Numerical study into the breakdown strength of a two phase (gas-liquid) insulation system

This paper investigates the electric potential and field of a two phase (gas-liquid) system. The study uses finite element analysis (FEA) techniques to investigate the impact of a gas bubble on the bulk electric field. The FEA model is expanded to consider the multiple bubble breakdown probability using Monte Carlo techniques. The numerical results demonstrate that compared with bubble quantity, bubble radius is the dominant factor for two phase system electrical breakdown. Furthermore, the effective breakdown strength of a two phase system has been determined as a function of gas phase volume fraction. The predicted two phase effective breakdown strength has then been compared against the mixture rule, where good agreement was achieved.