Why Are Epoxy Resin Insulators Unsuitable For Extremely Polluted Outdoor Ultra-high Voltage Lines?
The surface hydrophobicity of epoxy resin materials degrades significantly over time. Under UV radiation and temperature/humidity cycling, the molecular chains of epoxy resin materials undergo aging and degradation. Industrial dust and salt spray in heavily polluted areas form a conductive layer on the surface of epoxy resin insulator. The material itself lacks self-cleaning ability, and the rate of dirt accumulation is much faster than that of porcelain or composite insulators.
Creep distance design is limited by structural constraints. Ultra-high voltage lines require high voltage epoxy resin to have sufficient surface discharge paths, while high voltage standoff mostly adopts column or pillar structure, and the number and spacing of the umbrella skirts are difficult to meet the technical requirements of extremely high pollution levels. When contaminant particles dissolve in a humid environment, the formed electrolyte film significantly reduces the flashover voltage.
The material's tracking resistance is a weakness. Under long-term electric field conditions, leakage current generated by the contaminant layer will form carbonized channels on the surface of high voltage standoff insulators insulators. This irreversible damage will gradually expand, eventually leading to insulation breakdown. Porcelain insulators can be restored to their performance through cleaning, while high voltage epoxy insulators, once tracking occurs, must be replaced entirely.
