Moisture equilibrium in vegetable oil and paper insulation system

Zhang, Zhaotao; Li, Jian; Grzybowski, S.; Zou, Ping

doi:10.1109/ceidp.2011.6232686

Cited by 6 publications

(3 citation statements)

References 9 publications

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“…Water absorption capacity of the insulating oil reduces the moisture content in the solid insulation and hence its degradation. Water may be present in different forms in the oil, they may be physically present (in dissolved, dispersed or emulsified form) or chemically bound [31, 32]. In esters and silicone oil, water is in the dissolved and chemically bound form whereas, in mineral oil, it is only in the dissolved form.…”

Section: Ester Insulating Oilsmentioning

confidence: 99%

Review on natural ester and nanofluids as an environmental friendly alternative to transformer mineral oil

Jacob

Preetha

Sindhu

2020

IET Nanodielectrics

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The development of reliable, environmentally safe and economic insulating oil for the transformer is an endless effort of the electrical industry. Recent research is based on natural ester fluid, the green insulating oil which exhibits excellent dielectric performance and environment friendly characteristics. Nanofluids are also emerging as potential replacement for the conventional mineral oil used in transformers. Characterisation of nanoparticle filled mineral oil and natural esters have validated their improved dielectric behaviour in comparison to the unfilled oil. Although the applications are wide, the state of the art technology requires a deeper understanding of the underlying phenomenon. Much work is expected to be done in the application of nanofluids prepared with mineral oil and natural ester, particularly its effect on the cellulose insulation. The study provides an overview of the different materials that have been used as alternatives to the conventional transformer mineral oil, with special emphasis on natural esters and natural ester nanofluids, their advantages and challenges.

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Section: Ester Insulating Oilsmentioning

confidence: 99%

Review on natural ester and nanofluids as an environmental friendly alternative to transformer mineral oil

Jacob

Preetha

Sindhu

2020

IET Nanodielectrics

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“…In this line, Jovalekic obtained moisture equilibrium curves using natural esters as insulating liquids and high density (HD) pressboard and Nomex as cellulosic material [16], Vasovic developed moisture equilibrium curves using natural esters and a combination of Kraft paper and pressboard as cellulosic insulation [17] and Przybylek [18] determined moisture equilibrium curves in insulating systems combining cellulose materials with different ageing levels impregnated with different insulating liquids. Additionally, Zhang [19] and Villarroel [20] proposed expressions for the moisture diffusion coefficient of Kraft paper impregnated with a natural ester considering the dependence of the coefficient with temperature and moisture concentration.…”

Section: Introductionmentioning

confidence: 99%

Moisture dynamics in natural-ester filled transformers

Villarroel¹,

Burgos

García

2021

International Journal of Electrical Power & Energy Systems

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“…During the dynamic operation of transformers their temperature changes, because of load variations and changes on the ambient conditions; in consequence the moisture distribution will change as well, moving towards an equilibrium point which depends on the temperature, the geometry of the insulation and the moisture content of the system [7]. Several authors [9], [10], [11], [12] have previously obtained moistureequilibrium-charts which represent the relationship between the moisture levels of oil and paper in equilibrium conditions at different temperatures. It should be noted that moisture migration processes involve large time constants and therefore moisture migration processes will not always be completed.…”

Section: Introductionmentioning

confidence: 99%

A Multiphysical Model to Study Moisture Dynamics in Transformers

García

Villarroel

García

2019

IEEE Trans. Power Delivery

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Moisture is one of the key variables that must be considered when determining the load profiles that can be safely applied to a transformer. On one hand the presence of high amounts of water accelerates the ageing rate of the transformer solid insulation, shortening the life expectancy of the equipment. Moreover, the dynamic processes of moisture migration between paper and oil must be considered in order to avoid a potential cause of failure, such as the formation of bubbles in the interface paper-oil, or the moisture saturation and subsequent formation of liquid water in oil. These processes are linked to the changes of temperature, however, within the transformer, both processes have very different time constants what complicates the analysis. In this paper a mathematical model is presented that allows us to study the moisture dynamics in a transformer. The model considers a multiphisical approach incorporating a thermal module and a moisture dynamic module what makes possible to analyse the behaviour of the moisture for a certain load profile. Some application cases are included in the paper to illustrate the model operation.

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Moisture equilibrium in vegetable oil and paper insulation system

Cited by 6 publications

References 9 publications

Review on natural ester and nanofluids as an environmental friendly alternative to transformer mineral oil

Review on natural ester and nanofluids as an environmental friendly alternative to transformer mineral oil

Moisture dynamics in natural-ester filled transformers

A Multiphysical Model to Study Moisture Dynamics in Transformers

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