Influence of nonsoluble contaminants on the flashover voltages of artificially contaminated insulators

This paper describes the results of investigation into the influence of a kind of nonsoluble contaminant (Tonoko or Kaolin) on flashover voltages of artificially contaminated insulators. The deposit density of Kaolin on the insulator surface is less than that of Tonoko when contaminated with the suspension containing the same amount of Tonoko or Kaolin. However, a discernible difference is observed in contamination flashover voltage between these two nonsoluble contaminants, not only under DC but also under AC when nonsoluble contaminant deposit densities (NSDD) are adjusted to the same degree. The difference in the performance is considered attributable to the less uniform contaminant layer produced by Tonoko suspension compared with Kaolin. When a dispersion agent was added to Tonoko suspension, which does not give any influence on the conductivity of the suspension, the layer uniformity and flashover voltage (FOV) for this modified Tonoko suspension became almost equal to those for Kaolin