Tests on Salt-Contaminated Insulators in Artificial and Natural Wet Conditions

The results of experimental work on transmission line insulation contamination being performed at General Electric Project UHV are described. A stable steam fog generation system has been developed for use in simulating natural humidity conditions, and its validity has been proved in natural humidity tests conducted in the project´s outdoor test area. It is shown that different types of binders, when combined with salt, produce different critical flashover voltages for the same conductivities of binder and salt in solution. Flashover results are presented for a wide range of operating voltages, for contamination and under concentrations and for insulator lengths.