Antiaging Performance of Mixed Oil Insulation Developed Using Modified Neem Oil and Mineral Oil for Distribution Transformers

This study investigates the development of mixed oil insulation (MOI) using modified neem oil (MNO) and mineral oil (MO). The study reveals that the oil composition significantly influences dielectric breakdown voltage (BDV) within oil mixtures. Increasing MO at the expense of MNO leads to a significant enhancement in BDV, highlighting the superior insulating properties of MO. The optimal blend, Scheme D, consists of 80% MO and 20% MNO and exhibits the highest BDV at 73.44 kV. MNO’s unique characteristics, such as a strong positive electrostatic potential and high electron affinity, contribute to its ability to achieve elevated resistivity. It also exhibits a dissipation factor like MO, orienting dipoles within MOI toward MO. MNO stabilizes reactive OH sites within cellulose, reducing moisture solubility, and improving oxidation stability of MOI. MOI exhibits viscoelastic behavior, while neem oil (NO) presents complex resistance behavior under stress due to unequal storage and loss modules. Aging has a minor impact on the percentage relative crystallinity of solid insulation, with MOI experiencing only a 2.298% difference compared to virgin pressboard. These findings offer insights into the role of oil composition in insulation performance and aging processes, potentially enhancing the maintenance and longevity of electrical equipment.