The role of outgassing in surface flashover under vacuum

Neuber, A.; Butcher, M.; Krompholz, H.; Hatfield, L.L.; Kristiansen, M.

doi:10.1109/ppc.1999.825505

Cited by 8 publications

(8 citation statements)

References 6 publications

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“…However, when insulator length is relatively long and charge accumulation is enough, positive charges on insulator surface will arrest lots of electrons, guide electron impact with insulator surface, and result in the emission of secondary electrons. In addition, the role of outgassing [14] in a longer surface length would be much significant. These processes will make subsequent flashover development more quickly.…”

Section: Flashover Time Lag Of Nanosecond Pulse Appliedmentioning

confidence: 99%

Experimental investigation of surface flashover in vacuum using nanosecond pulses

Yan

Shao

Wang

et al. 2007

IEEE Trans. Dielect. Electr. Insul.

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Based on a Marx generator and a coaxial pulse forming line, an experimental investigation of surface flashover characteristics in vacuum is conducted by using nanosecond pulses of 10 ns rise time and 30 ns full width at half maximum (FWHM). Insulator dielectrics chosen for this investigation are Teflon, PMMA and Nylon. The tested factors include gas pressure, cone angle of conical frustum, diameter and length of cylindrical insulator, material and shape of electrode, and contact style between insulator and electrodes. The effects of these parameters on the surface flashover characteristics are described and analyzed in this paper. In addition, the character of flashover time lag in the nanosecond range, and surface flashover theory in vacuum charged by nanosecond pulses are also discussed.Index Terms -Surface flashover, vacuum, nanosecond pulse, cathode triple junction, electron emission. Ping Yan

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Section: Flashover Time Lag Of Nanosecond Pulse Appliedmentioning

confidence: 99%

Experimental investigation of surface flashover in vacuum using nanosecond pulses

Yan

Shao

Wang

et al. 2007

IEEE Trans. Dielect. Electr. Insul.

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“…FO development time T FO is defined from FO inception (when anode current begins to flow due to EEE) through the initial peak of anode current, as shown in Fig. Now, anode current in case of c-i-a flashover increases in two stages [4,12]. Now, anode current in case of c-i-a flashover increases in two stages [4,12].…”

Section: Extraction Of Features Of Various Discharge Patternsmentioning

confidence: 99%

Discharge Pattern Discrimination for Composite Insulation System in Vacuum

Kong

Kojima

et al. 2017

Electrical Engineering Japan

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In order to develop higher-voltage vacuum circuit breakers (VCBs), the investigation of discharge phenomenon in vacuum is necessary. In vacuum interrupters (VIs) with composite insulation systems, the discharge has complex and various patterns at the internal insulation failures. In this paper, based on the discharge development characteristics, we propose a discrimination method for the discharge pattern in vacuum. We measured the applied voltage, anode current, and shield potential waveforms, respectively. From the feature of the measured waveforms, we classified the discharge patterns. Furthermore, based on the relation between discharge development time and discharge path length, we estimated the discharge patterns and discharge path lengths. In addition, we conducted a verification experiment of the discrimination method using a VI model. Experimental results revealed that the estimated discharge patterns and discharge path lengths were consistent with the observed discharge ones and the effectiveness of the discrimination method was confirmed. C⃝

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“…The surface discharge in vacuum can be influenced by many factors such as charging on solid dielectrics [7][8][9], electric field distribution [10], insulator materials [11,12], and adsorption gas [12][13][14] etc. Generally, the surface discharge event in vacuum is considered to be a process that starts with the electron emission from the metal cathode (not only the cathode triple junction but also the center shield and/or the relaxation ring of the VI), giving rise to a secondary electron emission avalanche (SEEA) due to the collision of the emitted electrons from the dielectrics, and ends with the flashover occurring in the desorbed surface gas layer [15].…”

Section: Introductionmentioning

confidence: 99%

Pre-discharge and flashover characteristics of impulse surface discharge in vacuum

Nakano

Kojima

Hayakawa

et al. 2014

IEEE Trans. Dielect. Electr. Insul.

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Surface discharge on solid insulators is one of the significant issues in the development of vacuum circuit breakers (VCB) and vacuum interrupters (VI).We measured the charge activity on alumina dielectrics in vacuum through ultra-high speed and high sensitivity optical measurements. We identified the existence of charge activity with a small light emission on alumina dielectrics before the surface flashover development process, and defined this as a "pre-discharge" and measured its characteristics. We classified the charge activities into three processes: (1) pre-discharge, (2) surface flashover initiation, and (3) surface flashover expansion, in the development of surface discharge in vacuum. Utilizing this classification, we found that the surface predischarge in vacuum is generated by the electron emission from the cathode, and the subsequent flashover initiates with a steep increase in current and develops with the distortion of the electric field due to transiently-formed charging on the alumina dielectrics in vacuum.

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The role of outgassing in surface flashover under vacuum

Cited by 8 publications

References 6 publications

Experimental investigation of surface flashover in vacuum using nanosecond pulses

Experimental investigation of surface flashover in vacuum using nanosecond pulses

Discharge Pattern Discrimination for Composite Insulation System in Vacuum

Pre-discharge and flashover characteristics of impulse surface discharge in vacuum

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