Failure analysis of transformer liquid — solid insulation system under selective environmental conditions using Weibull statistics method

Madavan, R.; Balaraman, Sujatha

doi:10.1016/j.engfailanal.2016.03.017

Cited by 51 publications

(19 citation statements)

References 22 publications

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“…where x is a stress as a function of time; σ is the scale parameter for the Weibull distribution, σ = 1/β. β is the shape parameter for the insulation material and is obtained by combining accelerated aging tests and the maximum likelihood method [7]. When a dielectric failure occurs, the transformer has to be replaced.…”

Section: A Risk Analysismentioning

confidence: 99%

Risk and economic analysis of utilizing dynamic thermal rated transformer for wind farm connection

Turnell

Linnet

Tamadon

et al. 2018

2018 IEEE International Conference on Probabilistic Methods Applied to Power Systems (PMAPS)

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Dynamic transformer rating (DTR) can be used to load power transformers above nameplate rating, while respecting contingency loading limits and ensuring an acceptable risk level. Purchase of power transformers is a major contributor for high costs of building new substations. Application of DTR allows to postpone the investment in new power transformers in old substations, thus DTR has a potential to become an economically beneficial technology. A quantitative risk and economic evaluation of DTR application is performed for a wind farm connected transformer and thus for a highly variable load scenario. The risks analyzed in this project are increased loss of insulation life and the risk of dielectric failure, based on the Arrhenius-Weibull model. A comparative net present value calculation has been performed to investigate the profitability of replacing a 19.4 MVA transformer with a 16 MVA dynamically rated transformer. The feasibility of DTR application is analyzed and a methodology is developed to support both transformer manufacturer and potential customers, such as distribution system operators, in the decision-making process of purchasing of dynamically rated transformer for wind energy applications.

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Section: A Risk Analysismentioning

confidence: 99%

Risk and economic analysis of utilizing dynamic thermal rated transformer for wind farm connection

Turnell

Linnet

Tamadon

et al. 2018

2018 IEEE International Conference on Probabilistic Methods Applied to Power Systems (PMAPS)

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“…It was assumed that this behaviour was due to the transesterification process. The tensile strength of the paper, besides other characteristic properties of the oil degradation, was analysed by Madavan and Balaraman [81], who obtained that the paper aged in oils based on natural esters had a lower degradation compared to Kraft paper immersed in mineral oil. In recent years, different authors have tried to find additional methods to study paper degradation when this is aged thermally in laboratory.…”

Section: Accelerated Thermal Ageing In Laboratorymentioning

confidence: 99%

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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“…Many authors have analyzed ageing behavior of different insulation papers immersed in natural and synthetic esters [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. These studies and others have found that thermal ageing rates of insulation solids immersed in natural esters are reduced compared to those in mineral oil [9].…”

Section: Introductionmentioning

confidence: 99%

“…The insulation solids usually studied include papers such as Kraft paper [10][11][12][13][14][15][16], thermally upgraded papers [9,[17][18][19], aramid paper [1,[20][21], pressboard [20,22]. The paper degradation in thermal aging studies has been evaluated through the degree of polymerization [10][11][12][18][19], the tensile strength [13][14][15][16][19][20][21][22][23], differential scanning calorimetry [24], Fourier transform infrared spectroscopy (FTIR) or energy dispersive X-ray [12] being the DP and the tensile strength the most commonly used methods to evaluate the insulating paper condition. Even though, the degradation suffered by different insulation papers immersed in biodegradable oils during thermal ageing tests has been studied, there are few works that have analyzed the effect of insulation liquids on the deterioration of other cellulosic materials such as Diamond Dotted paper (DDP).…”

Section: Introductionmentioning

confidence: 99%

Kraft And Diamond Dotted Paper Thermally Aged In Mineral Oil And Natural Ester: Mechanical Characterisation

Fernández-Diego

Ortiz

Carrascal

et al. 2019

2019 IEEE 20th International Conference on Dielectric Liquids (ICDL)

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Oil-immersed transformers, whose lifespan is defined by cellulose insulation's lifetime, utilize frequently mineral oil. However, this insulating fluid is being replaced by alternative liquids such as natural and synthetic esters. This replacement requires to guarantee a similar behavior of solid insulating materials immersed in them. Although there are different authors who have concluded that Kraft paper reduces its deterioration rate when it is immersed in biodegradable fluids, there are few works that have analyzed the effect of insulation liquids on the mechanical properties of other cellulosic materials such as diamond dotted paper (DDP) during laboratory tests. This paper shows a comparative analysis of four paper/oil specimens (a standard Kraft paper and a diamond dotted paper aged in both mineral oil and natural ester) under controlled laboratory accelerated thermal ageing. This work focuses on changes in mechanical properties such as the energy consumed per unit volume of the failure zone (ER), rupture strength (σR) and strain under ultimate strength (εcm).

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Failure analysis of transformer liquid — solid insulation system under selective environmental conditions using Weibull statistics method

Cited by 51 publications

References 22 publications

Risk and economic analysis of utilizing dynamic thermal rated transformer for wind farm connection

Risk and economic analysis of utilizing dynamic thermal rated transformer for wind farm connection

Assessment of Dielectric Paper Degradation through Mechanical Characterisation

Kraft And Diamond Dotted Paper Thermally Aged In Mineral Oil And Natural Ester: Mechanical Characterisation

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