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
|
Published: 
30 April 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.

  References

Abedian B., Baker K N. (2008). Temperature Effects on the Electrical Conductivity of Dielectric Liquids. IEEE Transactions on Dielectrics and Electrical Insulation, vol. 15, n° 3, p. 888-892.

Augusta M., Martins G., Gomes A R. (2012). Vegetable Oils for Liquid-Filled Transformers. IEEE Electrical Insulation Magazine, vol. 18, n° 1, p. 6-11.

Badicu L. V., Gorgan B., Dumitran L. M., Notingher P. V. (2012). Assessment of Transformer Mineral Oil Condition Based on dc and ac Conductivity. IEEE Transactions on Dielectrics and Electrical Insulation, vol. 19, n° 5, p. 1544-1551.

Cho J. S., Fofana I., Beroual A., Aka-Ngnui T., Sabau J. (2012). Aged oils reclamation: Facts and arguments based on laboratory studies. IEEE Electrical Insulation Magazine, vol. 19,n° 5, p. 1583-1592.

Cho J. S., Fofana I., Beroual A., Aka-Ngnui T., Sabau J. (2011). The Gassing Tendency of Various Insulating Fluids under Electrical Discharge. IEEE Transactions on Dielectrics and Electrical Insulation, vol. 18, n° 5, p. 1616-1625.

Duval M. (2002). A Review of Faults Detectable by Gas-in-Oil Analysis in Transformers. IEEE Electrical Insulation Magazine, vol. 18, n° 3, p. 22-27.

Duval M. (1989). Dissolved Gas Analysis: It Can Save Your Transformer. IEEE Electrical Insulation Magazine, vol. 5, n° 6, p. 8-17.

Fofana I. (2013). 50 Years in the Development of Insulating Liquids. IEEE Electrical Insulation Magazine, vol. 29, n° 5, p. 13-25.

Fofana I;, Borsi H., Gockenbach E. (2001). Fundamental Investigations on Some Transformer Liquids under Various Outdoor Conditions. IEEE Electrical Insulation Magazine, vol. 8, n° 6, p. 1040-1047.

IEEE Std C 57.104. (2008). IEEE guide for the interpretation of gases generated in oilimmersed transformers.

Khan I. U., Wang Z., Cotton I., Northcote S. (2007). Dissolved Gas Analysis of Alternative Fluids for Power Transformers. IEEE Electrical Insulation Magazine, vol. 23, n° 5, p. 5-14.

Liao R., Hao J., Chen G., Ma Z., Yang L. (2011). A Comparative Study of Physicochemical Dielectric and Thermal Properties of Pressboard Insulation Impregnated with Natural Ester and Mineral Oil. IEEE Transactions on Dielectrics and Electrical Insulation, vol. 18, n° 5, p. 1626-1637.

Martin D., Guo W., Lelekakis N., Heyward N. (2011). Using a remote system to study the thermal properties of a vegetable oil filled power transformer: how does operation differ from mineral oil. IEEE PES Conference on Innovative SMART GRID Technologies 2011, Asia. Perth. Australia.

Moulai H., Nacer A., Beroual A. (2012). Dissolved Gases Analysis in Relation to the Energy of Electrical Discharges in Mineral Oil. IEEE Transactions on Dielectrics and Electrical Insulation, vol. 19, n° 2, p. 498-504.

Oommen T.V. (2002). Vegetable Oils for Liquid-Filled Transformers. IEEE Electrical Insulation Magazine, vol. 18, n° 1, p. 6-11. Paraskevas C. D., Vassiliou P., Dervos C. T. (2006). Temperature Dependent Dielectric Spectroscopy in Frequency Domain of High-Voltage Transformer Oils Compared to Physicochemical Results. IEEE Transactions on Dielectrics and Electrical Insulation, vol. 19, n° 6, p. 1851-1859.

Pradhan M. K., Yew K. J. H. (2012). Experimental Investigation of Insulation Parameters Affecting Power Transformer Condition Assessment using Frequency Domain Spectroscopy. IEEE Transactions on Dielectrics and Electrical Insulation, vol. 19, n° 6, p. 1851-1859.

Raymon A., Karthik R. (2015). Reclaiming Aged Transformer Oil with Activated Bentonite and Enhancing Reclaimed and Fresh Transformer Oils with Antioxidants. IEEE Transactions on Dielectrics and Electrical Insulation, vol. 22, n° 1, p. 548-555.

Singha S., Asano R., Frimpong G., Claiborne C., Cherry D. (2014). Comparative Aging Characteristics between a High Oleic Natural Ester Dielectric Liquid and Mineral Oil. IEEE Transactions on Dielectrics and Electrical Insulation, vol. 21, n° 1, p. 149-158.

Suleiman A., Muhamad N. A., Bashir N., Murad N. S., Arief Y. Z., Phung B.T. (2014). Effect of Moisture on Breakdown Voltage and Structure of Palm Based Insulation Oils. IEEE Transactions on Dielectrics and Electrical Insulation, vol. 21, n° 5, p. 2119-2126.

Toudja T., Moulai H., Nacer A., Beldjilali A., Khelfane I., Debche A. (2014). Moisture and electrical discharges effect on naphthenic mineral oil properties. IET Science, Measurement and Technology, vol. 8, n° 6, p. 588-594.

Wada J., Ueta G., Okabe S., Amimoto T. (2013). Inhibition technique of transformer insulating oil degradation - evaluation of the effectiveness of oxidation degradation inhibitors. IEEE Transactions on Dielectrics and Electrical Insulation, vol. 20, n° 5, p. 1641-1648.

Zhou Y., Hao M., Chen G. (2012). Frequency-dependence of conductivity of new mineral oil studied by dielectric spectroscopy. International Conference on High Voltage Engineering and Application 2012, Shanghai, China.