Preliminary report for the IEEE DEIS Liquid Dielectrics Committee international study group on "Streamer Propagation in Liquids"

Electrical and optical measurements investigation of the pre‐breakdown processes in natural ester oil under different impulse voltage waveforms

“…The quite well correlation between the current and light emission, which appeared during breakdowns was demonstrated, implying species ionisation/excitation in the oil by direct electron impacts. The light, which is emitted across the entire gap in both configurations during the breakdown, has a similar shape to that of the current, as referred in [9,10].…”

“…4) by gap relaxation oscillations of the plasma in the liquid. The number and amplitude of both streamer current and emitted light pulses increase when the voltage is increased [9,10]. No visible pre-breakdown phenomena are detected neither from current nor from light-emission records.…”

“…However, their usage is still restricted mainly to distribution transformers as well as capacitors, forasmuch as their lower breakdown voltage level is minor, compared with mineral oils, thus their implementation in high-power transformers is still inhibited. In the past decades, many researchers have made effort to study in depth pre-breakdown phenomena in mineral oils [5][6][7][8][9][10], and water [11] in order to better understand their differences and the breakdown mechanisms.…”

Alternative Fluids – with a Particular Emphasis on Vegetable Oils – as Replacements of Transformer Oil: A Concise Review

“…Considerable efforts regarding the study of paper/vegetable oil insulation have already been undertaken [83,84]. Detailed reports on pre-breakdown and breakdown phenomena regarding the vegetable oils must also be produced, as was the case in more conventional fluids [12,[85][86][87][88]. In conjunction to pre-breakdown and breakdown phenomena and related mechanisms, vegetable oil-based nanofluids must be investigated regarding their dielectric strength, volume resistivity, and dissipation factor [89].…”