An Investigation on Stability, Electrical and Thermal Characteristics of Transformer Insulting Oil Nanofluids

Transformer insulating oil nanofluid is made to improve dielectric and thermal properties of the oil byemploying nanoparticles with proper properties. In the current work, nanofluids based on transformermineral oil were prepared by three procedures using diamond nanoparticles with high thermalconductivity, as well as high dielectric properties. It was tried to consider the impacts of surfactants’presence and ball milling process in the preparation procedures. The effects of a variety of stabilizers(the amount and type) and also the ultrasonic time on diamond nanoparticles’ stability in the oil wereinvestigated and optimized experimentally. Using the optimized nanofluids, thermal conductivity andviscosity of the oil nanofluids were compared and discussed. In addition, the consistency of the thermalconductivity results with Maxwell and also Hamilton and Crosser theoretical models was examined. Itwas revealed that, the nanofluid preparation procedure, temperature and nanoparticles’ concentrationhave effects on thermal conductivity of the transformer oil nanofluid, while the presence of thenanoparticles has a slight impact on the viscosity of the fluid. Also the effect of diamond nanoparticles’presence on the electrical properties of transformer oil was studied. Based on the experimental results,adding diamond nanoparticles could lead to an increase in the transformer oil breakdown voltage,while it has nearly no effect on dielectric loss in low concentrations.