Electrostatic and dielectric performance of natural oils enhanced with nanoparticles and antioxidants

Power transformers are increasingly relying on insulating fluids, and researchers are exploring biologically based options to replace mineral oil, meeting the growing demand for these fluids. Using antioxidants and nanoparticles, this study investigates the efficacy of four natural oils Neem, Sunflower, Rice Bran, and Mahua as potential dielectric fluids for use in transformers. To enhance their dielectric characteristics, thermal stability, and oxidation resistance, the oils underwent chemical degradation and oxidation-related changes in the insulating oil with calibrated amounts of metallic oxide nanoparticles and natural antioxidants. Thermogravimetric evaluation (TGA) for thermal stability profiling, Finite Element Analysis (FEA) to simulate thermal performance under operational conditions, and Dissolved Gas Analysis (DGA) for degradation assessment were all part of the comprehensive assessment that utilized advanced diagnostic techniques. The findings reveal that the incorporation of antioxidants and nanoparticles has a tremendous effect on enhancing the dielectric strength, thermal stability and suppression of fault gas properties of the investigated oils. The result of the modified natural ester oils had significant improvement in the dielectric and thermal performance. The best overall characteristics were observed for the formulations that contained 0.02 wt % of the metal oxide nanoparticles as well as the synthetic antioxidant 2, 6-di-tert-butyl-p-cresol (BHT). They are subjected to various tests to increase their maximum breakdown voltage to 58 kV, flash point to 270°C, and to reduce the acidity to 0.02 mg KOH/g and the hotspot temperature to 105°C. The results obtained in this work confirm that the synergistic mixture of antioxidants and nanoparticles could be used in an environmentally-friendly insulating fluid in transformers.