Studying the Electrostatic Charging Tendency of some environmentally friendly fluids in a spinning disk system

The aim of this contribution is to report investigations on Electrostatic Charging Tendency (ECT) of two commercially available ester fluids. Comparisons are made with mineral oil, as this is a fluid we are familiar with. The investigations were carried out using a spinning disk system designed in our laboratory, where the disk is coated on both sides with different types of cellulose paper. It should be noticed that this system was adopted by CIGRE for international comparative measurements of both insulating liquids and solid transformer materials. The obtained results indicate that electrification current vary with fluid motion. This variation is very important at higher speeds (above 600 rpm). In the majority of the tests carried out, esters tend to generate more charges than mineral oil.