Modeling of insulating nanocomposites-electric and temperature fields

In this paper, simulation studies are carried out to enhance the understanding of the mechanisms for the reported improvements in breakdown strength of nanocomposites. Electric field driven partial discharges and temperature rise can lead to electrical breakdown and hence it is important to study the electric field distribution and temperature rise in nanocomposites. An FEM based software, COMSOL V4.1, has been used to carry out the simulations. The nanocomposite has been modeled as two cores around the nanoparticle in a polymer. The interface between the particle and polymer is called as 1st core and a shell around the 1st core is called as 2nd core. The mechanisms in the 2nd core are characterized by its electrical conductivity and dielectric constant. Various models are used for modeling the 2nd core. The electric field, resistive losses and temperature rise have been computed for static and quasi-static fields for the linear and nonlinear materials. For many models, it is tough to simultaneously get both |E|-fields and resistive losses and hence temperature rise lower than unfilled material both inside and outside the 2nd core region. Based on the magnitude of electric field, resistive losses and temperature rise under transient fields, two linear models of 2nd core support the argument of enhanced dielectric strength whereas most other models do not. Possible hypotheses have been proposed. The results reinforce the idea that interfaces are critical for the reported breakdown strength improvements.