Combined Effect of Temperature and Electrical Discharges on the Properties of Transformer Mineral Oils

Combined Effect of Temperature and Electrical Discharges on the Properties of Transformer Mineral Oils

Abderrahim Reffas Omar Idir Abderrahmane Ziani Slimene Ameur Hocine Moulai Azzedine Nacer Ilheme Khelfane Derradji Rebbouh

LSEI/FEI, USTHB: University of Sciences and Technology Houari Boumediene BP 32, Bab Ezzouar, Algiers, Algeria

Centre of Research and Development of Electricity and Gas (CREDEG) 36 Route de Ouled Fayet, El Achour, Algiers, Algeria

Corresponding Author Email: 
reffas.abderrahim@live.fr
Page: 
61-77
|
DOI: 
https://doi.org/10.3166/EJEE.18.61-77
Received: 
10 June 2015
| |
Accepted: 
22 January 2016
| | Citation

OPEN ACCESS

Abstract: 

The service life of power transformers is expected to be between 35 and 40 years. As a consequence of ageing, the transformer oil deteriorates gradually and becomes increasingly contaminated. Life of a power transformer depends primarily on life of its insulation system. Then, it is important to keep the oil’s properties near to those of new oil. One way to resolve the problem is to reclaim the insulating oil before the degradation goes too far. The reclaimed oil should have many similar characteristics of those of new oils. For instance, this work is devoted to study the physicochemical properties of reclaimed oil simultaneously submitted to thermal stresses and electric discharges. It will be compared with three transformer mineral oils of different levels of degradation. The first oil is new and untreated whereas the second is taken from a transformer still operational after thirty years of service, and the third oil is extracted from a transformer just having incurred a Buckholtz after eight years of service. The considered parameters are water content, breakdown voltage, dielectric constant, dissipation factor and resistivity. Dissolved gas analysis (DGA) has also been performed on the oil which is extracted from a transformer just having incurred a Buckholtz, and the reasons of such failure have been discussed.

Keywords: 

transformer oil, reclaimed oil, temperature, electrical discharges, dissolved gas analysis.

1. Introduction
2. Experimental Technique
3. Experimental Results
4. Conclusion
Acknowledgment

The authors would like to thank the Agence Thématique de Recherche en Sciences et Technologie-ATRST-DGRSDT-MESRS for grant in aid for this research through Nour21 research program, the Centre of Research and Development of Electricity and Gas (CREDEG-SONELGAZ) for their support in materials and in oil samples providing.

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