Semi-empirical models for temperature and electric field dependent complex permittivity of solid dielectrics

Abstract

In this paper, the authors present models for the temperature and electric field dependence of AC complex permittivity of solid dielectrics used for power cables. Until now, variation in permittivity, with temperature and field, has been more or less neglected. Although small, both real and imaginary components of the complex AC permittivity are somewhat nonlinear in nature and thus, determination of true behavior of the dielectric requires accurate modelling of the complex AC permittivity. Careful and intensive experimental investigations are carried out using Novocontrol Technologies' broadband dielectric spectrometer, for different temperatures and electric fields and constant frequency of 50Hz and the data is used for curve fitting and subsequent optimization. The suitability of the proposed models has been verified for two different dielectrics. Interesting results on coefficients of the models have been arrived at, that provide deeper insight into the dielectric behaviour.