Particle Contamination of High Voltage DC Insulators below Corona Threshold

A scaled dc transmission line insulator string has been implemented in sub-corona experiments to identify parameters important to the particle contamination process. Simple trajectory analysis of particle motion yields good agreement between predicted contamination features and observed phenomena, and suggests a model for the quantitative prediction of contamination of dc insulators on actual transmission lines in the field. The deposition rate on surfaces that become contaminated is experimentally shown to be given by the average product of particle mobility, particle mass density in the ambient air, and normal electric field on the insulator surface.