Comparison of streamer propagation in mineral oils under lightning and step impulse voltages

Liu, Qiang; Wang, Zhongdong; Lesaint, Olivier

doi:10.1109/icdl.2014.6893151

Cited by 4 publications

(6 citation statements)

References 8 publications

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“…Hence, a higher maximum applied voltage is required to induce breakdown. In such conditions, it was observed that the voltage V i at the instant of breakdown approximately equals the breakdown voltage V b measured under step impulse voltage [1], [16]. This supports the idea of a minimum propagation voltage of second mode streamers.…”

supporting

confidence: 74%

“…An early study of estimation of impulse breakdown voltage was carried out by considering voltage waveform and streamer propagation [15]. Then, breakdown phenomena observed under lightning impulse and step impulse were compared and discussed in [1] and [16]. Over a large range of gap distances, applied voltage, and liquid nature, the comparison is complex since breakdown occurs from streamers propagating according to different "modes" [17], ranging from second mode (velocity v ≈ 2 km/s, threshold propagation voltage V 2 ), third (v ≈ 10 km/s, V 3 ), and fourth (v > 100 km/s).…”

mentioning

confidence: 99%

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Streamer and Breakdown Characteristics of Dielectric Liquids Under Impulse Waveforms With Different Tail-Times

Liu

Xiang

Wang

et al. 2022

IEEE Trans. Dielect. Electr. Insul.

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Impulse waveforms have been widely used in the studies of streamer and breakdown phenomena in dielectric liquids. In this article, both experiments and analyses were carried out to investigate the effects of impulse tail-time on streamer and breakdown characteristics of a mineral oil and a synthetic ester liquid. A range of positive impulse waveforms with the same front-time of 0.8 µs but different tail-times from 8 to 3200 µs were considered. Needle-plane electrodes with a needle tip radius of 10 µm and a gap of 10 mm were used. It was found that reduction of tail-time leads to an increase of 50% impulse breakdown voltage, while the instant breakdown voltage and the timeto-breakdown remain constant. On this basis, an analytical method is developed to estimate the 50% impulse breakdown voltage under waveforms with various tail-times. The method is valid when streamers remain of second mode and in divergent fields. It was also observed that some "self-regulation" by branching explains the constancy of streamer propagation velocity when the applied voltage is increased.

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confidence: 74%

mentioning

confidence: 99%

Streamer and Breakdown Characteristics of Dielectric Liquids Under Impulse Waveforms With Different Tail-Times

Liu

Xiang

Wang

et al. 2022

IEEE Trans. Dielect. Electr. Insul.

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“…The ratio between acceleration and breakdown voltage has been observed to vary depending on the type of liquid, and is dependent upon the gap distance [17]. The streamer velocity will have a large influence on the breakdown level under lightning impulse stress as propagating streamers could be quenched and stop once the voltage at the tail of the impulse drops below what is required to sustain propagation [21].…”

Section: Introductionmentioning

confidence: 99%

Prebreakdown phenomena in hydrocarbon liquids in a point-plane gap under step voltage. Part 1: behaviour at positive polarity

et al. 2020

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This study addresses the dielectric performance of nonpolar hydrocarbon liquids and mineral oils under positive polarity stress. It is of interest to improve knowledge on how functional properties of dielectric liquids vary, as new brands arrive in the market, and existing standards are unsuited for documenting the dielectric functional parameters of these new liquids. Stopping length for nonbreakdown streamers, breakdown voltages and velocities for various pre-breakdown streamer modes have been studied for a selection of model liquids (cyclohexane and white oils), for a gas to liquid oil, and a refined naphthenic transformer oil. Studies of propagation modes were done using an 80 mm point to plane gap and a step voltage with a 0.5 μs rise time. Light emission and pre-breakdown currents have been recorded and instantaneous velocities have been derived from images of propagating streamers. There are clear differences in streamer stopping lengths and mode occurrence and mode velocities between these liquids. The differences seem to be influenced by molecular sizes governing evaporation energy for streamer formation and by concentration of aromatics which can be coupled to electron avalanche processes in the streamer heads.

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“…In past decades, pre-breakdown streamer phenomena in liquids under negative impulse voltages were thoroughly investigated, considering the effects of different testing conditions such as voltage waveform, liquid nature, additives and hydrostatic pressure [2][3][4][5][6][7][8][9][10][11][12][13][14]. Concerning the detailed propagation process of fast streamers above acceleration voltage, much fewer experiments were found under negative impulse voltages than those under positive impulse voltages [10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Pre-breakdown and breakdown mechanisms of an inhibited gas to liquid hydrocarbon transformer oil under negative lightning impulse voltage

Lü

Liu

Wang

2017

IEEE Trans. Dielect. Electr. Insul.

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In this paper, streamer and breakdown phenomena and their mechanisms of an inhibited Gas-To-Liquid (GTL) transformer oil under standard negative lightning impulse voltages were studied. A conventional inhibited mineral oil was also tested as the benchmark. Experiments were carried out in 25 mm and 50 mm point-plane gaps. Streamer and breakdown phenomena of both oils were observed from the streamer inception voltage level up to the voltage level at which fast streamer appears with velocity over 10 km/s. The results showed that the GTL oil has a higher breakdown voltage and a higher acceleration voltage compared to the mineral oil. This is due to the fact that the GTL oil has a much lower aromatic content compared to the mineral oil. The streamer investigations showed that the development of fast streamers in both oils is the consequence of transition from dark streamer channels to bright streamer channels. By comparing with the results obtained under positive polarity [1], the differences in the propagation mechanisms between the fast negative streamers and fast positive streamers were explained.

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Comparison of streamer propagation in mineral oils under lightning and step impulse voltages

Cited by 4 publications

References 8 publications

Streamer and Breakdown Characteristics of Dielectric Liquids Under Impulse Waveforms With Different Tail-Times

Streamer and Breakdown Characteristics of Dielectric Liquids Under Impulse Waveforms With Different Tail-Times

Prebreakdown phenomena in hydrocarbon liquids in a point-plane gap under step voltage. Part 1: behaviour at positive polarity

Pre-breakdown and breakdown mechanisms of an inhibited gas to liquid hydrocarbon transformer oil under negative lightning impulse voltage

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