Understanding the Ageing Performance of Alternative Dielectric Fluids

Gutiérrez, Cristina Méndez; Fernández, Alfredo Ortiz; Estébanez, Carlos Javier Renedo; Olmo, Cristian; Maina, R.

doi:10.1109/access.2023.3239895

Cited by 17 publications

(15 citation statements)

References 47 publications

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“…The chemical reaction between oxygen and the hydrocarbons of any insulating liquid causes deterioration in terms of oxidation and ageing of the liquid which leads to the formation of compounds like acids, sludge, water, and gases as presented in Table 10 with their corresponding effects [182], [183]. Also, the DGA results involving about 1.5 million samples based on IEEE C57.104-2019 standard revealed that the O2/N2 ratio is a prominent parameter that exerts a remarkable influence on the typical gas levels detected irrespective of the insulating liquid volume, rating, and voltage class.…”

Section: Oxygen and Ageingmentioning

confidence: 99%

Analyzing Transformer Insulation Paper Prognostics and Health Management: A Modeling Framework Perspective

Adekunle,

Fofana,

Picher

et al. 2024

IEEE Access

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In the era of Industry 4.0, digital transformation has spurred the swift advancement of technologies, including intelligent predictive maintenance scheduling, prognostics and health management. The accurate prediction of remaining useful life plays a crucial role in these technologies as it extends power equipment's safe operational duration and decreases the maintenance costs associated with unforeseen shutdowns. Also, the increased accessibility of data for monitoring system conditions has paved the way for the more immense adoption of machine learning models in prognostics and health management for power transformers. At the moment, with the ever-increasing demand for electricity, there is a corresponding increase in the degradation processes of power transformers. Transformers insulation system and more importantly, the paper insulation happens to be the principal part where the degradation is prominent. Therefore, an accurate prediction of the insulating paper condition through its degree of polymerization is required to guarantee the reliability of power transformers. In this regard, the predictions, reliability, and health monitoring of this power equipment can be actualized by modeling the degradation of transformer insulation paper through several machine learning frameworks. In this view, this review paper has been drafted not only to serve as a guide for researchers interested in the fields of transformer insulation system fault prognosis but also to offer insights into potential research directions as existing literature in modeling and evaluating transformer paper insulation is presented.INDEX TERMS Insulating paper, ageing, degree of polymerization, prognostics and health management, machine learning model.

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Section: Oxygen and Ageingmentioning

confidence: 99%

Analyzing Transformer Insulation Paper Prognostics and Health Management: A Modeling Framework Perspective

Adekunle,

Fofana,

Picher

et al. 2024

IEEE Access

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“…Moreover, retrofilling transformers with alternative oils reduces insurance costs, limits fire risk, and may extend the life expectancy of transformers [1,2]. It has been proven in the laboratory [3][4][5][6] that the presence of esters slows down the ageing rate of cellulose due to the higher hygroscopicity of these liquids and the hindrance of glucose chain cleavage by transesterification reactions. As a result of the reduced ageing rate of cellulose in the presence of esters, transformer insulation can safely withstand higher temperatures.…”

Section: Introductionmentioning

confidence: 99%

Life Expectancy of Transformer Paper Insulation Retrofilled with Natural Ester in the Laboratory

Montero,

García,

López

2023

Polymers

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The use of alternative insulating liquids instead of mineral oil in transformers is spreading around the world due to their superior fire resistance. Furthermore, researchers have demonstrated that these oils increase the lifespan of the solid insulation of the transformers and, thus, the life expectancy of the equipment. Retrofilling of transformers with natural and synthetic esters allows companies to benefit from the properties of using these liquids without making an investment into new machinery. This paper investigated the ageing process of Kraft paper that was retrofilled with a natural ester in the laboratory. The Kraft paper samples were subjected to accelerated thermal ageing in an oven at 130 °C, and markers such as the degree of polymerisation and tensile strength were measured. The ageing tests comprised a first period, where the samples were immersed in mineral oil, followed by a replacement of the oil with a natural ester. As moisture is a determinant factor for paper ageing, two sets of samples with different moisture contents were tested. The results showed that the retrofilling of the transformers may slow down the degradation rate of the solid insulation despite the presence of remaining mineral oil adsorbed in the paper.

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“…Each manufacturer purposefully adds different additives to their product to improve their behavior with respect to acidity, and sometimes their products are not "pure", since they have a mixture of different fluids. Table 1 includes typical values of the properties of different dielectric liquids [12]. The interest in these liquids since the early years of this century is demonstrated by the fact that in 2013 a review work was published in which the evolution of the different insulating liquids, as well as their blends, was exposed.…”

mentioning

confidence: 99%

“…Each manufacturer purposefully adds different additives to their product to improve their behavior with respect to acidity, and sometimes their products are not "pure", since they have a mixture of different fluids. Table 1 includes typical values of the properties of different dielectric liquids [12]. However, the use of these new dielectric fluids for transformers also has some drawbacks, among which two stand out:…”

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confidence: 99%

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A Brief Review of the Impregnation Process with Dielectric Fluids of Cellulosic Materials Used in Electric Power Transformers

et al. 2023

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In the manufacturing of power transformers, the impregnation of the solid electric insulation systems (cellulosic materials) with a dielectric liquid is a key issue for increasing the breakdown voltage of the insulation, and this prevents the apparition of partial discharges that deteriorate the insulation system. After introducing the problem, this article presents the theory of impregnation and later carries out a bibliographical review. Traditionally, mineral oils have been used as the dielectric liquid in electrical transformers, but for environmental (low biodegradability) and safety (low ignition temperature) reasons, since the mid-1980s, their substitution with other ester-type fluids has been studied. However, these liquids have some drawbacks, including their higher viscosity (especially at low temperatures). This property, among other aspects, makes the impregnation of cellulosic materials, which is part of the transformer manufacturing process, difficult, and therefore this tends to lengthen the manufacturing times of these machines.

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Understanding the Ageing Performance of Alternative Dielectric Fluids

Cited by 17 publications

References 47 publications

Analyzing Transformer Insulation Paper Prognostics and Health Management: A Modeling Framework Perspective

Analyzing Transformer Insulation Paper Prognostics and Health Management: A Modeling Framework Perspective

Life Expectancy of Transformer Paper Insulation Retrofilled with Natural Ester in the Laboratory

A Brief Review of the Impregnation Process with Dielectric Fluids of Cellulosic Materials Used in Electric Power Transformers

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