Postmortem Investigation of Power Transformers—Profile of Degree of Polymerization and Correlation With Furan Concentration in the Oil

Leibfried, Thomas; Jaya, M.; Majer, N.; Schäfer, Matthias; Stach, M.; Voss, Stephan

doi:10.1109/tpwrd.2013.2245152

Cited by 50 publications

(26 citation statements)

References 9 publications

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“…This is a non-intrusive technique, which can be used to estimate the ageing of the dielectric paper. It has been concluded by different authors [22][23][24][25][26][27][28][29][30][31][32] that there is a relation between furanic compounds and degree of polymerisation. This relation has been defined through mathematical models such as gathered in Table 1.…”

Section: Furanic Compounds Concentrationmentioning

confidence: 99%

“…Finally, they concluded that more post-mortem studies with detailed operational data would improve the knowledge of the correlation between 2-FAL in oil and the DP of insulating paper. DP was also used to estimate paper ageing in the post-mortem assessment carried out by other authors [28,48]. Leibfried et al [28] proposed a systematical method for taking paper samples from scrapped power transformers and a methodology for the evaluation of DP values suggesting a grouping into different types of transformers, at least in Germany, which the operation mode and consequently the ageing rate inside transformers is substantially different.…”

Section: Post-mortem Studiesmentioning

confidence: 99%

“…DP was also used to estimate paper ageing in the post-mortem assessment carried out by other authors [28,48]. Leibfried et al [28] proposed a systematical method for taking paper samples from scrapped power transformers and a methodology for the evaluation of DP values suggesting a grouping into different types of transformers, at least in Germany, which the operation mode and consequently the ageing rate inside transformers is substantially different. Using the data obtained in their study, Leibried et al derived a formula to estimate average DP through the 2-FAL concentration, although they obtained that this equation does not provide 100% reliable evaluation of transformer condition.…”

Section: Post-mortem Studiesmentioning

confidence: 99%

See 2 more Smart Citations

Assessment of Dielectric Paper Degradation through Mechanical Characterisation

Fernández-Diego¹,

Fernández²,

Fernández³

et al. 2018

Simulation and Modelling of Electrical Insulation Weaknesses in Electrical Equipment

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Power transformers life is limited fundamentally by the insulation paper state, which can be analysed through different techniques such as furanic compound concentration, dissolved gases, methanol concentration, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscope, refractive index of cellulose fibres, degree of polymerisation or tensile strength. The two last techniques provide the best way to evaluate mechanical resistance of insulation paper. This chapter describes briefly the most remarkable studies about post-mortem assessment and thermal ageing tests in which mechanical properties are some of the characteristics evaluated to determine paper degradation. This work also gathers the main relationships developed until now to relate different by-products generated during transformer operation with loss of paper mechanical properties. Finally, this chapter defines the future approaches, which could be used to study paper degradation.

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Section: Furanic Compounds Concentrationmentioning

confidence: 99%

Section: Post-mortem Studiesmentioning

confidence: 99%

Section: Post-mortem Studiesmentioning

confidence: 99%

See 1 more Smart Citation

Assessment of Dielectric Paper Degradation through Mechanical Characterisation

Fernández-Diego¹,

Fernández²,

Fernández³

et al. 2018

Simulation and Modelling of Electrical Insulation Weaknesses in Electrical Equipment

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“…Models are mostly based on results of in laboratory implemented accelerated aging and they cannot take into account many parameters (temperature of oil, content of water in paper, the oxygen content, the acidity of oil, the construction of transformer, type of used paper, the decrease in nothermetized devices) that affect the content of furans dissolved in oil, see for example the study [12] Values showed in Table 5 and used in correlation curve Figure 12 are calculated from relationship that is mentioned in study [13], proceeding from operating data and laboratory measurements. The equation for the relationship between DP value and the level of content of 2-furaldehyde, where 2FAL is the value in mg/l and it has the form:…”

Section: Analysis Of Furansmentioning

confidence: 99%

Life cycle management of power transformers: results and discussion of case studies

Mullerova

Hruza

Velek

et al. 2015

IEEE Trans. Dielect. Electr. Insul.

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The knowledge of a current state of running machines is of high importance for users and producers of transformers; especially the knowledge of the present state of their priority component -insulation system. The article deals with methodology of creating and utilization of the information about the condition of insulation system of transformers database as a tool for the transformer life management. The post-mortem analysis of the insulation systems condition of transformers that have already grown old and are intended for liquidation were used a source for the database. The procedure of sampling is described. Analytically determined values of degree of polymerization (DP) and tensile strength (R) are accompanied with information from running history of a transformer (especially DGA and 2FAL values). Individual case studies, whose results are shown in the article, are realized in most cases for transformers with the highest voltage 400 kV but they differ in type (power transformers, autotransformer), manufacturer (4 providers) and also in construction. The study deals with generalization of reciprocal relationships of analysed quantities for typical representatives of individual machine groups as well as with the impact of non-standard events during the running of particular transformer.

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“…Additionally, it could be possible to estimate the remaining lifetime of transformers wich are identical in their design if loading conditions and maintenance are available [10]. Different authors have published end-of-life studies of scrapped transformers [11][12][13][14][15][16]. All these works are based on the measuring DP which constitutes one of the most important parameters of the insulation conditions.…”

Section: Introductionmentioning

confidence: 99%

Assessment of the temperature distribution into a transformer through tensile index

Fernández¹

2016

REPQJ

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Abstract. Power transformers are electrical machines which are one of the most critical components in power distribution systems worldwide. Their failure generally is due to the degradation of its insulating system (insulating oil and paper insulation). This deterioration is produced by electrical, mechanical, chemical and thermal stresses which power transformers suffer during their operational lifetime. When dielectric paper has aged severely it loses its tensile strength and its capability to withstand electrical faults decreases considerably. This paper describes an end of life study carried out on a distribution transformer. This analysis has used the tensile index of the dielectric paper to estimate the temperature distribution in the windings of the electric machine. The tensile index is a mechanical parameter associated with the state of the paper insulation that protects the conductors of the windings. By knowing the value of this magnitude for a new and for an aged paper, and the period of operation of a transformer, the temperature distribution along the height of the windings can be estimated. These results and the load rate that a transformer has endured during its life can provide useful information for future designs or for similar transformers still in operation.

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Postmortem Investigation of Power Transformers—Profile of Degree of Polymerization and Correlation With Furan Concentration in the Oil

Cited by 50 publications

References 9 publications

Assessment of Dielectric Paper Degradation through Mechanical Characterisation

Assessment of Dielectric Paper Degradation through Mechanical Characterisation

Life cycle management of power transformers: results and discussion of case studies

Assessment of the temperature distribution into a transformer through tensile index

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