Computer simulation of space charge distribution in an XLPE-EPR sandwich

In joints and terminations of HV cables, a dielectric-dielectric interface exists between the cable insulation (i.e. cross-linked polyethylene XLPE) and the accessory insulation (i.e. ethylene propylene rubber EPR). Under DC voltages this interface brings together a potentially mechanically weak boundary with a large field gradient and a corresponding interface charge. It is therefore likely that electrical failure will be initiated there. For this reason it is important to understand the way in which space charge is accumulated at and around the interface. Here we report the results from a computer simulation of an XLPE/EPR sandwich system based on a previous model. Results of this dynamical model will be compared with calculation based on the Maxwell-Wagner theory, and with experimental space charge measurements. Finally, we shall discuss the model limitations and expected improvements.