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Theses

Développement de nouvelles méthodes de diagnostic et de régénération des huiles pour transformateurs de puissance

Abstract : A power transformer outage has a dramatic financial consequence not only for electric power systems utilities but also for interconnected customers. In order to prevent any failure and to optimize their maintenance, various diagnostic techniques and tools have been developed. Insulating oil contains about 70% of diagnostic information on the transformer condition. The challenge is to access and use them efficiently. To meet this objective reliable diagnostic techniques are required. In addition to traditional testing methods, three recently developed ASTM testing techniques were used: (1) oil stability testing that simulates the behaviour of oil under electrical stress by providing information on its quality; (2) the UV/Visspectrophotometry that measures the amount of the relative dissolved decay products in insulating oil; and (3) the turbidity that measures the purity of virgin and aged oil. A quantitative laboratory technique capable of determining the parameters affecting the formation of corrosive sulphur deposition on copper conductors in power transformer is proposed. It is shown among other that the gassing tendency of natural esters is lower than that of the other types of insulating fluids (mineral oil, synthetics esters and silicone oil). The turbidity and UV/Vis spectrophotometry allow quantifying effectively, the relative amount of contaminants resulting from electrical discharge in oils. A large number of reclamation cycles (around 15 passes) are required for in-service aged oil to regenerate to the level of new oil. Anew technique enabling reducing the number of reclamation cycles is proposed; this latter consists in the use of Fuller’s Earth previously treated with dry nitrogen. It is also shown that time is the most influential parameter in the formation of corrosive sulfur. The process is accelerated when time and aggressiveness of oxygen are partnered.
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Submitted on : Thursday, September 29, 2011 - 5:38:27 PM
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  • HAL Id : tel-00627891, version 1

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Janvier N'Cho. Développement de nouvelles méthodes de diagnostic et de régénération des huiles pour transformateurs de puissance. Autre. Ecole Centrale de Lyon, 2011. Français. ⟨NNT : 2011ECDL0004⟩. ⟨tel-00627891⟩

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