Distribution of high-voltage and high frequency impulse breakdown sparks in conditioned contact surface

The objective of this paper is to experimentally investigate the distribution of high-voltage and high-frequency (HVHF) impulse breakdown sparks in conditioned contact surface. A 10 kV commercial vacuum interrupter (VI) is used, which is machined with a glass envelope and an observing window on the main shield. The distribution of the breakdown position in contact surface follows the Gaussian probability density. The breakdown sparks gradually concentrate in the center of contact surface, with a continue applying of the impulse voltage after a sufficient conditioning process. The frequency of the impulse voltage has slight impact on the distribution of breakdown sparks. However, a higher amplitude of the impulse voltage results in a more concentrative distribution of the breakdown sparks. The larger of the contact gap, the more concentrative of the breakdown sparks in contact surface. The mean value μ of the breakdown position in contact surface shifts to the lower h value of the contact edge gap. The higher of the non-parallelism of the facing contact surface, the more concentrative of the breakdown sparks.