Analysis of cumulative number and polarity of creeping discharges initiated at solid/liquid interfaces subjected to AC voltage

This paper deals with the influence of voltage and the nature of solid sample on the cumulative number of creeping discharge events and their locations on one voltage cycle. It´s shown that the total number of discharges recorded during 500 cycles of voltage increases significantly with the voltage. The threshold voltage U_i of discharges depends on the kind of material; and the average number of discharges (n_moy) increases with the dielectric constant, ¿_r, of insulator. For instance, n_moy is the highest for Bakelite (¿_r = 4.8) and the lowest for Polycarbonate (¿_r = 2.9). On the other hand, n_moy of negative discharges seems to be slightly higher than that of positive ones whatever the solid sample and the amplitude of voltage.