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The effect of water content on the electrical properties of transformer oil

Abdi, S., Safiddine, L., Boubakeur, A. and Haddad, A. ORCID: 2019. The effect of water content on the electrical properties of transformer oil. Presented at: 21st International Symposium on High Voltage Engineering, Frankfurt, Germany, 11-15 March 2019. Proceedings of the 21st International Symposium on High Voltage Engineering Volume 2. Lecture Notes in Electrical Engineering. Lecture Notes in Electrical Engineering , vol.2 Springer Science Business Media, pp. 518-527. 10.1007/978-3-030-31680-8_52

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The condition monitoring of insulating oil used in high voltage apparatus is based on assessing its electrical, physical and chemical properties. During their service life, these apparatuses such as transformers are subjected to several stresses which reduce their insulating capacity. Water and oxygen are the most important factors that accelerate the aging and degradation of transformer oil. There is a strong relationship between the presence of water in oil and the degradation of its electrical properties. This paper presents an experimental investigation to quantify and correlate the change in water content in transformer oil and its effect on their electrical properties. For this purpose, three samples of oil are used: new uninhibited, regenerated and used oil. A physical treatment using a MAXEI station is applied to the three samples to reduce their water content. The treatment is an operation of filtration, degassing and dehydration which is a necessary step before injection of the oil in transformer and during maintenance operations. During the physical treatment, the electrical properties of the oil samples are measured. The breakdown voltage, the dielectric loss factor, the permittivity and the resistivity were measured in according to the standards IEC 60156 and IEC 60247. The results revealed that for the three oil samples; new, regenerated and used, the electrical properties are strongly correlated with the change in water content in oil. The breakdown voltage and resistivity increase considerably when the water content is reduced. If the water content is reduced under 5 ppm, the breakdown voltage remains practically constant. The dielectric loss factor decreases by the water content variation. By decreasing the water content in oil, the insulating properties of transformer oil are improved. The analysis of the results shows that a strong correlation exists between the breakdown voltage, resistivity and the presence of water in oil.

Item Type: Conference or Workshop Item (Paper)
Date Type: Published Online
Status: Published
Schools: Engineering
Publisher: Springer Science Business Media
ISBN: 9783030316792
ISSN: 1876-1100
Last Modified: 07 Nov 2022 11:17

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