Any transformer oil undergoes continuous degradation because of all electric, thermal, mechanical, and climatic stresses it suffers while operating in the transformer. Therefore, the oil has to be checked on regular basis in order to decide whether it is necessary to regenerate or replace it, avoiding thus a sudden failure of the transformer. This article presents results of in-the-laboratory-performed experiments on transformer mineral oil samples. Those samples came from a power transformer that works in the Romanian power network. There were three monitoring stages conducted over four-and-a-half years. We used two measuring techniques: (i) measurement of the state parameters of transformer oil (breakdown voltage, loss factor, water contents, acidity index, interfacial tension, number of particles larger than 5 microns, and gas contents) in order to describe the oil condition during the monitoring period and to anticipate any severe fault. This enables the user to take preventive action before a severe fault might eventually occur; (ii) thermal analysis (TA) and Fourier transform infrared spectroscopy (FTIR), in order to determine the stability of oil samples. By using TA and FTIR, and by evaluating each and every significant parameter, it has been proven that the tested oil is still adequate for further employment in the power transformer.
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EL-Sayed MM, Mohamed RS, Wael AA. Prediction of the characteristics of transformer oil under different operation conditions. World Acad Sci Eng Technol. 2005;53:764–8.
Huimin H, Xiaotian X. Study on transformer oil dissolved gas online monitoring and fault diagnosis method. In: International conference on condition monitoring and diagnosis (CMD). Bali. 2012:593–6.
Gradnik T, Gradnik-Koncan T, Petric N, Muc N. Experimental evaluation of water content determination in transformer oil by moisture sensor. In: IEEE international conference on dielectric liquids. Trondheim, Norway. 2011:1–4.
De Sousa Rios MA, Mazzetto SE. Effect of organophosphate antioxidant on the thermo-oxidative degradation of a mineral oil. J Therm Anal Calorim. 2013;111:553–9.
Batista DA, Patriarca PA, Trindade EM, Wilhelm HM. Colorimetric methodology for monitoring the cellulose insulating paper degradation in electrical equipments filled with mineral oil. Cellulose. 2008;15:497–505.
Lipshtein RA, Shtern EN. Effect of hydrocarbon composition of transformer oil on dielectric losses. Chem Tech Fuels Oil+. 1967;3:363–6.
Reykherdt AA, Davydov V. Case studies of factors influencing frequency response analysis measurements and power transformer diagnostics. IEEE Electr Insul Mag. 2011;27:22–30.
Warren L. Transformers-oil sampling—the comprehensive transformer health test. 2010. http://www.electricalreview.co.uk/features/6760-118924.
Cargol T. An overview of online oil monitoring technologies. Fourth Annual Weidmann-Acti Technical Conference. San Antonio, 2005:1–6.
Shukla P, Sood YR, Jaria RK. Experimental evaluation of water content in transformer oil. Int J Innov Res Sci Eng Technol. 2013;2:284–91.
IEC 60422 International Standard. Mineral insulating oils in electrical equipment – Supervision and maintenance guidance. Fourth ed. International Electrotechnical Commission, 2013.
IEEE Std C57.106 International standard. IEEE guide for acceptance and maintenance of insulating oil in equipment, Institute of Electrical and Electronics Engineers, 2006.
PE 129:1999, Romanian regulation, Mineral oils technical exploitation regulatory statement, National Electricity Company – S. A. Romania, 1999. Accessed from http://www.scribd.com/doc/181437335/PE129-99
Felea I, Coroiu N, Boja I. The influence of the stress level on electro isolating oil state from the electric power transformers. In: The 6th international power systems conference. Timişoara. 2005:223–30.
Meshkatoddini Mohammad R. Aging study and lifetime estimation of transformer mineral oil. Am J Eng Appl Sci. 2008;1:384–8.
Korobeynikov SM, Soloveichik YG, Bychkov AL, Vagin DV, Melekhov AV, Ryzhkina AY. Dissolution of diagnostic gas bubbles in transformer oil. High Temp+. 2011;49:744–9.
IEC 60599 International Standard. Mineral oil-impregnated electrical equipment in service. Guide to the interpretation of dissolved and free gases analysis. Ed. 2.1. International Electrotechnical Commission, 2007.
IEC 60156 International Standard. Insulating liquids – Determination of the breakdown voltage at power frequency – Test method. Second ed. International Electrotechnical Commission, 1995.
