Inhomogeneous field breakdown in GIS-the prediction of breakdown probabilities and voltages. I. Overview of a theory for inhomogeneous field breakdown in SF/sub 6/

Wiegart, N.; Niemeyer, L.; Pinnekamp, Friedrich; Kindersberger, J.; Morrow, R.; Zaengl, W.S.; Zwicky, M.; Gallimberti, I.; Boggs, S.A.

doi:10.1109/61.193869

Cited by 104 publications

(40 citation statements)

References 3 publications

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“…Cosmic particles are responsible for the natural ionization of gases, also inside compartments [8]. It is assumed that they have sufficient energy for the ionizion of any kind of gas.…”

Section: Time Lagsmentioning

confidence: 99%

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Partial discharges and breakdown in C₃F₈

Koch¹,

Franck²

2014

J. Phys. D: Appl. Phys.

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Abstract. Traditional search processes of gases or gas mixtures for replacing SF 6 involve time consuming measurements of partial discharges and breakdown behaviour for several voltage waveforms and different field configurations. Recently a model for prediction of this behaviour for SF 6 was described in literature. The model only requires basic properties of the gas such as the critical field strength and the effective ionization coefficient, which can be obtained by swarm parameter measurements, and thermodynamic properties, which can be calculated. In this paper, we show for the well-known and electronegative gas octafluoropropane (C 3 F 8 ) that it is possible to transfer the model developed for SF 6 to this gas to describe the breakdown behaviour of C 3 F 8 . Thus the model can be beneficial in the screening process of new insulation gases.

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“…Cosmic particles are responsible for the natural ionization of gases, also inside compartments [8]. It is assumed that they have sufficient energy for the ionizion of any kind of gas.…”

Section: Time Lagsmentioning

confidence: 99%

“…For SF 6 there exist a detailed understanding of the discharge processes, the conditions leading to breakdown and the modelling thereof [8,9,10,11,12]. In the course of searching for replacement candidates for SF 6 , there will be the need to understand and model the discharge and breakdown behaviour of this new insulating gas.…”

Section: Introductionmentioning

confidence: 99%

Partial discharges and breakdown in C₃F₈

Koch¹,

Franck²

2014

J. Phys. D: Appl. Phys.

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“…In literature several different waiting times to sufficiently approximate equilibrium ion densities are given. Wiegart et al [2] suggest a time between successive voltage applications of 6 minutes at 0.1 MPa and 7 minutes at 0.4 MPa. According to Kindersberger et al [6] periods in the range of 10 minutes would ensure the zero field equilibrium number of ions in the test gap.…”

Section: Introductionmentioning

confidence: 98%

“…The former is connected to the question how long it takes that an electron starting the breakdown process is detached within the critical volume (i.e. the volume with positive effective ionization coefficient) [2].…”

Section: Introductionmentioning

confidence: 99%

Determination of waiting times between successive breakdown experiments

Koch

Straumann

Franck

2012

2012 Annual Report Conference on Electrical Insulation and Dielectric Phenomena

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A common duty in high voltage engineering is the experimental determination of the breakdown voltage probability distribution of gaseous insulated electrode configurations. Due to electron detachment from negative ions in the case of electron attaching gases, the breakdown probability does not only depend on the gas and its density, but also on the ion density in the gas. If a disruptive discharge occurs in a gas gap, the number of ions in the gap is significantly increased compared to the equilibrium state at zero voltage. If the time until the next voltage application is too short, the statistical time lag will be decreased and, as a consequence, the probability of breakdown will be increased. To perform statistical independent breakdown experiments it is necessary to ensure identical ion densities in the gas gap before every new voltage application. In the literature waiting times mostly around six minutes are proposed as sufficient for ion density equalization in sulfur hexafluoride (SF 6 ). However, simulations of the behavior of SF 6 performed for the present contribution reveal that six minutes are not always sufficient to achieve statistical independent results. Especially at higher pressures longer waiting times are necessary. To investigate this problem, measurements of the natural ion pair generation in SF 6 were performed at different laboratories. Based on this data the temporal development of the ion distribution in the gas is calculated. Two cases are of interest: the changes in ion density after a disruptive discharge and in case the gap withstood the applied voltage and therefore all ions are swept out. After transformation of the temporal ion density into breakdown probability curves it is possible to estimate the necessary waiting time.

