High performance insulator materials for high current switching applications

This investigation discusses the relative performance and degradation mechanisms of various thermoset plastic and ceramic insulators which are subjected to high current (- 300 kA) stationary surface discharges at atmospheric air and pressure. Test diagnostics include the surface voltage holdoff recovery and the eroded mass loss of the insulator. Test results are reported for several types of aluminum and magnesium silicates, several alumina and zirconia composites, aluminum and silicon nitride, and glass reinforced epoxies and melamine. The results indicate that the performance (i.e. , the lifetime and the erosion rate) of a thermoset plastic can be improved (up to a factor of 3) by a judicious choice of electrode material and/or by the U.V. stabilization of the insulator. Additionally, a new "figure of merit" is presented which predicts the relative performance of a given ceramic insulator for applications of this nature.