Thermal aging properties of transformer oil-based TiO2 nanofluids

The insulation properties of aged transformer oil-based TiO₂ nanofluids were investigated in this paper. Firstly, both pure oil and TiO₂ nanofluids were accelerated thermal aged at 130 °C for 36 days. During the accelerated thermal aging process AC (50 Hz) breakdown voltage, lightening impulse breakdown voltage, and partial discharge inception voltage (PDIV) of both samples were measured periodically. The results shows that TiO₂ nanofluids possessed better insulation properties than pure oil even though insulation properties of both aged pure oil and nanofluids were decreased during the aging process. After aging for 36 days, the PDIV and AC breakdown strength of nanofluids was 1.1 and 1.4 times as that of pure oil respectively. Possible mechanisms of the phenomenon above were also discussed. In conclusion, the transformer oil-based TiO₂ nanofluids process a better anti-aging property than that of pure oil,but the stability of nanofluids need be further improved to bear the complex and extreme condition inside high-voltage level and heavy load transformers in service.