Enhanced dielectric breakdown performance of anatase and rutile titania based nano-oils

TL;DR

This study demonstrates that dispersing anatase and rutile TiO2 nanoparticles in transformer oils significantly enhances dielectric breakdown strength, with heat treatment and elevated temperatures further improving performance, attributed to electron trapping mechanisms.

Contribution

The research provides novel experimental evidence that anatase and rutile titania nanoparticles improve transformer oil insulation properties, a previously unexplored area.

Findings

Nano oils show higher dielectric breakdown voltage than base oils.

Heat treatment of nano oils further enhances breakdown performance.

Performance varies between anatase and rutile due to electronic structure differences.

Abstract

Nano oils synthesized by dispersing dielectric nanostructures counter common intuition as such nano oils possess substantially higher positive dielectric breakdown voltage with reduced streamer velocities than the base oils. Nano oils comprising stable and dilute homogeneous dispersions of two forms of titanium (IV) oxide (TiO2) nanoparticles (Anatase and Rutile) have been experimentally examined and observed to exhibit highly enhanced dielectric breakdown strength compared to conventional transformer oils. Indepth survey of literature yields that research on enhancing insulation properties of mineral oils by utilizing anatase and rutile titania nanoparticles is nought. The present study involves titania dispersed in two different grades of transformer oils, both with varied levels of thermal treatment, to obtain consistent and high degrees of enhancement in the breakdown strength, as well as high degrees of increment in the survival of the oils at elevated electrical stressing compared to the base oils, as obtained via detailed twin parameter Weibull distribution analysis of the experimental observations. It is also observed that heat treatment of the nano oils further enhances the dielectric breakdown performance. Additionally, further enhancements are observed at elevated operational temperatures. Detailed studies on the performance of the nano oils in presence of variant quantities of moisture have also been put forward. The grossly different charging dynamics of dielectric nanoparticles localized within the oil has been proposed to be responsible for efficient electron trapping, leading to decrease in the positive streamer velocity and resulting in high dielectric breakdown voltage. The differences in the performance of anatase and rutile has been explained based on the electronic structure of the two and the affinity towards electron scavenging.