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Author: search.filters.author.Maneerot, SakdaSubject: search.filters.subject.Natural ester

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    Physical and chemical properties’ comparison of natural ester and palm oil used in a distribution transformer
    (2023-03-01)
    Kittikhuntharadol, Yannaphol
    ;
    Pattanadech, Norasage
    ;
    Maneerot, Sakda
    ;
    Jongvilaikasem, Korraya
    ;
    Jariyanurat, Kittipod
    Because of its low cost and suitable qualities, mineral oil (MO) has been commonly employed in transformers. Alternative liquid insulations with great characteristics have recently been presented. Natural ester (NE) and palm oil (PO) are considered alternative liquid insulations. This paper aims to study the physical and chemical properties of NE and PO which were used in a transformer for 21 months. All of the liquid insulation test specimens were sampled every 3 months. Physical properties of the liquid insulation, i.e., interfacial tension (IFT), viscosity, and particles count, were examined. Chemical properties of the liquid insulation, i.e., moisture content, acidity, corrosive sulfur, and furanic compound (2-FAL), were investigated. IFT, particles count, moisture content, acidity, and 2-FAL test results indicated deterioration of liquid insulations of the used liquid insulation; however, there is no observation change for particles amount and acidity of NE. The other test results were not found significantly change.
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    The comparative study of physical and chemical properties of palm oil and mineral oil used in a distribution transformer
    (2020-10-25)
    Maneerot, Sakda
    ;
    Pattanadech, Norasage
    This paper represents the physical and chemical characteristics of palm oil compared with mineral oil as insulating liquid. Two identical single-phase transformers with rated 22000/230V 30kVA were designed and constructed. The first transformer used palm oil and the second transformer used mineral oil as dielectric liquid. The physical and chemical properties of new liquids were investigated before and during transformer operation. The physical properties and chemical properties such as interfacial tension, viscosity, moisture content, acidity, and corrosive sulfur of the liquid specimen were tested according to international standards. Then these liquids were filled in the transformer. After that, transformers were operated at 80 % of designed rated with inductor load for two years by which the temperature, current, and voltage were recorded every hour. Every three months, the liquid insulation was sampling from each transformer to be investigated as the same mentioned items. From the preliminary test results (six months after transformer operation), it can be concluded that palm oil is the potentially alternative liquid insulation for using in the transformer.
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    Partial discharge characteristics of mineral oil immersed transformer compared with natural ester and palm oil immersed transformer under different periods of impregnation
    (2020-09-13)
    Maneerot, Sakda
    ;
    Pattanadech, Norasage
    This paper represents the partial discharge (PD) characteristics of mineral oil immersed transformer compared with natural ester, and palm oil immersed transformer under different periods of impregnation. Three identical three-phase transformers with 22kV/400V 50 kVA rated were designed and constructed. The first transformer was fully filled with mineral oil. The second transformer was fully filled with natural ester (FR3), and the third transformer was fully filled with palm oil. The partial discharge at 1.1Urated of these transformers with various conditions, i.e., non-impregnated paper, impregnated paper with 3 hours, and 6 hours was investigated. The impregnation process was done with 65 <sup>o</sup>C liquid temperature and 5 mmbar pressure. From the test results, it can be concluded that PD characteristics of the mineral oil immersed transformer was obviously different compared with these of the natural oil (FR3) immersed transformer and the palm oil immersed transformer. Moreover, the impregnation impacted PD characteristics of the tested transformers, which were analyzed and reported in this paper.
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    Comparison of dissolved gases in natural ester under partial discharges
    (2019-06-01)
    Jongvilaikasem, Korraya
    ;
    Maneerot, Sakda
    ;
    Jariyanurat, Kittipod
    ;
    Pattanadech, Norasage
    Currently, natural ester is alternative liquid insulation applied for both distribution and power transformers. Generally, transformers are expected to operate stably and reliably. However, their functions may fail during operation. Dissolved gases analysis is one of the worldwide accepted diagnostic techniques to examine the insulation integrity of the transformers. This paper presents the analysis of dissolved gases generated from partial discharge (PD) experiments i.e. corona discharge, surface discharge and internal discharge which were conducted in the test cell filled with natural ester (FR3). To simulate corona discharge, a needle electrode with a tip radius of 10, 20, and 40 micrometers was used as high voltage electrode and the plane electrode with a diameter of 45 mm was used as a grounded electrode. The gap distance was fixed at 32 mm. The corona discharge experiment was performed for 2 hours at the test voltage level of 35, 40, 45 kV respectively. In case of surface discharge, the pressboard samples i.e. non-impregnated pressboards, 8-hour impregnated pressboards, and 16-hour impregnated pressboards were inserted between the 20-micrometer tip radius needle and grounded plane. Then, the test voltage of 25 kV was applied to the electrode system for 1 hour. Besides, the surface discharge was tested at 35 and 45 kV respectively. For internal discharge, the pressboard samples i.e. non-impregnated pressboards, 8-hour impregnated pressboards, and 16-hour impregnated pressboards were inserted between the plane-plane electrodes. Then the test voltage of 25 kV was applied to the electrode system for 1 hour. Moreover, the internal discharge was tested also at 35 and 45 kV. Their natural ester samples were sampling from the test cell for each experiment and the dissolved gases were measured and analyzed. From the test results, it was found that the types and quantity of dissolved gases depended strongly on the type of discharge and material samples.
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    Dielectric response analysis of mineral oil immersed transformer, Natural Ester(FR3) immersed transformer, and palm oil immersed transformer
    (2019-06-01)
    Maneerot, Sakda
    ;
    Nimsanong, Phethai
    ;
    Siriworachanyadee, Jompatara
    ;
    Leelajindakrairerk, Monthon
    ;
    Jariyanurat, Kittipod
    Currently alternative liquid insulation such as natural ester (FR3) is widely used as distribution transformer insulation because it provides outstandingly dielectric characteristics and natural friendly including highly affordable fire safety. Besides, palm oil is interesting liquid insulation for such transformers because of its distinguish dielectric properties. To analyze the dielectric properties of insulating material, polarization and depolarization current (PDC) measurement is one of the widely accepted non-destructive test technique. This paper presents the dielectric response analysis for the insulation system of a mineral oil immersed transformer, a natural ester (FR3) immersed transformer, and a palm oil immersed transformer by analyzing PDC test results. Three identical single phase transformers with 22kV/460V 30 kVA rated were designed and constructed. The first transformer was fully filled with mineral oil. The second and the third transformer was fully filled with natural ester (FR3) and palm oil respectively. After finishing the construction process, PDC measurement technique was applied for these transformers. The PDC measurement were performed for three case studies as follows: 1) dielectric response for the insulation between high voltage winding and low voltage winding, 2) dielectric response of high voltage winding insulation and low voltage connected to ground 3) dielectric response of high voltage and low voltage winding insulation by which the high voltage lead was connected to the low voltage lead. From the test results, it can be concluded that the dielectric response of the insulation system of the mineral oil immersed transformer was obviously different compared with that of the natural oil (FR3) immersed transformer and the palm oil immersed transformer. Moreover, the PDCs obtained from the tests were also analyzed and reported in this paper.