Identification of Critical Values Based on Natural Ester Oils as Potential Insulating Liquid for High Voltage Power Transformers

Pamuk, Nihat

doi:10.2339/politeknik.369050

Cited by 3 publications

(3 citation statements)

References 9 publications

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“…As described above with cellulose paper, the technical life of natural esters depends on the raw materials from which they are made (internal factors) as well as the environment to which they are exposed (external factors). The major degradation processes of natural esters are hydrolysis [28], polymerization [29], oxidation [30], and hydrogenation [31].…”

Section: Degradation Processes In Natural Estersmentioning

confidence: 99%

Various Aging Processes in a Paper-Natural Ester Insulation System in the Presence of Copper and Moisture

et al. 2020

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This article adds more information to the problem of natural ester use as an electroinsulating fluid in cellulose paper-oil systems, e.g., for use in power transformers. An accelerated thermal aging (120, 140 and 160 • C) of samples consisting of cellulose paper (transformerboard), a treated natural ester (filtered, basic Al 2 O 3 , 0.53% DBPC), a copper plate and moisture was studied. Research was especially focused on the impact of moisture on the aging of the above system. Samples with three different oil moisture levels (80, 143 and 305 ppm water content) were subjected to thermal aging to display the change in a selection of properties (tanδ, acid number, water content). For a study of the polarization effects, broadband dielectric spectroscopy (BDS) was performed to observe the complex permittivity and conductivity dependencies on the temperature and frequency (±30 • C, 0.01-10 7 Hz). Havriliak-Negami (H-N) diagrams were used to further understand the results. The degradation products during thermal aging were recognized by Fourier transform infrared (FT-IR) spectroscopy. Hydrolysis and hydrogenation occurred in the insulating system with a natural ester aged by elevated temperatures, which is in contrast to CO 2 formation in the case of electric aging. The results showed an increase in the acid number, dissipation factor, and number of hydrolysis and hydrogenation products. Furthermore, changes in polarization were observed as a consequence of the thermal aging of paper-natural ester insulation system with the presence of copper and moisture. INDEX TERMS Aging, dielectrics, hydrogenation, hydrolysis, oil insulation, paper-oil insulating system, natural ester, complex permittivity.

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Section: Degradation Processes In Natural Estersmentioning

confidence: 99%

Various Aging Processes in a Paper-Natural Ester Insulation System in the Presence of Copper and Moisture

et al. 2020

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“…• ASTM D971: Standard test method for interfacial tension of oil against water by the ring method. Because of the high hydrophilic nature of natural esters when new, the interfacial tension is lower when compared to mineral oils (the highest values are in the mid-20s mN/m) [27]- [29]. Under service conditions, acids and [3] and [8] for unused liquids received in equipment before energizing.…”

Section: B Acceptance and Monitoringmentioning

confidence: 99%

On Some Imperative IEEE Standards for Usage of Natural Ester Liquids in Transformers

2020

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From the recent past, biodegradable dielectric fluids are becoming popular across the global utilities for use in oil-filled transformers. To date, several utilities have started using biodegradable insulating fluids for new and retro-filled power and distribution transformers. The intent of this article is to compare and analyze various aspects that are involved in the successful operation and maintenance of mineral oil and ester filled transformers. The comparative analysis in this article is aimed at properties, condition monitoring, diagnostic, and reclamation aspects of ester filled transformers. The imperative and pertinent standards, including IEEE Std C57.106, IEEE Std C57.104, IEEE Std 637, IEEE Std C57.147, and IEEE Std C57.155 remain the target objectives for potential analysis. It is hoped that this critical analysis will be useful for utility and condition monitoring engineers in understanding several key aspects of ester fluids vis-à-vis traditional insulating fluids. The present analysis might also be useful for researchers and industry interested in alternative dielectric fluids for transformer insulation technology.

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“…This increases the losses in power transformers. If the losses in the power transformers are not kept under control, it causes the temperature in the power transformer core to increase and the insulation deteriorates (Pamuk, 2017;Mariprasath and Ravindaran, 2022). Load losses in power transformers are examined in three main sections.…”

Section: Introductionmentioning

confidence: 99%

Determining Accuracy of Temperature Limit Change in Power Transformer Core Using Temperature-Time Parameter Method

PAMUK

2023

Black Sea Journal of Engineering and Science

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The efficient transmission of electrical energy depends on amplifying voltage values with power transformers. To obtain higher efficiency from transformers, the core and winding type of transformer, the geometric structure of the core, and the shaping techniques in the windings are changed. This requires modeling transformer windings with equivalent circuits and calculating the inductance and electrical parameters appropriately. In this study, two-dimensional (2D) finite element solutions with energy perturbation and flux-coupling methods are used. The correctness of the inductance values of transformer windings was established, and the design was performed, by considering the inductance and electrical parameter values, which are comparable to the energy perturbation and flux connection. However, when two-dimensional calculated fields are used, the flux coupling method requires less computation and gives numerically more accurate results than the energy perturbation method. So, it is concluded that the flux-coupling approach should be chosen as the preferred method for calculating the inductance and electrical parameters of transformer windings. The numerical properties and equivalence of energy perturbation and flux-connection methods, the “apparent” inductance value of the primary and secondary field windings of power transformer operating under transient conditions, using the temperature-time parameter method, are calculated and its accuracy is demonstrated.

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Identification of Critical Values Based on Natural Ester Oils as Potential Insulating Liquid for High Voltage Power Transformers

Cited by 3 publications

References 9 publications

Various Aging Processes in a Paper-Natural Ester Insulation System in the Presence of Copper and Moisture

Various Aging Processes in a Paper-Natural Ester Insulation System in the Presence of Copper and Moisture

On Some Imperative IEEE Standards for Usage of Natural Ester Liquids in Transformers

Determining Accuracy of Temperature Limit Change in Power Transformer Core Using Temperature-Time Parameter Method

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