Pre-Breakdown Current and Light Emission in Transformer Oil

Yamashita, H.; Amano, Hiroshi

doi:10.1109/tei.1985.348827

Cited by 54 publications

(19 citation statements)

References 9 publications

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“…The full curve represents E/Emin (theoretical value) for a conducting sphere concentric to the point for rpl L = 0.1.] la lumière émise qui accompagne le streamer comme celà a été rapporté par d'autres chercheurs [4,5].…”

Section: Propagation Des Streamersunclassified

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Propagation et génération des streamers dans les diélectriques liquides

Béroual¹,

Tobazéon²

1987

Rev. Phys. Appl. (Paris)

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2014 Cette étude concerne la génération et la propagation des streamers en géométrie pointe-plan sous créneau de tension. Un nouveau dispositif expérimental a permis de montrer qu'il existe une relation étroite entre la forme du streamer, sa vitesse de propagation, la forme du courant et la lumière qu'il émet qu'elles que soient la polarité de la pointe et la nature du liquide. Plus le streamer est filamentaire, plus il est rapide et réciproquement. La distribution de vitesse admet un minimum pour un très grand nombre de liquides isolants pur ou renfermant divers additifs. L'amplitude des vitesses dépend d'une manière importante des propriétés électroniques du liquide et des additifs. L'effet de la pression hydrostatique sur l'apparition des streamers dans les deux polarités, indique l'existence d'une phase gazeuse. Il semble que le mécanisme de cavitation induite par des mouvements électrohydrodynamiques résultant d'une injection unipolaire de charges ne soit pas à l'origine de cette phase gazeuse.Abstract. 2014 This study concerns the initiation and propagation of streamers in point-plane geometry. Our experimental set-up has permitted us to show the existence of a close correlation between the shape of the streamer, its propagation velocity, the current shape and the light it emits, whatever are the polarity of the point and the liquid nature. The more filamentary the streamer, the higher its velocity. The propagation velocity has a minimum for a large variety of insulating liquids wheter pure or containing different additives. The amplitude of the velocity depends strongly on the electronic properties of the liquid and additives. The effects of hydrostatic pressure on the streamer appearance for both polarities suggest the existence of a gas phase. It appears that electrohydrodynamically induced cavitation phenomena, resulting from unipolar charge injection, are not responsible for the gas phase.

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Section: Propagation Des Streamersunclassified

“…6). Ce phénomène paraît général, alors qu'il n'a été observé que dans le n-hexane en pointe positive [5] et dans l'huile de transformateur en pointe négative [4].…”

Section: De Plus Les Courants Sont Parfaitement Corrélés Avecunclassified

Propagation et génération des streamers dans les diélectriques liquides

Béroual¹,

Tobazéon²

1987

Rev. Phys. Appl. (Paris)

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“…Electronic theory for liquid pre-breakdown has been proposed for several decades and, evidence of it has often been reported. The following had been discussed in detail: the process from escape of electrons, travel through mean free path, formation of a low-density region, increase of mean free path, and emerging and developing of a streamer, to partial discharge at last [14][15][16][17][18][19][20][21][22][23][24][25]. Comprehensive summaries of evidence that support this theory had been listed in [14].…”

Section: Electronic Theory On Liquid Pre-breakdown Mechanismsmentioning

confidence: 99%

“…Comprehensive summaries of evidence that support this theory had been listed in [14]. Focal points of this theory, like mechanism of emission [14,17,19,20], differences in formation and propagation of negative and positive streamers [14][15][16][17][18][19][21][22][23][24][25], and field distortion owing to space charge effect [14,16,17,[19][20][21]25], had been studied with different methods and apparatus.…”

Section: Electronic Theory On Liquid Pre-breakdown Mechanismsmentioning

confidence: 99%

Research on a practical de-noising method and the characterization of partial discharge UHF signals

Wang

et al. 2014

IEEE Trans. Dielect. Electr. Insul.

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Experimental studies on partial discharges (PD) occurred in oil-insulated devices using ultra-high frequency (UHF) sensors to detect PD signals and using wavelet analysis to process the acquired UHF signals are presented, and a threshold selecting method adapting to various noise circumstances when de-noising UHF signals using wavelet transform is proposed in this paper. The threshold method was based on numerical fitting of standard deviations and manual setting thresholds for brush-fire samples from a large scale. Horizontal comparisons between different geometries and vertical comparisons between different intensities of partial discharges in oil were also discussed and the mathematical tool was wavelet analysis. Multi-resolution analysis (MRA) results show the significant differences that can be used to recognize the discharge pattern and to judge the intensity. Particularly attention was given to needle-plate discharge geometry, which was often used by researchers focusing on the mechanism of pre-breakdown phenomena in liquid dielectrics. The results of needle-plate model show good agreement with electronic theory of liquid pre-breakdown mechanism.Index Terms -Partial discharge, wavelet analysis , de-noising, pre-breakdown.

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“…As shown in Figure l(b), a series of current pulses having charge amplitudes of 18 -55 pC were observed at 2.13 ps after the voltage application, which was 4.50 ns prior to the streamer inception. These current pulses believed to cause the streamer in the liquid as well as in transformer oil [7] and hydrocarbon liquid [8,9]. Figure 2 shows a negative streamer propagation obtained by using 500 ns frame interval.…”

Section: Experimental Apparatusmentioning

confidence: 99%

Simultaneous measurements of streamer and partial discharge processes in perfluorinated polyether

Yamashita

Okumura

Yamazawa

et al.

Proceedings of 1994 4th International Conference on Properties and Applications of Dielectric Materials (ICPADM)

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In this paper, the effect of polarity on prebreakdown phenomena in perfluorinated polyether (PFPE) under non-uniform field was investigated. The inception and propagation of streamers were observed using a high speed and high magnification shadowgraph system. The current pulses were also measured simultaneously using a LED current pulse measurement system. The streamer inception voltage for both polarities were -9.99 kV and +12.86 kV, respectively. The deviation of time delay from the voltage application to the streamer inception was larger for a positive point than a negative. The initial shape of the negative streamer was a filament which emanated from a needle tip. On the other hand, for a positive point, a filamentary streamer started at about 9 μm away from a needle tip, and propagated toward a needle tip. These experimental results suggested that the inception of a positive streamer needs much higher field than a negative one due to the higher ionization potential of fluorine atom in PFPE as well as breakdown voltage

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Pre-Breakdown Current and Light Emission in Transformer Oil

Cited by 54 publications

References 9 publications

Propagation et génération des streamers dans les diélectriques liquides

Propagation et génération des streamers dans les diélectriques liquides

Research on a practical de-noising method and the characterization of partial discharge UHF signals

Simultaneous measurements of streamer and partial discharge processes in perfluorinated polyether

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