Positive discharge development in insulating oil: optical observation and simulation

Modeling of impulse electric discharge propagation in a condensed dielectric

“…Some of the side branches stop and collapse already when the discharge structure grows. As a whole, the shape of channel structures is identical to that observed experimentally in the breakdown of centimeter gaps in liquids and polymers [7,9,10,[12][13][14][15][16], but differs by more intensive branching and bending from that observed in crystalline dielectrics [17].…”

“…The formation of stochastically bending and branching channels was first described for a fractal model of dielectric breakdown [4,5]. In [6][7][8], the model of dielectric breakdown was generalized by consideration of charge motion through discharge channels and variations of their electrical conduction. This has allowed the researchers to describe both space-time and electric discharge characteristics.…”

“…However, in these studies the discharge propagation was considered under constant voltage disregarding the parameters of actual high-voltage generators. Since the velocity and mode of the discharge propagation for continuous or stepwise (leader) channel growth depend on the relationship between impedances of the generator and propagating discharge channels [7,9], the electrodynamic processes in the dielectric should be calculated together with the operation of the high-voltage generator.…”

Optical observation of streamer propagation and breakdown in seed based insulating oil under impulse voltages

“…On the other hand, a number of studies on traditional mineral oil were published (Lesaint and Massala, 1998;Massala and Lesaint, 2001;Linhjell et al, 1994;Torshin, 2003Torshin, , 2009Lopatin et al, 1998) describing the streamer initiation and propagation in terms of velocity and shape, streamer mechanism and streamer modeling. It is acknowledged that impulse pre-breakdown and breakdown characteristics are related to chemical composition of the liquid, so application of esters (with composition different to mineral oil) calls for detailed investigation under impulse voltage.…”

Contribution to study of visible discharge initiation and development on the ice surface =

“…Framing cameras were used in the past for investigations of discharge propagation in liquid dielectrics [5] [7] [65], [68], [82] and also for the breakdown processes along solid insulating surfaces in air [100] [101]. Furthermore, a single frame high-speed camera system was used to investigate of discharge initiation in SFg/N 2 gas mixtures under very fast transient voltage stress [86], whereas [43] used an ICCD camera for studies on avalanches and streamer formation along Teflon spacers in dry air.…”