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Modélisation numérique des phénomènes de transport électrique dans un isolant polyéthylène sous contrainte électrique

Abstract : Undergrounding overhead electrical lines is a define goal for the European Commission. Synthetic materials used as insulators in electric cables for the transport of electricity gave entire satisfaction as compared to the traditional techniques. However, polymers used as insulators in those high voltage cables suffer degradations, causing early aging of the material. This aging comes from the space charge created in the dielectric, due to injection or dissociation inside the bulk. Those charges induce such distortions of the field that it can cause the dielectric rupture of the material. In order to overcome this problem, it is necessary to understand the transport mechanisms in polymeric dielectrics. Thus, we developed a simple numerical model, able to reproduce the experimental results and to obtain some responses about the charge generation and conduction phenomena in polyethylene. It is an original approach, as we studied charge transport in non-stationary states. This study takes into account microscopic characteristics of the LDPE, but the modelling is macroscopic. It strongly allies numerical modelling and experiments. Space charge, electroluminescence and current measurements provide in a first step some parameters for the modelling. In a second step, they permit to adjust the parameters, in order to valid the model. A unique set of parameters has been chosen, and the results of the simulation have been compared to different experiments, traducing the global behaviour of the polyethylene. Different protocols of application of the voltage have been used to valid the model, under DC and AC.
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https://tel.archives-ouvertes.fr/tel-00347923
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Submitted on : Wednesday, December 17, 2008 - 10:29:54 AM
Last modification on : Wednesday, December 9, 2020 - 9:40:02 AM
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Séverine Le Roy. Modélisation numérique des phénomènes de transport électrique dans un isolant polyéthylène sous contrainte électrique. Autre. Université Paul Sabatier - Toulouse III, 2004. Français. ⟨tel-00347923⟩

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