This study provides comprehensive and quantitative assessments of the electrical insulation

viscosity

thermal conductivity

flash point

acidity

and stability of dielectric nanofluids. In the experiment

naphthenic mineral oil was chosen as the base fluid. MgO

Al2O3

and SiO2 were preferred as nanoparticles. In the dielectric breakdown voltage (BDV) tests performed

increased values were observed at certain concentrations for each nanofluid

with the highest value in the SiO2-based nanofluid being 83.47 kV at a concentration rate of 0.05 g/L. Adding nanoparticles to the base oil increased the viscosity of all suspensions. Except for MgO-based dielectric nanofluid

the flash points of other nanofluids increased as compared to pure oil. Total acid number (TAN) values

on the other hand

increased for SiO2- and Al2O3-based nanofluids but decreased for MgO-based nanofluids. However

all values are quite below the standard limit of 0.25 mgKOH/g. The percentage transmittance values calculated from the ultraviolet and visible light (UV–vis) spectrophotometry results differed for each nanofluid. However

they were all lower than the base oil. In general

the results indicate that the use of dielectric nanofluids in electrical systems will be beneficial

provided that the problem of long-term stabilisation is solved.