Insulating and aging properties of transformer oil-based TiO2 nanofluids

A transformer oil based nanofluid has been prepared by dispersing TiO₂ nanoparticles into mineral oil to improve insulating properties of the host oil. The AC, DC and lightening impulse breakdown voltage and partial discharge characteristics of fresh and aged samples were measured according to IEC standard methods. The results indicated that breakdown strength of nanofluids under all test voltages were increased by 20% as compared to that of the base oils. The partial discharge resistance of nanofluid was also improved. Furthermore, TiO₂ nanofluid exhibited good anti-aging performance under accelerated thermal aging conditions at 130°C for 6 days. The AC breakdown voltage of aged nanofluid was 1.19 times that of aged base oil. The mean value of PDIV of aged nanofluid was also enhanced by 16% compared to that of aged base oil. The possible modification mechanisms of TiO₂ nanoparticles on the insulating properties of fresh and aged transformer oil was discussed depending on the trap characteristics of the host oil and nanofluids.