Impulse breakdown characteristic of mineral oil based nanofluid

Mineral-oil based nanofluids are proved that the addition of suitable nanoparticles can increases the AC breakdown voltage and Partial Discharge Inception Voltage (PDIV) compared with those of the unmodified mineral oil. In this paper, a standard impulse breakdown voltage of the mineral oil and the mineral-oil based nanofluids is investigated. Three types of nanoparticle, i.e., Zinc oxide (ZnO), Barium titanate (BaTiO₃) and Titanium dioxide (TiO₂) with the mean diameter less than 100 nm are used to prepare the nanofluid samples. The first group of the nanofluid sample consists of the mineral oil mixed with the 0.01% volume fraction of nanoparticle. Another group of nanofluid sample comprises the mineral oil mixed with the 0.03% volume fraction of nanoparticle. Besides, the surfactant sorbitan monooleate (Span 80) is added in order to modify the surface of the nanoparticles. The needle-sphere electrode configuration with the gap spacing of 15 mm is employed for impulse breakdown voltage investigation of the dielectric liquids. The test circuit is set up in accordance with IEC 60897, and the test experiment is performed at the room temperature. The results show that the addition of ZnO and TiO₂ nanoparticle leads to the change in the impulse breakdown characteristics of the mineral oil in both positive and negative impulse polarities. However, no significant change in the impulse breakdown characteristics is observed when adding BaTiO₃ to the oil.

I. Introduction

Mineral oil has been used since the first commercial oil-filled transformer was introduced, while dielectric fluids such as synthetic ester and natural ester are seen as a modern alternative. However, mineral-oil still plays an important role in the insulation of high voltage apparatus, especially power transformers and instrument transformers [1]–[2]. Focusing on the advancement of nanotechnologies and their application, nanoparticles hold promise that they can be used with mineral-oils to enhance their properties, which may lead to more compact designs and the reduction of manufacturing costs [3]–[4].