SF(sub)6 switchgear [Books and Reports]

Ryan, H. M.; Jones, G.R.

doi:10.1109/mper.1991.90687

Cited by 4 publications

(5 citation statements)

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“…Figure 9 shows σ SF 6 ,a(1) , σ SF 6 ,a (2) , σ CF4,a(1) and σ CF4,a(2) . Figure 8(b) indicates η/N in the gas mixture at X CFBN = 50% and also shows its components y j η j, a /N.…”

Section: Analysis Of Contributions To Reduced Electron Attachment Coe...mentioning

confidence: 99%

“…SF 6 circuit breakers interrupt the large alternating currents arising from electric power transmission system faults by utilizing the transient response of arc discharges established between electrical contacts. The circuit breaker must successfully operate during two periods: (i) the thermal recovery period that persists for several microseconds after the current zero at the end of the current wave, and (ii) the dielectric recovery period following the thermal recovery period [1,2].…”

Section: Introductionmentioning

confidence: 99%

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Predominant reaction products and dielectric breakdown properties of gas mixtures consisting of SF₆ and ablation products of C₂F₄/BN in the temperature range of 300–3000 K

Yokomizu¹,

Terada²,

Kodama³

et al. 2021

J. Phys. D: Appl. Phys.

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For a high voltage SF6 circuit breaker equipped with a boron nitride (BN)-filled polytetrafluoroethylene ((C2F4) n ) nozzle, the predominant reaction products in a high-temperature SF6 mixture with vapor decomposition of C2F4 and BN at temperatures of 300–3000 K are determined based on calculations of equilibrium composition. The calculation is performed by considering the molecular products obtained by chemical reactions with boron atoms (e.g. BN, BS, BC, BF, BF2 and BF3), nitrogen atoms (e.g. N2, N3, CN, NS, NF, NF2 and NF3) and carbon atoms (e.g. CS, CS2, C2F4, CF2, CF3 and CF4). The results obtained for the C2F4–BN molar fraction X C F B N of 20%–80% reveal that BF3, N2 and CF4, the molecules originating from the nozzle material, are produced at high molar fractions over a range of 300–3000 K. Such an evaluation of the gas composition allows the derivation of a reduced collision ionization coefficient α/N and a reduced electron attachment coefficient η/N of the gas, considering various electron impact processes such as BF3 + e → BF2 + F− and CF4 + e → CF3 + F−. The evaluation subsequently enables us to determine a critical reduced electric field strength E c r / N causing ( α − η ) / N = 0 . The results suggest that the decomposed C2F4–BN mixture at X C F B N of 80% causes the reduction of E c r / N to 110 Td in the range of 1000–2000 K at a gas pressure of 1.0 MPa. This strength E c r / N is 20 Td lower than that determined separately for the SF6 gas mixture with only 80% C2F4 vapor decomposition, because of the CF4 molar fraction reduction in the SF6/C2F4–BN mixture.

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“…Figure 9 shows σ SF 6 ,a(1) , σ SF 6 ,a (2) , σ CF4,a(1) and σ CF4,a(2) . Figure 8(b) indicates η/N in the gas mixture at X CFBN = 50% and also shows its components y j η j, a /N.…”

Section: Analysis Of Contributions To Reduced Electron Attachment Coe...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Predominant reaction products and dielectric breakdown properties of gas mixtures consisting of SF₆ and ablation products of C₂F₄/BN in the temperature range of 300–3000 K

Yokomizu¹,

Terada²,

Kodama³

et al. 2021

J. Phys. D: Appl. Phys.

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“…Gaseous insulation is used in many high voltage applications as, for example, gas-insulated switchgear (GIS) and circuit breakers (CB) [1][2][3][4][5][6]. For compact insulation compressed gas in the pressure range of 0.13-1 MPa is used.…”

Section: Introductionmentioning

confidence: 99%

Breakdown at Multiple Protrusions in SF6 and CO2

Feet¹,

Seeger²,

Over³

et al. 2020

Energies

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The electric breakdown at single and multiple protrusions in SF6 and CO2 is investigated at 0.4 and 0.6 MPa, respectively. Additionally, the breakdown fields at rough surfaces of two different areas were determined. From the measurements, breakdown probability distributions for single protrusions were determined and fitted by Weibull distributions. This allowed the determination of statistical enlargement laws for the 50% breakdown probability fields E50. Such enlargement laws describe, for example, the scaling of breakdown field with electrode area or number of protrusions. The predictions were compared to the experimental data, and both agreement and discrepancies were observed depending on polarity and number of protrusions and gas. Discharge predictions including first electron, streamer inception and crossing, as well as leader propagation, gave further insight to this. It was found that predictions from enlargement laws based on statistical processes may not describe the measured breakdown fields well and that relevant physical breakdown criteria must also be considered.

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“…When grounding faults occur in power systems, high-voltage SF 6 gas circuit breakers are responsible for extinguishing SF 6 arc plasmas rapidly, removing the line faults and protecting other transmission devices with high reproducibility [1][2][3][4]. At the AC current-zero points, the electrical currents are interrupted temporarily.…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional electron density characterisation of arc interruption phenomenon in current-zero phase

Inada¹,

Kamiya²,

Matsuoka³

et al. 2017

J. Phys. D: Appl. Phys.

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Two-dimensional electron density imaging over free burning arcs and gas-blast arcs was conducted at current zero using highly sensitive Shack–Hartmann type laser wavefront sensors in order to experimentally characterise electron density distributions for the success and failure of arc interruption in the thermal reignition phase. The experimental results under an interruption probability of 50% showed that free burning arcs with axially asymmetric electron density profiles were interrupted with a success rate of 88%. On the other hand, the current interruption of gas-blast arcs was reproducibly achieved under locally reduced electron densities and the interruption success rate was 100%.

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SF(sub)6 switchgear [Books and Reports]

Cited by 4 publications

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Predominant reaction products and dielectric breakdown properties of gas mixtures consisting of SF₆ and ablation products of C₂F₄/BN in the temperature range of 300–3000 K

Predominant reaction products and dielectric breakdown properties of gas mixtures consisting of SF₆ and ablation products of C₂F₄/BN in the temperature range of 300–3000 K

Breakdown at Multiple Protrusions in SF6 and CO2

Two-dimensional electron density characterisation of arc interruption phenomenon in current-zero phase

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SF(sub)6 switchgear [Books and Reports]

Cited by 4 publications

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Predominant reaction products and dielectric breakdown properties of gas mixtures consisting of SF6 and ablation products of C2F4/BN in the temperature range of 300–3000 K

Predominant reaction products and dielectric breakdown properties of gas mixtures consisting of SF6 and ablation products of C2F4/BN in the temperature range of 300–3000 K

Breakdown at Multiple Protrusions in SF6 and CO2

Two-dimensional electron density characterisation of arc interruption phenomenon in current-zero phase

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Predominant reaction products and dielectric breakdown properties of gas mixtures consisting of SF₆ and ablation products of C₂F₄/BN in the temperature range of 300–3000 K

Predominant reaction products and dielectric breakdown properties of gas mixtures consisting of SF₆ and ablation products of C₂F₄/BN in the temperature range of 300–3000 K