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Author: search.filters.author.Jariyanurat, K.Subject: search.filters.subject.natural ester

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    Studies of Electrical and Thermal Characteristics of Natural Ester Immersed Transformer Compared with Mineral Oil Immersed and Palm Oil Immersed Transformer
    (2018-11-14)
    Maneerot, S.
    ;
    Jariyanurat, K.
    ;
    Nimsanong, P.
    ;
    Bunlaksananusor, C.
    ;
    Kunakorn, A.
    This paper represents studies of electrical and thermal characteristics of natural ester immersed transformer compared with mineral oil immersed and palm oil immersed transformer by designing and constructing three single-phase transformers with rated 400/1000V 10kVA, the first transformer used mineral oil, the second transformer used natural ester, and the last one used palm oil, for studying about electrical properties, thermal properties and chemical properties under different types of liquid insulation in each transformer. First of all, three types of liquid insulation were tested with many item such as dielectric breakdown strength according to IEC 60156, dielectric dissipation factor following to ASTM D924-99. Besides, dielectric breakdown strength of impregnated pressboard were also investigated following to IEC 60243-1. Moreover, the chemical properties of the insulations were tested for some properties such as moisture content in accordance with ASTM D1533-00, interfacial tension according to ASTM D0971-99, acidity according to ASTM D974-02. After that, transformers were operated at 100 % of designed rated with inductor load for four months by which the temperature, current, and voltage were recorded every hour. Every two months, the liquid insulation was sampling from each transformer to be investigated. From the test results, they can concluded that natural ester are the alternative liquid insulation for using instead of mineral oil. In part of palm oil, it has good properties but it has the weak points about dielectric dissipation factor and acidity which are higher than the others.
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    Electrical characteristics of natural ester impregnated pressboards under different periods of impregnation
    (2016-11-28)
    Jariyanurat, K.
    ;
    Maneerot, S.
    ;
    Pattanadech, N.
    ;
    Potivejkul, S.
    This paper represents electrical characteristics of natural ester impregnated pressboards under different impregnation period. Each pressboard specimen was prepared as a rectangular shape having the width of 100 mm and the length of 100 mm as well. Two thickness dimensions of the pressboard for the experiment were 1.6 mm and 3.2 mm respectively. All pressboards were dry up in the oven with temperature at 60°c for 1 hour. Next, these pressboards were divided into three groups according to the impregnation periods. The first group was impregnated with natural ester (FR3) for 3 hours with temperature at 60°c and 200 mbar pressure controlled condition. The second and third group were impregnated for 6 and 9 hours respectively with the same temperature and pressure condition. Then, the breakdown voltage characteristic of the impregnated pressboards were investigated according to IEC 60243-1. Besides, the capacitance and dielectric dissipation factor of the natural ester with various conditions were examined in accordance with IEC 60247. According to the test results, the pressboard impregnated for longer period provided higher breakdown voltage than the pressboards impregnated for shorter period by which the breakdown voltage of the pressboard impregnated for 9 hours was higher than the pressboard impregnated for 6 hours about 8-24% and the breakdown voltage of the pressboard impregnated for 6 hours was higher than the pressboard impregnated for 3 hours about 5-19%. Whereas the dielectric dissipation factor of the natural ester utilized for pressboard impregnation process for 3 hours was higher than the natural ester utilized for such process for 6 and 9 hours about 5% and 12% respectively. Moreover, the electrical characteristics of pressboard impregnated with natural ester was compared with that of the pressboard impregnated with mineral oil. The breakdown voltage of natural ester impregnated pressboard was higher than the mineral oil impregnated pressboard about 5-11% but the dielectric dissipation factor of natural ester was 30 times higher than mineral oil. It is clear that the time for impregnation significantly affects the breakdown characteristic of the natural ester impregnated pressboard. Furthermore, impregnation of the pressboard with natural ester provides better breakdown strength than the pressboard impregnated with mineral oil.