Surface Charging On Epoxy Spacer At Dc Stress In Compressed SF6 GAS

The charge accumulation and its mechanisms are studied based on the experiments of post and conical epoxy spacers subjected to high dc voltages in compressed SF6 gas. The charge measurement is performed using electrostatic probe and dust figure techniques. The charge accumulation is strongly influenced by the surface condition of epoxy spacer. Heterocharge deposits locally on the surface of untreated spacer. The flashover voltage of highly charged spacer decreases considerably at the time of polarity reversal. In the case of epoxy surface treated with horning, only a small quantity of charge is deposited uniformly on the surface of spacer. The mechanism of inhomogeneous surface conduction is suggested by the local surface charging on the untreated spacer. Field emission is also found as the other charging mechanism on the conical spacer set in rough finish electrode system.