation.