| Abstract: | The contributions of the electrohydrodynamic (EHD) motion to the dc electric conduction in insulating oils are presented. The effects of solid/liquid interfaces on the EHD motion have been studied with a mineral oil-polypropylene mixed dielectric and a mineral oil single dielectric. The time dependence of current, schlieren images of EHD motion induced in the oil layer and response signals of density change in the vicinity of the electrode/oil interfaces after application of step voltage are observed. The results are as follows: (1) the EHD motion occurs at the positive electrode/oil interfaces when a voltage above critical voltage is applied; (2) a time delay exists between the application of step voltage and the onset of EHD motion. The time is inversely proportional to the applied voltage; (3) the EHD motion increases current and produces a peak phenomena in the current waveform; and (4) the time difference between peak current time and the delay time is inversely proportional to applied voltage. |
