Effect of Fe3O4 and Al2O3 Nanoparticles on AC Breakdown Voltage and Partial Discharge Activity of Synthetic and Natural Esters

This paper aims to study the impact of conducting (Fe3O4, 20 nm) and insulating (Al2O3, 20 - 30 nm) nanoparticles (NPs) on the AC dielectric strength and partial discharges activity of synthetic ester MIDEL 7131 (SE) and natural ester FR3 (NE). First, the procedure for preparing nanofluids (NFs), including high-speed agitation and ultrasonication, is presented. Then, the AC breakdown voltage (AC BDV) and partial discharges (PD) activity are measured according to the IEC 60156 and IEC 60270. It is shown that adding Fe3O4 and Al2O3 NPs improves the AC BDV of SE and NE, Fe3O4 NPs manifest the best improvement at a concentration (optimal concentration) of 0.4 g/L with SE and NE, while the optimal concentrations for Al2O3 NFs are at 0.3 g/L with SE and 0.2 g/L with NE. In addition, the PD investigation shows that overall, the Al2O3 NPs positively impact the PD performances of SE and NE (except peak charge with NE), while Fe3O4 has a positive effect on the PD of SE and NE (except average charge with SE and peak charge with both esters).