Effect of magnetic nanoparticles on the lightning impulse breakdown voltage of transformer oil

• Transformer oil-based nanofluid is produced by dispersion of nanoparticles within the mineral transformer oil.
• The use of magnetic nanoparticles in transformer oil at optimum volume fraction improves impulse breakdown voltage of nano-oil compared to the base oil.
• Magnetic nanoparticles by trapping and capture the free electrons, decrease the speed of expansion of steamers, and delay breakdown.
• Transformer oil containing magnetic nanoparticles can be a good alternative to transformer mineral oil under impulse conditions in appropriate volume concentrations.

In this study, the lightning impulse breakdown voltage of magnetic nanofluids based on transformer mineral oil for use in power systems was reviewed. Magnetic nanofluids are obtained from dispersion of the magnetic nanoparticles (Fe3O4Fe3O4) within transformer oil, as the base fluid. The Fe3O4Fe3O4nanoparticles, using a coprecipitation method, were synthesized, coated with a surfactant, and dispersed using an ultrasonic processor, within the uninhibited transformer mineral oil NYTRO LIBRA. The lightning impulse breakdown voltage was obtained using sphere–sphere electrodes in an experimental setup for nano-oil, in volume concentration of 0.1–0.6%. Results indicate improved lightning impulse breakdown voltage under optimal conditions. Increase in the lightning impulse breakdown voltage of the nano-oil is mainly due to the dielectric and magnetic properties of Fe3O4Fe3O4 nanoparticles, acting as free electrons snapper, and reduce the rate of free electrons production in the ionization process.