Comparison of electrostatic charging tendency of Jarylec and mineral oil.

This paper deals with a comparative study of the electrostatic charging tendency (ECT) of a synthetic oil namely mono/dibenzyltoluene (M/DBT known as Jarylec, a product widely used for impregnating and filling power capacitors; and a mineral oil largely used in high-voltage oil-filled electrical equipment and which is Nynas Nytro Gemini X (NGx). The ECT of insulating oils generated by the charge concentration gradient at the oil-pressboard interface is investigated on a spinning disk system (CIGRE Cell) covered on its both sides with pressboard of different thicknesses versus the rotating speed of the disk and thickness of pressboard. Experimental outcomes show that the ECT of the two investigated liquids is very close at low rotating speeds of the disk that is for 200 and 400 rpm/min. While the ECT of Jarylec is higher than that of mineral oil NGx for higher velocity (600 and 700 rpm/min); the difference increases with the rotating speed of the disk and the thickness of pressboard. However, the observed difference is not so alarming and cannot be exclusive of this synthetic oil for possible use in power transformers provided that it fulfills the other required criteria. [ABSTRACT FROM AUTHOR]