Lightning impulse dielectric properties of nano-modified insulating fluids

Naphthenic mineral oils are widely used as electrical insulation in power equipment. However, stringent environmental protection regulations encourage operators and manufacturers of high-voltage equipment to use more environmentally friendly, bio-degradable insulating liquids with low toxicity. In response to this demand, Natural, organic oils and synthetic esters are considered as potential substitutes for traditional naphthenic mineral oils due to their higher flash temperature and lower toxicity. However, the dielectric properties of ester fluids are not yet fully known. Beside that, more and more published results indicate that adding magnetite nanoparticles into insulating fluids would improve their dielectric performance. But under the strong electrical field, these polar particles would be polarized and agglomerated which would bring the particle pollution issue and lead the insulating failure. In this paper, a type of neutral nanoparticles, titanium dioxide (TiO2) would selected to adding into different insulating fluids to prepare the nano-modified fluids and investigate their dielectric performance. The results of an experimental investigation into impulse breakdown voltages and pre-breakdown times of mineral oil, synthetic and food grade natural ester fluids with titanium dioxide (TiO2) nanoparticles were presented.1The experimental results show that the dielectric properties of insulation fluids would be enhanced by adding TiO2 nanoparticles and the optimal weight concentration were 0.0006%~0.004%. The results also provide, in some particle condition, natural ester nano-modified liquid would provide similar or better dielectric performance compare with industry products and would be treat as the substitute for the mineral oil.