Specifying RTV Silicone Coatings for Overhead Transmission Lines by Jean-Marie George
Silicone coatings to mitigate contamination problems on insulators have been used at substations for decades and more recently on a large scale on overhead lines as well. Over time, coating line insulators has moved progressively from application in the field to a more consistent process whereby insulators are coated in an industrial facility to take advantage of relatively clean and better controlled work environments. This presentation discusses two sets of parameters of interest to ensure long-term pollution mitigation performance. For one, selecting the most appropriate coating material is key to ensure long lasting hydrophobicity as well as a resistance to erosion under severe pollution and related corona activity. The second major point is the application process itself, which must be carefully considered to avoid accelerated degradation in pollution performance of coated insulators. CIGRE is currently working to provide a Technical Brochure that will offer guidelines for coatings and their applications through the activities of WG B2 69. Major insulator manufacturers can contribute to this process based on many years of experience monitoring and supplying coated insulators. For example, a variety of coating materials have been screened at the Sediver Research Center in Saint Yorre. Moreover, continuous monitoring of coated insulators that have been installed across the globe has allowed validation of the choices made as part of the company’s development programs while also continuously challenging findings from research as well as laboratory testing.