TSDC characteristics of extruded polymer insulated cables

Four XLPE and TRXLPE insulated 15 kV cables were characterized using the thermally stimulated discharge currents (TSDC) technique in order to investigate the effect of the roughness and cleanliness of the semiconductive shield/insulation interface. The XLPE cables, Cable A and Cable B, had nominally the same compound formulation. However, the materials were reportedly cleaner for Cable B compared to Cable A. The cables were tested in the 0 to +/-140 kV voltage range. Cable B, gave a lower TSDC at all voltages when compared to Cable A, at positive and negative polarization. In addition, two 15 kV TRXLPE cables were tested. Cable C has a conventional conductor shield compound while cable D had a supersmooth conductor shield. Some possible interpretations of the TSDC responses are presented.