Electrostatic charging tendency of natural transformer ester - impact of the surface state of solid on electrification currents

This paper deals with the static electrification phenomena of natural ester for the use in power transformers. The spinning disk method was used in the study. The rate of oil flow on the surface of solid material is simulated by the rotational speed of the disk. The dependency of the electrification current of the natural ester versus the flow velocity of the oil and the type of roughness of the surface of the solid material has been investigated; the different roughnesses are obtained by making different scratches' patterns on the rotating disc. As with mineral oils, the static electrification current of natural ester oil increases with the flow rate and/or the surface roughness.