Space charge analysis of modified and unmodified XLPE model-cables under different electric fields and temperatures

The introduction of HVDC links into the power grid have made polymeric cables for DC transmission a subject of great interest. XLPE is a widely used insulation material for HVDC cables. However, dealing with space charge accumulation in XLPE cables still remains a challenge. New insulating materials offer new possibilities facing these challenges, if their properties are well understood. Two model-cables with equal dimensions but different XLPE insulation are investigated in this study. One material is “conventional” XLPE, which is normally used for AC-cables, while the other is treated to introduce additional functionality into the polymer composition. The cables were exposed to a number of different combinations of applied electric field and isothermal temperature conditions, while space charge measurements on the samples were performed, using the PEA-method. The slight modification of the polymer composition of XLPE leads to considerable changes in space charge development. The modification influences injection, transport and recombination of charges in the sample.