Articles de revues : « Transformers oils »

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Ponomarenko, Serhii. « Comparative analysis of oil ageing intensity in 110 kV transformers and 330 kV autotransformers ». Bulletin of the National Technical University "KhPI". Series : Energy : Reliability and Energy Efficiency, n^o 2 (3) (30 décembre 2021) : 124–36. http://dx.doi.org/10.20998/2224-0349.2021.02.06.

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The results of transformer oil ageing intensity analysis in 110 kV transformers and 330 kV autotransformers are presented. Using a mathematical model of variance linear regression analysis (covariance analysis model), applied to the results of periodic tests on 231 transformers of 110 kV and 49 autotransformers of 330 kV, several statistical hypotheses have been tested to estimate the intensity of drift of oil indicators during long-term operation of transformers. The following hypotheses were tested as statistical hypotheses: the hypothesis of a significant systematic drift in the values of oils during long-term operation, which allows assessing the presence of transformer oil ageing processes. The hypothesis of equality of partial angular coefficients for regression models based on test results for each of the oil in individual transformers (regression lines are parallel), which allows estimating the differences in the ageing intensity of oils in individual transformers. The hypothesis that the group averages lie on a straight line, that is, the drift of the oil in the different transformers occurs at the same rate. The hypothesis of equality of partial free terms for regression models based on test results for each of the oil indicators in individual transformers, which allows assessing the presence of differences in the values of oil indicators at the time of commissioning of transformers, that is, the actual presence of differences in the quality of the poured oil. The results of the analysis for both 110 kV transformers and 330 kV autotransformers showed not only an additive and multiplicative bias between individual series of oil parameters, but also a significant systematic component, indicating the aging of transformer oils in the analysed transformers. It was found that the intensity of drift of oil indicators in 110 kV transformers and in 330 kV autotransformers significantly differs, which should be taken into account when building models for the early recognition of the condition of transformer oils by the results of periodic tests.

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Ahmed, Usman Omeiza, Yekini Suberu Mohammed et Nasiru Audu. « Potential Characterization of Bush Mango Oil for Application in Transformer Insulation ». Asian Journal of Engineering and Applied Technology 12, n^o 1 (29 juin 2023) : 51–54. http://dx.doi.org/10.51983/ajeat-2023.12.1.3685.

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In recent times, the suitability of some oils from edible fruits as a replacement for mineral oils used in transformers has been proven in different literature. The use of edible oils as transformer insulation fluid gives rise to the concept of green insulation in transformers. Research in the use of edible oil in the production of transformer oil has been one of the major researches in high voltage engineering. The existence of paucity of knowledge on the use of bush mango oil as dielectric fluid in transformers led to the idea of this research work. Therefore, this study focuses on the investigation of the suitability of using Irvingia Gabonensis Oil (IGO) for insulation in power transformers. From the series of analyses conducted, it has been established that the Irvingia Gabonensis (Bush Mango) oil is not suitable for transformer insulation oil. This is because the biobased green oil produced presented characteristics that are not suitable to match the standards recommended by the International Electrochemical Commission (IEC) and the American Society for Testing and Materials (ASTM).

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Serhii, Zaitsev, et Kishnevsky Victor. « IMPROVEMENT OF THE METHOD OF DIAGNOSTICS OF HIGH-VOLTAGE TRANSFORMERS VOLTAGE BASED ON THE RESULTS OF CHROMATOGRAPHIC ANALYSES OF TRANSFORMER OILS ». Collection of scholarly papers of Dniprovsk State Technical University (Technical Sciences) 2, n^o 43 (25 décembre 2023) : 100–111. http://dx.doi.org/10.31319/2519-2884.43.2023.11.

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The relevance of the work is due to the need to improve methods for diagnosing high-voltage oil-filled voltage transformers with paper-oil electrical insulation, which makes it possible to solve the problems of monitoring the technical condition, finding the place and determining the causes of failure (malfunction), and predicting the technical condition of this equipment on the basis of appropriate diagnostic software. The aim of the work is to ensure the reliability of operation of high-voltage oil-filled voltage transformers with paper-oil electrical insulation by improving the method of their diagnosis based on the results of analyses of samples of mineral transformer oils by gas chromatography. In accordance with the research objective, the following tasks were solved: 1. Determine the content of such dissolved diagnostic components in samples of mineral transformer oils from high-voltage oil-filled voltage transformers of NKF-110, NKF-220, NKF-330 types as gases H2, CH4, C2H6, C2H4, C2H2, CO, CO2, O2, N2; additive "Ionol"; furan compounds (2-furyl alcohol; 2-furfural; 2-acetylfuran; 5-methyl-2-furfural) and the sum of their concentrations. 2. The basic procedures for diagnosing high-voltage oil-filled voltage transformers based on the results of analyses of mineral transformer oil samples with the determination of the content of dissolved diagnostic components in them were improved. For the diagnosis of high-voltage oil-filled voltage transformers based on the results of gas chromatographic analyses of samples of mineral transformer oils from this equipment, it is recommended to use the following methods: "Limit level of concentrations", "Tabular method", "Graphic images of defects", "ETRA", "Duval triangle", "Visual inspection after disassembly of high-voltage oil-filled voltage transformers". To determine the degree of danger of the development of the identified probable defects, the method of determining the "Relative growth rate of dissolved gas concentrations" can be used. The prospect of practical application of the results of the work is to ensure the reliability of operation of high-voltage oil-filled voltage transformers by improving the method of their diagnosis based on the results of analyses of samples of mineral transformer oils with simultaneous determination of the content of dissolved gases, the additive "Ionol", furan compounds by gas chromatography.

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Ghani, Sharin Ab, Mohd Shahril Ahmad Khiar, Imran Sutan Chairul et Muhammad Imran Zamir. « Effect of repeated electrical breakdowns on mineral and natural ester insulating oils ». Bulletin of Electrical Engineering and Informatics 10, n^o 6 (1 décembre 2021) : 2989–96. http://dx.doi.org/10.11591/eei.v10i6.3258.

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Transformer insulating oils are exposed to repeated electrical discharge or breakdowns inside power transformers. Durability tests are conducted to analyze the ability of oil to resist decomposition due to such high electrical stresses. With the increasing demand for alternative insulating oils for oil-immersed transformers, it is worthy to compare the performance of different types of insulating oils (conventional mineral-based insulating oil and natural ester-based insulating oil) under repeated electrical breakdown. In this paper, the AC breakdown voltage of different mineral-based and natural ester-based insulating oils is reported. Durability tests were conducted based on the AC breakdown voltage behavior of insulating oils after 50 electrical breakdown shots. The AC breakdown voltage of each insulating oil sample was assessed according to the ASTM D1816 standard test method. Based on the results, it can be concluded that the dissimilarity in chemical composition of the insulating oils has a significant effect on the AC breakdown voltage behavior of these oils under repeated electrical breakdowns.

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M.Jamail, N. A., N. A. Azali, E. Sulaiman, Q. E. Kamarudin, S. M. N. S. Othman et M. S. Kamarudin. « Breakdown Characteristic of Palm and Coconut Oil with Different Moisture ». Indonesian Journal of Electrical Engineering and Computer Science 12, n^o 1 (1 octobre 2018) : 363. http://dx.doi.org/10.11591/ijeecs.v12.i1.pp363-369.

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Oils acts as insulation and cooling agent in the transformer. Petroleum-based oils are widely used in transformers due to their qualified properties as good insulation materials. Unfortunately, the used of petroleum-based oils has adverse effects on environment in the event of any failure to transformers such as tank leakage or explosions. Therefore, researchers have been studied and have found environmentally friendly oil that is suitable as substitutes in transformer. Thus, breakdown voltage tests using direct current and alternating current with the addition of different water content were performed to identify the potential of palm oil and coconut oil in the transformer isolation system. Refined, Bleached and Deodorized oil (RBDPO) and coconut oil samples were selected to be test in this study. The oil samples were test by varies the gap distance of test cell electrode and the level of water content. As a conclusion, RBDPO oil has greater breakdown voltage test under DC breakdown voltage test in term of increment of the gap distance.

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Prasad, D., et S. Chandrasekar. « EFFECT OF NANO-SiO2 PARTICLES ON PARTIAL DISCHARGE SIGNAL CHARACTERISTICS OF FR3 TRANSFORMER OIL ». JOURNAL OF ADVANCES IN CHEMISTRY 13 (7 février 2017) : 6208–17. http://dx.doi.org/10.24297/jac.v13i0.5687.

