Assessment of water content in an impregnated pressboard based on DC conductivity measurements theoretical assumptions

¿ukowski, Pawe¿; Ko¿tunowicz, Tomasz N.; Kierczy¿ski, Konrad; Subocz, J.; Szrot, M.; Gutten, Miroslav

doi:10.1109/tdei.2014.6832274

Cited by 54 publications

(25 citation statements)

References 13 publications

(18 reference statements)

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“…References [23,24] have pointed out that the activation energy of oil-impregnated paper is 0.8~0.9 eV. By data fitting, we obtained that u a = 0.84 eV, which was consistent with the literature.…”

Section: Electro-thermal Breakdown Simulationsupporting

confidence: 90%

A Combined Electro-Thermal Breakdown Model for Oil-Impregnated Paper

Huang

Zhou

et al. 2017

Energies

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Abstract:The breakdown property of oil-impregnated paper is a key factor for converter transformer design and operation, but it is not well understood. In this paper, breakdown voltages of oil-impregnated paper were measured at different temperatures. The results showed that with the increase of temperature, electrical, electro-thermal and thermal breakdown occurred successively. An electro-thermal breakdown model was proposed based on the heat equilibrium and space charge transport, and negative differential mobility was introduced to the model. It was shown that carrier mobility determined whether it was electrical or thermal breakdown, and the model can effectively explain the temperature-dependent breakdown.

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Section: Electro-thermal Breakdown Simulationsupporting

confidence: 90%

A Combined Electro-Thermal Breakdown Model for Oil-Impregnated Paper

Huang

Zhou

et al. 2017

Energies

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“…In the paper by _ Zukowski et al (2014) it has been found that conduction in a moist oil-impregnated pressboard is realized as a hopping exchange of electrons (tunneling) and is determined by the presence of water molecules there. In the papers ( _ Zukowski et al 2014( _ Zukowski et al , 2015a it was found that in a composite of cellulose, mineral oil, and water nanoparticles, the conductivity results from electron tunneling between potential wells formed by nanodrops of water.…”

Section: Introductionmentioning

confidence: 99%

“…In the papers ( _ Zukowski et al 2014( _ Zukowski et al , 2015a it was found that in a composite of cellulose, mineral oil, and water nanoparticles, the conductivity results from electron tunneling between potential wells formed by nanodrops of water. The well, from which the electron hops, gets positively charged, while the well into which the electron hops obtains the negative charge.…”

Section: Introductionmentioning

confidence: 99%

Permittivity of a composite of cellulose, mineral oil, and water nanoparticles: theoretical assumptions

et al. 2015

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The paper presents results of testing permittivity of an oil-impregnated electric pressboard containing water nanoparticles depending on AC frequency, moisture content level and the temperature of samples. A new method has been developed for converting experimentally obtained frequency dependences of permittivity determined with the frequencydomain spectroscopy (FDS) to the reference temperature of 293 K (20°C) using exponential dependence of the relaxation time versus temperature. Activation energy of the permittivity relaxation time has been determined for a moist oil-impregnated electric insulation pressboard. It has been established that variations of the moisture content level in a composite of cellulose, mineral oil, and water nanoparticles do not cause any changes in the relaxation time activation energy value, neither in energy states of electrons in potential wells nor in the structure of water nanoparticles. It has been also found that the conversion of experimentally obtained permittivity versus frequency dependences determined with the FDS method to the reference temperature of 293 K (20°C) eliminates temperature dependences that occur in characteristics based directly on measurement results. Once the relative permittivity is converted to the reference temperature it is only its dependence on the moisture content level that remains.

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“…As shown in Figure 7.11, for mineral oil and 164 | P a g e NE impregnated pressboard insulation, the activation energies found are 0.90 eV and 0.91 eV respectively and they show a good match with the values given in [124,253]. On the other hand, synthetic ester impregnated pressboard insulation possesses activation energy of 0.79 eV indicating its less temperature dependence behaviour.…”

Section: 5mentioning

confidence: 53%

“…Here we hypothesise that the effect of mobile charge density is dominant when a sample contains low moisture level and thereby, effective DC conductivity of ester impregnated pressboard should be higher than that of mineral oil impregnated pressboard. We propose that the number of charge transport paths across a sample is solely determined by the concentration of water and moreover, charge mobility is inversely proportional to the distance between water molecules [253]. Thus, DC conductivity for all type of oil impregnated pressboard insulation with higher moisture level should be in a similar range.…”

Section: Through Modelling Of Fds Datamentioning

confidence: 99%

Condition monitoring of biodegradable oil filled transformer

Mudiyanselage¹,

Bandara²

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Natural and synthetic ester insulating oils have higher fire points and excellent biodegradable characteristics. Therefore, in order to reduce the adverse environmental impact and to improve the fire safety of transformers, there is an increasing demand for natural and synthetic ester insulating liquids as a transformer insulating oil. However, present understanding on ageing behaviour of ester oil-paper composite insulation system and knowledge on application of existing condition monitoring tools for ester based insulation systems are inadequate. This impedes the cost effective and reliable field applications of ester insulating oils, particularly application of natural esters. To reduce this knowledge gap, series of controlled ageing experiments are performed in this research project to provide a better and comprehensive understanding on ageing behaviour of ester oil-paper insulation systems. Furthermore, applicability of existing chemical and electrical based condition monitoring techniques for ester oil-paper insulation systems is systematically investigated in this research project.In this thesis, ageing behaviour of dry pressboard insulation in mineral and three different ester insulating oils under simulated transformer operating environment is investigated. Moreover, the ageing behaviour of natural ester-pressboard composite insulation in moisture rich environment is also compared with that of mineral oil-pressboard system. Degree of polymerisation of pressboard samples measured at different ageing interval is used in this research to determine the ageing condition of pressboard. Moreover, applicability of oil related diagnostic parameters such as concentration of dissolved furanic compounds, acidity value, Dielectric Dissipation Factor (DDF), viscosity and colour to assess the degree of degradation of both ester and mineral insulating oils is thoroughly investigated in this research project. The potential of FTIR (Fourier Transform Infrared spectroscopy) techniques for characterising the degree of degradation of paper insulation is also discussed in this thesis. In addition, this thesis concentrates on characterisation of the charge dynamic in insulating oil through modelling of their dielectric responses.The comparison of gassing behaviour of ester and mineral insulating oils under two different low temperature faults and low energy electric discharge condition is also presented in this thesis.Dissolved Gas Analysis (DGA) results presented in this thesis depicts that faults gases detected in ester and mineral oil samples subjected to a similar fault are akin in type but quantitatively different. The quantity of fault gases produced in two different natural ester oils is also dissimilar.For example, soy-based natural ester produces a large quantity of ethane (C2H6) under low temperature overheating condition than sunflower oil based natural ester. Therefore, this research project investigates the applicability of well-established DGA interpretation schemes namely Duval II | P a g e triangle, IE...

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Assessment of water content in an impregnated pressboard based on DC conductivity measurements theoretical assumptions

Cited by 54 publications

References 13 publications

A Combined Electro-Thermal Breakdown Model for Oil-Impregnated Paper

A Combined Electro-Thermal Breakdown Model for Oil-Impregnated Paper

Permittivity of a composite of cellulose, mineral oil, and water nanoparticles: theoretical assumptions

Condition monitoring of biodegradable oil filled transformer

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