An electrostatic approach for the calculation of breakdown voltage for quasi-homogeneous sphere-plane gaps

Sphere-plane gaps constitute one of the most, theoretically and practically, interesting electrode configurations in High Voltage testing. Up to now, most of the studies available in the literature are, almost entirely, based on laboratory experiments and the specification of the Critical Flashover Voltage (CFO). The methodology, presented in this paper, for the calculation of breakdown voltage, is based on the specification of the maximum electric field and the place on the electrode configuration where this appears. The proposed simulation model is studied under electrostatic conditions using Finite Element Method (FEM). Assumptions and outcomes from previous works are also considered, both during the simulation [1] and the calculation [2] procedures. The obtained results indicate a significant convergence with already published test measurements and calculation results, especially for gap distances where the electric field is considered as uniformly and quasi-uniformly [2] distributed. Finally, useful conclusions are derived, regarding both the electric field distribution and the behaviour of the breakdown voltage.