Influence of Thickness of Solid Insulators on Creeping Discharges Propagating over Epoxy and Glass Insulators Immersed in Coconut Oil

This paper deals with the effect of thickness of the solid dielectrics on creeping discharges propagating over glass and epoxy dielectric materials immersed in coconut oil under AC voltage. A test setup based on a point plane electrode system with a HVAC transformer connected to it is used to study the discharges under a laboratory environment. Field values given by a three-dimensional simulated model are used to analyze the field distribution at the tip of the point electrode with different considered material samples and to explain experimental observations. Test results show that the thickness of the solid insulator changes the capacitance of it and electric field distribution at the tip of the point electrode on the solid material interface and the pattern propagation. The area of the discharge patterns follows an exponential variation with the applied voltage.