Enhancing Dielectric Properties of Aged Mineral and Natural Ester Oils with Nanofillers

The dielectric stability of insulating oils is essential for the reliable operation of transformers. However, this stability can degrade over time due to aging and oxidation. This study investigates the enhancement of dielectric properties in two types of insulating oils: mineral oil (Shell Diala S2 ZU-I) and natural ester oil (Envirotemp FR3), both subjected to accelerated thermal aging equivalent to six years. To improve the dielectric characteristics of these oils, titanium oxide (TiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>) nanofillers are incorporated with a concentration of 0.01 g/L, which is the most effective concentration for enhancing different properties. Its effect on breakdown voltage is examined. In addition, Weibull distribution analysis is used to have breakdown voltages at lower probabilities. A comparative analysis is carried out for the percentage enhancements of both oils after adding nanofillers, considering the inherent properties of the oils, particularly moisture content and acidity.