Mitigation of Electrical Stresses on Outdoor Polymeric Insulator Using Nano-Zinc Oxide Coating: Simulation and Experimental Validation

The high electric field stress on the high voltage (HV) end of polymeric outdoor insulator degrades its insulation properties. An alternate approach is needed to mitigate the electrical stresses on its surface since replacing such affected insulators is expensive. This paper proposes to mitigate the electrical stresses on polymer insulators by coating their surface with a thin layer of zinc oxide (ZnO) nanoparticles. The effectiveness of nano-ZnO coating on the 11 kV polymer insulator is analyzed using simulation and experimental studies. For simulation, the 11 kV polymeric insulator model is constructed in COMSOL Multiphysics, and the electric field intensities at its crucial areas are measured. For experimental validation, nano-ZnO coating is applied on the surface of polymer insulators using the nozzle spraying and drying processes. The effectiveness of nano-ZnO coating is analyzed through the leakage currents and breakdown strength measurements. With the application of ZnO nanocoating, the average leakage current is minimized by 4.12%, and the breakdown strength is improved by 8.9%. The simulation and experimental investigations show that the nano-ZnO coating on the insulator surface can significantly reduce the electrical stress at the triple junction and improve its breakdown strength.