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Liquid insulation for high voltage transformer applications based on natural esters derived from abundantly available vegetable oils are becoming popular in recent times. Since these natural ester based oils have environmental advantages and superior thermal performance, electrical utilities are slowly replacing the conventional mineral oils with natural ester based vegetable oils. FR3 oil, which is a soya based natural ester oil with superior dielectric and thermal characteristics, is becoming popular as an alternate insulating medium for high voltage transformers. With recent developments in nanotechnology field, it is possible to enhance the dielectric performance characteristics of natural ester based oils, which is a major constraint for high voltage transformer applications. However few research reports are only available in the area of nanofluids based on natural esters for high voltage insulation applications. In depth analysis and collection of large data base of insulation performance of natural ester based vegetable oils is important to improve the confidence level over nano-fluids based on natural esters. Considering these facts, in the present work, partial discharge characteristics of nano-SiO2 modified FR3 oil at different electrode configurations are investigated at different %wt filler concentrations. Important parameters such as partial discharge inception voltage, stable PD formation voltage, partial discharge amplitude at different voltage magnitude and PD signal frequency characteristics are evaluated. From the results, it is observed that the partial discharge performance of FR3 oil is significantly improved with the addition of nano-SiO2 filler. Since in recent times FR3 oil is commercially used in many transformers, these results will be useful for enhancing the dielectric strength of high voltage transformers.

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Ab Ghani, Sharin, Zulkarnain Ahmad Noorden, Nor Asiah Muhamad, Hidayat Zainuddin et Mohd Aizam Talib. « A Review on the Reclamation Technologies for Service-Aged Transformer Insulating Oils ». Indonesian Journal of Electrical Engineering and Computer Science 10, n^o 2 (1 mai 2018) : 426. http://dx.doi.org/10.11591/ijeecs.v10.i2.pp426-435.

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Power transformers are the backbone of electricity transmission and distribution systems throughout the world. The price of power transformers is exorbitant (costing millions of dollars per unit) and therefore, frequent maintenance is necessary to ensure that these systems are highly reliable during their operation. The service life of mineral insulating oils is typically 30 to 40 years for power transformer applications. However, all insulating oils (regardless of their type) are subjected to thermal, electrical and chemical degradation, which will deteriorate the oil-paper insulating system and consequently reduce the capability of the oil as an electrical insulator. For these reasons, service-aged insulating oils are treated by two types of processes (i.e. reclamation and reconditioning) in order to prolong the service life of these oils. Reclamation (regeneration) is used to treat insulating oils with high levels of acidity and sludge. In this paper, a brief review on the reclamation technologies used to treat service-aged insulating oils is presented, covering various aspects such as the standard test methods that need to be complied with, the types of adsorbents used to reduce acidity and sludge of the used insulating oils, as well as the findings of several key studies related to the evaluation of the effectiveness of the reclamation process. This review will indeed benefit researchers and practitioners in this field since it provides an overall picture of the recent progress in reclamation technologies for service-aged transformer insulating oils

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Vysogorets, S. P., A. N. Nazarychev et A. A. Pugechov. « METHOD FOR EXPERIMENTAL DETERMINATION OF THE LIQUID DIELECTRIC RESOURCE AND MEASURES FOR ITS RESTORATION ». Kontrol'. Diagnostika, n^o 254 (2019) : 36–41. http://dx.doi.org/10.14489/td.2019.08.pp.036-041.

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The theoretical foundations of changes in the transformer oil quality characteristics, depending on the aging degree, are presented. The introduction of a new indicator of the exploitational transformer oils quality – “stability against oxidation” – is substantiated as a way of solving the scientific and technical problem of assessing the resource characteristics of a transformer insulating system. In order to select the best measures to maintain the quality of power transformers insulating oils, a newly developed “Method for the Experimental Determination of the Luquid Dielectric Resource and Measures for its Restoration” is presented.

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Zdanowski, Maciej. « Streaming Electrification Phenomenon of Electrical Insulating Oils for Power Transformers ». Energies 13, n^o 12 (22 juin 2020) : 3225. http://dx.doi.org/10.3390/en13123225.

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The subject matter of this study was the problem of the ECT (electrostatic charging tendency) of mineral insulation oils during their flow. The electrostatic charges generated may lead to partial discharges, and as a consequence, to the breakdown of a power transformer insulation system. In this study, the results of the ECT of mineral oils used in transformers were compared. The method of streaming electrification of insulation liquids using a flow-through system was used. The influence of flow speed, temperature, and the pipe material on the values of the electrification current and volume charge density qw were analyzed. The results obtained in this study should be taken into account regarding the operation of power transformers.

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Boukounacha, Ahmed Yassine, Boubakeur Zegnini, Belkacem Yousfi et Tahar Seghier. « Factors affecting the thermal conductivity of dielectric nanofluids for use as alternative fluids in power transformers ». South Florida Journal of Development 5, n^o 9 (2 septembre 2024) : e4314. http://dx.doi.org/10.46932/sfjdv5n9-001.

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The high heat transfer capabilities of dielectric fluids used in power transformers are considered one of the most important properties responsible for increasing the efficiency of these devices, as these oils transfer the heat generated from the internal parts of the transformer to the external environment. The application of nanotechnology in liquid insulators will increase the heat transfer rates through the thoughtful incorporation of nanoparticles (NPs) in these insulating media. Nanofluids (NFs) have higher thermal conductivity compared to conventional insulating oils found in power transformers, which nominates them as promising alternatives in the field of high voltage. This paper focuses on the thermal conductivity capabilities of dielectric nanofluids as well as the analysis of different factors affecting thermal conductivity. It also presents some theoretical models to determine the thermal conductivity of NFs with the possibility of applying these dielectric nanofluids to improve the heat transfer performance of power transformer.

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Salerno, Elisabetta, Adriano Leonforte, Mattia Grespan, Diego Angeli et Mauro A. Corticelli. « CFD Analysis of the Thermal-Hydraulic Performance of Traditional and Alternative Oils for Transformer Cooling ». Applied Sciences 14, n^o 21 (24 octobre 2024) : 9736. http://dx.doi.org/10.3390/app14219736.

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The search for alternative, more environmentally friendly coolants to replace mineral oils in power transformers represents a relevant challenge for the power industry. In this frame, a CFD analysis is carried out by means of an open-source, conjugate heat transfer Finite Volume solver to assess the heat transfer performance of different coolants in a disc-type winding of an oil-immersed power transformer, whose geometry is taken from a reference case in the literature. Four different oils are considered: two mineral oils widely established among power transformer manufacturers, a synthetic ester and a natural ester. The latter two represent environmentally friendly alternatives to mineral oils, of great interest for the specific sector. The influence of temperature-dependent thermophysical properties on the overall flow and on the location and value of the hot spots in the copper conductors is discussed, highlighting the strength and weaknesses of the four oils as transformer coolants. In particular, the natural ester exhibits the best heat transfer performance, whereas high hot-spot temperatures and strong fluctuations are found for both mineral oils and the synthetic ester.

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S. Chandrasekar. « Understanding the Lightning Impulse Discharge Characteristics of Nano Silica Modified Sunflower Oil for High-Voltage Insulation Applications ». Journal of Environmental Nanotechnology 11, n^o 2 (30 juin 2022) : 01–03. http://dx.doi.org/10.13074/jent.2022.06.222452.

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Vegetable oils with nanotechnology added to them are a possible replacement for mineral oils in power transformer applications today. Because of the size and production cost reductions as well as the oil's high level of biodegradability, this could result in an increase in the dielectric strength of insulating fluid. Since transformers are mainly used for outdoor applications, understanding the capability of insulating fluid to withstand lightning discharge is a vital issue. This study used experimental analysis to compare the lightning discharge performance of pure sunflower oil and sunflower oil modified with SiO2 (Nano) at various weight-per-volume concentrations of 0.01 %, 0.05 %, and 0.1 %. This experimental work was conducted with 1.2/50 µs of standard lightning impulse voltage with positive polarity. The result illustrated that the nano-modified sunflower oil had greater lightning impulse withstand strength than the pure sunflower oil.

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Anggara, Gustio Riki Kartiko, Suprihadi Prasetyono et RB Moch Gozali. « ANALISIS KARAKTERISTIK DIELEKTRIK BERBAGAI MINYAK NABATI SEBAGAI ALTERNATIF ISOLASI CAIR UNTUK TRANSFORMATOR TENAGA ». Jurnal Arus Elektro Indonesia 8, n^o 1 (30 avril 2022) : 1. http://dx.doi.org/10.19184/jaei.v8i1.26079.

