Electric Field Distribution and Dielectric Losses in XLPE Insulation and Semiconductor Screens of High-Voltage Cables

This article presents the electric field distribution E and dielectric losses Delta P-diel. in the insulation system of high-voltage cables. Such a system consists of inner and outer semiconductor screens and XLPE insulation. The aim of this study was to compare the values of E and Delta P-diel. between semiconductor screens and XLPE insulation. The objects of the research were high-voltage cables of 110 kV, 220 kV, 400 kV, and 500 kV. The geometrical dimensions of the cables, especially the radii of individual layers of insulation, as well as the electrical properties of the screens and XLPE, were taken from the literature. Semiconductor screens and XLPE insulation were treated as a system of three concentric cylinders. When determining the electric field distribution, both the electrical permittivity and electrical conductivity, which, in the case of semiconductor screens, play important roles, were taken into account. The obtained results prove that both the electric field distribution E and dielectric losses P-diel. are significantly larger in XLPE insulation than in semiconductor screens. The intensity E in XLPE insulation is about four orders of magnitude greater than the intensity in semiconductor screens. Dielectric losses Delta P-diel. in XLPE insulation are about eight orders of magnitude greater than the losses occurring in semiconductor screens.