Effect of Non-Linear Permittivity on Electric Field in Multi-layer Dielectrics in Cylindrical Geometry

When operating under alternating current fields, the capacitive effect of cable insulation takes precedence over the resistive effect and its permittivity assumes a higher importance compared to electrical conductivity towards the distribution of electric field. Research in the past has shown that relative permittivity of a dielectric has a dependence on operating temperature, electric field and frequency. In this paper, the authors present a study on the effect of temperature and field dependent, non-linear permittivity on the resultant radial electric field distribution in case of a multi-dielectric insulation system in a two-dimensional cylindrical geometry. The effects of permittivity coefficients, conductor boundary temperature and applied average electric field on the distribution and peak of resultant field have been investigated. The authors believe that these results will prove to be useful in selection of additional layers of insulation in multi-dielectric power cables and cable joints.