Streaming Electrification of Different Insulating Fluids in Power Transformers

Arputhasamy Joseph Amalanathan, Maciej Zdanowski () and Ramanujam Sarathi
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Arputhasamy Joseph Amalanathan: Department of High Voltage Engineering, Faculty of Electrical Engineering and Informatics, University of Applied Sciences, 02763 Zittau, Germany
Maciej Zdanowski: Department of Electric Power Engineering and Renewable Energy, Faculty of Electrical Engineering, Automatic Control and Computer Science, Opole University of Technology, Prószkowska 76, 45-758 Opole, Poland
Ramanujam Sarathi: Department of Electrical Engineering, Indian Institute of Technology Madras, Chennai 600036, India

Energies, 2022, vol. 15, issue 21, 1-20

Abstract: This paper presents a detailed review of the streaming electrification phenomena of different insulating fluids for power transformers. The comparison of different techniques used to assess the charging tendency of fluids is discussed depending on the flow type (planar or centrifugal), volume of oil, and interface material. The charge separation between the insulating fluid and metallic/pressboard interfaces is explained in terms of the electrical double layer formation involving a fixed layer and diffuse layer. Based on the experimental results, the streaming electrification is observed to be a function of various factors such as speed, temperature, electric field, and surface roughness. Depending on the molecular structure of insulating liquids that come into contact with solid insulation at the interface, the streaming current can increase; hence, a suitable additive (benzotriazole, fullerene, Irgamet 39) is selected based on the type of fluid and charge polarity. The degradation of the insulating liquid upon ageing, which increases the streaming current and reclamation of such aged fluids using adsorbents (Fuller’s earth, activated carbon, bentonite, and alumina), is a possible method to suppress the static current through improving its dielectric properties. The nanofluids show a higher streaming current compared to base fluid with no change observed even after the reclamation process. The energization process using alternating current (AC) and direct current (DC) impacts the streaming phenomenon depending on its magnitude and polarity. The diffusion of sulfur compounds in the insulating liquid is another major hazard to transformers because the sulfide ions affect the physio-chemical reaction at the interface material, which is responsible for the formation of streaming current.

Keywords: power transformers; insulation diagnostics; dielectric liquids; streaming current; flow pattern; double layer; interfacial zone; additives; electric field; reclamation; sulfur (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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