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This article discusses the analysis of the dielectric characteristics of various vegetable oils as an alternative to liquid insulation for power transformers. Vegetable oil in this study focused on three kinds of vegetable oil, namely kemiri sunan oil, castor oil, and palm oil. This study reviews the dialectical characteristics of the three oils with respect to temperature changes. This vegetable oil will be compared with transformer oil, namely Shell Diala B, to determine the feasibility of vegetable insulating oil. This article uses literature study and data collection methods, using the basic theory of transformers, namely when alternating electric current flows around an iron core, the iron core will turn into a magnet. The results of this study indicate that these three vegetable oils have the same breakdown voltage characteristics to temperature changes, namely at a temperature voltage of 30°C. Furthermore, these three types of oil are still below the standard SPLN 49-1: 1982 which is 30 kV and still do not have the feasibility of transformer insulation oil. When palm oil is increased to 70°C, the breakdown voltage increases quite drastically, which is 48.58 kV. This has met the standard when compared to Sell diala B oil which when the temperature changes 70°C the breakdown voltage is 47.09 kV.

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Haramija, Veronika, Dijana Vrsaljko, Vedran Đurina et Domagoj Vrsaljko. « Thermal stability change of synthetic ester-based transformer oil ». Journal of Energy - Energija 63, n^o 1-4 (4 juillet 2022) : 135–40. http://dx.doi.org/10.37798/2014631-4171.

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For good transformer condition assessment it is necessary to determine the condition of insulating materials, both liquid and solid. Transformer is reliable for as long as its insulation system resists deterioration. Therefore, thermal and oxidation stability are important characteristics of transformer oil. It is a measure of oil resistance for decomposition by the influence of oxygen and temperature. Oils with good thermal and oxidation stability retain their characteristics regardless the thermal stress. Because of environmental and safety issues, the use of synthetic ester-based transformer oils is increasing. Although they have been in use in smaller transformers (distributive, traction, …) for decades, limit values for chemical and physical characteristics are still discussed. New methods for thermal stability evaluation can be useful for insulation condition assessment.

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Sutan Chairul, Imran, Sharin Ab Ghani, Norazhar Abu Bakar, Mohd Shahril Ahmad Khiar, Nor Hidayah Rahim et Mohamad Nazri Mohamad Din. « Comparative study of moisture treatment techniques for mineral insulating oil ». Bulletin of Electrical Engineering and Informatics 12, n^o 6 (1 décembre 2023) : 3256–62. http://dx.doi.org/10.11591/eei.v12i6.5927.

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The presence of moisture is one of the factors that promote degradation of transformer insulating oils and deterioration of cellulose insulation materials in oil-immersed power transformers, which affect the lifespan of the transformers. Realizing the importance of moisture in transformer insulating oils, this study compares the effectiveness of three moisture treatment techniques nitrogen bubbling technique (NBT), molecular sieve technique (MST), and vacuum oven technique (VOT)) for mineral oil (MO). The moisture content and AC breakdown voltage of the MO samples before and after moisture treatment were measured using Karl Fischer coulometric titrator and portable oil tester, respectively, in accordance with the American Society for Testing and Materials (ASTM) D1533 and ASTM D1816 standards. The results showed that NBT is the best moisture treatment technique for the MO, where the NBT reduced 80.79% of moisture present in the oil, followed by MST and VOT, which reduced 72.87 and 42.28% of moisture, respectively. The results also showed that the AC breakdown voltage of the MO samples after moisture treatment was improved owing to the reduction in moisture content.

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Šárpataky, Miloš, Juraj Kurimský et Michal Rajňák. « Dielectric Fluids for Power Transformers with Special Emphasis on Biodegradable Nanofluids ». Nanomaterials 11, n^o 11 (28 octobre 2021) : 2885. http://dx.doi.org/10.3390/nano11112885.

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This review is focused on the research of dielectric fluids, especially commonly used power transformer oils enhanced by nanoparticles, i.e., nanofluids. There are differences between various combinations of base fluids and nanoparticles prepared in different ways. The main goal of this review was to present recent research in this field sorted by the used nanoparticles. Nanofluids based on mineral oils, natural, or synthetic esters were investigated in terms of the nature of nanoparticles, particularly Al2O3, TiO2, Fe2O3, Fe3O4, graphene, fullerene, and others. The combinations of environmentally friendly oils and nanoparticles were presented. Finally, the article focused on the description of current dielectric fluids usable in power transformers and the possibilities of improving new and existing fluids with nanoparticles, especially their physical, dielectric, and chemical properties, but with regard to environmental aspects.

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Denmukhammadiev, A. M., D. T. Yusupov, Sh A. Shoyusupov, A. U. Djalilov et O. A. Nazarov. « Diagnostics of power transformers operating for many years in the power supply system through gases in the composition of transformer oil ». Journal of Physics : Conference Series 2176, n^o 1 (1 juin 2022) : 012064. http://dx.doi.org/10.1088/1742-6596/2176/1/012064.

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Abstract Oiled power transformers and autotransformers 40-60 years ago are still in operation in Uzbekistan. At the same time, diagnostic methods for determining faults in transformers and autotransformers remained the same. This article partially analyzes the factors affecting the oils of power transformers and autotransformers used in the agricultural sector. It is known that transformer oil performs the functions of cooling and insulation. During use, the oil is in direct contact with air through the respiratory system. There is a process of transition of moisture and various gases in the composition of the air into the composition of the oil. By the composition of gases, it is possible to determine the reasons for the deterioration in the quality of the main and additional insulation of oil-immersed power transformers. The issues of influence on the state of insulation of marsh gases appearing inside (at the bottom) of the tank of oil transformers and partial discharges in oil-gas medium have been little studied.

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Garifullin, Marsel Sh, Marina N. Lyutikova, Adelya R. Kuchkarova, Azat R. Bikzinurov et Yuliya N. Solobodina. « Application of IR spectroscopy to control oxidation inhibitor (ionol) concentration in mineral transformer oils ». E3S Web of Conferences 216 (2020) : 01056. http://dx.doi.org/10.1051/e3sconf/202021601056.

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Mineral insulating oils used as dielectric and heat dissipating agent in high voltage oil-filled equipment are subject to oxidation. Oxidation results in the appearance of undesirable substances that reduce the electrical insulating properties of liquids. Therefore, to inhibit the oxidation process, an antioxidant additive is introduced into transformer oils. In the overwhelming majority, 2,6-di-tert-butyl-4-methylphenol (ionol) is used as an inhibitor. Residual concentration of ionol is a regularly monitored parameter. In Russia, the main method for determining the concentration of ionol in oil is gas chromatography. However, fourier-transform infrared spectroscopy should be considered as an alternative method for monitoring the ionol content as it has a number of advantages over the gas chromatographic method. The paper compares the results of the determination of ionol in operational transformer oils using gas chromatography and the IR method. We justified that the method of IR spectroscopy has no limitations as applied to oils from power transformers equipped with adsorption purification systems.

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Fal, Jacek, Omid Mahian et Gaweł Żyła. « Nanofluids in the Service of High Voltage Transformers : Breakdown Properties of Transformer Oils with Nanoparticles, a Review ». Energies 11, n^o 11 (28 octobre 2018) : 2942. http://dx.doi.org/10.3390/en11112942.

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The continuous development of electrical systems and high voltage transformers builds the need for looking for new insulating media or to improve the insulating properties of commercially available transformer oils (TO) by various modification techniques. One of these techniques is the modification of existing mineral oils by the addition of different types of nanoparticles in various concentrations. These types of materials, suspensions of nanoparticles called nanofluids, have found numerous applications in the energy industry, especially in heat exchanger systems and solar cells. Much research has been done on attempts to replace mineral oils (MO), which are harmful for the environment, with natural ester oils (NE), but to make this possible, it is necessary to improve the insulating properties of these oils, for example by adding nanoparticles. This paper presents an extensive overview of the insulating properties; including for AC, DC and the lightning impulse breakdown voltage; for both mineral and natural ester oils containing various type of nanoparticles (NP). It is presented that the use of nanofluids could improve the efficiency of existing high voltage infrastructures with a low financial cost.

