Qualitative model of breakdown in SF<sub>6</sub>in inhomogeneous gaps

Pinnekamp, Friedrich; Niemeyer, L.

doi:10.1088/0022-3727/16/7/019

Cited by 62 publications

(10 citation statements)

References 6 publications

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“…Theoretical work on leaders in strongly electronegative gases like SF6 has been very scarce so far. Niemeyer and Pinnekamp (1983) attempted a physical interpretation of their results concerning the leader stage and succeeded in giving a qualitative description of the leader breakdown (Pinnekamp and Niemeyer 1983). The theoretical approach followed in this study gives some new insight into the necessary conditions for leader inception, although a complete mathematical description is not yet possible.…”

Section: Introductionmentioning

confidence: 99%

Streamer and leader formation in SF₆and SF₆mixtures under positive impulse conditions. II. Streamer to leader transition

Gallimberti

Wiegart

1986

J. Phys. D: Appl. Phys.

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For pt.I see ibid., vol.12, p.2351 (1986). This second paper on the breakdown mechanisms in electronegative gases under non-uniform field conditions deals with the development of the leader type of discharge, the emphasis being laid on details of the streamer to leader transition, which is found to be very much different from the corresponding process in air. In a strongly electronegative gas, the streamer to leader transition involves a 'leader precursor' that has been observed for the first time. A hypothesis relating precursor inception to an ion drift phenomenon is shown to explain the observed parameter dependences satisfactorily. Numerical simulations have been performed, revealing details of precursor formation. Some experimental results concerning the further development of the leader channel are also presented.

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Section: Introductionmentioning

confidence: 99%

Streamer and leader formation in SF₆and SF₆mixtures under positive impulse conditions. II. Streamer to leader transition

Gallimberti

Wiegart

1986

J. Phys. D: Appl. Phys.

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“…Pinnekamp states that there has been no consistent model of breakdown in inhomogeneous geometries because both streamer and leader modes exist in these geometries and confuse the issue [73]. Pinnekamp previously did a series of breakdown experiments over a wide pressure range and came up with some breakdown characteristics, but not a quantitative model.…”

Section: Pinnekamp 1983mentioning

confidence: 99%

Surface interactions involved in flashover with high density electronegative gases.

Hodge¹,

Warne²,

Jorgenson³

et al. 2010

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This report examines the interactions involved with flashover along a surface in high density electronegative gases. The focus is on fast ionization processes rather than the later time ionic drift or thermalization of the discharge. A kinetic simulation of the gas and surface is used to examine electron multiplication and includes gas collision, excitation and ionization, and attachment processes, gas photoionization and surface photoemission processes, as well as surface attachment. These rates are then used in a 1.5D fluid ionization wave (streamer) model to study streamer propagation with and without the surface in air and in SF6. The 1.5D model therefore includes rates for all these processes. To get a better estimate for the behavior of the radius we have studied radial expansion of the streamer in air and in SF6. The focus of the modeling is on voltage and field level changes (with and without a surface) rather than secondary effects, such as, velocities or changes in discharge path. An experiment has been set up to carry out measurements of threshold voltages, streamer velocities, and other discharge characteristics. This setup includes both electrical and photographic diagnostics (streak and framing cameras). We have observed little change in critical field levels (where avalanche multiplication sets in) in the gas alone versus with the surface. Comparisons between model calculations and experimental measurements are in agreement with this. We have examined streamer sustaining fields (field which maintains ionization wave propagation) in the gas and on the surface. Agreement of the gas levels with available literature is good and agreement between experiment and calculation is good also. Model calculations do not indicate much difference between the gas alone versus the surface levels. Experiments have identified differences in velocity between streamers on the surface and in the gas alone (the surface values being larger).

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“…On the other hand, in the gas pressure region of P = 0.3 to 0.4 MPa, nonlinearity of the BDVpressure characteristic shows up (this is a feature of SF 6 gas in a nonuniform electric field, the so-called N-characteristic). With a rod-toplane electrode system in SF 6 gas, dc-positive PD evolves from a streamer into an unstable leader; breakdown may occur almost simultaneously with PD, while the BDV is lower for positive dc [12]. Thus, we may suppose that in the case of a VLF voltage, the positive and negative cycles have characteristics that are similar to, respectively, positive and negative dc; that is, when metallic particles are available near a high-voltage conductor, the BDV is lower in the positive cycle.…”

Section: Dependence On Gas Pressurementioning

confidence: 99%

Metallic particle motion and breakdown characteristics in GIS with 0.1‐Hz VLF (very low frequency) high voltage applied

Saitô

Takahashi

Hayakawa

et al. 2002

Electrical Engineering Japan

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SUMMARYVLF (Very Low Frequency) high voltage with frequency of 0.1 Hz will be utilized for an on-site test of XLPE underground cables, instead of conventional dc high voltage test. Since XLPE cables are connected to GIS (Gas Insulated Switchgears) in substations, the influence of VLF voltage application to GIS insulation should be investigated. One of the most important characteristics for GIS insulation lies in the metallic particle contamination and its behavior, which may induce breakdown in GIS.From the above viewpoint, this paper discusses the metallic particle behavior and breakdown characteristics under VLF voltage application in GIS. Experimental results revealed that (1) Particle motion under VLF condition was similar to that under dc condition, while specific in the transient behavior at the polarity reversal. (2) Breakdown was induced by particles located in the vicinity of high voltage conductor at the instance of crossing the gap or in the firefly conditions. (3) Breakdown voltage in positive half cycle was higher than that in negative half cycle at the lower gas pressure, while lower at the higher gas pressure, which was attributed to the particle behavior and the breakdown mechanism of SF 6 gas.Consequently, metallic particles in GIS under VLF voltage application exhibited the specific behavior associated with the slow change of instantaneous voltage and polarity, and resulted in the complex pressure dependence of breakdown characteristics.

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Qualitative model of breakdown in SF₆in inhomogeneous gaps

Cited by 62 publications

References 6 publications

Streamer and leader formation in SF₆and SF₆mixtures under positive impulse conditions. II. Streamer to leader transition

Streamer and leader formation in SF₆and SF₆mixtures under positive impulse conditions. II. Streamer to leader transition

Surface interactions involved in flashover with high density electronegative gases.

Metallic particle motion and breakdown characteristics in GIS with 0.1‐Hz VLF (very low frequency) high voltage applied

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Qualitative model of breakdown in SF6in inhomogeneous gaps

Cited by 62 publications

References 6 publications

Streamer and leader formation in SF6and SF6mixtures under positive impulse conditions. II. Streamer to leader transition

Streamer and leader formation in SF6and SF6mixtures under positive impulse conditions. II. Streamer to leader transition

Surface interactions involved in flashover with high density electronegative gases.

Metallic particle motion and breakdown characteristics in GIS with 0.1‐Hz VLF (very low frequency) high voltage applied

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Qualitative model of breakdown in SF₆in inhomogeneous gaps

Streamer and leader formation in SF₆and SF₆mixtures under positive impulse conditions. II. Streamer to leader transition

Streamer and leader formation in SF₆and SF₆mixtures under positive impulse conditions. II. Streamer to leader transition