The Impact of Contaminant Particles on the AC Breakdown Voltage of Transformer Oil Mixed with TiO₂ Nanoparticles

Contaminants have huge influences on withstand voltage of transformer oil. Contaminant particles caused by electrical stress and internal mechanisms of transformers affect oil quality, which directly affects insulating ability afterwards. So far, there have been only a few research studies on impacts of contaminants while nanoparticles have recently gained more interest among people in terms of mixing those particles with of transformer oil to increase much better efficiency of transformer insulators. This research mainly focused on 20 μm cellulose-based contaminants in transformer oil and the one mixed with TiO2 nanoparticles at 0.01% concentration of transformer oil volume. Then, they were compared with 4 samples of regular oil. Next, electrical properties were studied by testing the AC breakdown voltage in order to assess quality of liquid insulators in accordance with ASTM D877. The testing results indicated that in case of no contamination, transformer oil mixed with TiO2 nanoparticles contained significantly better withstand voltage than regular transformer oil. This implied higher insulation efficiency nanoparticles were added into transformer oil. Furthermore, in case of cellulose-based contaminants, the testing results also revealed transformer oil mixed with TiO2 nanoparticles contained better withstand voltage than regular transformer oil with cellulose-based contaminants. This implied that nanoparticles could reduce the impact of contamination on insulation of transformer oil.