Simulation of electric field distribution in nanodielectrics based on XLPE

Abstract

Recently, there has been a growing interest in the use of nano-sized fillers in order to enhance the properties of a material. The mechanical, barrier and electrical properties of polymers can be enhanced by use of nanofillers in appropriate amounts. The tremendous improvement in polymer properties on incorporation of nanoparticles arises from large interfacial area and large interfacial interaction between the nanofiller and the polymer matrix. There is several reported literature on the influence of nanofillers on dielectric properties of polymeric insulators, mainly epoxy resins. Literature on theoretical analysis for determining the influence of fillers and the dependence of its size, shape and composition on the electrical properties of the composite are limited. Cross linked polyethylene (XLPE) is widely used as insulation in underground high tension cables. The life of cables can be extended by delaying the breakdown of insulation. The breakdown of insulation depends on the distribution of electrical stress in insulation. The electric field and stress distribution in polymer insulation can be altered by adding nanoparticles, depending on permittivity of the nanofiller and its weight percentage in the polymer. This paper attempts to simulate the electric field distribution in XLPE and the effect of different kinds of nanofillers, namely nanoclay, nanosilica and nanoclacium carbonate on the same. Simulations were also performed in COMSOL Multiphysics software to evaluate the effect of nanofiller content on electrical field distribution in XLPE. It was found that the composite with the highest difference in the electric field values between the polymer and the nanofiller offers the best resistance against electric field propagation and that the dielectric properties of the nanocomposites become better with increased amount of nanofillers. However, at a very high weight percentage, the properties of the composite deteriorate due to the fact that for higher weight percentage the inter-particle distance reduces allowing for more agglomeration. The nano-filler with the highest difference is found to be nano-silica.