Investigation of Electrode Conditioning Mechanism in Vacuum with Impulse Voltage Application

The clarification of breakdown (BD) characteristics is very important in order to improve an electrical insulation technique for high voltage vacuum circuit breakers. In this paper, the authors discuss the electrode conditioning characteristics under non-uniform electric field in vacuum. Firstly, the authors investigated conditioning characteristics using different procedures of impulse voltage application. Negative standard lightning impulse voltages were applied to a rod-to-plane electrode configuration. Experimental results revealed that conditioning characteristics such as the BD field strength and the number of voltage applications required for conditioning were much different depending on the voltage application procedures. Secondly, the authors quantified the conditioning characteristics by relating the discharge energy to the reduction of an equivalent field intensification factor on the electrode surface