Estimating the erosion and degradation performance of ceramic and polymeric insulator materials in high current arc environments

Modeling the erosion and holdoff degradation performance of various commercially available polymeric and ceramic insulators is addressed. The insulators are tested on a surface discharge switch at approximately 300 kA in atmospheric air. Test diagnostics include the surface voltage holdoff recovery and the eroded mass loss of the insulator and electrode materials used. The ceramic materials tested include several types of aluminum and magnesium silicates, several alumina and zirconia composites, and aluminum and silicon nitride. The polymeric insulators include polyvinyl chloride, low- and high-molecular-weight polyethylene, polytetrafluoroethylene, polyamide, acetyl, polyamide-imide, and several types of glass-reinforced epoxies, melamines, and phenolics. The test results indicate that the holdoff degradation resistance and erosion rates can be qualitatively predicated by the use of merit figures which are based on the thermochemical properties of the insulator. The results also show that the holdoff degradation and erosion rates can be improved for some thermoset polymers by a suitable choice of electrode material and/or by the ultraviolet stabilization of the insulator.<
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