Research on ablation characteristics of XLPE Cable buffer layer based on electrothermal coupling method

Abstract

Ablative white spots are often been found on the buffer layer by disassembling high-voltage XLPE fault cables. To study the ablation characteristics of buffer layer, the white spot chemical elements in different positions of the buffer layer were analysed by using Energy Dispersive Spectrometer (EDS), and the conductivity of the white spots buffer layer were measured. The results of EDS showed that the white spots outside the buffer ablation area are the gouache precipitated by itself. The Conductivity measurements results showed that the precipitation of sodium polyacrylate reduces the conductivity of the buffer layerCwhich affected the local resistance heating when the overvoltage happened. Based on the experimental results of conductivity measurement, the electrothermal coupling simulation model of high voltage XLPE cable was established, and the heat generation characteristics of white spots buffer layer were calculated when the high frequency overvoltage happening. The simulation results show that the higher the overvoltage frequency is, the greater the resistance heating is generated and the higher the temperature is caused around the white spots buffer layer, finally it may be ablated by electric heating.