Study on dielectric breakdown at DC polarity reversal in oil / pressboard-composite insulation system

Nara, T.; Katō, K.; Endo, Fumio; Ōkubo, H.

doi:10.1109/ceidp.2009.5377777

Cited by 9 publications

(2 citation statements)

References 12 publications

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“…According to IEC62199, the time of the polarity reversal mainly depends on the testing equipment available and should be as short as possible, but there are few cases longer than 2 min . Hence, in this simulation, the duration time of polarity reversal is set to a short one, which is much less than the diffusing time of the space charge and thus poses little influence on the dynamic characteristics of the space charge . The pre‐stressing DC voltage lasts 300 min, followed by the polarity reversal voltage lasting 600 min.…”

Section: Electric Field Analysis With Space Charge Effectsmentioning

confidence: 99%

Electric field computation of ±1000 kv dc wall bushing with consideration of space charge effects

Zhang

et al. 2013

Int. Trans. Electr. Energ. Syst.

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SUMMARY ±1000 kV DC wall bushing under planning is a complex insulation system which bears the effects imposed by different working conditions. The existence of space charge distorts the electric field distribution, which might result in electric breakdown especially when polarity reversal occurs. Based on space charge theory, the amount of space charge can be calculated. A finite‐element model for ±1000 kV DC wall bushing is established to analyze the electric field distribution under DC, AC and polarity reversal conditions especially considering the space charge effects. The electric field distribution with thermal stress is also calculated in this paper to incorporate the influence of the dielectric temperature gradients. The research results provide useful reference for electric field computation and further insulation optimization in developing ultra high voltage DC wall bushings. Copyright © 2013 John Wiley & Sons, Ltd.

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Section: Electric Field Analysis With Space Charge Effectsmentioning

confidence: 99%

Electric field computation of ±1000 kv dc wall bushing with consideration of space charge effects

Zhang

et al. 2013

Int. Trans. Electr. Energ. Syst.

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“…In 1994, Takahashi studied the influence of electrical stress on the conductivity of oil-impregnated pressboard; however, the results were qualitative and cannot be adopted to determine the electric field strength within oil-pressboard insulation [15]. In real converter transformers, the pressboard of the valve-side windings needs to handle a very strong DC electric field, normally 10 7 V/m or higher [16]. Under such a strong electric field, the conductivity of the oil-impregnated pressboard will exhibit certain characteristics.…”

Section: Introductionmentioning

confidence: 99%

Study on the Influence of Temperature, Moisture and Electric Field on the Electrical Conductivity of Oil-Impregnated Pressboard

Zhou

Zhu

et al. 2019

Energies

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The main insulation of converter transformers consists of transformer oil and oil-impregnated pressboard. Under operating conditions, the valve-side winding of the converter transformer is subject to DC voltage components. Therefore, studies on the characteristics of oil-impregnated pressboard conductivity are necessary. In this paper, the temperature, moisture and electric field dependency of pressboard conductivity are investigated based on a specially designed three-electrode experimental chamber, which allows for a variation in temperature ranging from 25 °C to 120 °C and an electric field strength ranging from 0 to 30 kV/mm. The experimental results show that, within the experimental conditions, the conductivity of oil-impregnated pressboard increases exponentially with increasing moisture and temperature. High moisture and temperature will increase both the carrier concentration and carrier mobility, which explains the exponential correspondence. Furthermore, the electric field dependency of the conductivity is more obvious for wet pressboard than for dry pressboard. Protons in the wet pressboard are more easily accelerated by the electric field than the impurity ions in the oil of the dry pressboard, which leads to an obvious electric field dependency of the wet pressboard conductivity.

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Flow electrification characteristics of oil-pressboard insulation under polarity reversal electric field

Gao

Chen

Chi

et al. 2013

2013 Annual Report Conference on Electrical Insulation and Dielectric Phenomena

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Study on dielectric breakdown at DC polarity reversal in oil / pressboard-composite insulation system

Cited by 9 publications

References 12 publications

Electric field computation of ±1000 kv dc wall bushing with consideration of space charge effects

Electric field computation of ±1000 kv dc wall bushing with consideration of space charge effects

Study on the Influence of Temperature, Moisture and Electric Field on the Electrical Conductivity of Oil-Impregnated Pressboard

Flow electrification characteristics of oil-pressboard insulation under polarity reversal electric field

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