Enhancements in the lightning impulse breakdown characteristics of natural ester dielectric liquids

Unge, Mikael; Singha, Santanu; Dũng, Nguyễn Văn; Linhjell, D.; Ingebrigtsen, S.; Lundgaard, L.E.

doi:10.1063/1.4803710

Cited by 50 publications

(43 citation statements)

References 11 publications

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“…However, in this experiment it has an effect similar to but weaker than with DMA, and this experiment alone cannot tell if the effect is caused by the low excitation level or the ionization potential which is lower than in the base liquid but still higher than in DMA. That the effect is weaker than in DMA, which has a lowest excitation level almost twice as high as azobenzene, might indicate that it is not the excitation level which is important, but this is contrary to the discussion in a paper about a long gap experiment with a natural ester as base liquid [19].…”

Section: Acceleration Voltage Vs Additive Mole Fractioncontrasting

confidence: 53%

“…Azobenzene was included as an additive because of a hypothesis that the lowest electronic excitation level might have an influence [11,12,19], particularly at the higher local fields which may exist in front of a streamer tip, since the ionisation potential may be so reduced with increased field [10,11] that it approaches the lowest excitation level. However, in this experiment it has an effect similar to but weaker than with DMA, and this experiment alone cannot tell if the effect is caused by the low excitation level or the ionization potential which is lower than in the base liquid but still higher than in DMA.…”

Section: Acceleration Voltage Vs Additive Mole Fractionmentioning

confidence: 99%

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Positive Breakdown Streamers and Acceleration in a Small Point-Plane Liquid Gap and Their Variation with Liquid Properties.

Linhjell¹,

Ingebrigtsen²,

Lundgaard³

et al. 2018

NORD-IS

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<p>Positive breakdown streamers have been investigated in a short (5 mm) point-plane gap in cyclohexane and n-tridecane with and without the additives N,N-dimethylamine (DMA) with low ionization potential and azobenzene with a not quite as low ionization potential but a very low lowest excitation level. The effects off additives are fairly similar to what is known from longer gaps with DMA or pyrene added: the additives caused reduced breakdown voltage, significantly increased acceleration voltage and increased streamer velocity around breakdown. Molecule for molecule, azobenzene has less effect than DMA. The ratio between the acceleration and the breakdown voltage is significantly higher than in long gaps, though. Nonetheless, tests in short gaps are sufficiently good for screening (a large number of) liquid combinations.<br />The two base liquids without additives, and also neat trichloroethene and DMA have been tested with and without a tube causing spatial restriction of the streamer. Restriction causes increased breakdown voltage and promotes the fastest streamer modes.</p>

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Section: Acceleration Voltage Vs Additive Mole Fractioncontrasting

confidence: 53%

Section: Acceleration Voltage Vs Additive Mole Fractionmentioning

confidence: 99%

Positive Breakdown Streamers and Acceleration in a Small Point-Plane Liquid Gap and Their Variation with Liquid Properties.

Linhjell¹,

Ingebrigtsen²,

Lundgaard³

et al. 2018

NORD-IS

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“…4,5 Much work has been done to explore the effective way to inhibit the development of positive streamers in transformer oil with an attempt to improve its dielectric strength. 6,7 Fe 3 O 4 nanoparticles with unique electrical and physical properties have shown a great potential in improving breakdown strength of transformer oil. It was found that the positive impulse breakdown voltage of transformer oil can be increased by 82.6% by adding a proper concentration of Fe 3 O 4 nanoparticles.…”

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confidence: 99%

Effect of Fe3O4 nanoparticles on positive streamer propagation in transformer oil

Wang

Zhou

et al. 2016

AIP Advances

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Fe3O4 nanoparticles with an average diameter of 10 nm were prepared and used to modify streamer characteristic of transformer oil. It was found that positive streamer propagation velocity in transformer oil-based Fe3O4 nanofluid is greatly reduced by 51% in comparison with that in pure oil. The evolution of streamer shape is also dramatically affected by the presence of nanoparticles, changing from a tree-like shape with sharp branches in pure oil to a bush-like structure with thicker and denser branches in nanofluid. The TSC results reveal that the modification of Fe3O4 nanoparticle can greatly increase the density of shallow trap and change space charge distribution in nanofluid by converting fast electrons into slow electrons via trapping and de-trapping process in shallow traps. These negative space charges induced by nanoparticles greatly alleviate the electric field distortion in front of the positive streamer tip and significantly hinder the propagation of positive streamer.

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“…Photoionization and excitation is also essential in the streamer breakdown mechanism. It has been shown that additives with low-ionization potential and excitation energies in mineral oil can increase branching of streamers leading to decreased electrical field in the streamer and reduced speed of the propagation at specific voltages [4].…”

Section: Ionization and Excitationmentioning

confidence: 99%

Kraft-Pulp Based Material for Electrical Insulation

Hollertz¹,

Wågberg²,

Pitois

2017

NORD-IS

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The dielectric properties of the electrical insulation material have a significant influence on the performance and reliability of components in electrical equipment. The influence of the chemistry and electronic structure of the different constituents of the kraft pulp (used in electrical insulation) on some dielectric properties is discussed in this paper. The studies and mechanisms discussed indicate that the presence of different wood polymers (cellulose, hemicellulose and lignin), have different effects on dielectric properties (static electrification and high frequency response). Our results show that the dielectric response of lignin is different compared with the response of hemicellulose and cellulose and this is also expected from the chemical structure of the different components. The lignin molecule has a higher polarizability at frequencies of significance for streamer inception and propagation. With spectroscopic ellipsometry measurements it has also been shown that the energy for electronic transitions in this spectral region is lower for lignin. The results also clearly indicate that the role of cellulose, lignin and hemicellulose should be further investigated for improving electrical breakdown strength of paper based insulation materials.

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Enhancements in the lightning impulse breakdown characteristics of natural ester dielectric liquids

Cited by 50 publications

References 11 publications

Positive Breakdown Streamers and Acceleration in a Small Point-Plane Liquid Gap and Their Variation with Liquid Properties.

Positive Breakdown Streamers and Acceleration in a Small Point-Plane Liquid Gap and Their Variation with Liquid Properties.

Effect of Fe3O4 nanoparticles on positive streamer propagation in transformer oil

Kraft-Pulp Based Material for Electrical Insulation

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