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KOZLOV, V. K., et O. E. KURAKINA. « INFLUENCE OF TRANSFORMER OIL CHEMICAL COMPOSITION ON ITS TECHNICAL CHARACTERISTICS ». Herald of Technological University 27, n^o 3 (2024) : 35–40. http://dx.doi.org/10.55421/1998-7072_2024_27_3_35.

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Transformer oils are used to fill power and measuring transformers, reactor equipment and oil circuit breakers. Depending on the origin of the oil from which transformer oils are produced, as well as the production technology, the physical and chemical properties of oils may differ significantly, which affects their operational properties. These differences are a consequence of a significant difference in their structural group composition, as well as different molecular composition within the structural groups, which leads to different behaviour of oils in the process of degradation. The article considers the peculiarities of technological production and raw materials used in the manufacture of the most widely spread transformer oils, as well as the processes of their degradation. The analysis of literature data showed a significant difference in the chemical composition of transformer oils depending on the origin of oil and production technologies. The aim of the work is to establish the relationship between the chemical composition of transformer oil samples and their technical characteristics. The paper presents the results of the study of structural and group composition of transformer oil of different grades (GK, VG, T-1500, TKp, Nytro) by spectroscopy in the visible and near infrared spectral region. On the basis of the analysis of literature data and conducted research, the dependence of oil stability (oxidation stability) on the concentration of aromatic hydrocarbons was established, namely, the higher the concentration of aromatic hydrocarbons, the lower the stability of oils, which is confirmed by spectral measurements of oils. This method of analysing transformer oil samples allows to determine its structural-group composition and estimate the depth of purification, which is valuable information for the possibility of mixing oils in combination with mandatory types of tests.

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Romeiro, Amanda F., Hudson J. B. Rodrigues, Cauã C. Miranda, Markos P. Cardoso, Anderson O. Silva, João C. W. A. Costa, M. Thereza R. Giraldi, Jose L. Santos et Ariel Guerreiro. « D-Shaped Photonic Crystal Fiber SPR Sensor for Humidity Monitoring in Oils ». EPJ Web of Conferences 305 (2024) : 00002. http://dx.doi.org/10.1051/epjconf/202430500002.

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This theoretical study presents a D-shaped photonic crystal fiber (PCF) surface plasmon resonance (SPR) based sensor designed for humidity detection in transformer oil. Humidity refers to the presence of water dissolved or suspended in the oil, which can affect its dielectric properties and, consequently, the efficiency and safety of the transformer’s operation, failures in the sealing system and the phenomenon of condensation can be the main sources of this humidity. This sensor leverages the unique properties of the coupling between surface plasmons and fiber guided mode at the Au-PCF interface to enhance the sensitivity to humidity changes in the external environment. The research demonstrated the sensor’s efficacy in monitoring humidity levels ranging from 0% to 100% with an average sensitivity of measured at 1106.1 nm/RIU. This high sensitivity indicates a substantial shift in the resonance wavelength corresponding to minor changes in the refractive index caused by varying humidity levels, which is critically important in the context of transformer maintenance and safety. Transformer oil serves as both an insulator and a coolant, and its humidity level is a key parameter influencing the performance and longevity of transformers. Excessive humidity can lead to insulation failure and reduced efficiency and, therefore, the ability to accurately detect and monitor humidity levels in transformer oil can significantly enhance preventive maintenance strategies, reduce downtime, and prevent potential failures, ensuring the reliable operation of electrical power systems.

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Yusupov, D. T., B. K. Avazov, O. M. Kutbidinov et M. Bazarov. « Cleaning of transformer oils using the electric field ». IOP Conference Series : Earth and Environmental Science 1231, n^o 1 (1 août 2023) : 012024. http://dx.doi.org/10.1088/1755-1315/1231/1/012024.

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Abstract A used oil sample of KTPJO 10/27.5/023 of power transformers which are used on the railway was selected and cleaned by means of electric field. This process was carried out using a device assembled on the basis of a special scheme. Unrefined and refined oil samples were tested for electrical strength, i.e. breakdown voltage, on AID-70m and HUAZHENG (HZJQ-X1 Transformer Oil BDV Tester) dielectric testers. The results were compared and analyzed by the regression method. It was determined that the operational characteristics of the oil were improved.

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Senoussaoui, Mohammed El Amine, Mostefa Brahami et Issouf Fofana. « Transformer Oil Quality Assessment Using Random Forest with Feature Engineering ». Energies 14, n^o 7 (24 mars 2021) : 1809. http://dx.doi.org/10.3390/en14071809.

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Machine learning is widely used as a panacea in many engineering applications including the condition assessment of power transformers. Most statistics attribute the main cause of transformer failure to insulation degradation. Thus, a new, simple, and effective machine-learning approach was proposed to monitor the condition of transformer oils based on some aging indicators. The proposed approach was used to compare the performance of two machine-learning classifiers: J48 decision tree and random forest. The service-aged transformer oils were classified into four groups: the oils that can be maintained in service, the oils that should be reconditioned or filtered, the oils that should be reclaimed, and the oils that must be discarded. From the two algorithms, random forest exhibited a better performance and high accuracy with only a small amount of data. Good performance was achieved through not only the application of the proposed algorithm but also the approach of data preprocessing. Before feeding the classification model, the available data were transformed using the simple k-means method. Subsequently, the obtained data were filtered through correlation-based feature selection (CFsSubset). The resulting features were again retransformed by conducting the principal component analysis and were passed through the CFsSubset filter. The transformation and filtration of the data improved the classification performance of the adopted algorithms, especially random forest. Another advantage of the proposed method is the decrease in the number of the datasets required for the condition assessment of transformer oils, which is valuable for transformer condition monitoring.

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Felix, Stephanie Azlyn Anak, et Muhamad Faiz MD Din. « Effect of Proper Treatment on Mineral Oils ». ASEAN Journal of Science and Engineering 3, n^o 3 (13 juin 2022) : 281–88. http://dx.doi.org/10.17509/ajse.v3i3.49523.

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For over a century, a transformer act as a crucial part of the high voltage system. This also acts as an energy alteration device that is used to step-up and step-down voltage for power distribution from power generation to the consumers. Maintaining a transformer is important since a single mistake can lead to a vast amount of problems in a high voltage system in terms of cost. Thus, nowadays, many researchers study the important parts of a transformer, making it to function more effective. One of the studies involves improving treatment in the insulation medium of transformers to improve its function and performance. Here, the focus of this experiment was to study the effect of proper treatment on mineral oil in terms of electrical properties as an insulator in the transformer. The drying process was the main concern in this experiment. Parameters such as AC breakdown voltage, Tan Delta value, Raman measurement, resistivity, and relative permittivity were particularly measured. Origin software was used to analyze the data obtained from the experiment. The results expected from the experiment is that the proper preparation plays the role in tuning the AC breakdown voltage.

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Carvalhosa, Salvador, Helder Leite, Mário Soares, Fábio Branco, Carlos A. Sá, Ricardo Castro Lopes et Joáo Espírito Santo. « Ester-based Dielectric Fluid for Power Transformers : Design and Test Experience under the GreenEst Project ». Journal of Physics : Conference Series 2213, n^o 1 (1 mars 2022) : 012026. http://dx.doi.org/10.1088/1742-6596/2213/1/012026.

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Abstract Ester-based dielectric fluids have now been on the market for several decades, providing fire-safe and environmentally friendly alternatives to mineral oils, which have traditionally been used in transformers and other electrical equipment. This opens the door to innovation in power transformers. However, the use of esters-based dielectrics in power transformers is still very limited, especially for the higher voltage levels. The usage of these esters-based dielectrics in higher voltage power transformers is not yet consensual. this work present results with the use of natural esters in power distribution transformers. Tests carried out on mineral oil and natural ester oil found that the ester-based dielectric can withstand higher voltage thresholds for AC and Impulses tests, mainly within the specs of destructive tests, e.g., the natural ester was able to withstand a 185kV impulse without registering dielectric rupture while the natural oil registered a dielectric rupture with a 160kV impulse. Heating and mechanical tests demonstrated that ester-based dielectric oils for power transformers lead to a flow reduction between 16,8% and 18,2% in the cooling system that was design for mineral oils but they achieve a higher heat transfer coefficient, between 0,5% to 5% depending on the location of measurement.

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Oommen, T. V. « Vegetable oils for liquid-filled transformers ». IEEE Electrical Insulation Magazine 18, n^o 1 (janvier 2002) : 6–11. http://dx.doi.org/10.1109/57.981322.

