Influence of surface trap parameters on AC / DC flashover of epoxy resin

The surface flashover of electrical epoxy resin has been regarded as a key issue in high voltage insulation system. It is of great significance to study the influence factors on flashover properties of epoxy resin. Surface charge accumulation and decay is one of the key factors in flashover properties. In this paper, three types of epoxy resin samples, including CYD-128, DER-311 and 0164 were prepared, the influence of trap parameters of the epoxy resin samples on the surface flashover performance was investigated. Samples with a diameter of 50 mm and the thickness of 1 mm and 0.2 mm were prepared by the same curing procedure. Surface potential decay, DC surface flashover under SF
6
atmosphere, AC flashover in air under a standard atmospheric pressure were measured. The result shows that the sample DER-311 presented the highest deep trap energy level of 1.08eV. Its DC flashover voltage (33.56kV) and AC flashover voltage (6.37kV) had the lowest values. DC flashover voltage (34.56kV) of sample 0164 and its AC flashover voltage (7.46kV) are higher than that of sample DER-311. Sample CYD-128 has a proper deep trap energy level of 0.9geV and shallow trap density of 7.91×10
²²
eV-
¹
m
^-3
and it had the highest flashover voltage. It is found that the flashover voltage decreased when the shallow trap density and the deep trap energy level increased. The deep trap captured a large number of electrons, leading to the surface charge accumulation. Meanwhile, the surface charges on the discharge path caused the electron avalanche and decrease in the flashover voltage. When the shallow trap density increased large enough, the migration of electrons on the sample surface becomes more easier, resulting in the decrease of the flashover voltage.