Influence of charging period on electrical conduction in mineral oil associated with EHD motions

The results of investigation on the relationship of electrical conduction and EHD motion induced in mineral oil by change of electrode polarity are presented. The experiments are carried out under the following condition: DC voltages of constant amplitude are periodically applied in order of positive, negative and positive. The first and the third periods are fixed and three different periods are used in the second period. The phenomena to be observed are the time dependence of current and the schlieren images of EHD motion taking place within mineral oil. Experimental results are explained by the residual conductivity of the oil, EHD motion moving between electrodes and charge carrier accumulating in the vicinity of electrode surfaces.