IEC 60247 International Standard. Insulating liquids – Measurement of relative permittivity, dielectric dissipation factor (tan δ) and d.c. resistivity. Third ed. International Electrotechnical Commission, 2004
IEC 60814 International Standard. Insulating liquids – Oil-impregnated paper and pressboard—determination of water by automatic coulometric Karl Fischer titration. Second ed. International Electrotechnical Commission, 1997.
IEC 62021 International Standard. Insulating liquids. Determination of acidity Part 1: Automatic potentiometric titration, International Electrotechnical Commission, 2003.
STAS 9654, Romanian Standard, Mineral oils. Determination of interfacial tension against water, 1974. Accessed from ASRO Romanian Standards Association. http://magazin.asro.ro/index.php?lg=2&pag=3&cls=1&dom=75&gr=100&id_p=17644438
IEC 60970 International Standard. Insulating liquids–Methods for counting and sizing particles. Second ed. International Electrotechnical Commission, 2007.
IEC 60567 International Standard. Oil-filled electrical equipment–Sampling of gases and of oil for analysis of free and dissolved gases-Guidances. Fourth ed. International Electrotechnical Commission, 2011.
EN ISO 3170 European Standard. Petroleum liquids, Manual sampling, European Committee for Standardization, 2004. Accessed from http://www.scribd.com/doc/157615057/SR-EN-ISO-3170
Moanta A, Tutunaru B, Rotaru P. Spectral and thermal studies of 4-(phenyldiazenyl)phenyl 2-furoate as corrosion inhibitor for carbon steel. J Therm Anal Calorim. 2013;111:1273–9.
Rotaru A. Thermal analysis and kinetic study of Petrosani bituminous coal from Romania in comparison with a sample of Ural bituminous coal. J Therm Anal Calorim. 2012;110:1283–91.
Moanta A, Ionescu C, Rotaru P, Socaciu M, Harabor A. Structural characterization, thermal investigation and liquid crystalline behavior of 4-[(4-chlorobenzyl)oxy]-3,4′-dichloroazobenzene. J Therm Anal Calorim. 2010;102:1079–86.
ISO 4407 International Standard. Hydraulic fluid power – Fluids contamination – Determination of particulate contamination by the counting method using an optical microscope, International Organization for Standardization, 2002.
Kok MV, Gul KG. Thermal characteristics and kinetics of crude oils and SARA fractions. Thermochim Acta. 2013;569:66–70.
Kok MV. The thermal characterization of crude oils in a limestone matrix of different particle size. Energ Source Part A. 2014;36:923–8.
Gundogar AS, Kok MV. Thermal characterization, combustion and kinetics of different origin crude oils. Fuel. 2014;123:59–65.
Kok MV, Gundogar AS. DSC study on combustion and pyrolysis behaviors of Turkish crude oils. Fuel Process Technol. 2013;116:110–5.
Al-Sammerrai D. Study of thermal stabilities of some heat transfer oils. J Therm Anal Calorim. 1985;30:763–70.
Mojumdar SC, Sain M, Prasad RC, Sun L, Venart JES. Selected thermoanalytical methods and their applications from medicine to construction. J Therm Anal Calorim. 2007;90:653–62.
Sestak J. Thermal science and analysis. J Therm Anal Calorim. 2013;113:1049–54.
Streibel T, Fendt A, Geißler R, Kaisersberger E, Denner T, Zimmermann R. Thermal analysis/mass spectrometry using soft photo-ionisation for the investigation of biomass and mineral oils. J Therm Anal Calorim. 2009;97:615–9.
Warne SJ, Dubrawski JV. Applications of DTA and DSC to coal and oil shale evaluation. J Therm Anal Calorim. 1989;35:219–42.
Rotaru A, Goşa M, Rotaru P. Computational thermal and kinetic analysis. Software for non-isothermal kinetics by standard procedure. J Therm Anal Calorim. 2008;94:367–71.
Rotaru A, Goşa M. Computational thermal and kinetic analysis. Complete standard procedure to evaluate the kinetic triplet form non-isothermal data. J Therm Anal Calorim. 2009;97:421–6.
Cavallaro G, Lazzara G, Milioto S. Sustainable nanocomposites based on halloysite nanotubes and pectin/polyethylene glycol blend. Polym Degrad Stabil. 2013;98:2529–36.
Samide A, Tutunaru B, Negrila C, Dobritescu A. Study of the corrosion products formed on carbon steel surface in hydrochloric acid solution. J Therm Anal Calorim. 2012;110:145–52.
Tutunaru B, Samide A, Negrila C. Thermal analysis of corrosion products formed on carbon steel in ammonium chloride solution. J Therm Anal Calorim. 2013;111:1149–54.
