Etude du phénomène d'électrisation par écoulement sur les cartons des transformateurs de puissance

Abstract : Flow electrification phenomena in power transformers take place at the oil-cellulosic material interface. Oil flowing past the pressboard generates electrical charges at the interface: the pressboard becomes negatively charged, the oil becomes positively charged. This phenomenon can lead to electrical discharges and, in the worst cases, to the transformer failure. To protect power transformers from this phenomenon, the materials involved in the electric charge generation have to be studied in detail. The first experiments have shown that the chemical nature of the cellulosic pulp used to manufacture the pressboard has an influence on the electrical charge generation. The role of acidic functional groups ionisable at low pH, such as carboxyl groups, was studied in detail. Several additives, incorporated in the oil or in the cellulosic material, were tested to improve the understanding of flow electrification and find a remedy against it. An important work has been done testing the effect of different chemical salts to neutralise the carboxyl groups. Acido-basic compounds were added in the oil, and they reduced the charge generation. Moreover, interesting results were found with surfactants (charge inversion), especially with Triton X100. Finally, it was shown that one part of the charge generation is due to interactions between water and impurities contained in the oil with fibres carboxyl groups of fibres. Considering all the results obtained, interpretations concerning the physical chemical phenomena taking place at the interface have been proposed.
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Submitted on : Wednesday, May 2, 2007 - 3:30:54 PM
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  • HAL Id : tel-00144284, version 1

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Audrey Bourgeois. Etude du phénomène d'électrisation par écoulement sur les cartons des transformateurs de puissance. Génie des procédés. Institut National Polytechnique de Grenoble - INPG, 2007. Français. ⟨tel-00144284⟩

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