Fractal characteristics of creeping discharges propagating on nano-epoxy composite insulators immersed in coconut oil

Abstract

A solid/liquid dielectric interface is considered to be one of the weakest points in a composite insulation system, as it facilitates creeping discharges on the interface when the electric field strength exceeds a threshold value. This paper presents a study on the use of nano epoxy composite to minimize the effect of damage which occurs due to creeping discharge activity, when it was immersed in coconut oil. A point-plane electrode arrangement-based test apparatus, energized by a high voltage supply, was used for analysing the propagation of creeping discharges over solid/liquid interfaces using visual observation. An algorithm was used to determine the fractal dimension of creeping discharges propagating over various solid/liquid insulating interfaces. In particular, it focused on the variation in creeping discharge patterns with the use of pure epoxy and nano-composite epoxy samples. The results showed that the use of nanofillers can increase the dielectric breakdown strength of epoxy by 7%. The results also showed nanofillers of 20 nm with 1% concentration do not affect the tortuosity of the creeping discharge pattern on the solid material immersed in coconut oil. However, it can increase the possibility of flashover due to creeping discharge propagation over epoxy insulating material immersed in coconut oil by around 12%.