▎ 摘　　要

Graphene oxide is one of the latest in- trend nanomaterials in the field of nanotechnology which is being studied in various engineering fields. Yet, its effects on the transformer solid insulation remain unexplored. In this research, the transformer pressboard and Kraft paper are impregnated with nonconductive graphene oxide dispersed vegetable ester-based insulating nanofluid and the behavior of impregnated solid insulation is studied under different thermal aging conditions. The results show that after 60 days of aging, the crystallinity of nanofluid impregnated pressboard is 24.9% more than that of the base oil-blend (OB) impregnated pressboard whereas the crystallinity of nanofluid impregnated Kraft paper is 3.8% more than that of the base OB impregnated Kraft paper. In terms of dielectric properties, the ac breakdown voltage (BDV) of nanofluid impregnated pressboard and Kraft paper is 29.5% and 41% more than the OB impregnated pressboard and Kraft paper, respectively. The dielectric stress is more uniform in nanofluid-based insulation system as compared to the base OB-based insulation system leading to a better design clearance. Therefore, graphene oxide dispersed ester oil (EO)-based nanofluid impregnated solid insulation has better mechanical and dielectric properties, thus leading to an increased lifespan of the transformer.