Oil Impregnation in Transformer Boards (1) Measurement of Impregnation Depth and Internal Pressure

Suzuki, Toshio; Takagi, Masami

doi:10.1109/tei.1984.298808

Cited by 8 publications

(11 citation statements)

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“…This is due to the prevalence of the external pressure and the capillary effect over the inner pressure. A way to enhance this prevalence is by removing the inner pressure by the application of vacuum in the solid samples prior the impregnation [7], a widespread technique in impregnation studies [5] [8]. Another technique is to increase the external pressure once the solid samples are completely submerged and the pores are isolated from the atmosphere by the oil [7].…”

Section: Impregnation Theoretical Basismentioning

confidence: 99%

“…A way to enhance this prevalence is by removing the inner pressure by the application of vacuum in the solid samples prior the impregnation [7], a widespread technique in impregnation studies [5] [8]. Another technique is to increase the external pressure once the solid samples are completely submerged and the pores are isolated from the atmosphere by the oil [7]. To able tracing the impregnation evolution based on the appearance, the solid samples to impregnate should not be submerged in the fluid.…”

Section: Impregnation Theoretical Basismentioning

confidence: 99%

“…Examples of this are the impregnation under vacuum or at elevated temperatures, that eases the complete entrance of oil in the solid without comprising the final properties [1], or the use of equipment specifically designed to ensure the contact between oil and solid [6]. This was based on a deeper knowledge of the phenomena that underlies this process: the existence of forces that supposes the entrance of fluid in the pores of a material and their dependence on several parameters to be considered [7].…”

Section: Introductionmentioning

confidence: 99%

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Study of the Impregnation of Power-Transformer Cellulosic Materials With Dielectric Ester Oils

Sanz

Sancibrian

Olmo³

et al. 2021

IEEE Access

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The application of alternative dielectric oils as esters in power transformers is hindered by the lack of knowledge regarding their properties and respecting which are the best techniques to ensure their proper performance. In this sense one of the fields needing an impulse is the impregnation processes of transformers cellulosic materials with these alternative oils, currently impregnated in most of the cases with mineral oils. This paper studies the impregnation behavior of eight usual dielectric solids, with two esters and a traditional mineral oil. Empirical equations of the impregnation evolution with time have been obtained, from these the rigid cellulosic materials present in the transformers and the viscosity of the dielectric oils have been identified as the key materials and properties to consider during impregnation. An adaptation of the current impregnation processes to the alternative oils have been proposed by increasing their temperature from ambient temperature up to 61-74ºC, depending on the viscosity of the oil used. INDEX TERMS dielectric, ester, impregnation, model, transformer, temperatureThis work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.

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Section: Impregnation Theoretical Basismentioning

confidence: 99%

Section: Impregnation Theoretical Basismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Study of the Impregnation of Power-Transformer Cellulosic Materials With Dielectric Ester Oils

Sanz

Sancibrian

Olmo³

et al. 2021

IEEE Access

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“…Additionally, they studied the effect of temperature on the impregnation time. Subsequently, in 1984 researchers from Toshiba Corporation also studied the impregnation of transformer board in mineral oil [17,18]. They obtained in their first work that temperature and vacuum level increase have a positive effect on impregnation rate.…”

Section: Introductionmentioning

confidence: 99%

Impregnation processes of insulation rigid components of cellulose in synthetic ester and mineral oil

Ortiz

Sanz

Pérez

et al. 2019

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

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Although oil-immersed power transformers generally use mineral oil as insulation and cooling fluid, this liquid does not meet the new technical requirements of dielectric fluids such as high biodegradability, non-toxicity and high safety. For these reasons, natural and synthetic esters as alternative to mineral oil have increased their utilization in some transformers installations. Despite the fact that there are several works that have demonstrated the suitability of these insulation fluids from the point of view of their stability, dielectric and thermal properties, there are very few works focused on the study of the effects of these liquids on impregnation process. The aim of this work is provide information about the behavior of different rigid insulation materials, not studied until now, during the impregnation process in a synthetic ester compared with a mineral oil.

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“…It means the reduction of air pressure inside the capillaries (PI) is important for an efficient impregnation process. Therefore, the oil impregnation process is generally performed under very high vacuum condition [43][44][45].…”

Section: Oil Impregnationmentioning

confidence: 99%

Condition monitoring of biodegradable oil filled transformer

Mudiyanselage¹,

Bandara²

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Natural and synthetic ester insulating oils have higher fire points and excellent biodegradable characteristics. Therefore, in order to reduce the adverse environmental impact and to improve the fire safety of transformers, there is an increasing demand for natural and synthetic ester insulating liquids as a transformer insulating oil. However, present understanding on ageing behaviour of ester oil-paper composite insulation system and knowledge on application of existing condition monitoring tools for ester based insulation systems are inadequate. This impedes the cost effective and reliable field applications of ester insulating oils, particularly application of natural esters. To reduce this knowledge gap, series of controlled ageing experiments are performed in this research project to provide a better and comprehensive understanding on ageing behaviour of ester oil-paper insulation systems. Furthermore, applicability of existing chemical and electrical based condition monitoring techniques for ester oil-paper insulation systems is systematically investigated in this research project.In this thesis, ageing behaviour of dry pressboard insulation in mineral and three different ester insulating oils under simulated transformer operating environment is investigated. Moreover, the ageing behaviour of natural ester-pressboard composite insulation in moisture rich environment is also compared with that of mineral oil-pressboard system. Degree of polymerisation of pressboard samples measured at different ageing interval is used in this research to determine the ageing condition of pressboard. Moreover, applicability of oil related diagnostic parameters such as concentration of dissolved furanic compounds, acidity value, Dielectric Dissipation Factor (DDF), viscosity and colour to assess the degree of degradation of both ester and mineral insulating oils is thoroughly investigated in this research project. The potential of FTIR (Fourier Transform Infrared spectroscopy) techniques for characterising the degree of degradation of paper insulation is also discussed in this thesis. In addition, this thesis concentrates on characterisation of the charge dynamic in insulating oil through modelling of their dielectric responses.The comparison of gassing behaviour of ester and mineral insulating oils under two different low temperature faults and low energy electric discharge condition is also presented in this thesis.Dissolved Gas Analysis (DGA) results presented in this thesis depicts that faults gases detected in ester and mineral oil samples subjected to a similar fault are akin in type but quantitatively different. The quantity of fault gases produced in two different natural ester oils is also dissimilar.For example, soy-based natural ester produces a large quantity of ethane (C2H6) under low temperature overheating condition than sunflower oil based natural ester. Therefore, this research project investigates the applicability of well-established DGA interpretation schemes namely Duval II | P a g e triangle, IE...

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Oil Impregnation in Transformer Boards (1) Measurement of Impregnation Depth and Internal Pressure

Cited by 8 publications

References 0 publications

Study of the Impregnation of Power-Transformer Cellulosic Materials With Dielectric Ester Oils

Study of the Impregnation of Power-Transformer Cellulosic Materials With Dielectric Ester Oils

Impregnation processes of insulation rigid components of cellulose in synthetic ester and mineral oil

Condition monitoring of biodegradable oil filled transformer

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