Mitigating the Impact of Aging Byproducts in Transformer Oil Using TiO2 Nanofillers

After several operating years of power transformers, the oil is aged resulting in deterioration in oil properties. This deterioration is attributed to the effect of aging byproducts represented by acidity and moisture content. From this view point, this study aims to mitigate the impact of aging byproducts and enhance the aged oil properties with the aid of nanofillers to be reused in the transformer. To simulate actual operating period of the transformer, accelerated aging test is carried out in the laboratory. This test mainly depends on heating the oil in an oven at 120 degrees C for different number of days. Through these conditions, one day in the oven is considered to simulate one year in the field. Aged oil-based nanofluids are obtained through direct mixing and dispersion of nanoparticles with the aged oil. Titanium oxide is selected as the filled nanoparticles through this study. After the preparation, the samples of aged oil and aged oil-based nanofluids are tested. Different concentrations of nanoparticles are considered. The breakdown voltage (BDV) for the prepared nanofluids is measured and compared to that of pure aged oil. Also, dielectric constant, dielectric dissipation factor (DDF) and conductivity have been measured. Nanofluids exhibited significant enhancement regarding BDV. Also, DDF and conductivity enhanced to some extent. With the aid of acidity, moisture content and particle size measurements, the physical mechanisms behind the obtained enhancement have been discussed considering the effect of aging, the role of nanofiller and the effect of weight fraction. It is found that nanoparticles alleviate the effect of moisture through adsorbing moisture species and forming hydroxyl groups around the surface of nanoparticles.