Insulators with Contaminated Surfaces, Part I: Field Conditions and Their Laboratory Simulation

Physical and chemical analyses done on suspension insulator surface contaminants and fog water collected in the field showed significant water-soluble material in both. At one location the soluble material in both the fog water and surface deposit was gypsum, whereas the insoluble component of the surface deposit was mostly alpha quartz. A laboratory simulation system was used to produce flashover on a single-suspension insulator with contamination conditions and voltage typical of field experience. To achieve this it was required that the laboratory simulation of the fog include a horizontal wind and that of the surface deposit include a substance (bentonite was used here) that would allow water to permeate (spread out) on the surface. The simulation produced the major phenomena believed to occur when suspension insulators suffer contamination flashover.