Impulse breakdown characteristics of the plane-to-plane electrode system with a needle-shaped protrusion in SF6

Lee, Bok-Hee; Baek, Young-Hwan; Choi, H. K.; Oh, S.K.

doi:10.1016/j.cap.2006.09.022

Cited by 21 publications

(7 citation statements)

References 3 publications

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“…13,14 Influence of the lightning impulsive waveform of the electrical discharge on breakdown characteristics was also investigated. 15,16 Even if SF 6 gas is a good switchgear, 17,18 it has a number of disadvantages, including a reduction in the breakdown field in the presence of metal particles and the fact that it contributes to the greenhouse effect. Therefore, it has been proposed [19][20][21][22][23] to use a mixture of nitrogen and SF 6 .…”

Section: Introductionmentioning

confidence: 99%

Analytical investigation of electrical breakdown properties in a nitrogen-SF6 mixture gas

et al. 2010

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The electrical breakdown properties in nitrogen gas mixed with SF6 are analytically investigated in this article by making use of the ionization and attachment coefficients of the mixed gas. The ionization coefficients of nitrogen and SF6 gas are obtained in terms of the electron temperature Te by assuming a Maxwellian distribution of the electron energy. The attachment coefficient of SF6 gas is also obtained in terms of the gas temperature Te. An algebraic equation is obtained, relating explicitly the electron breakdown temperature Tb in terms of the SF6 mole fraction χ. It was found from this equation that the breakdown temperature Tb increases from approximately 2 to 5.3 eV as the mole fraction χ increases from zero to unity. The breakdown temperature Tb of the electrons increases very rapidly from a small value and then approaches 5.3 eV slowly as the SF6 mole fraction increases from zero to unity. This indicates that even a small mole fraction of SF6 in the gas dominates the electron behavior in the breakdown system. The breakdown electric field Eb derived is almost linearly proportional to the breakdown electron temperature Tb. The experimental data agree remarkably well with the theoretical results. Therefore, it is concluded that even a small fraction of SF6 gas dominates nitrogen in determining the breakdown field. In this context, nearly 25% of the SF6 mole fraction provides a reasonable enhancement of the breakdown field for practical applications.

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Section: Introductionmentioning

confidence: 99%

Analytical investigation of electrical breakdown properties in a nitrogen-SF6 mixture gas

et al. 2010

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“…[1][2][3][4][5][6][7][8][9][10][11][12]) at the high field electrode, for which the breakdown voltage is much lower than for negative polarity (e.g. [13][14][15]). The results of these studies have usually been presented in the form of voltage-pressure diagrams (figure 1(a)), in which streamer inception (broken curve), PD activity (shaded area) and breakdown voltage (solid curve) are the main references.…”

Section: Introductionmentioning

confidence: 99%

Partial discharges and breakdown at protrusions in uniform background fields in SF₆

Seeger¹,

Niemeyer²,

Bujotzek³

2008

J. Phys. D: Appl. Phys.

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The breakdown mechanism of compressed SF6 in gas insulation is known to be controlled by stepped leader propagation. This process is reasonably well understood for strongly non-uniform insulation gaps (‘point-to-plane’) and in the absence of pre-breakdown discharge activity (‘corona stabilization’). Open questions still remain for weakly non-uniform insulation gaps with small electrode protrusions (particles, surface roughness), in which pre-breakdown partial discharge (PD) activity is present. This paper presents a first attempt to derive a consistent picture under these conditions, which are characteristic for practical gas insulation systems. Experiments were carried out in a uniform field gap with a short protrusion on one electrode. This configuration was studied at various pressures from 0.1 to 0.5 MPa and both polarities using electrical and optical diagnostics. The results are interpreted using a quantitative model and order-of-magnitude estimates. The emerging picture allows prediction of most of the technically relevant aspects of the discharge processes and their main parameter dependences. It comprises statistical time lags, formative time lags including pre-breakdown PD activity and breakdown fields as a function of gas pressure, protrusion length and polarity.

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“…Consequently, the pre-breakdown development is initiated by the streamer corona and the streamer to leader transition takes place after a dead time and this discharge process is repeated. Two physical processes, namely the ionic drift and the channel expansions occur during the pause time between the current pulses [16], [17].…”

Section: Pre-breakdown Development Processesmentioning

confidence: 99%

Underwater Discharge Phenomena in Inhomogeneous Electric Fields Caused by Impulse Voltages

Lee¹,

Kim²,

Choi³

2010

Journal of Electrical Engineering and Technology

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-The paper describes the electrical and optical properties of underwater discharges in highly inhomogeneous electric fields caused by 1.2/50 ㎲ impulse voltages as functions of the polarity and amplitude of the applied voltage, and various water conductivities. The electric fields are formed by a point-to-plane electrode system. The formation of air bubbles is associated with a thermal process of the water located at the tip of the needle electrode, and streamer coronas can be initiated in the air bubbles and propagated through the test gap with stepped leaders. The fastest streamer channel experiences the final jump across the test gap. The negative streamer channels not only have more branches but are also more widely spread out than the positive streamer channels. The propagation velocity of the positive streamer is much faster than that of the negative one and, in fact, both these velocities are independent of the water conductivity; in addition the time-lag to breakdown is insensitive to water conductivity. The higher the water conductivity the larger the pre-breakdown energy, therefore, the ionic currents do not contribute to the initiation and propagation of the underwater discharges in the test conditions considered.

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Impulse breakdown characteristics of the plane-to-plane electrode system with a needle-shaped protrusion in SF6

Cited by 21 publications

References 3 publications

Analytical investigation of electrical breakdown properties in a nitrogen-SF6 mixture gas

Analytical investigation of electrical breakdown properties in a nitrogen-SF6 mixture gas

Partial discharges and breakdown at protrusions in uniform background fields in SF₆

Underwater Discharge Phenomena in Inhomogeneous Electric Fields Caused by Impulse Voltages

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Impulse breakdown characteristics of the plane-to-plane electrode system with a needle-shaped protrusion in SF6

Cited by 21 publications

References 3 publications

Analytical investigation of electrical breakdown properties in a nitrogen-SF6 mixture gas

Analytical investigation of electrical breakdown properties in a nitrogen-SF6 mixture gas

Partial discharges and breakdown at protrusions in uniform background fields in SF6

Underwater Discharge Phenomena in Inhomogeneous Electric Fields Caused by Impulse Voltages

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Partial discharges and breakdown at protrusions in uniform background fields in SF₆