Experiments and New Mathematical Models for Prediction of Transformer Oil Characteristics under Environment Pressure Stress
Subject Areas : electrical and computer engineeringMohammad Mirzaie 1 * , Ahmad Gholami 2 , H. R. Tayebi 3
1 - University of Science and Technology
2 - University of Science and Technology
3 -
Keywords: Mineral oilair pressureinsulationmodeling,
Abstract :
Mineral oil in transformer is used for its insulation property and thermal transfer to external environment. Transformer oil is always under air pressure variation effects due to contact to external by silica gel chamber and the pressure which depends on the height of sea level. Therefore air pressure can affect on insulation parameters and its age. Air pressure changing can cause oil viscosity variation. In this paper, the air pressure effects on oil properties are studied by the use of tests carried out and measuring of the insulation characteristics. In a laboratory environment, air pressure was changed from 40 to 1250 mmHg using a pump. Then conductivity/leakage current and breakdown voltage are measured and analyzed. These results are used to presenting estimation models and also for suggestion of a new simple model by mathematical methods and then the models were compared to each other.
[1] A. Nosseir, N. Higgi, H. Said, and M. Awad, "Effect of ageing on the characteristics of mineral oil," in Proc. IEEE 11th Int. Conf. ICDL, pp. 451-455, Switzerland, Jul. 1993.
[2] M. A. A. Wahab, M. M. Hamada, A. G. Zeitoun, and G. Ismail, Novel Modeling for the Prediction of Aged Transformer Oil Characteristics, Elsevier, Electric Power Systems Research 51, pp. 61-70, 1999.
[3] P. R. Krishnamoorthy, K. R. Krishnaswamy, S. Vijayakumari, and K. Kumar, "Ageing of mineral oils-a diagnostic study," in Proc. the 3th Int. Conf. on Properties and Applications of Dielectric Materials, vol. 1, pp. 59-62, Tokyo, Japan, Jul. 1991.
[4] T. K. Saha, M. Darveniza, D. J. T. Hill, and T. T. Le, "Electrical and chemical diagnostics of transformers insulation-part B: accelerated aged insulation samples," IEEE Tran. on Power Delivery, vol. 12, no. 4, pp. 1555-1561, Oct. 1997.
[5] J. J. Kelly and D. P. Mayers, "Transformer life extension through proper reinhibiting and preservation of the oil insulation," IEEE Tran. on Industrial Applications, vol. 31, no. 1, pp. 185-193, Jan./Feb. 1995.
[6] M. Mirzaie, A. Gholami, and H. R. Tayebi, "Thermal degradation of cellulose insulation in power transformers," in Proc. IEEE Int. Conf. on Solid and Dielectric Industrial Applications, pp. 673-676, Winchester, UK, Jul. 2006.
[7] International Electrotechnical Commission, IEC60156, Method for the Determination of the Electric Strength of Insulation Oils, 1963.