Rotaru A, Bratulescu G, Rotaru P. Thermal analysis of azoic dyes. Part I non-isothermal decomposition kinetics of [4-(4-chlorobenzyloxy)-3-methylphenyl](p-tolyl)diazene in dynamic air atmosphere. Thermochim Acta. 2009;489:63–9.
Rotaru A, Mietlarek-Kropidłowska A, Constantinescu C, Scarisoreanu N, Dumitru M, Strankowski M, Rotaru P, Ion V, Vasiliu C, Becker B, Dinescu M. CdS thin films obtained by thermal treatment of cadmium(II) complex precursor deposited by MAPLE technique. Appl Surf Sci. 2009;255:6786–9.
Kropidłowska A, Rotaru A, Strankowski M, Becker B, Segal E. Heteroleptic cadmium(II) complex, potential precursor for semiconducting CdS layers. Thermal stability and non-isothermal decomposition kinetics. J Therm Anal Calorim. 2008;91:903–9.
Constantinescu C, Palla-Papavlu A, Rotaru A, Florian P, Chelu F, Icriverzi M, Nedelcea A, Dinca V, Roseanu A, Dinescu M. Multifunctional thin films of lactoferrin for biochemical use deposited by MAPLE technique. Appl Surf Sci. 2009;255:5491–5.
Rotaru A, Kropidłowska A, Moanta A, Rotaru P, Segal E. Thermal decomposition kinetics of some aromatic azomonoethers. Part II. Non-isothermal study of three liquid crystals in dynamic air atmosphere. J Therm Anal Calorim. 2008;92:233–8.
Rotaru A, Moanta A, Rotaru P, Segal E. Thermal decomposition kinetics of some aromatic azomonoethers. Part III. Non-isothermal study of 4-[(4-chlorobenzyl)oxy]-4′-chloroazobenzene in dynamic air atmosphere. J Therm Anal Calorim. 2009;95:161–6.
Constantinescu C, Morintale E, Emandi A, Dinescu M, Rotaru P. Thermal and microstructural analysis of Cu(II) 2,2′-dihydroxy azobenzene and thin films deposition by MAPLE technique. J Therm Anal Calorim. 2011;104:707–16.
Rotaru A, Constantinescu C, Rotaru P, Moanta A, Dumitru M, Socaciu M, Dinescu M, Segal E. Thermal analysis and thin films deposition by matrix assisted pulsed laser evaporation of a 4CN type azomonoether. J Therm Anal Calorim. 2008;92:279–84.
Samide A, Tutunaru B, Ionescu C, Rotaru P, Simoiu L. Aminophylline: thermal characterization and its inhibitory properties for the carbon steel corrosion in acidic environment. J Therm Anal Calorim. 2014;118:631–9.
Manolea HO, Rotaru P, Manolea G, Morintale E, Rica R. Thermal and spectral behaviour of a light-cured methacrylate-based composite material used in dentistry. J Therm Anal Calorim. 2013;114:1325–31.
Rotaru A, Constantinescu C, Mandruleanu A, Rotaru P, Moldovan A, Gyoryova K, Dinescu M, Balek V. Matrix assisted pulsed laser evaporation of zinc benzoate for ZnO thin films and non-isothermal decomposition kinetics. Thermochim Acta. 2010;498:81–91.
Samide A, Rotaru P, Ionescu C, Tutunaru B, Moanta A, Barragan-Montero V. Thermal behaviour and adsorption properties of some benzothiazole derivatives. J Therm Anal Calorim. 2014;118:651–9.
Zakharich MP, Zaitsev II, Komar VP, Nikonovich FN, Ryzhkov MP, Skornyakov IV. Analysis of transformer oil using IR analyzers. J Appl Spectrosc. 2001;68:61–5.
Zamkovets AD, Zakharich PM, Komar VP, Skornyakov IV. Infrared filters and analyzers of the composition of substances based on them. J Appl Spectrosc. 1998;65:66–77.
This work was supported by the S.C. Hidroelectrica S.A., Romania, as partner in the project 536/28.07.2009 covering expenses related to theoretical and applicative researches on the mineral oils used in the power transformers that work in the Romanian power network.
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Degeratu, S., Rotaru, P., Rizescu, S. et al. Condition monitoring of transformer oil using thermal analysis and other techniques. J Therm Anal Calorim 119, 1679–1692 (2015). https://doi.org/10.1007/s10973-014-4276-3
- Transformer mineral oil
- Thermal analysis
- Fourier transform infrared spectroscopy
- Off-line monitoring