Mechanism of Impulse Creepage Discharge Propagation on Charged Dielectric Surface in SF₆ Gas

Abstract

This paper describes the mechanism of creepage discharge propagation on charged dielectric surface in SF6 gas. Experimental results revealed that the surface charging having the opposite polarity to the applied impulse voltage increased the discharge extension length by enhancing the electric field strength at the discharge head. The charging potential of-12 kV for the 1 mm-thick PMMA sample doubled the mean step length and halved the pulse interval of stepwise discharge propagation. The influence of the charged surface on creepage discharge propagation was interpreted in terms of two processes: (a) streamer propagation and (b) streamer-to-leader transition based on the precursor mechanism.

Surface Discharges and Flashover Modelling of Solid Insulators in Gases

“…Fundamental studies have been conducted to understand the inception and (insulator shape, electrodes form…), etc. Fundamental studies have been conducted to understand the inception and propagation of creeping discharges in various gases [7][8][9][10][11][12][13][14]. It appears from the reported results that the phenomena start with corona discharges that evolves into ramified streamers.…”

“…The creeping discharge propagation dynamics in SF6 (sulfur hexafluoride) has been investigated by many researchers [7][8][9][10][11]. Okubo et al [8] reported that the creeping discharge has the same dynamics as in air (Figure 1).…”

“…Different models have been proposed in order to compute the inception voltage of creeping discharges and flashover voltage of insulator in air at atmospheric pressure [2,3,13,14]. Hayakawa et al [7] analysed the mechanism of impulse creeping discharge propagation on charged PMMA (poly-methyl methacrylate) surface. Their results showed that the discharge propagation is influenced by the charged surface and can be explained by the streamer propagation and streamer-to-leader transition based on the precursor mechanism.…”