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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. [ABSTRACT FROM AUTHOR]

In this work, graphene oxide nanoparticles are dispersed in different concentrations in a soyabean extracted natural ester-based oil-blend having mineral oil as secondary oil and the resulting nanofluids are tested for various dielectric and physio-thermal properties. The results show that with the addition of nanoparticles, the breakdown voltage of nanofluids increases up to 42% as compared to pure mineral oil, 17% as compared to pure ester oil and 15% as compared to the base oil-blend. Relative permittivity and dissipation factor parameters follow a similar trend as well. Thus, the prepared nanofluids can be used as alternative insulating oils in place of the conventional mineral oil in oil-filled transformers. [ABSTRACT FROM AUTHOR]