Determination of Breakdown Voltage Along the Surface of a Cylindrical Insulator

This article investigates the electric breakdown along the surface of a cylindrical dielectric, part of a coaxial transmission line. The particular geometry of the insulator is very common, as it is used at the input or output of most high-power, high-voltage (HV) generators. The streamer propagation criterion is used to calculate the flashover voltage. Studies of the dependence of the flashover voltage on the distance between the electrodes obtained in tests with dc voltage and also by applying voltage impulses with different durations and rise times are reported. The highest difference between the estimated values and the experimental data is less than 15%, which proves the applicability of the criterion for determining the surface breakdown voltage within the geometry under study. In particular, the results of these studies are used in the design of a compact 0.5-MV pulsed power system currently under development.