Résumé
This paper is focused on the electric field computation in a cylindrical joint model whose insulation consists of two insulating layers (XLPE and EPR). The quasi-stationary regime was considered and the volume charge density (pv) and the superficial one at the XLPE/EPR interface (rho(s)) were taken into account. The electrical conductivity was measured on XLPE (A), EPR (B) and XLPE/EPR (C) flat samples for electric field values E = 1 ... 10 kV/mm and the permittivity for frequencies f = 10(-3)-10(6) Hz. Using the conductivities on flat samples A and B, the equivalent conductivity sigma(Cc), of sample C was computed. The presence of the space charge leads to the modification of the electric field E. The most significant influence is given by the presence of both space and superficial charge, E increasing with 100 % on the outer surface (EPR).