Analysis on Buffer Layer Discharges Below the Corrugated Aluminum Sheath of XLPE Cables and Comparison with Other Metal Sheath Structures

The spiral corrugated aluminum sheath is most commonly used in HV XLPE land cables in China. In recent years, cable faults caused by discharge ablation of semi-conductive buffer layer below the aluminum sheath have been frequently reported, and a large scale of discharge traces on insulation screen surface have been found in the dismantled cables, which has aroused widespread concern. In this paper, after a brief summary of this kind of failure phenomena, the theoretical and experimental researches on the cause and mechanism of buffer layer failure are provided, with relevant conclusions listed. This is thought to be important for XLPE cables' structure optimization and performance improvement. Several kinds of aluminum sheath structures commonly used in HV XLPE cables out of China are also introduced, with their advantages and disadvantages as well as their application scopes, which has reference value for the development of cable industry.