AC breakdown voltage of Fe3O4 based nanodielectric fluids. Part 2: Analysis of fluids with high moisture content

Several authors have suggested that one of the main differences between conventional insulating liquids and nanodielectric fluids is the behavior of the water in the nanodielectric fluid. It has been reported that the impact of water on the dielectric strength is reduced when nanoparticles are dispersed in the fluid, and that nanodielectric fluids present higher breakdown voltage values than the base liquids under similar moisture content. The second part of this two-part paper analyzes the effect of the presence of water on the AC breakdown voltage of several nanodielectric fluids prepared from mineral oil and Fe
₃
O
₄
nanoparticles in different concentrations. The fluids were conditioned to a range of moisture contents and tested under different conditions. An exhaustive measuring campaign was carried out that was completed with a non-parametric and a parametric statistical analysis of the results. As will be shown in the paper, an increase on the solubility of nanodielectric fluids has been observed which is related with the enhancement of the breakdown voltage of these liquids. The evolution of the breakdown voltage was analyzed both for fluids with similar absolute moisture contents and also for fluids with similar relative saturation conditions.