Dependence of positive corona streamer propagation on air pressure and water vapor content

Phelps, C. T.; Griffiths, R.F.

doi:10.1063/1.323084

Cited by 114 publications

(86 citation statements)

References 13 publications

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“…Then, assuming that RC is the radius of the charged envelope of the leader channel, we have only a weak logarithmic dependence of C i on the reduced air density 5 because, for a given value of the voltage drop AUt, the radius varies with Sas RC where the relation between the electric field in the streamer channel and 8, Es 613 has been supported both experimentally and numerically (Phelps and Griffiths, 1976;Bazelyan, 1996, Ba.zelyan and). …”

Section: Criterion For Leader Viability At Reduced Air Densitiesmentioning

confidence: 72%

The effect of air density on atmospheric electric fields required for lightning initiation from a long airborne object

Bazelyan

Aleksandrov

Raǐzer

et al. 2007

Atmospheric Research

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Section: Criterion For Leader Viability At Reduced Air Densitiesmentioning

confidence: 72%

The effect of air density on atmospheric electric fields required for lightning initiation from a long airborne object

Bazelyan

Aleksandrov

Raǐzer

et al. 2007

Atmospheric Research

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“…These knife electrodes produced the nonuniform field that the electric field strength was inhomogeneous with the gap distance. It is well known that this non-uniform field leads to the formation [35] and the progress [36] of corona with increasing humidity and applied voltage. A corona discharge was also observed during the surface flashover progress in this experiment.…”

Section: Surface Flashover Voltage Characteristicsmentioning

confidence: 99%

Study on oxygen/nitrogen gas mixtures for the surface insulation performance in gas insulated switchgear

Lim

Bae

2015

IEEE Trans. Dielect. Electr. Insul.

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This paper presents a comparative study on SF 6 alternative candidate gases for the surface insulation performance of eco-friendly Gas Insulated Switchers (GIS) and Solid Insulated Switchers (SIS). The candidate gases including N 2 /O 2 mixture gas, dry air, and compressed air were proposed based on AC surface flashover experiment. These gases were compared and examined based on their surface insulation performance, pressure and gap dependence, surface insulation reliability in different temperatures, economic feasibility and easiness of manufacture. The comparison results verified that dry air had excellent properties on the comparison criteria and was the most suitable eco gas among the candidate gases for eco-friendly GIS and SIS. In addition to the comparative study on the candidate gases, their surface flashover characteristics were described in detail based on the effect of moisture contained in the candidate gases on flashover voltage and the correlation among electric field intensity, collision-ionization coefficient, electron attachment coefficient, and gap length.

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“…The electric field required for sustained positive corona streamer propagation shows a strong linear dependence on the water vapor partial pressure [48]. Yamashita et al [49] performed experiments using several photomultipliers to observe the propagation of local discharge on an electrolyte surface.…”

Section: *2 Mechanisms Of Discharge Propagation Over An Electrolytementioning

confidence: 99%

Mechanisms of arc propagation over an ice surface /

Farokhi¹

2010

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Outdoor insulation design with regard to pollution and icing performance is a critical factor for reliability of overhead transmission lines. The majority of failures occurring on transmission lines are caused by environmental conditions such as lightning, pollution and/or ice. Accumulated ice on insulators may initiate corona discharge; these partial arcs sometimes lead to flashover. This phenomenon is mainly caused by the presence of a highly conductive water film on the surface of the ice and ice-free zones, often called air gaps, along the insulators, and decreased insulator leakage distance caused by ice bridging.The general objective of this research is to investigate the physical mechanisms involved in the propagation of electric arc on the surface of ice. In the present research work, high-speed photography techniques was combined with synchronized electrical measurements to study the various parameters of arc on an ice surface, such as channel radius and propagation velocities. These results, together with studying the propagation patterns and arc foot geometries, provide background information for understanding the complete flashover phenomenon. Arc root structure, current profile, propagation pattern and velocity were investigated under positive and negative polarities. Water film conductivity and thickness, and relative air humidity were also analyzed as influencing parameters of arc propagation. The effects of different mechanisms, e.g. collision and thermal ionization, buoyancy force and electrostatic force, on different stages of arc propagation are also discussed.Repetitive patterns corresponding to arc decays were observed during arc propagation. During arc re-ignitions, an anode-directed streamer was found to be dominant, regardless of the polarity of applied voltage. The arc root under de-positive applied voltage was branched; on the contrary, the negative arc root appeared as a diffused luminous region. In the arc channel section, two distinct regions were distinguished. A linear relationship between the initiation current and the inverse of residual resistance was established, showing how important is the effect of water film thickness on the initiation of discharge. It was found there is a direct relationship between the slope of current increase and the applied water conductivity. Air humidity increases the voltage gradient along the arc channel and reduces the discharge activities at the arc tip. However, it could influence the arc formation and its propagation by changing the thickness of the water film. A change in the dominant mechanism from thermal ionization to collision ionization in the enhanced electric field was found to be responsible for the flashover. Tare. L'effet de différents mécanismes comme les collisions et l'ionisation thermique, la force de flottabilité et la force électrostatique sur les différentes étapes de la propagation de l'arc ont également été discutés. 11 RESUME

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Dependence of positive corona streamer propagation on air pressure and water vapor content

Cited by 114 publications

References 13 publications

The effect of air density on atmospheric electric fields required for lightning initiation from a long airborne object

The effect of air density on atmospheric electric fields required for lightning initiation from a long airborne object

Study on oxygen/nitrogen gas mixtures for the surface insulation performance in gas insulated switchgear

Mechanisms of arc propagation over an ice surface /

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