Surface discharge imaging in presence of deposited space charges in non‐uniform DC electric field

Abstract

An investigation is made of the influence of an accumulated charge sprinkled on the surface of an epoxy resin plate in corona mode on partial discharge inception and its forms as analyzed by optical imaging at DC voltage. The effects of the polarities of both the deposited hetero-and homocharges were investigated. The occurrence of first streamer discharges was detected electrically and observed by optical imaging. The various forms of streamers were acquired by optical imaging and associated with the polarity and intensity of the accumulated surface charges. Surface charge sprinkling on the epoxy specimen surface was quantitatively evaluated by surface charge mapping. In addition, the effect of the subsequent discharges occurring in a heterocharge configuration above the inception voltage was observed. In terms of their directions and lengths, the kinetics of the streamer filaments revealed a strong dependence on both the polarity and the intensity of an accumulated charge. Compared with the reference charge-free surface, the strongest drop in dielectric strength in the interelectrode space with a sprinkled charge was obtained for the heterocharge configuration. The presented results provide a contribution to the assessment of streamer behaviour in the presence of accumulated surface charges, including its polarity and intensity.This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Surface flashover in 50 years: Theoretical models and competing mechanisms

“…Florkowski et al. [163] studied the influence of corona accumulated charge on the surface of an epoxy resin plate on partial discharge inception and discharge forms analysed by optical imaging. The results indicate an electric field enhancement between the surface charge spot and protrusion when preset hetero‐space charges, while the homo‐space charges attenuate the electric field in the same area.…”

Two-Phase-Interfaced, Graded-Permittivity Titania Electrical Insulation by Atmospheric Pressure Plasmas

“…Recently, with the increase of the voltage level and capacity of electrical equipment (e.g., in power transmission grids or pulsed power devices, etc. ), the electrical insulation often fails when high electric fields are generated. , For example, once the surface flashover (the discharge phenomenon along a solid insulator surface as shown in Figure S1) occurs in power transmission lines, with currents up to ∼kA, the electrical equipment may burst into flames or explode by overheat, which is hazardous and detrimental to power system safety. , …”

“…4,5 For example, once the surface flashover (the discharge phenomenon along a solid insulator surface as shown in Figure S1) occurs in power transmission lines, with currents up to ∼kA, the electrical equipment may burst into flames or explode by overheat, which is hazardous and detrimental to power system safety. 6,7 Therefore, solid insulation materials with high surfaceinsulating performances (high flashover threshold voltage) are pursued over the last half a century. 8 The methods for improving surface-insulating performances include electric field optimization, 9,10 surface modification, 11−13 bulk modification, 14,15 and so forth.…”

Surface streamer patterns induced by a strong vertical electric field under impulse voltages

“…Surface discharge on dielectrics material pose a hazardous influence on high voltage devices, which threaten the development of high voltage transmission systems [1,2]. Discharge along an insulation surface is always initiated with the occurrence of effective electrons, the development of an electron avalanche, the formation of a streamer, the transition from streamer to leader, ultimately leading to the occurence of surface flashover [3].…”