Abstract
Nanoparticles currently in use are challenged in further improving the dielectric strength of insulating oil. There is a great need for a new type of nanoparticle to promote the application of insulating oil-based nanofluids in electric industries. This paper experimentally investigates the effect of nanoparticle morphology on pre-breakdown and breakdown properties of insulating oil-based nanofluids. The positive impulse breakdown voltage of insulating oil can be significantly increased by up to 55.5% by the presence of TiO2 nanorods, up to 1.23 times that of TiO2 nanospheres. Pre-breakdown streamer propagation characteristics reveal that streamer discharge channels turn into a bush-like shape with much denser and shorter branches in the nanofluid with TiO2 nanorods. Moreover, the propagation velocity of streamers is dramatically decreased to 34.7% of that in the insulating oil. The greater improvement of nanorods on the breakdown property can be attributed to the lower distortion of the electric field. Thus, when compared with nanospheres, pre-breakdown streamer propagation of nanofluid is much more suppressed with the addition of nanorods, resulting in a greater breakdown voltage.
Highlights
Nanoparticles have shown a promising prospect in improving the electric performance of dielectric materials [1,2]
The insulating oil-based nanofluids exhibit great potential to address the strong demands for power equipment with large capacity, high dielectric strength and small volume in an ultra-high voltage power grid [3,4]
The dielectric strength of insulating oils is closely related to the breakdown event, which is caused by the initiation and propagation of charged gaseous channels called “streamers” at the pre-breakdown stage [5]
Summary
Nanoparticles have shown a promising prospect in improving the electric performance of dielectric materials [1,2]. The lightning impulse breakdown voltage of insulating oil can be improved by 82.6% with the addition of Fe3O4 nanoparticles [8]. This conductive nanoparticle may increase the electrical conductivity of the insulating liquid and be influenced by a magnetic field which restricts its practical application [12]. The nanoparticle morphology may shed light on the enhancement of the dielectric strength of insulating oil-based nanofluid. The effect of the TiO2 nanoparticle morphology on the dielectric strength of insulating oil-based nanofluids is investigated. The effect mechanism of nanoparticle morphology on the improvement of dielectric strength of insulating oil is proposed
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