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%.

This paper presents a study on the use of different solid insulators and oil volumes inside oil-filled high voltage equipment to minimize the effect of damage that occurs due to creeping discharge activity. A point-plane electrode arrangement-based test apparatus, energized by a high voltage supply, is used for analyzing the propagation of creeping discharges over solid/coconut oil interfaces using visual observation. In particular, the effect of oil level and the effect of the kind of solid insulators, such as glass and acrylic, are analyzed incorporating the discharge length associated with pattern propagation. The result shows that the glass and acrylic insulators do not have a significant effect on the discharge length when they are immersed in coconut oil even if the breakdown voltage of acrylic is higher than that of glass by 28%. The results also show that when the oil level inside the test cell increases, the amount of ramification and propagation of streamers decreases, reducing the discharge length. The fall of the coconut oil level under electric field-generated electrodynamics motion inside the oil-filled high voltage equipment can create an opposition force on the discharge propagation. However, such a phenomenon can initiate discharge propagation at low voltage values.