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“…To date, the breakdown processes in air and pressurized SF 6 have been investigated intensely, but formulae for the breakdown voltage have mainly been derived for the most critical cases. These are the positive leader breakdown in air for large gaps for AC or switching impulse voltage [52], and in SF 6 the positive lightning impulse voltage for strongly inhomogeneous field distributions as they occur in GIS with long protrusions [53,54,55]. In defect free SF 6 GIS, the breakdown mechanism depends on the applied voltage wave shape, polarity and surface roughness and it is not generally possible to state the most critical case.…”

Section: Breakdown Voltage Predictionmentioning

confidence: 99%

An Efficient Procedure to Identify and Quantify New Molecules for Insulating Gas Mixtures

Franck

Dahl

Rabie

et al. 2013

Contrib. Plasma Phys.

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Author(s):Franck, Christian M.; Dahl, Dominik A.; Rabie, M.; Haefliger, P.; Koch, M. Publication Date: 2014 Permanent Link:https://doi.org/10.3929/ethz-a-010881816 Originally published in:Contributions to plasma physics 54(1), http://doi.org/10.1002/ctpp.201300030 Rights / License:In Copyright -Non-Commercial Use Permitted This page was generated automatically upon download from the ETH Zurich Research Collection. For more information please consult the Terms of use. ETH LibraryThis is the pre-peer reviewed version of the following article: In this contribution, a new procedure to systematically identify and quantify novel molecular gases with low global warming potential for application in high voltage insulation as gas mixtures is presented. The attention is focused on highly efficient procedures to be able to scan a large number of candidate gases. To identify new molecules, we derived an empirical correlation between the electric strength of a gas and certain molecular properties, like polarizability or dipole moment, which can be calculated by means of density functional theory. The swarm parameters of these pre-selected molecules in mixtures with buffer gases is then quantified, using a newly set-up Pulsed Townsend experiment. The setup operates with a high degree of automation to enable systematic evaluation of gas mixtures not to miss possible synergistic effects. Key element of this PT setup is a new photocathode that works with a high quantum efficiency and long lifetime even when exposed to reactive species during the measurements. Moreover, for an automated operation it is important to know precisely in which range the experiment can be operated, i.e. for example to know up to which electron density space charge effects can be neglected. Finally, the measured swarm parameters need to be translated into breakdown voltage strengths of different electrode arrangements and different applied voltage wave shapes. For this, a model of the the streamer to leader transition in SF6 will be applied to general strong electronegative gases in future studies.

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Inhomogeneous field breakdown in GIS-the prediction of breakdown probabilities and voltages. I. Overview of a theory for inhomogeneous field breakdown in SF/sub 6/

Cited by 104 publications

References 3 publications

Partial discharges and breakdown in C₃F₈

Partial discharges and breakdown in C₃F₈

Determination of waiting times between successive breakdown experiments

An Efficient Procedure to Identify and Quantify New Molecules for Insulating Gas Mixtures

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Inhomogeneous field breakdown in GIS-the prediction of breakdown probabilities and voltages. I. Overview of a theory for inhomogeneous field breakdown in SF/sub 6/

Cited by 104 publications

References 3 publications

Partial discharges and breakdown in C3F8

Partial discharges and breakdown in C3F8

Determination of waiting times between successive breakdown experiments

An Efficient Procedure to Identify and Quantify New Molecules for Insulating Gas Mixtures

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Product

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Partial discharges and breakdown in C₃F₈

Partial discharges and breakdown in C₃F₈