The results of an experimental investigation into the influence ofimpurities on liquid velocity and charge transfer produced byelectrohydrodynamic (EHD) motion in insulating oils are reported. Testsamples were subjected to a voltage step applied to plane parallelelectrodes. The concentration of naturally occurring particles wasmodified by filtering the oils to varying degrees. Artificialcontamination was added in the form of conducting particles and also anionic additive. Experiments involving various levels of filtrationindicate that particles of size <1.2 μm have greater influence onthe development of EHD instability than larger particles. While bothconducting particles and an ionic additive increase liquid motion, theinduced motion has a greater influence on the conduction current if thecharge carriers causing liquid motion are ionic in nature
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