The vacuum arc is an electric discharge in metal vapours produced by electric contacts after disconnecting of an AC inductive load. When a current of tens of amperes is disconnected, the vacuum arc has a low energy (diffuse arc) and it cannot longer sustain itself, therefore the current suddenly “chop” to zero. If the value of chopping current is high enough, this fast variation of the current along with circuit impedance can produce over-voltages. In this paper, experiments made on the different contact materials in order to reduce de value of the chopping current, are reported. The chopping current measurements were carried out with a demountable vacuum chamber in a synthetic test circuit that can produces a current pulse with an amplitude up to 100A.
Chopping Current Phenomena for Various Contact Materials
AUTHORS: Alexandru RADULIAN, Nicolae MOCIOI, Ionuț DEACONU