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Oparanti, Samson Okikiola, Ungarala Mohan Rao et Issouf Fofana. « Natural Esters for Green Transformers : Challenges and Keys for Improved Serviceability ». Energies 16, n^o 1 (21 décembre 2022) : 61. http://dx.doi.org/10.3390/en16010061.

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The service of mineral insulating oils for power transformer insulation and cooling aspects cannot be disavowed. However, the continued use of mineral oils is questionable due to environmental unfriendliness and the divestment from fossil fuels. This has provoked the quest for green alternative insulating liquids for high-voltage insulation. Natural esters are among the remaining alternatives that are renewable and environmentally friendly. Regardless of their environmental and technical merits, natural esters have some limitations that are slowing down their total acceptance by transformer owners and utilities. Critical limitations and concerns include esters’ pour point, viscosity, oxidative stability, and ionization resistance. In this work, the state of the art of “natural esters for transformers” is explored with the aim of potential improvements. The sections of the article are geared towards technical viewpoints on improving the overall workability and serviceability of natural esters in high-voltage applications. A comprehensive review of the existing literature is achieved, based on performance improvements of the natural ester using “additives” and “chemical modification”. The authors hope that this report may be helpful to transformer owners as well as influence the progression of natural esters for power transformer applications.

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Kolarski, Dejan, Jelena Lukić, Valentina Vasović, Jelena Janković et Draginja Mihajlović. « Results of the GreenCleanS Project funded by the Science Fund of the Republic of Serbia ». Zbornik radova Elektrotehnicki institut Nikola Tesla, n^o 34 (2024) : 83–94. https://doi.org/10.5937/zeint34-54867.

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The project funded by the Science Fund of the Republic of Serbia, Development of Green Technology to Mitigate Power Transformer Failures Induced by Elemental Sulphur and Change Current Hazardous Practice in Transformer Oil Regeneration, under the acronym GreenCleanS focuses on developing a new technology for removing elemental sulphur molecule (S₈) from mineral insulating oils used in power transformers (PT) utilization an innovative low-temperature desulfurization process. The technology development includes experimental work at the laboratory scale and pilot scale level (technology readiness level, TRL 4), as well as the demonstration of the technology in an operational environment, involving the treatment of 3 tons of oil in a mobile desulfurization unit to achieve TRL 7. The implementation of this innovative technology will contribute to reducing the number of transformer failures caused by mineral oils containing S₈, a highly corrosive compound.

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Chera Anghel, Irina Alina, et Loredana Popescu. « Optimizing characteristics in mineral insulating oil used in high power transformers ». SIMI 2019, SIMI 2019 (20 septembre 2019) : 222–28. http://dx.doi.org/10.21698/simi.2019.fp29.

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The most commonly used insulating liquid in transformers is mineral oil. Special synthetic applications such as silicone, ester, perchloroethene, etc. are used today in special applications, with different characteristics, very low or nonexistent toxicity to mineral oils used in transformers. On the other hand, they have a much better biodegradability than mineral oils in both aerobic and anaerobic conditions. But they cannot directly replace the mineral oil in operation or in repaired units. They have dielectric properties and good heat transfer but have limited their use to special transformers due to the relatively high cost and availability.

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Méndez, Cristina, Cristian Olmo, Ismael Antolín, Alfredo Ortiz et Carlos J. Renedo. « Analysing the Suitability of Using Different Biodegradable Fluids for Power Transformers with Thermally Upgraded Paper ». Sustainability 16, n^o 8 (13 avril 2024) : 3259. http://dx.doi.org/10.3390/su16083259.

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Mineral oil has been used for many years in various electrical equipment, including transformers, as a cooling and insulation medium. However, its low biodegradability and poor performance in terms of fire protection have prompted the search for fluids to replace it, with vegetable oils being prominently considered. In this study, the dielectric, chemical, and physical properties of four vegetable oils obtained from different seeds (sunflower, rapeseed, soybean, and palm) and a biodegradable synthetic fluid are analysed throughout their lifespan in transformers. Their performances are compared with a traditional mineral oil to assess which one is more suitable for use in transformers employing this type of paper. To achieve this, the fluids were subjected to thermal ageing in combination with copper and a thermally upgraded kraft (TUK) paper, with its degradation controlled by measuring the degree of polymerisation. The results demonstrate that the origin of the vegetable oils affects their properties and degradation rates. It was found that most of the alternative fluids are suitable for use in transformers with the TUK paper and that they can increase their lifespan.

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Saodah, Siti, Bella Eliana et Jakariya. « Influence of thermal aging on dielectric characteristics of transformer insulating oils ». E3S Web of Conferences 479 (2024) : 05004. http://dx.doi.org/10.1051/e3sconf/202447905004.

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Transformer oil is a liquid insulating material used in transformers as insulation and coolant. Particular characteristics insulating oil materials must be able to withstand breakdown voltages, while transformer oil as a coolant must be able to minimize heat generated, so that transformer oil is expected to protect the transformer from disturbances with these two characteristics. In order to reduce the percentage of transformer failures, it is necessary to maintain the purity of the oil. The features of aged transformer oil and pure transformer oil are investigated in this study. Pure transformer oil is heated to a particular temperature and cycled to create samples of aged transformer oil. The electric field intensity of transformer oil is measured to estimate the dielectric strength of aged transformer oil. FEM analysis is used to determine the intensity of an electric field. At aging temperatures of 130°C and 150°C, the dielectric characteristics of transformer oil for both Shell Diala and Triapar types are investigated. As a result, not only the electrical characteristics but also the effects of thermal aging on the physical and chemical properties of transformer oil are reported in this study.

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Garifullin, M. Sh, Y. N. Slobodina, A. R. Bikzinurov, R. A. Giniatullin et V. A. Chernyshov. « Study of the presence of pro-oxidative properties in phenolic oxidation inhibitors in relation to modern transformer oils ». Power engineering : research, equipment, technology 26, n^o 6 (13 janvier 2025) : 30–41. https://doi.org/10.30724/1998-9903-2024-26-6-30-41.

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ACTUALITY. In the community of Russian specialists servicing oil-filled transformers, there is an established opinion that when the concentration of the phenolic oxidation inhibitor Ionol (DBPC) in the oil drops below 0.1% (wt.), the transformer oil begins to oxidize faster than in the absence of Ionol. This is the so-called “pro-oxidizing effect” described in 1968. Modern hydrocracking transformer oils differ significantly from the former oils in terms of hydrocarbon composition, but the opinion about the pro-oxidizing properties of Ionol remains, despite the lack of such information in foreign studies. OBJECTIVE. To reveal the presence or absence of pro-oxidative action of phenolic antioxidants, Ionol and 2,6-DTBP, when their concentration in transformer oil is reduced. METHODS. Two series of oil samples were prepared for the study: with Ionol and 2,6-DTBP additive. The concentration of additives: 0; 0.05; 0.1 and 0.2 % (wt.). VG grade oil produced by hydrocracking technology was used as a base mineral oil. All oils were subjected to accelerated thermal degradation at elevated temperature. Destructive changes in the hydrocarbon base of oils were analyzed by IR absorption spectra. Changes in the relative content of degradation products dissolved in the oil were analyzed using UV-visible absorption spectra. RESULTS. On the basis of the analysis of optical spectra of both series of oils, it was obtained that as the initial concentration of any of the phenolic oxidation inhibitors in the oil decreases, the intensity of thermodestructive changes in the hydrocarbon composition of the oils consistently increases. It is shown that in transformer oils produced by hydrocracking technology both additives in the concentration range of 0.05÷0.1 % do not show pro-oxidizing properties. It is concluded that the widespread idea about pro-oxidizing effect of Ionol at its concentration in transformer oil less than 0.1 % should be considered as not corresponding to reality.

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Ponomarenko, Serhii. « ANALYSIS OF FACTORS INFLUENCING THE INTENSITY OF TRANSFORMER OIL AGEING IN LONG-TERM OPERATION ». Bulletin of the National Technical University "KhPI". Series : Energy : Reliability and Energy Efficiency, n^o 1 (2) (2 juillet 2021) : 3–9. http://dx.doi.org/10.20998/2224-0349.2021.01.01.

