Ac minimum flashover voltages and wave number of occurrence of local discharges prior to flashover on polluted insulators

摘要

The relation between ac minimum FO voltages V? and voltage build-up rates B has been investigated with respect to the wave number of occurrence N of local discharges prior to FO. The results show that V? occurs when N equals N? (5～11); i.e. N? increase from 5 to 11 as the pollution levels increase, and is independent of lengths for a given width. Additionally, similar informations are obtained for the cyclic number of ac minimum reignition voltages in contaminated conditions. It is also shown that the relation between the minimum FO voltages and the wave number of occurrence of local discharges is able to explain qualitatively with respect to the accumulation of Na atoms in discharge space at FO.