Ceramic insulators coated with titanium dioxide films: Properties and self-cleaning performance

• Ceramic insulators were coated with hydrophilic titanium dioxide.
• Coatings were nanometric and composed only by anatase phase.
• Coating does not affect the electrical properties of insulators.
• Self-cleaning effect was evident in the site with organic soiling.
• Self-cleaning effect was not evident in the site with cement particulate soiling.

Ceramic insulators used in power transmission lines were coated with titanium dioxide films with the aim of reducing atmospheric soiling accumulation over its surface. Properties as adhesion, thickness, roughness and phase composition of films were evaluated. Contac angle was also measured. Dry-flashover and leakage current electrical tests were carried out in coated and un-coated insulators to evaluate the influence of titanium dioxide film in electrical properties. The in-service behavior of coated and un-coated insulators installed in power transmission towers were evaluated in two sites with different soiling source. Surface characterization of insulators before and after field exposition was performed by Micro-Raman Spectroscopy. The coatings exhibited self-cleaning properties and electrical properties of insulators were not affected. After 5 months of exposure in the energized power line, a decrease in the surface soiling was observed in Balsillas (organic soiling). Nevertheless, in Calera (inorganic soiling) self-cleaning effect was not observed.