Voltage Effects of Low and HIgh Current Arcing on Vacuum Interrupter Contacts

Experiments are described which indicate the effect upon pulse breakdown voltage of high current arcing between copper electrodes in vacuum. Our results indicate a moderate degradation of breakdown voltage occurs when the electrode surfaces have been arced at currents exceeding 5000 A peak. This change is probably associated with the melting and erosion of the contacts by the arc. The degradation at the arc anode and the arc cathode appear to be about equal for all currents up to 45 kA peak.