Abstract: This paper contributes reports on the phenomena related to degradation of XLPE cables due to various factors. This study focuses on underground XLPE cables which rated at 11 kV for both 1-core and 3-core types. It was shown, that at the highest operating temperature, values of the cable dissipation factor (tan d) significantly increased with ageing. In practice, the cable insulation is subjected to a positive feedback, leading to rise of temperature breakdown risk. Insulation properties changes with time, and it is very necessary that key parameters are tested accurately, to guide on the relative deterioration level of the insulation. The cables are damage due to the adverse installation conditions during cable laying Most of the failures that occur in cable system have a cause that is well known. For instance, failures due to digging activities of other utilities which damages our cable or due to ageing of older components.
Keywords: XLPE cable, tan delta, dissipation factor, vlf.