Drying of Transformer Board |
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Authors: | M El Bari M Rueff M Renaud P Francois |
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Affiliation: |
a Laboratoirc de Genic des Proceed Papetiers (URA CNRS 1100 - INPG) Ecole Francaise de Papeteric etdes lndustrial Graphiques, Saint Martin, France
b Societe Jeumont Schneider Transfomature 84, Avenue Paul Santy, Lyon Cedcx 08, France |
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Abstract: | The internal insulation in shell type power transforms is usually ensured by the stacking of plates of board impregnated with oil. A board is in equilibrium with the atmosphere at a moisture content varying from seven to eight percent by weight, but, when the insulating function is required, the water content must be lower than 0.5 %. The aim of the present work is the understanding and the modelling of transformer boards drying.
The first part of this work presents experimental studies showing that the drying of transform board follows two regimes :
- a fast regime in the fim period
- a slow regime, up to 99 percent of dryness.
The effect of heating and the influence of the board thickness on the drying rate also studied. In the second part of this paper, we presnt a model capable to represent the observed kinetics of transformer board drying. This model is based on the diffusion of water vapour in the gaseous phases combined with the transfer of water vapor from the fibres to the -us phase. The due of the average global transfer coefficient can be deduced from the slope of the curve 1 f(drying time), where x |
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Keywords: | Sorption Isatherms Modelling Physical Properties Global Transfer Coefficient |
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