Preparation and breakdown properties of mineral oil based alumina nanofluids

Transformer oil-based nanofluids were prepared by suspending non-conductive Al2O3 nanoparticles to enhance the insulating properties of transformer oil. Breakdown voltages under positive and negative lightening impulse voltages were measured for all the prepared samples according to IEC standards. The results indicated that the inclusion of Al2O3 nanoparticles to the base oil can modify the breakdown strength of the base oil. The results showed that addition of alumina nanoparticles improve the mean lightening impulse breakdown voltages of nanofluids and were 1.09 times as compared to base transformer oil but not the negative lightening impulse breakdown strength. A possible mechanism of insulative nanoparticles was also used to explain the difference among nanofluids and base oil.