THERMAL SCIENCE

International Scientific Journal

THE OIL - PAPER INSULATION RELIABILITY ESTIMATION OF 420 KV TRANSFORMER CONCERNING THERMAL STRESSES DURING EXPLOITATION CONDITIONS

ABSTRACT
The calculating of reached ageing based on the history of loading according of International Electrotechnical Commission standard algorithm is the first task. In order to verify the obtained results, measurements of polymerization index were made on 28 paper samples taken directly from low voltage terminals (winding ends) and bus connections of the transformer under test rated 380 MVA, 2´15,75 kV/420 kV. The complete procedure of paper sample locations and taking off is described, thereby providing a manner of how this should be done, determined by specific conditions of the transformer under test. Furthermore, the determination of limit viscosity and using its relationship function with polymerization index are explained together. Comparison is made with those of liquid chromatography of oil. The results of particle sort and size analysis are shown. Finally, an estimation of the transformer life remainder is made, which is of paramount importance when defining the steps that have to be made either in revitalization process or in transformer replacement planning.
KEYWORDS
PAPER SUBMITTED: 2015-04-09
PAPER REVISED: 2016-01-09
PAPER ACCEPTED: 2016-01-13
PUBLISHED ONLINE: 2016-01-30
DOI REFERENCE: https://doi.org/10.2298/TSCI150409003A
CITATION EXPORT: view in browser or download as text file
THERMAL SCIENCE YEAR 2016, VOLUME 20, ISSUE 5, PAGES [1713 - 1723]
REFERENCES
  1. CIGRÉ Working Group 12-09 on Thermal Aspects: Lifetime Evaluation of transformers, Electra, No.150, 1993, pp 39-52
  2. de Pablo, A., et al., Furanic Compounds Analysis as a Tool for Diagnostic and Maintenance of Oil-Paper Insulation System, CIGRÉ Symp. Berlin, 1993, Proceedings Paper 110-09
  3. Pablo, A., Pahlavanpour, B., Furanic Compounds Analysis: A Tool for Predictive Maintenance of Oil filled Electrical Equipment, Elektra, No 175, 1997, pp. 9-31
  4. Saha, T. K., Rewiew of Modern Diagnostic Techniques for Assessing Insulation Condition in Aged Transformers, IEEE Trans. Dielect. El. In., Vol 10, No. 5, 2003, pp. 903 - 917
  5. Lazarević Z., et al., Application of Kerr Electro-optic Effect to Electric Field Measurements in Transformer Oils, J. Optoelectron. Adv. M., Vol. 8, No. 3, 2006, pp. 1273-1277
  6. Osmokrović, P., et al., Transient Electric Field Measurement in the Liquid Dielectrics Using Computerized laser Tomography, IEEE Trans. Instrum. Meas., Vol. 56, No. 6, 2007, pp. 2538-2547
  7. Vereb, L., et al., Prospects of Constructing 20 kV Asynchronous Motors, IEEE Trans. on Dielectr. El. In., Vol. 16, No. 1, 2009, pp. 251-256
  8. Lundgaard, L.E., et al., Ageing of Oil-Impregnated Paper in Power Transformers, IEEE Trans. Power Deliver., Vol 19, No.1, 2004, pp. 230-239
  9. Bengtsson, C., Status and Trends in Transformer Monitoring, IEEE Trans. Power Deliver., Vol. 11, No.3, 1996, pp. 1379-1384
  10. Saha, T. K., et al., Investigation of Interfacial Polarization Spectra Parameters for Accelerated Aged Oil-Paper Insulation and its Cor-relation with Molecular Weights and Furan compounds, CIGRE Symp. Paris, 2000, Proceedings Paper 15-201
  11. Evans,, R., Wallis, A. F. A., Cellulose Molecular Weights Determined by Viscosimetry, J. Appl. Polym. Sci., Vol 37, No. 8, 1989, pp. 2331-2340
  12. Marx, M., Uber die Bestimmung de moleculargewichts von cellulose in kupferathylendiamin, Das Papiers, helt 7/8, 1956, pp. 135
  13. Pešić, M., et al., Scaling law applicability to oil-insulated parallel-plate capacitors, IEEE Trans. Dielect. El. In., Vol. 14, No. 4, 2007, pp. 1002-1006
  14. Lungaard, L., et al., Ageing of oil impregnated paper in Power Transformers, IEEE Trans. Power Deliver., Vol. 19, No. 1, 2004, pp. 230 - 239
  15. Osmokrovic, P., et al., Influence of transformer oil particle contamination on dielectric hardnes, J. Optoelectron. Adv. M., Vol. 9, No 12, 2007, pp. 3885-3888
  16. Chendong, X., Monitoring Paper Insulation Ageing by Measuring Furfural Contents, 7th International Symposium of High Voltage Engineering, Technische Universität Dresden, 1991, pp. 139-142

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