Ageing Study of Palm Oil and Coconut Oil in the Presence of Insulation Paper for Transformers Application (original) (raw)
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Energies, 2018
This paper presents a high temperature ageing study of refined, bleached, and deodorized palm oil (RBDPO) olein at 170 • C in the presence of air. In total, two types of RBDPO were examined. The physiochemical and dielectric properties of RBDPO were measured and analysed. We found that the moisture and viscosities for both RBDPO increased as the ageing progressed, whereas the acidities fluctuated at very low levels at less than 0.005 mg KOH/g. The ageing on the AC breakdown voltages of both RBDPO were not affected throughout the ageing processes. The dielectric dissipation factors and relative permittivities for both RBDPO increased as the resistivities decreased with the ageing time.
2020 IEEE 3rd International Conference on Dielectrics (ICD), 2020
In this paper, dielectric properties (BDV and permittivity) of two vegetable oils (Palm Fatty Acid Ester and FR3) used in power transformers are studied. Also, partial discharge inception voltage (PDIV) of Kraft paper impregnated with these oils is measured. All the tests were carried out at room temperature and the samples were prepared following the same procedure. Both the impregnated paper and the vegetable oils were aged at 140ºC for 11 days to study the evolution of the dielectric properties with the thermal aging. PDIV has been also measured for different number of paper sheets (from 4 to 6), analyzing the dependence of PDIV on the thickness of solid insulation. Dielectric characterization of the oils showed that they are suitable to use in power transformers. BDV of the oils decreased with the aging and PFAE performance was better. Dielectric constant of both oils is almost the same. PDIV results showed that both oils are suitable for the impregnation of Kraft paper in terms of dielectric properties. PDIV of FR3 insulating system was higher than PFAE system in all the studied cases. FR3 insulating systems showed a decrease of PDIV value after the aging process, whereas PFAE one remained almost constant.
Assessment of Long Thermal Ageing on the Oil-Paper Insulation
Advances in Electrical and Electronic Engineering, 2016
Electric power equipment has complex construction. Therefore, it is very important to have enough information about the state of equipment. High voltage transformers play a very important role in the electric power system. One of the most important parts of electric power equipment is the insulation system. Insulation system must be in a good condition for reliable and safe operation of electrical devices. Insulation system of electrical equipment is exposed to various factors which could have negative influence on its condition. Oil impregnated insulation paper is one of the oldest insulation systems used in electrical power equipment. Mineral oils have been used for decades as transformer fluids because of their excellent dielectric properties and availability. However, performance of mineral oil starts to be limited due to environmental consideration. The aim of this paper is to simulate a real insulation system of transformer and to show the influence of accelerated thermal ageing on the insulation system. Properties such as relative permittivity, dissipation factor and the breakdown voltage will be described and analysed.
Journal of Electrical Engineering and Technology, 2016
In this paper, a study is carried out to investigate the dielectric, physical and chemical properties of Palm Oil (PO) and Coconut Oil (CO) under open thermal ageing condition. The type of PO used in this study is Refined Bleached and Deodorized Palm Oil (RBDPO) Olein. The ageing experiment was carried at 85 °C and 115 °C for 1, 3, 5, 7 and 14 days. Several parameters were measured such as AC breakdown voltage, dielectric dissipation factor, relative permittivity, resistivity, viscosity, moisture and acidity throughout the ageing duration. Based on the study, it is found that there are no significant changes on the AC breakdown voltages and relative permittivities for both RBDPO and CO. At ageing temperature of 115°C, there are clear reduction trends of dielectric dissipation factor for CO and resistivities for most of RBDPO. On the other hand, no clear trends are observed for viscosities, moisture and acidities of RBDPO and CO throughout the ageing duration.
In this contribution, dielectric measurements in the frequency domain spectroscopy (FDS) were undertaken on oil impregnated paper samples in order to assess, with accuracy, the state of the solid insulation used in power transformers. The dielectric dissipation factor (tanδ) and the angle (phase shift) of the impedance of new and aged oil impregnated paper samples were measured; the moisture content served as parameter. These investigations aim at improving our understanding onto the effects of aging and moisture on the quality of the solid insulation (paper and paperboard) used in power transformers. Such investigations might be helpful in the separation of these two effects when doing FDS measurements.
Effect of Electrical Accelerated Aging on DC Resistivity of Mineral Oil Used in Power Transformers
Energies
Power transformers are still equipment of primary importance within power grids. The recent paradigm changes registered in the field of energy require the interconnection of electrical grids of much larger areas, even up to the level of an entire continent. In this context, knowing the state of the electrical equipment and that of the power transformers is an essential aspect to ensure safe operation conditions. The present work is related to the vulnerability of the oil–paper insulation systems of power transformers to different aging factors and their quick degradation under certain conditions. In this regard, the study proposed in this paper considers the measurement of DC resistivity on mineral oil samples contaminated with small amounts of accelerated aging oil under the action of high-strength electric field and partial discharges. In the absence of standardized procedures for accelerated electrical aging of mineral oil, an original method presented and discussed in previous a...
Electric Power Components and Systems, 2011
Power transformers are of the key and the most expensive devices used in electrical power transmission systems. Maintenance is essential in increasing the life time of these devices [1]. Degradation and aging of the insulation is recognized as one of the major causes of transformer breakdowns [2]. Characterization and analysis of the dielectric fluid quality level are used to ensure the proper functioning of the insulation [3-5]. This helps understanding the causes of possible internal defects [1, 6]. The purpose of this study is to investigate on service-aged oil transformers as well as on oil aged ones in laboratory conditions. Accelerated thermal and chemical aging procedures were performed in the laboratory [7]. IDA 200 was used to evaluate the frequency scan of insulation material properties. The dissipation factor, conductivity, real, imaginary part of permittivity, were measured as function of the temperature and the frequency. Through this study, it was found that despite the approximation of test conditions, the results obtained for these samples are different. However, the results indicate that the accelerated aging in the laboratory conditions does not really reflect the state of the oil.
Performance of oil and paper in transformers based on IEC 61620 and dielectric response techniques*
IEEE Electrical Insulation Magazine, 2010
This article demonstrates how to identify conduction and polarisation in oil and paper of a power transformer. In the first part, polarisation, which refers to deterioration products, are characterized at room temperature by the oil conductivity test according to the method in IEC61620. The results from more than 1,000 oil samples are discussed and acceptance criteria are included. The second part presents dielectric responses in time and frequency domain of transformers having different insulation conditions. It shows how to assess the condition of oil-paper interface and how to characterize the aging type of paper material.
Sustainability
This paper gives information on the electrical and physiochemical characteristics of six different types of palm oil compared with traditional mineral oil. We found that natural processed crude palm oil (PO-C) had a higher resistance to AC breakdown voltage than other types of palm oil, including traditional mineral oil. The results of the positive lightning impulse voltage test for PO-C were still the highest compared to other types of palm oil, including traditional mineral oil, at 58.26%. The summarised dissipation factors of all tested crude palm oils were significantly higher than those of mineral oils, which will make the palm oil less insulating, especially in PO-A palm oil (36.197%), where the values were higher than those of other oils, while mineral oil has a slightly increased dispersion factor. For relative permittivity, all palm oils were compared, and it was found that PO-C had a lower relative permittivity than the other oils. In terms of physical and chemical propert...