Streamer Inception from Ultra-Sharp Needles in Mineral Oil Based Nanofluids

Abstract

Positive and negative streamer inception voltages from ultra-sharp needle tips (with tip radii below 0.5 µm) are measured in TiO 2 , SiO 2 , Al 2 O 3 , ZnO and C 60 nanofluids. The experiments are performed at several concentrations of nanoparticles dispersed in mineral oil. It is found that nanoparticles influence positive and negative streamers in different ways. TiO 2 , SiO 2 and Al 2 O 3 nanoparticles increase the positive streamer inception voltage only, whilst ZnO and C 60 nanoparticles augment the streamer inception voltages in both polarities. Using these results, the main hypotheses explaining the improvement in the dielectric strength of the host oil due to the presence of nanoparticles are analyzed. It is found that the water adsorption hypothesis of nanoparticles is consistent with the increments in the reported positive streamer inception voltages. It is also shown that the hypothesis of nanoparticles reducing the electron velocity by hopping transport mechanisms fails to explain the results obtained for negative streamers. Finally, the hypothesis of nanoparticles attaching electrons according to their charging characteristics is found to be consistent with the results hereby presented on negative streamers.

Investigation of the Lightning Impulse Breakdown Voltage of Mineral Oil based Fe3O4 Nanofluids

“…As can be seen, there is a decrease of about a 40 % in the speed of propagation of positive impulses when NP are added to the MO, while the presence of NP does not seem to affect the speed of propagation of negative streamers. This result is in agreement with the theories and results reported by other authors [16,[39][40][41], and confirm that the variation of the streamer propagation speed is deeply related with the improvements observed of the BDV values. If the propagation is slower there is a higher probability of the streamer being extinguished and the rupture does not take place.…”

Analysis of Water Solubility in natural-ester based nanodielectric fluids

“…This result is in agreement with the theories and results reported by other authors [65,13,135,136], and confirm that the variation of the streamer propagation speed is deeply related with the improvements observed of the BV values. If the propagation is slower there is a higher probability of the streamer being extinguished and the rupture does not take place.…”

Finite Element Based Comparative Analysis of Positive Streamers in Multi Dispersed Nanoparticle Based Transformer Oil

“…The higher the electrical conductivity is, the lower the relaxation time constant will be, which traps the electrons very quickly and hinders the streamer transmission velocity [12][13]. The dispersion of NPs can augment the positive streamer inception voltage, but it has proven less efficacy towards the negative streamer dynamics [14]. A detailed review report on potential application of TO based NDFs are available in [1][2].…”