Analysis of impulse withstand voltage of ester-based nanofluids

Abstract

Ester-based nanofluids constitute an effective ecological alternative to petroleum-derived dielectric fluids for electrical engineering industry. Pulse induced dielectric breakdown is a key cause of power device failure. In this paper, we deal with the lightning impulse breakdown voltage (LI BDV) in natural and synthetic ester-based (NE and SE) nanofluids with various concentrations of magnetite (Fe3O4) and fullerene (C60) nanoparticles. The nanofluids show a decrement in positive polarity LI+ BDV as compared with the base ester. Negative polarity LI- BDV in the nanofluids is similar to that of base oils. Weibull statistical distributions are applied to analyse the results at different cumulative probabilities of 1 %, 10 %, and 50 %. Natural ester with C60 nanoparticles shows higher positive LI+ BDV values at a low probability level, while the negative LI- BDV reaches higher values at higher probability levels. The decreased LI BDV in NE and SE due to the magnetite nanoparticles are attributed to the nanoparticle clustering and percolation. The tendency of C60 nanoparticles to enhance the LI BDV in NE but not in SE is interpreted in the view of the nanoparticle concentration and oil's viscosity effect on the streamer branching and propagation.