Comparison of Nano-Oils with Different Initial Breakdown Voltages

This study presents the results of investigating the dielectric strength of nanofluids based on transformer oil with varying initial values of breakdown voltage. The nanofluids were prepared by dispersing TiO2 nanoparticles in samples of utilized transformer oil with low initial breakdown voltage and samples of fresh dehydrated and filtered oil with high breakdown voltage. A comparative analysis of the experimental data revealed that the influence of nanoparticles on the dielectric strength of the fluid decreases as the initial value of breakdown voltage increases. A hypothesis to explain the observed effect is proposed based on the mechanism of interaction between nanoparticles and ions present in the fluid. Nanoparticles, by adsorbing free ions in liquid, reduce the probability of generating the electron capable of initiating breakdown, thereby increasing the breakdown voltage of the nanofluid. As the degree of oil purification increases, the content of impurities generating free ions decreases, which, in turn, weakens the effect of nanoparticles on the breakdown voltage of the system. Based on this hypothesis, it is noted that nanoparticles are inefficient in increasing the breakdown voltage of fresh oil but show potential for purifying utilized oil. While nanoparticles do not significantly degrade breakdown voltage, they also may be useful for enhancing other properties, such as thermal conductivity. Further research is needed to confirm the hypothesis and understand the underlying mechanisms.