Breakdown properties of transformer oil-based TiO2 nanofluid

A new class of colloidal dielectric fluids is formulated by mixing TiO₂ nanoparticle with transformer oil in order to enhance the dielectric performance of mineral oil. To investigate the impact of this change, both AC and lightning breakdown voltage tests were carried out according to IEC standard respectively. The results of AC tests indicate that mean value and 1% probability breakdown voltage of nanofluid achieves an increase of 1.15 and 1.43 times that of transformer oil respectively. For lightning breakdown voltage, nanofluid was 13.3KV higher than that of transformer oil. It is considered to be mainly attributed to polarization of TiO₂ nanoparticles, which may act as electron traps in the process of electron transfer in electrically stressed nanofluids. Furthermore, the high specific surface area of nanoparticles also increases the probability of electron scattering in the nanofluids, which reduces the impact energy of electrons and prevents the oil from ionizing. All these results confirmed that transformer oil modified with TiO₂ nanoparticles hold a promise to improve its insulating properties.