Mechanism of contaminant accumulation and flashover of insulator in heavily polluted coastal area

This paper attempts to address the issue of serious insulator string partial discharge activity and flashover resulted from severe contaminant accumulation of insulators on a 220 kV transmission line in coastal areas during winter when the rain is sparse and heavy contamination accumulates over time. Samples of silicone composite insulators, glass insulator with RTV coating and ceramic station insulator are tested in a series of experiments including ESDD and NSDD measurement, hydrophobicity classification, the measurement of static contact angle, TGA and FTIR analysis. Taking the terrain of the transmission line into consideration, it probes into the mechanism of contaminant accumulation and flashover of insulators in heavily polluted coastal areas. A conclusion has been made that the high salt deposit on the surface of the insulators resulted from peculiar terrain and the dampening effect on hydrophobicity transfer characteristic of silicone composite material lower the flashover voltage of silicone composite insulators and ceramic or glass insulators with RTV coatings leading to severe partial discharge activity and flashovers during dry winter. Finally it sums up the lessons in regards to this problem and proposes appropriate solutions.