Conditioning mechanism of Cu-Cr electrode based on electrode surface state under impulse voltage application in vacuum

Because of high insulation performance and environmental-friendliness, vacuum is attracting considerable attention, and vacuum circuit breakers (VCBs) are expected to develop into higher voltage level. In this paper, we investigated the relationship between the surface condition and the conditioning mechanism of Cu-Cr electrode during impulse voltage application in vacuum. The experimental results showed that a layer of anode material was deposited on the cathode surface, owing to the impulse voltage applications. In addition, we investigated the content ratio of cathode and anode material on the surface after the saturation of electrode conditioning and relationship between the breakdown (BD) discharge area and deposited area during electrode conditioning process. We found that under impulse voltage application, the cathode surface characteristics approach the anode material characteristics, but that the content ratio of Cu to Cr differed between the electrodes. This means that anode material could determine the final state of the conditioning process.