Journal ArticleDOI
Ageing rate of paper insulation used in power transformers Part 2: Oil/paper system with medium and high oxygen concentration
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In this paper, the ageing rate of dry paper in air (excess oxygen) has been studied for thermally upgraded Kraft paper in medium and high oxygen with varying water content, and it has been shown that the paper with the same water content increased with oxygen content in the oil.Abstract:
Utility asset managers and engineers are concerned about the life and reliability of their power transformers which depends on the continued life of the paper insulation. The ageing rate of the paper is affected by water, oxygen and acids. Traditionally, the ageing rate of paper has been studied in sealed vessels however this approach does not allow the possibility to assess the affect of oxygen on paper with different water content. The ageing rate of paper has been studied for dry paper in air (excess oxygen). In these experiments we studied the ageing rate of Kraft and thermally upgraded Kraft paper in medium and high oxygen with varying water content. Furthermore, the oxygen content of the oil in sealed vessels is low which represents only sealed transformers. The ageing rate of the paper has not been determined for free breathing transformers with medium or high oxygen content and for different wetness of paper. In these ageing experiments the water and oxygen content was controlled using a special test rig to compare the ageing rate to previous work and to determine the ageing effect of paper by combining temperature, water content of paper and oxygen content of the oil. We found that the ageing rate of paper with the same water content increased with oxygen content in the oil. Hence, new life curves were developed based on the water content of the paper and the oxygen content of the oil.read more
Citations
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Journal ArticleDOI
Ageing rate of paper insulation used in power transformers Part 1: Oil/paper system with low oxygen concentration
TL;DR: In this article, the authors used a special test rig to compare the ageing rate to previous work and to determine the ageing effect of paper by combining temperature, water content of paper and oxygen content of the oil.
Journal ArticleDOI
An Updated Model to Determine the Life Remaining of Transformer Insulation
TL;DR: An algorithm is tested which takes the synergistic effect of water and oxygen on increasing the rate of paper aging into account and shows better agreement with the test results than that given from using the IEEE standard.
Journal ArticleDOI
The effect of acid accumulation in power-transformer oil on the aging rate of paper insulation
TL;DR: In this article, the aging of paper insulation in order to prolong the life of transformers is discussed. But the paper becomes severely degraded, it loses its mechanical strength and thus its ability to insulate the windings.
Journal ArticleDOI
Studying the loss of life of natural-ester-filled transformer insulation: impact of moisture on the aging rate of paper
TL;DR: In this article, an equation to determine the reduction of service lifetime of transformer solid insulation subjected to increased temperature and with increased moisture content is proposed, which is based on an analytical model.
Journal ArticleDOI
Temperature correction to dielectric modulus and activation energy prediction of oil-immersed cellulose insulation
TL;DR: In this paper, the authors report an approach for understanding the temperature impact on both Μ∗(ω) and activation energy (E a ) of transformer immersed cellulose insulation.
References
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Journal ArticleDOI
Aging of oil-impregnated paper in power transformers
TL;DR: In this article, the effects of moisture, oxygen, and acidity upon the aging of Kraft and thermally upgraded ("Insuldur/spl reg/") papers have been studied in detail.
Journal ArticleDOI
Degradation of cellulosic insulation in power transformers. Part 3: effects of oxygen and water on ageing in oil
TL;DR: In this article, the effects of heat, water and oxygen on cellulose insulation degradation in electrical transformers have been studied over a number of years using degree of polymerization (DP) of the paper as a measure of ageing.
Journal ArticleDOI
Ageing of Mineral Oil Impregnated Cellulose by Acid Catalysis
TL;DR: In this paper, acid catalyzed ageing of oil impregnated kraft paper has been studied experimentally and five carboxylic acids (formic, acetic, laevulinic, stearic and naphtenic acid) have been added to mineral oil to reach a neutralization value of 0.4 mg KOH/g.
Journal ArticleDOI
Degradation of electrical insulating paper monitored with high performance liquid chromatography
J. Unsworth,F. Mitchell +1 more
TL;DR: In this article, the degradation of electrical kraft paper under carefully controlled laboratory experiments is examined in order to find correlations between the change in dielectric and mechanical properties and the increase in concentration of furan compounds in the oil.
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