Relationship between the expressions for electrical resistivity and the field profiles in HVDC cable insulation

The electric field in the insulation wall of HVDC cables depends on the volume electrical resistivity of cable insulation. As a consequence, the DC field profiles are affected by the experimentally-based relationships that are used for expressing the dependence of electrical resistivity on temperature and electric field. In this paper, the way these relationships affect the field profiles in HVDC cable insulation is investigated from the analytical viewpoint first. Then, for the sake of illustration, calculations are made for Poly-Propylene Laminated Paper (PPLP) insulation so as to evaluate how a particular experimental expression of the electrical resistivity of PPLP affects the DC field profiles within the PPLP insulation of an HVDC cable.