Revealing the Contaminant Characteristics and Accumulation Variations of Composite Insulators in the Direct Current Field

The contaminant distribution on the composite insulator has acted a prominent impact on the pollution flashover voltage, and the accumulated pollution caused the insulator to discharge, resulting in a depressurization operation and threatening the safety of power system. In this study, by selecting a series of the composite insulators on the arresters in the direct current (DC) field area, the pollution levels of the insulators at different positions and the different surfaces of the same group of the insulators were regularly collected and analyzed. Combined with the content variation and component characteristics of atmospheric particle pollutants, the contaminant degree of the composite insulators was correlated with the characteristics of atmospheric particle pollutants, and the contaminant accumulation characteristics of composite insulators in DC field environments were sufficiently clarified. The results revealed that the equivalent salt density and gray density of the lower surface of the insulator were larger than those of the upper surface under normal conditions. The effect of atmospheric precipitation on the insulator dirt was relatively weak, and the composition and content of the dirt between the upper and lower surfaces of the same insulator as well as insulators with different columns were essentially the same. A negative correlation was existed between the particle size of the insulator dirt and the equivalent salt density and equivalent gray density of the insulator. This work illustrates the contaminant accumulation characteristics of composite insulators in the DC field, and provides a scientific basis for ensuring the safe operation of power system.