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The results of the analysis of influence of operational factors and peculiarities of transformer design on intensity of oxidative reactions of transformer oils in the tanks of 110 kV high-voltage power transformers are presented. As a result of two-way analysis of variance it was found that with increasing operating time there is a statistically significant increase in the value of the organic acid content in the oil. At the same time the rate of increase in the organic acids content in the transformer oil, operated under different conditions, significantly differs, which indicates a significant influence of operating conditions on the intensity of oxidative reactions. The results of two-way analysis of variance also show that the effects of changes in factor levels are not additive, that is, the effect of a change in the level of influence of one factor leads to a change in the effect of the level of influence of another. In other words, the process of oil oxidation is cumulative and a certain level of organic acids in the oil can be achieved either over a longer period of operation, but with relatively 'light' operating conditions, or over a shorter period of time, but with more 'heavy' operating conditions. In order to determine the factors most affecting the intensity of oxidative reactions, an analysis of the quality of filled oil, operating time, the influence of the region, the influence of the type and nominal characteristics of transformers on 6 data sets with identical rates of oxidative reactions was carried out. The results of the analysis show that the intensity of oxidation reactions is strongly influenced by the operating time, the transformer loading factors, the consumer composition (region of Ukraine) as well as the type and quality of oils. At the same time, factors such as rated capacity, type of transformer, number of windings, and the value of rated voltage on the medium and low voltage windings do not influence the intensity of oxidation of oils. The results obtained allow the correction of the maximum permissible values of oil acidity, taking into account the factors affecting the intensity of oxidation of oils.

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Ridzuan, N. L. M., N. A. Bakar, S. A. Ghani, I. S. Chairul et N. H. A. Aziz. « Comparative study on the accelerated thermal aging behavior between palm and rapeseed natural ester oils ». Bulletin of Electrical Engineering and Informatics 8, n^o 3 (1 septembre 2019) : 735–43. http://dx.doi.org/10.11591/eei.v8i3.1590.

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The suitability of natural ester oils as an insulating medium in power transformers is discussed in this paper. Owing to environmental concerns, natural ester oils have great potential as mineral oil substitutes in power transformers. In this paper, the aging behaviors of palm and rapeseed natural ester oils were compared with that for mineral oil. The performance of these natural ester oils was assessed based on their properties (moisture content, acidity, and relative content of dissolved decay products) after accelerated thermal aging. The results showed that the palm oil has better performance compared to the rapeseed oil after accelerated thermal aging for 1500 h because of its lower acidity. This was further supported by the presence of sludge in the rapeseed oil after 1500 h of aging.

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Shutenko, O. V., et S. H. Ponomarenko. « CORRECTION OF TRANSFORMER OIL BREAKDOWN VOLTAGE MAXIMUM PERMISSIBLE VALUES BY THE MINIMUM RISK METHOD ». Bulletin of the National Technical University "KhPI". Series : Energy : Reliability and Energy Efficiency, n^o 1 (1) (30 décembre 2020) : 105–14. http://dx.doi.org/10.20998/2224-0349.2020.01.16.

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The method of correction of maximum permissible values of breakdown voltage of transformer oils in order to minimize possible economic damage in case of making erroneous decisions during diagnostics of the condition of transformer oils according to the results of periodic tests is proposed. An algorithm for statistical processing of the periodic test results is described, the use of which allows forming arrays with homogeneous values of the indicators under a priori limited measuring information. Analysis of distribution laws of breakdown voltage values for the transformer oils suitable and unsuitable for operation according to the values of this indicator is done. According to the results of the analysis, it was found that the breakdown voltage values of oils with different states have Weibull distribution. It was determined that the values of mathematical expectations of breakdown voltage of serviceable oils with the ageing of transformer oils shifts to the area of low values. It means that the breakdown voltage maximum permissible values of oils for the given distributions should be different. It is confirmed by the previously known fact that for unimodal distributions, the maximum permissible values of indicators that provide a minimum of risk are in an interval bounded by the mathematical expectation of the indicator distributions with different states. A decisive rule is formulated and an average risk function is compiled to adjust the maximum permissible breakdown voltage values of transformer oils. Based on the minimisation of the average risk function by Newton's method, the maximum permissible values of the breakdown voltage of oils have been determined. The made comparative analysis has shown that the correction of maximum permissible values of breakdown voltage of oils allows decreasing the risk values by 1.52÷19.13 times in comparison with risks, which provide the use of maximum permissible values, regulated in standards. It was found that the maximum permissible values of the breakdown voltage of oils, providing a minimum value of average risk, are not constant. They vary depending on the values of faulty decision prices and the probabilities of occurrence of different defective and defect-free oil states of transformers.

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Qian, Yi Hua, Hong Hong Hu et Zhi Li. « Analysis and Countermeasure of Transformer Faults Caused by Corrosive Sulfur ». Applied Mechanics and Materials 71-78 (juillet 2011) : 3958–62. http://dx.doi.org/10.4028/www.scientific.net/amm.71-78.3958.

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Based on electrical and chemical analysis in oils of some fault transformers in Shenzhen, it indicates that the corrosive sulfur contained in insulating oils may cause faults. Corrosive sulfur would react to copper wire and engender Cu2S during the operation of transformer. Because of the electric characteristic of Cu2S, this substance will penetrate and pollute insulating paper of the wire, and then weaken the insulation intensity. At last it would wear out coil insulation. Experiments indicate that adding passivator to insulating oil is an effective method to solve the problem. Passivator can form a protection layer on the surface of copper, which can avoid copper corrupting and can stop copper deposition in the presence of potentially corrosive sulfur compounds as well.

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RADULESCU, CRISTIANA, IOANA DANIELA DULAMA, IOAN ALIN BUCURICA, SORINA GEANINA STANESCU et ION VASILE. « OCCURRENCE, COMPOSITION PROFILES AND POTENTIAL RISK ASSESSMENT OF POLYCHLORINATED BIPHENYLS (PCBS) IN TRANSFORMER OILS ». Journal of Science and Arts 20, n^o 3 (30 septembre 2020) : 739–48. http://dx.doi.org/10.46939/j.sci.arts-20.3-b05.

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One of the most common problems encountered in everyday life is the pollution of the environment. Therefore, regardless of the nature of the daily activities of the population, this destructive effect of the natural balance finds its origin perhaps in the lack of capacity over time to treat the problem of waste (industrial and domestic) as it should. Although important steps have been taken in this regard, and prevention and control rules have been imposed in most countries of the world, these steps must be supported by all socio-economic / political components through clear measures, anchored to global developments. There are among these generic sources of pollution, which are referred to above, processes that requires high power equipment (generators, transformers, etc.) or hydraulic who which also requires thermal insulation fluids. The aim of this study is to investigate the polychlorinated biphenyls (PCBs) presence in the dielectric oil of power transformers. In this matter, fifteen samples were collected from transformer oils, in the summer of the year 2017, and analyzed from a physicochemical point of view. A more specific aim was to corroborate the findings regarding the amount of chlorine in oil samples with the age of the power transformer using statistical methods. The cluster's analysis indicated that the investigated samples are clustered into four major groups, providing useful information for further studies on PCBs mobility in the environment.

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Farade, Rizwan A., Noor Izzri Abdul Wahab, Diaa-Eldin A. Mansour, Norhafiz B. Azis, Jasronita bt. Jasni, Manzoore Elahi M. Soudagar et Vasudevamurthy Siddappa. « Development of Graphene Oxide-Based Nonedible Cottonseed Nanofluids for Power Transformers ». Materials 13, n^o 11 (4 juin 2020) : 2569. http://dx.doi.org/10.3390/ma13112569.

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Sustainable materials, such as vegetable oils, have become an effective alternative for liquid dielectrics in power transformers. However, currently available vegetable oils for transformer application are extracted from edible products with a negative impact on food supply. So, it is proposed in this study to develop cottonseed oil (CSO) as an electrical insulating material and cooling medium in transformers. This development is performed in two stages. The first stage is to treat CSO with tertiary butylhydroquinone (TBHQ) antioxidants in order to enhance its oxidation stability. The second and most important stage is to use the promising graphene oxide (GO) nanosheets to enhance the dielectric and thermal properties of such oil through synthesizing GO-based CSO nanofluids. Sodium dodecyl sulfate (SDS) surfactant was used as surfactant for GO nanosheets. The nanofluid synthesis process followed the two-step method. Proper characterization of GO nanosheets and prepared nanofluids was performed using various techniques to validate the structure of GO nanosheets and their stability into the prepared nanofluids. The considered weight percentages of GO nanosheets into CSO are 0.01, 0.02, 0.03 and 0.05. Dielectric and thermal properties were comprehensively evaluated. Through these evaluations, the proper weight percentage of GO nanosheets was adopted and the corresponding physical mechanisms were discussed.

