Exploring the Dielectric Strength Enhancement of Virgin Coconut Oil as an Alternative Transformer Liquid Insulation through Nanomaterial Additives

Virgin coconut oil (VCO) is a biodegradable natural ester whose dielectric strength and thermal performance remain below those of mineral oil. This study enhanced VCO with surface-modified TiO₂, Al₂O₃ and SiO₂ nanoparticles (0.01–0.05% w/v), prepared by magnetic stirring and ultra-sonication and characterized by XRD, SEM/TEM, EDX, FTIR, UV–Vis and zeta potential analysis. AC breakdown voltage peaked at 0.03% w/v for all three Nano fluids, reaching 58 kV for TiO₂ (mineral oil: 45 kV; ester oil: 55 kV), an increase of 25–30% over pure VCO. TiO₂ also raised thermal conductivity from 0.32 to 0.38 W/m·K and retained 95% of its initial UV–Vis absorbance after 90 days. No degradation of copper, transformer steel or Kraft paper was observed. TiO₂-VCO Nano fluid is a technically viable, sustainable liquid insulation candidate for distribution transformers.