Surface morphology and flashover performance of epoxy resin in SF<inf>6</inf> after discharge aging

Abstract

The study of the surface morphology changes in epoxy resin under direct current power supply in SF <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</inf> is of great significance to research into the surface flashover mechanism and the improvement of flashover voltage. In this paper, the epoxy resin was subjected to different degrees of aging in an electric field formed by rod-rod and pin-pin electrodes. Taking the pin-pin electrode as an example, the surface morphology of the same position with different number of flashovers were measured by atomic force microscopy and scanning electron microscopy, and the surface chemical characteristics were explored by Fourier transform infrared spectroscopy and energy dispersion spectrum. Meanwhile, the fractal dimension was introduced to characterize the surface morphology in a quantitative manner: the influence of aging on the flashover voltage was then explored. The research results showed that swelling, cracking, and granular bumps, were three typical surface features, and these were successively formed during aging. As the aging time increased, organic groups on the surface of epoxy resin decreased in number, whilst the inorganic filler mass fraction increased. Moreover, with increasing number of flashovers, the surface morphology gradually changed from disorderly to orderly, from complex to simple, from chaotic to self-similar, when the aging region was changed from the electrode position to the middle of the two electrodes. Furthermore, with prolonged aging, the flashover voltage was reduced to a certain extent.