High-Density Conducting Mist Test for Insulator Evaluation

A technique is described for rapid reproducible testing of contaminated outdoor insulators. The test parameters can be controlled to permit comparison of insulators under different conditions. Erosion and tracking resistance of polymeric insulators in functional designs can be studied by controlling the test parameters. A conductive mist is sprayed on the insulator while oscilloscope traces of the current wave are measured and examined. Test variables that can be controlled include voltage, spray volume, conductivity of the contaminant, and time. The insulator test features rapidity and reproducibility allowing the user to quickly compare new designs with conventional geometries. It is possible to vary the test parameters so as to represent a variety of environmental conditions that may exist in the field. The test method makes no attempt to simulate a specific environmental condition. Illustrative data are included for conventional porcelain-suspension insulators that are compared to results for a DuPont Teflon polytetrafluoroethylene rod and a quartz rod.