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Bin Yahya, Muhammad, et Raja Muhammad Khidir Raja Chik. « Study on Breakdown Voltage for Vegetable Oils With Additive TiO2 ». Indonesian Journal of Electrical Engineering and Computer Science 12, n^o 1 (1 octobre 2018) : 175. http://dx.doi.org/10.11591/ijeecs.v12.i1.pp175-181.

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High voltage power transformers commonly used petroleum-based mineral oil for cooling and insulation purposes. Researchers are looking for suitable vegetable oils as alternatives to mineral oil to be used as transformer oil. The alternative vegetable oils are biodegradable, non-toxic and environmentally friendly. They may require some processing and modification to improve some of their properties to ascertain their safe use in power and distribution transformers as well as in high voltage equipment. This paper presents a study on the AC breakdown voltages of Palm Oil (PO) and Coconut Oil (CO) with presence of an additive. PO and CO are chosen as they are locally produced oils in Malaysia and easily obtained. The type of additive used in this study is Titanium dioxide TiO2. TiO2 nanoparticles was added into PO and CO at volume concentration of 0.1% to 0.5%. The effect of different gap distance of electrode 1.5mm, 2.5mm and 3.5mm was studied. The temperature of oil is controlled at 30oC. This paper provides a comparative assessment of breakdown properties through experimental investigation of PO and CO before and after the additive is added according to ASTM D1816 standard. From the experimental result, the PO have slightly higher breakdown voltage compared to CO. From all oil sample data recorded, it can be concluded that the breakdown voltage had increased to the increase in gap distance of electrode under presence of TiO2.

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Ponomarenko, Serhii. « Formation of reference trajectories for transformer oil indicators for 330 kV autotransformers ». Bulletin of the National Technical University "KhPI". Series : Energy : Reliability and Energy Efficiency, n^o 1 (4) (2 juillet 2022) : 62–72. http://dx.doi.org/10.20998/2224-0349.2022.01.11.

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The article describes the procedure of statistical processing of the results of periodic operational tests of transformer oils condition in 330 kV autotransformer tanks with the purpose of forming the reference trajectories of indicators for early diagnosis of transformer oils. The proposed procedure for statistical processing of the results of periodic operational condition tests of transformer oils includes two stages. At the first stage of statistical processing, to reduce the influence of errors characteristic of in-service control, the stationary dependences of transformer oil indicators on the operation time are eliminated according to mathematical expectation. To solve this problem it was proposed to use a mathematical apparatus of single-factor regression analysis of the indicator of oils on the operation time. Practical realisation of such approach has shown that use of the regression analysis allows to reveal not only stationary dependences of oil indicators (that is those dependences for which with growth of operation time no statistically significant change of mathematical expectation of the indicator is observed, that is equivalent to equality to zero of value of angle coefficient of the regression model), but also dependences of oil indicators distorted by a sign of a pair correlation coefficient of oil indicator on operation time. At the second stage of statistical processing the direct formation of reference trajectories of indicators is carried out. To take into account the non-linear nature of the dependences of oil indicators on the operation time and significant differences in the intensity of ageing of transformer oils in individual transformers, due to differences in design and cooling systems of autotransformers, as well as different brands of transformer oils and differences in operating modes of autotransformers, the criterion of maximum correlation of oil indicator on the operation time was used. The use of this criterion allowed to form the reference trajectories of transformer oil indicators in 330 kV autotransformers even in conditions of limited information about operating modes of analysed autotransformers. The given example of practical use of the proposed procedure in the formation of reference trajectories of organic acids content in oil has demonstrated its high efficiency.

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Djurdjevic, Ksenija, Mirjana Vojinovic-Miloradov et Slobodan Sokolovic. « Life cycle of transformer oil ». Chemical Industry 62, n^o 1 (2008) : 37–46. http://dx.doi.org/10.2298/hemind0801037d.

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The consumption of electric power is constantly increasing due to industrialization and population growth. This results in much more severe operating conditions of transformers, the most important electrical devices that make integral parts of power transmission and distribution systems. The designed operating life of the majority of worldwide transformers has already expired, which puts the increase of transformer reliability and operating life extension in the spotlight. Transformer oil plays a very important role in transformer operation, since it provides insulation and cooling, helps extinguishing sparks and dissolves gases formed during oil degradation. In addition to this, it also dissolves moisture and gases from cellulose insulation and atmosphere it is exposed to. Further and by no means less important functions of transformer are of diagnostic purpose. It has been determined that examination and inspection of insulation oil provide 70% of information on transformer condition, which can be divided in three main groups: dielectric condition, aged transformer condition and oil degradation condition. By inspecting and examining the application oil it is possible to determine the condition of insulation, oil and solid insulation (paper), as well as irregularities in transformer operation. All of the above-mentioned reasons and facts create ground for the subject of this research covering two stages of transformer oil life cycle: (1) proactive maintenance and monitoring of transformer oils in the course of utilization with reference to influence of transformer oil condition on paper insulation condition, as well as the condition of the transformer itself; (2) regeneration of transformer oils for the purpose of extension of utilization period and paper insulation revitalization potential by means of oil purification. The study highlights advantages of oil-paper insulation revitalization over oil replacement. Besides economic, there are advantages concerning environmental protection, starting from unrecoverable resources (petroleum) saving through power and energy saving to waste reduction. Adequate management of transformer oil life cycle, meaning timely and technologically updated regeneration process, prevents waste production. Regeneration by means of synthetic adsorbents in laboratory conditions as well as on site has ensured and provided satisfactory results with reference to oil quality improvement. It has also confirmed and substantiated the necessity of regeneration implementation before the paper insulation is damaged.

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Ab Ghani, Sharin, Imran Sutan Chairul, Mohd Shahril Ahmad Khiar, Nor Hidayah Rahim et Syahrun Nizam Md Arshad@Hashim. « Effect of mixing ratio on the breakdown voltage of mineral and natural ester insulating oil blends ». Bulletin of Electrical Engineering and Informatics 11, n^o 5 (1 octobre 2022) : 2418–24. http://dx.doi.org/10.11591/eei.v11i5.3723.

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To date, the most common insulating oil used in oil-immersed transformers is mineral insulating (MI) oil, which is derived from petroleum. Owing to the depletion of petroleum over the years, it can be anticipated that petroleum-derived products such as MI oils will also deplete in the future. MI oils are not only non-renewable, but they are also non-biodegradable, where these oils are harmful to the environment in cases of oil spillage. Therefore, the aim of this study is to investigate the potential of mixing MI oil with natural ester insulating (NEI) oil in order to reduce the high dependency on MI oil for transformer applications. The MI and NEI oils were mixed with different mixing ratios. AC breakdown voltage test was conducted on the MI-NEI oil blends according to the ASTM D1816 standard. From the results, it is found that the following mixing ratios (30% of MI oil + 70% of NEI oil, 20% of MI oil + 80% of NEI oil) result in significant improvement in terms of the AC breakdown voltage compared with unused MI oil. The flash point and corrosivity levels of the oil blends were also examined.

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Mansouri, Abderrezak, Khadra Kessairi, Mounia Hendel, Fadila Benabed et Mohammed El Amine Abed. « Electrical breakdown voltage measurement in a contaminated transformers oil and thermal performance evaluation ». STUDIES IN ENGINEERING AND EXACT SCIENCES 5, n^o 2 (13 août 2024) : e6645. http://dx.doi.org/10.54021/seesv5n2-091.

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The transformer is the most important element in the electrical power systems and it’s expected that the service life to be between 35 and 40 years. The principal problems occurred are related to the defects and the degradation of the insulating oil. In fact, under service conditions, the electrical and thermal stresses or chemical contaminants affect the insulation oil. As a consequence of ageing, the transformer oil deteriorates gradually and becomes increasingly contaminated which reduce its service life. In this work, the efficiency of transformer oils was assessed through a detailed study of the dielectric properties of mineral insulating oil, specifically focusing on breakdown voltage under various experimental conditions. This involved precisely inserting two standardized semi-elliptical steel electrodes into the oil and conducting a meticulous analysis by varying the distance between two electrodes and adjusting the oil temperature The results of these experiments demonstrate a notable increase in breakdown voltage as the distance between electrodes and the temperature of the oil increase. Specifically, at an electrode gap of 5 mm, the mineral oil exhibited a breakdown voltage of 6.2 kV, significantly lower than the expected 31 kV, indicating considerable impurity contamination. These experimental findings prompted the application of Fourier transform infrared spectroscopy (FTIR) to delve deeper into the molecular composition of the oils. FTIR analysis revealed the presence of carbon dioxide (CO2) in the oil, a clear indicator of hydrocarbon oxidation due to dissolved oxygen (O₂). This oxidation process primarily occurs through the reaction of oxygen with hydrocarbons present in the oil. At elevated temperatures, this reaction intensifies, leading to the formation of various degradation products, including CO2. The presence of oxygen in the oil was identified as a critical factor contributing to reduced breakdown voltage, thereby accelerating the degradation process of transformer oils. Where these detailed insights contribute significantly to our understanding of the dielectric properties of mineral oil, offering valuable perspectives for optimizing the performance and reliability of electrical transformers while mitigating the risk of operational failure.

