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Piekary Śląskie, Poland

Romanyuk F.,Belarusian National Technical University | Novash I.,Belarusian National Technical University | Loman M.,Belarusian National Technical University | Wegierek P.,Lublin University of Technology | Szrot M.,Power Engineering Research Center Ltd.
Przeglad Elektrotechniczny | Year: 2014

Comparison of results of mathematical modeling and field tests of a transformer differential protection is presented in this paper. An inrush current mode, external two-phase and three-phase faults are considered. Proposed mathematical model can be used to test differential protection in different modes of transformer operation. Source


Sebok M.,University of Zilina | Zukowski P.,Lublin University of Technology | Koltunowicz T.N.,Lublin University of Technology | Kierczynski K.,Lublin University of Technology | And 2 more authors.
10th International Conference, ELEKTRO 2014 - Proceedings | Year: 2014

The article presents the results of research based on the DC electrical conductivity of wet paper depending on the moisture content and temperature of the samples. The change of moisture content does not change the activation energy of conductivity. The conductivity is performed by the hopping mechanism between the nearest possible holes which are formed in the material with nanodrops of water by the plotting of theoretical dependence that accurately describes the dependence of the conductivity of the water content and temperature. Medium size of nanodrops was about 1.5 nm, and the composition contains about 220 molecules of water. © 2014 IEEE. Source


Jurcik J.,University of Zilina | Gutten M.,University of Zilina | Korenciak D.,University of Zilina | Zukowski P.,Lublin University of Technology | And 4 more authors.
10th International Conference, ELEKTRO 2014 - Proceedings | Year: 2014

In paragraph are presented the results of research based on the AC conductivity of the wet oil-impregnated insulating paper, depending on the moisture content and temperature of the samples. This is a new experimental method, which converts the results from the FDS to the reference temperature of 293.15 K (20 ° C). Takes account of the activation energy for conduction and relaxation time © 2014 IEEE. Source


Zukowski P.l,Lublin University of Technology | Koltunowicz T.N.,Lublin University of Technology | Kierczynski K.,Lublin University of Technology | Subocz J.,West Pomeranian University of Technology | Szrot M.,Power Engineering Research Center Ltd.
Cellulose | Year: 2015

This article presents results on the DC conductivity of moist pressboard impregnated with insulating oil and its dependence on the moisture and temperature of the samples. The transfer of charges was found to take place because of electron hopping between potential wells produced by water nanodrops. The average dimension of the nanodrops was around 2.32 nm, forming approximately 220 water molecules. © 2015, The Author(s). Source


Zukowski P.,Lublin University of Technology | Koltunowicz T.N.,Lublin University of Technology | Kierczynski K.,Lublin University of Technology | Rogalski P.,Lublin University of Technology | And 5 more authors.
Cellulose | Year: 2016

The paper presents an analysis of test results by Frequency Domain Spectroscopy (FDS) of the loss tangent (tgδ) in electrotechnical pressboard impregnated with insulating oil and containing nanoparticles of water depending on the frequency of alternating current, sample temperature and degree of moisture. We found tgδ reduction in areas of low and ultra-low frequency. It is associated with relaxation due to the hopping conductivity (tunnelling) of electrons between moisture nanoparticles occurring in the cellulose impregnated with insulating oil. In frequency areas close to the local minimum of tgδ and higher, relaxation does not depend on the moisture content and is associated with other polar molecules which are part of the cellulose. We developed a new method converting experimental frequency dependence of the loss angle tangent, measured by the FDS method to the reference temperature of 293 K (20 °C), using the exponential dependence of the relaxation time on the temperature, was developed. The activation energy of the relaxation time was determined based on the loss angle tangent of moist electrotechnical pressboard impregnated with insulating oil. It was found that the variation in moisture content in the composite cellulose–mineral oil–water nanoparticles do not cause changes in the activation energy of the relaxation time. The conversion of experimental frequency dependence of the loss angle tangent determined by the FDS method to the reference temperature of 293 K (20 °C) eliminates the temperature dependence in the areas of ultra-low and low frequencies occurring in the runs made directly on the basis of the measurement results. After calculating the frequency dependence of the loss angle tangent to the reference temperature, all that remains is its dependence on the moisture content. © 2016 The Author(s) Source

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