Estimation of properties of contact materials used in vacuum interrupters based on investigations of the microdischarge phenomenon

The paper presents electroinsulating properties of the vacuum gap between chosen contact materials used in vacuum interrupters. Cu-Cr25, Cu-Cr50, W-Cu30 sinter materials were investigated. Microdischarges-typical phenomena in the pre-breakdown stage were analyzed using the arrangement for partial discharge measurements as well as the multichannel analyzer. It has been noted that there is a very strong relation between the breakdown voltage in the vacuum gap and parameters describing microdischarges. >