Development and characterization of mineral oil–neem oil ester mixed insulation for transformer applications

This study aims to establish an optimal ratio of Mineral Oil (MO) and Neem Oil After Esterification (NOAE)to develop a Mixed Insulation (MXI) that effectively replaces the MO for oil-filled transformers and other oil-filled electrical equipments. The effective use of two-stage esterification technique using Neem Oil (NO) as a base oil and concentrated sulfuric acid (H₂SO₄) and potassium hydroxide (KOH) as acid and base catalysts had been adopted to transform NO into NOAE. Further, the FAME formation is confirmed using the ¹H-NMR. By lowering the impact of MO in oil-cooled transformers, the proposed MXI’s dielectric properties are critically analysed using its AC breakdown voltage (BDV) in sphere-sphere and point-plane, kinematic viscosity (KVIS), corona inception voltage (CIV) and interfacial tension (IFT), and other dielectric properties. The MXI proportions are subject to accelerated thermal ageing in the presence of a pressboard and copper plate. The changes in their dielectric properties are reported along with the information about the material characteristics using an FTIR. Further, the validation of the samples is verified using Weibull distribution and Kurtosis and Skewness values. The current study on MXI is given credence by the discovery that sample X30, or the optimal MO: NOAE blending ratio, is 70:30. The X30’s dielectric properties showed a notable level of durability after ageing, which helped to explain its high resistance and low conductivity.