AC (60 Hz) and impulse breakdown strength of a colloidal fluid based on transformer oil and magnetite nanoparticles

Segal, V. M.; Hjortsberg, A.; Rabinovich, A. L.; Nattrass, D.; Raj, K.

doi:10.1109/elinsl.1998.694869

Cited by 175 publications

(132 citation statements)

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“…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. 8 Electrical breakdown testing of vegetable oil-based Fe 3 O 4 nanofluids also indicated that positive impulse breakdown voltage of vegetable oil was enhanced by Fe 3 O 4 nanoparticles. 9 Moreover, positive switching impulse withstand voltage of transformer oil was increased by modification of Fe 3 O 4 nanoparticles.…”

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confidence: 99%

“…10 An electron-scavenging model is proposed and generally used to explain these phenomena based on modeling the electrodynamic process in Fe 3 nanofluids. 8,9,11 Some researchers think the potential well generated by induced or polarized charges on the surface of nanoparticles can capture the passing electrons and enhance the breakdown performance of transformer oil. 10,12 In comparison with the dielectric breakdown strength of nanofluid, its prebreakdown streamer propagation behavior is more important to understand the fundamental modification effect of nanoparticle, which can give valuable insight into the events leading to breakdown.…”

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confidence: 99%

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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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Effect of Fe3O4 nanoparticles on positive streamer propagation in transformer oil

Wang

Zhou

et al. 2016

AIP Advances

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“…power transformers. Many studies showed that these ferrofluids withstand higher voltages than pure transformer oils, the property often presented as a paradox [3,4]. In this context, a theoretical modelling has indicated that nanoparticles in transformer oil can act as free charge scavengers which slow down the streamer velocity leading to dielectric breakdown [5].…”

Section: Introductionmentioning

confidence: 99%

AC Magnetic Susceptibility of Ferrofluids Exposed to an External Electric Field

Kim

Park

2017

Acta Phys. Pol. A

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It is known that ferrofluid superparamagnetic nanoparticles response to external magnetic fields, often resulting in the formation of elongated clusters along the field. This has a notable impact on dielectric properties of ferrofluids. Here we report on indications of a contrary effect when the magnetic susceptibility of ferrofluids based on transformer oil is influenced by an external electric field. This effect is associated with structural changes in the ferrofluids induced by the external electric fields. Particularly, we focus on a steady state electric field effect, which gives rise to forces acting on the magnetite nanoparticles, leading to the formation of aggregates. In this condition we have measured the ferrofluid AC magnetic susceptibility in parallel and perpendicular configuration of magnetic and electric fields at room temperature. The measurements in both configurations yielded a noticeable decrease in the real susceptibility values with increasing electric field intensity. The result is believed to be caused by the reduction in the total magnetic moment of the ferrofluid. This can be a consequence of the superspin interactions in the aggregates, minimizing the aggregate's energy. Finally, we highlight the necessity of NMR and small angle scattering of polarized neutrons investigations in order to obtain exact information on the magnetic structure induced by the electric forces.

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“…Usually, the base fluid is distilled water, 2-4 ethylene glycol, [5][6][7][8][9] or a certain oil. [10][11][12][13][14] Numerous papers on experimental and theoretical properties of nanofluids and their potential applications in the industry have been published so far. A broad field of applications of the nanofluids is in the systems related to heat transfer.…”

Section: Introductionmentioning

confidence: 99%

Dielectric Properties of Boron Nitride-Ethylene Glycol (BN-EG) Nanofluids

Fal

Cholewa

Gizowska

et al. 2016

Journal of Elec Materi

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This paper presents the results of experimental investigation of the dielectric properties of ethylene glycol (EG) with various load of boron nitride (BN) nanoparticles. The nanofuids were prepared by using a two-step method on the basis of commercially available BN nanoparticles. The measurements were carried out using the Concept 80 System (NOVOCONTROL Technologies GmbH & Co. KG, Montabaur, Germany) in a frequency range from 10 Hz to 10 MHz and temperatures from 278.15 K to 328.15 K. The frequency-dependent real (e 0 ) and imaginary (e 00 ) parts of the complex permittivity (e Ã ) and the alternating current (AC) conductivity are presented. Also, the effect of temperature and mass concentrations on the dielectric properties of BN-EG nanofluids are demonstrated. The results show that the most significant increase can be achieved for 20 wt.% of BN nanoparticles at 283.15 K and 288.15 K, that is eleven times larger than in the case of pure EG.

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AC (60 Hz) and impulse breakdown strength of a colloidal fluid based on transformer oil and magnetite nanoparticles

Cited by 175 publications

References 1 publication

Effect of Fe3O4 nanoparticles on positive streamer propagation in transformer oil

Effect of Fe3O4 nanoparticles on positive streamer propagation in transformer oil

AC Magnetic Susceptibility of Ferrofluids Exposed to an External Electric Field

Dielectric Properties of Boron Nitride-Ethylene Glycol (BN-EG) Nanofluids

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