Cellulose insulation in oil-filled power transformers: Part I - history and development

Prevost, Thomas; Oommen, T.V.

doi:10.1109/mei.2006.1618969

Cited by 228 publications

(127 citation statements)

References 7 publications

(6 reference statements)

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“…As the insulating medium of power transformers, oil-impregnated paper (OIP) degrades under interaction with heat, moisture, oxygen, and acids [2,3]. Among those aging factors, heat is the main cause of insulation aging, and thus reduces its mechanical strength and electrical performance.…”

Section: Introductionmentioning

confidence: 99%

Breakdown Voltage and Its Influencing Factors of Thermally Aged Oil-Impregnated Paper at Pulsating DC Voltage

Zhang

Wang

et al. 2017

Energies

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Abstract:Breakdown strength is an important electrical property of insulating paper. Oil-impregnated paper of various aging states was prepared. Its breakdown voltage was then measured at pulsating direct current (DC) voltage with various ripple factors, and alternating current (AC) and DC voltage for comparison, respectively. The AC breakdown voltage is the smallest, and pulsating DC (r = 1/5) breakdown voltage is the greatest before the paper reaches its end of life. A dielectric model was adopted to investigate the difference in magnitude of breakdown voltage at different voltage waveforms. Meanwhile, it was found that breakdown voltage fluctuated and even increased occasionally during the thermal aging process, and a somewhat opposite changing tendency versus aging time was observed for breakdown voltage at DC voltage and pulsating DC voltage with small ripple factors (r = 1/5 and 1/3), compared with AC voltage. The degree of polymerization (DP) and moisture content of the paper were measured, and the characteristics of the pores and cracks of the paper were obtained to investigate the possible influencing factors of breakdown voltage at different aging states. The results showed that the moisture content, oil absorption ability associated with pores and cracks of paper, and the damage to paper structure all contributed to the variation of the breakdown voltage versus aging time, while the importance of their influence differed as the aging state of paper varied.

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Section: Introductionmentioning

confidence: 99%

Breakdown Voltage and Its Influencing Factors of Thermally Aged Oil-Impregnated Paper at Pulsating DC Voltage

Zhang

Wang

et al. 2017

Energies

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“…1) [9]. Cellulose degradation is an irreversible process which is characterized by the breakdown of macromolecular chains.…”

Section: Paper Degradationmentioning

confidence: 99%

“…Furfural (2-furaldehyde or 2-FAL) is one of the main products that are released due to the degradation of all cellulose containing materials inside the transformer. The furfural content can be measured by High Performance Liquid Chromatography (HPLC) [3,9,15].…”

Section: Improved Paper Degradation Modelmentioning

confidence: 99%

Calculation of the remaining lifetime of power transformers paper insulation

Gorgan

Notingher

Wetzer

et al. 2012

2012 13th International Conference on Optimization of Electrical and Electronic Equipment (OPTIM)

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Abstract-This paper presents the remaining lifetime calculation of power transformers paper insulation and consequently of power transformers. The calculations are performed based on two models, which are related to the thermal degradation of the cellulose winding paper insulation: the common IEC loading guide and a paper degradation model. The paper insulation model's prediction can be improved by involving data from furfural analysis. The remaining lifetime is extracted from the fault probability (reliability) of the paper insulation. The two models are brought together, to aid the asset manager in the decision making process. A probabilistic approach is used, which can be coupled to analysis in terms of risks, benefits, costs, and availability by the asset manager.

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“…C Cellulose materials including presspaper and pressboard have been used together with mineral oil in power transformers for more than 70 years. 1 The mismatch of relative permittivity between insulating presspaper and mineral oil, which will lead to an electric field distortion inside the composite system, is one of the main drawbacks for the combination. 2 Therefore, a better understanding of the effective permittivity of presspaper, which are composed of cellulose fibers and air voids, will be of theoretical importance and practical significance to enhance the electrical performance of oil-paper composite insulation.…”

mentioning

confidence: 99%

Modeling of the effective permittivity of insulating presspaper

et al. 2016

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Effective permittivity model of insulating presspaper is built on the basis of the microstructure of the material. Due to the essentially layered structure in z-direction of presspaper, air voids inside the mixture can be treated as right prismatic inclusions. Analytical formula for the prediction of the effective permittivity of insulating presspaper is derived. Interestingly, the derived formula equals to the mixing equation applied for dielectrics in series. Numerical simulation was used to validate the analytical results by considering the air voids as cubical inclusions. Results show a good agreement between the analytically and numerically calculated effective permittivity values. Furthermore, dielectric permittivity results of commercial kraft paper and laboratory-made presspaper at 50 Hz were measured and compared with modeled data. It turns out that the deduced results give a good accuracy for the effective permittivity determination.

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Cellulose insulation in oil-filled power transformers: Part I - history and development

Cited by 228 publications

References 7 publications

Breakdown Voltage and Its Influencing Factors of Thermally Aged Oil-Impregnated Paper at Pulsating DC Voltage

Breakdown Voltage and Its Influencing Factors of Thermally Aged Oil-Impregnated Paper at Pulsating DC Voltage

Calculation of the remaining lifetime of power transformers paper insulation

Modeling of the effective permittivity of insulating presspaper

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