Types of reignition following high-frequency current zero in vacuum interrupters with two types of contact material

In a special medium-voltage circuit, the mechanism of reignition after high-frequency vacuum arc current zero is investigated experimentally for two types of contact material, i.e., AgWC (low-surge) and CuCr (conventional). For this circuit, the principle of synthetic testing is adopted. Based on a large number of observations, four different types of reignitions can be observed in interrupters with each type of contact material. The types of reignition are classified according to the duration of the currentless pause (5 ns-50 mu s) between interruption and reignition. Analysis of the experiments shows that the breakdown voltage of the gap following high-frequency arcing can both increase and decrease, depending on the high-frequency arc activity. In a tentative analysis, the value of fi/sup 2/dt of prior HF arcing may be considered as a quantitative measure of the influence of the arc on breakdown voltage.<>