Surface Flashover of Dielectric Materials Used in Pulsed Power Research

Summary form only given. Insulator technology has evolved steadily for power transmission and distribution applications over the past 30 years, allowing for reliable design rules and testing procedures to be developed. These rules and procedures have been validated for applications under DC. and power frequency conditions (50/60 Hz and 400 Hz in aircraft applications), allowing for the appropriate choice of insulation to be made. Selection procedures for insulators to be used under high voltage/high-current pulsed power conditions are however, not well defined, and insulator failure has occurred in large pulsed power facilities when the materials were selected based on experience with low frequency systems. This work is being undertaken to investigate dielectric material behavior under high dE/dt conditions. A 10-stage Marx generator, capable of producing output voltages in the region of 750 kV, is used in conjunction with an adaptable test assembly to determine the flashover properties of different materials. Results on the dielectric behavior and ageing of solid insulators are reported, along with hold-off voltage performance and degradation due to surface discharges.