Dimensioning Silicone Coated Glass Insulators for Polluted Environments
by Hector de Santos

Application of RTV silicone coatings to glass insulators has grown as utilities look to keep the properties of toughened glass such as mechanical reliability and ease of inspection while enhancing pollution performance. But the hydrophobicity transfer properties of coatings is a complex topic and the most common practice is to dimension with the same USCD as uncoated glass. This presentation outlines a probabilistic approach to dimension coated glass insulators in polluted environments based on field leakage current monitoring, quick-flashover laboratory tests and the relative performance of coated and uncoated glass. It will also explain how this can help evaluate flashover risk and quantify the benefit of hydrophobicity.