Evaluation Dielectric Properties of Transformer Oil Filled with Fe₃O₄-Coated SiO₂ Core-shell Nanoparticles

This paper investigates the impact of Fe<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf>O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf>-coated SiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> core-shell nanoparticles on enhancing the dielectric properties of transformer mineral oil. The nanoparticles were synthesized with different shell thicknesses. Nanofluids were prepared using a two-step method: the nanoparticles were calibrated to concentrations of 0.04, 0.07, and 0.1 g/L, followed by their mixing with base oil and dispersed via ultrasonication. All samples were subjected to vacuum for 24 hours to remove any moisture before testing. Each sample was tested for AC breakdown strength. Additionally, Weibull distribution analysis was performed on the AC breakdown voltage test data. The results indicate that the nanofluid samples exhibited improved properties compared to the base oil. The physical discussion explored potential reasons for improvements in AC breakdown voltage. The discussion covered the influence of electronegativity on improvements in AC breakdown voltage, van der Walls effect on the higher concentrations as well as the effects of nanoparticle concentrations.