Partial discharge analysis to monitor the condition of oils

Abstract

Partial discharges in oils are influenced by the actual dielectric properties of the liquid and especially degradation products may influence the phenomena. As a consequence of partial discharge processes, there may be bond scission and molecules of the dielectric may be degraded and/or split into molecules of shorter lengths that form a gaseous phase. This second phase can be generated in solids as well as in liquids. In solids the pressure in this gas phase will increase in accordance to the concentration of gas molecules. In liquids an increase of the concentration of molecules will lead to an extension of the gas volume until the pressure within the void corresponds to the external gas pressure. Consequently, in accordance to Faschen's law there will be gas discharges in this gas phase.