Dependence of TiO2 and ZnO nanoparticle concentration on electrical insulation characteristics of insulating oil

This paper presents that mineral oil and linear alkylbenzene with dispersed metal oxide nanoparticles were investigated to clarify the effect of nanoparticles on AC breakdown strength and relative permittivity characteristics. The materials of nanoparticles were selected at TiO₂ (crystal structure of anatase and rutile) and ZnO. The nanoparticle concentrations of samples were prepared varying from 0 to 0.5 vol% into mineral oil or linear alkylbenzene by ultrasonic dispersion. AC (60 Hz) breakdown test was performed in a sphere-sphere electrode (diameter φ=12.5 mm, stainless steel) with gap length 2.0 mm, and also relative permittivity was measured at 60 Hz at room temperature. The breakdown strength increased by about 5 to 15% with the addition of nanoparticles. Relative permittivity increased with the addition of nanoparticles. With some combinations of insulating oil and nanoparticle, the measured relative permittivity agreed with the calculation with the random arranged model. But there are some combinations that the measured relative permittivity and the calculated one aren´t coincident. These instructions give basic guidelines for illuminating their insulating characteristics.