Atmosphere Dependence of DC Surface Flashover Voltage of Insulators

Abstract

According to the existing vacuum surface flashover theory, the flashover breakdown discharge is a plasma discharge channel formed in the thin layer of desorbed gas. Therefore, the degassing of the dielectric material in a closed environment is a key factor affecting the flashover performance. The continuous degassing of the solid material will accumulate in a closed environment, causing a low-pressure discharge phenomenon under an applied electric field. In this paper, DC surface flashover experiments of composite sample containing micro and nano-semiconductor additives are studied in different pressures to reveal the surface flashover mechanism. When the electrode spacing is 1mm and the air pressure is in the range of 10−4~10−1 Pa, the flashover voltage remains basically constant. The DC flashover voltage is rapidly reduced from 10−1 Pa and reaches a minimum around 15Pa. The flashover voltage of the micro-composite sample is approximately similar to the pure sample. The DC discharged voltage of the nano-modified sample slightly increased compared with the pure sample, and the amplitude of the flashover voltage did not change significantly in the range of 5 to 500 Pa. The experiments suggest that the reasons for the results may be as follows: Firstly, the outgassing of the solid surface has less effect on the degree of vacuum at low pressure. Secondly, when the air pressure is used as an independent variable, the influence of other factors is negligible.