Superhydrophobic coating for enhancing porcelain insulators performance under pollution conditions

Abstract

The outdoor insulators suffer external effects that adversely impact their performance and lifespan. Wettability and pollution have a negative role by increasing the likelihood of insulators surface flashover. Coatings are applied on the insulators to enhance surface hydrophobicity to cope with these external effects. Besides experimental testing, simulating the electric field distribution is a useful tool to study the insulator performance and where the surface discharges initiate. In this work, finite element method simulation is used for analyzing the electric field distribution of uncoated and coated insulators under different environmental conditions. The case of uniformly distributed wettability/pollution and perfect coating, with same thickness, on insulators surfaces is assumed. Cap and pin U40B-class porcelain 11 kV single disc and 33 kV three discs string insulators are considered. The studied coatings include two conventional hydrophobic, Al2O3 and RTV-SR, and one proposed superhydrophobic PTFE materials. The results of the maximum electric field of coated insulators are compared with respect to their equivalents of wet-polluted uncoated insulators. The proposed PTFE coating yielded the highest percentages of maximum electric field reduction compared to the other two conventional coatings. The PTFE coating for 11 kV single porcelain insulator yielded reduction for the maximum electric field by 84.754 % under rain condition and 98.848 % under fog condition while for 33 kV three discs string porcelain insulators, the percentages reached 84.288 % under rain condition and 97.315 % under fog condition. PTFE material has a good potential for insulator coating yielding less flashover likelihood and better insulator performance under pollution conditions.

Keywords

• Coatings
• Electric fields
• Flashover
• Insulator contamination
• Porcelain insulators
• Water pollution