Effect of isolation mode and surface condition of an insulating barrier on the performance of a non-uniform field electrode system under positive DC voltage

The aim of this paper is the study of the effect of the isolation and the surface condition of an insulating barrier on the performance of a non-uniform field electrode system. The study is carried out under positive DC voltage. The dielectric properties of the material were measured using the Schering bridge. The effect of the material isolation mode in the point-plane air gap system on the optimisation of its performance was analyzed. Moreover we present findings of experiments which allow quantifying the effects of the clean or polluted atmosphere and the contamination severity level on the electric strength of the air gap system. Finally, this investigation has been supported by laboratory observations of the discharge phenomena in the air gap from inception to full flashover in all cases using a video camera system. The results from this study show that there is a distance limit of the isolation barrier beyond which its performance is optimal. In addition, a limit level of pollution, from which its minimal electric strength is equivalent to that of a conducting barrier, has been detected.