Influence of Electrode Coatings on Space Charge Distributions in Transformer Oil

Abstract

WHEN a static electric field is applied to a liquid insulant contained between two electrodes, an accumulation of charge carriers takes place at the electrode-liquid boundaries. The transient disturbances which occur during conduction current measurements, following the sudden application, removal or alteration of the applied voltage, are indicative of such space charge formation. It has recently been shown also that the build-up of space charges by static prestressing can significantly affect the pulse breakdown strength of a liquid dielectric¹. The presence of space charges in an insulating gap produces a non-uniform distribution of voltage within that gap; a knowledge of this distribution and how it is affected by conditions at the electrode surfaces should contribute to a better understanding of the conduction and breakdown mechanisms in liquid dielectrics.