Effects of interfacial pressure on tracking failure at XLPE cable joint by analyzing discharge light distribution

This paper investigated the effects of interfacial pressure on the discharge and tracking failure at the interface between XLPE and silicon rubber by analyzing the distribution of discharge light emitted during the failure process. The test sample was made by pressing together a piece of XLPE and a piece of transparent silicon rubber with the pressure of 20 kN/cm², 100 kN/cm² and 300 kN/cm², respectively. Test voltage was applied to a pair of plate-needle electrodes sandwiched at the interface with the insulation distance of 10 mm. The initial discharge voltage, the discharge light from discharge to tracking failure and the tracking patterns after failure were recorded with a digital camera. Then the discharge light was analyzed with an image processing method. Results show that the initial discharge voltage increases with the increase of pressure, which significantly influences the distribution characteristics of the discharge light and tracking pattern at the interface. The analysis of discharge light distribution is helpful in understanding the failure process and its mechanism at the interface between XLPE and silicon rubber found in prefabricated cable joint.