S Jafar Madar - Department of mechanical engineering, University of Urmia, Urmia, Iran
J Ghasemi - Department of mechanical engineering, University of Zanjan, Zanjan, Iran
M Nazari - Department of mechanical engineering, University of Urmia, Urmia, Iran

In this study, the AC dielectric breakdown voltage and thermal efficiency of magnetic nanofluids based onmineral oil for use in power systems is reviewed. Magnetic nanofluids are obtained from dispersion of the magneticnanoparticles ]U± within the mineral insulating oil NYTRO LIBRA as the base fluid. Nano oil samples with volumeconcentration of 0.1% were studied under dielectric and thermal tests. The AC breakdown voltage was measuredaccording to IEC 60156 standard using the spherical electrodes and the thermal analyze was carried out in anexperimental setup for studying the heat transfer coefficient. Results indicate improved dielectric breakdown voltageand heat transfer coefficient. Increase the breakdown voltage of the transformer oil-based Nano oil is mainly due todielectric and magnetic properties of Fe3O4 nanoparticles that act as free electrons snapper, and reduce the rate of freeelectrons in the ionization process. Mineral oil based magnetic nanofluids are good alternative for use as insulating andcooling material in power systems.

Magnetic nanoparticles; Dielectric breakdown voltage; Heat transfer coefficient; Mineral oil