Numerical analysis of the SF6 dielectric recovery in high voltage circuit-breakers around current zero

This paper is devoted to the numerical simulation of breakdown process for high voltage circuit-breakers. To optimise the design of switchgears for dielectric phase, it is required to build criteria based on the breakdown electric field strength calculations of hot SF6. This critical electric field is calculated for large temperature and pressure ranges including both electron and ion kinetics. Gas behaviour is calculated thanks to specific simulation tool which takes into account the electric arc, its interaction with material and numerous compressibility effects of the gas . Thus, using different geometrical configurations, it is possible to get an insight into the capabilities of the circuit -breaker to succeed in tests from the dielectric phase point of view. Two studies for both arcing contacts and parallel contacts are presented, compared to test results and commented.