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Sanz, J., C. J. Renedo, A. Ortiz, P. J. Quintanilla, F. Ortiz et D. F. García. « A Brief Review of the Impregnation Process with Dielectric Fluids of Cellulosic Materials Used in Electric Power Transformers ». Energies 16, n^o 9 (25 avril 2023) : 3673. http://dx.doi.org/10.3390/en16093673.

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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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Guney, Ezgi, et Okan Ozgonenel. « An Eco-Friendly Gas Insulated Transformer Design ». Energies 14, n^o 12 (21 juin 2021) : 3698. http://dx.doi.org/10.3390/en14123698.

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Electricity companies around the world are constantly seeking ways to provide electricity more safely and efficiently while reducing the negative impact on the environment. Mineral oils have been the most popular transformer insulation, having excellent electrical insulating properties, but have many problems such as high flammability, significant cleaning problems, and are toxic to fish and wildlife. This paper presents an alternative approach to mineral oil: a transformer design that is clean and provides better performance and environmental benefits. A 50 kVA, 34.5/0.4 kV gas insulated distribution transformer was designed and evaluated using the COMSOL Multiphysics environment. R410A was used as insulation material. R410A is a near-azeotropic mixture of difluoromethane (CH2F2, called R-32) and pentafluoro ethane (C2HF5, called R-125), which is used as a refrigerant in air conditioning applications. It has excellent properties including environmentally friendly, no-ozone depletion, low greenhouse effect, non-explosive and non-flammable, First, the breakdown voltage of the selected gas was determined. The electrostatic and thermal properties of the R410A gas insulated transformer were investigated in the COMSOL environment. The simulation results for the performance of oil and SF6 gas insulated transformers using the same model were compared. The gas-insulated transformer is believed to have equivalent performance and is an environmentally friendly alternative to current oil-based transformers.

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Jung-Il Jeong, Jung-Sik An et Chang-Su Huh. « Accelerated aging effects of mineral and vegetable transformer oils on medium voltage power transformers ». IEEE Transactions on Dielectrics and Electrical Insulation 19, n^o 1 (février 2012) : 156–61. http://dx.doi.org/10.1109/tdei.2012.6148514.

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Rafiq, Muhammad, Yuzhen Lv et Chengrong Li. « A Review on Properties, Opportunities, and Challenges of Transformer Oil-Based Nanofluids ». Journal of Nanomaterials 2016 (2016) : 1–23. http://dx.doi.org/10.1155/2016/8371560.

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The mineral oil or synthetic oil in conjunction with paper is mainly being applied as dielectric medium in many of the high voltage apparatus. However, the advent of high voltage levels such high voltage alternating current (HVAC) and high voltage direct current (HVDC) has prompted researchers to direct their focus onto an insulation system which can bear the rising high voltage levels. The modern insulating liquid material development is guided by various factors such as high electrical insulation requirements and other safety and economic considerations. Therefore transformer manufacturer companies have to design transformers with these new specific requirements. The transformer oil-based nanofluids with improved dielectric and thermal properties have the potential to replace mineral oil base products in the market place. They are favorable because they function more superior than mineral oil and they contribute definite insulating and thermal gains. This paper reviews recent status of nanofluids use as transformer oils. The nanofluids used as transformer oils are presented and their advantages are described in comparison with mineral oil. The multiple experimental works carried out by different researchers are described, providing an overview of the current research conducted on nanofluids. In addition scope and challenges being confronted in this area of research are clearly presented.

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Felix, Stephanie Azlyn Anak, Muhamad Faiz Md Din, Asnor Mazuan Ishak, Jianli Wang, Nurul Hayati Idris et Wan Fathul Hakim Wan Zamri. « Investigation of the Electrical Properties of Mineral Oils with and without Carbon Nanotube Concentration under Different Magnetic Fields Applied in Transformer Applications ». Energies 16, n^o 8 (12 avril 2023) : 3381. http://dx.doi.org/10.3390/en16083381.

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The increased voltage loading of transformers has led to research on improving transformers’ lifespans to meet demand. Insulation oil acts as cooling medium that can significantly affect the performance of a transformer. This paper discusses an experimental study on the influences of the doping of carbon nanotube (CNT) particles and magnetic fields on the electrical properties of mineral oil (MO). An analysis of electrical properties was conducted using AC breakdown tests, Tan Delta tests, Raman measurements, and simultaneous thermal analysis. Proper preparation was considered before starting the analysis of the electrical properties. The AC breakdown voltages before and after modification were measured. The experiment results indicated that the AC breakdown of mineral oil with a suitable amount of carbon nanotube particles (0.005 g/L) and a suitable magnetic field (0.45 T) gives the highest breakdown voltage. It was found that the proper treatment of nanofluid also greatly influences breakdown voltage. Additionally, Raman measurements analyzed the physical changes in the samples. From the results obtained, the addition of carbon nanotubes and the magnetic field of mineral oil leads to an improved performance of the transformer.

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Khan, Suhaib Ahmad, Mohd Tariq, Asfar Ali Khan, Basem Alamri et Lucian Mihet-Popa. « Assessment of Thermophysical Performance of Ester-Based Nanofluids for Enhanced Insulation Cooling in Transformers ». Electronics 11, n^o 3 (26 janvier 2022) : 376. http://dx.doi.org/10.3390/electronics11030376.

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Nanotechnology provides an effective way to upgrade the thermophysical characteristics of dielectric oils and creates optimal transformer design. The properties of insulation materials have a significant effect on the optimal transformer design. Ester-based nanofluids (NF) are introduced as an energy-efficient alternative to conventional mineral oils, prepared by dispersing nanoparticles in the base oil. This study presents the effect of nanoparticles on the thermophysical properties of pure natural ester (NE) and synthetic ester (SE) oils with temperature varied from ambient temperature up to 80 °C. A range of concentrations of graphene oxide (GO) and TiO2 nanoparticles were used in the study to upgrade the thermophysical properties of ester-based oils. The experiments for thermal conductivity and viscosity were performed using a TC-4 apparatus that follows Debby’s concept and a redwood viscometer apparatus that follows the ASTM-D445 experimental standard, respectively. The experimental results show that nanoparticles have a positive effect on the thermal conductivity and viscosity of oils which reduces with an increase in temperature.

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Hendri, Hendri, Yanuar Zulardiansyah Arief et Abdul Syukur. « Testing of Palm Oil-Based Electric Power Transformer Insulation Oil as a Renewable Energy Source ». Jurnal Pendidikan Teknologi Kejuruan 6, n^o 1 (28 février 2023) : 56–63. http://dx.doi.org/10.24036/jptk.v6i1.32323.

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Reducing petroleum resources and environmental problems, alternative insulating oils with biodegradable characteristics have become an alternative. Esterification of palm-based oil is expected to provide better and optimum electrical properties. The esterification of palm oil will be carried out as a test sample and observed for its electrical, physical and chemical properties such as PD characteristics, breakdown voltage, dissipation factor, viscosity, flash point, etc. The effect of thermal aging on oil samples will also be carried out to simulate real situations in power transformer applications. Then after obtaining the best formulation from the sample it will be used as insulating oil in electric power transformers (100kVA). The purpose of this research is to apply esterified palm oil as an electric power transformer oil. The method used in this research includes field research. Field research includes taking oil samples, measuring the breakdown voltage of transformer oil, and the color of transformer oil. The results obtained are insulating oil for electric power transformers based on palm oil. Palm oil has the advantage of being an environmentally friendly, biodegradable and renewable oil compared to the transformer oil used today which is based on petroleum. With the realization of transformer oil based on palm oil, it is hoped that it can provide great economic opportunities for Indonesia as one of the largest palm oil producers in the world and can also provide added value and increase the competitiveness of the palm oil industry in the future.

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