Experimental investigation of al₂o₃ nanoparticle-enhanced natural ester oil as a biodegradable liquid dielectric for transformers

Mineral oil has been widely used as a liquid dielectric in transformers, serving as both an insulating and heat dissipation medium. However, its poor biodegradability, low fire resistance, and environmental concerns limit its long-term viability. To address these challenges, this study investigates natural ester oil (NEO) as an eco-friendly, biodegradable alternative, offering enhanced insulation and thermal performance. The research focuses on evaluating NEO's key characteristics, aging behavior, and failure probability, with and without Al₂O₃ nanoparticle enhancement. A 60-day accelerated thermal aging test at 100 °C was conducted to assess the degradation resistance of NEO compared to mineral oil. The effects of partial discharge, creepage failure, and electrical stress were analyzed, and a Weibull statistical model was applied to predict insulation failure probabilities. Experimental results confirm that NEO demonstrates superior breakdown strength, lower degradation rate, and higher fire safety. The addition of Al₂O₃ nanoparticles significantly improves dielectric properties, reduces viscosity, and enhances the thermal stability of NEO, making it more suitable for transformer applications. This research establishes nano-enhanced NEO as a superior alternative to mineral oil, offering higher insulation performance, improved thermal durability, and enhanced fire safety. The findings advocate for its adoption as a sustainable, high-performance dielectric for modern transformers, promoting both reliability and environmental compliance.