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Author: search.filters.author.Kittikhuntharadol, YannapholSubject: search.filters.subject.natural ester

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    Polarization and Depolarization Current of Pressboard Impregnated with Natural Ester under Thermal Stress
    (2022-01-01)
    Kittikhuntharadol, Yannaphol
    ;
    Worthong, Tehneht
    ;
    Pattanadech, Norasage
    Mineral oil has long been utilized in transformers due to its low cost and suitable qualities. Alternative liquid insulations with great characteristics have recently been presented, and natural ester was considered. Pressboard is a type of cellulose insulation used for electrical insulation and mechanical support. This paper intends to study pressboard impregnated with natural ester under thermal stress. The pressboards and the natural ester were prepared for the experiment. Vacuum ovens were used for moisture elimination of materials and the impregnation process. The test specimens consisted of impregnated pressboards for 0, 8, 16, and 24 hours with thermal stress by heating at 150 degrees Celsius in a vacuum oven for 0, 30, and 90 days. Polarization and depolarization current (PDC) of the test specimens were investigated in each period by PDC-Analyser 1MOD. The test cell for PDC measurement was designed according to JIS C2111, and it was clean before the experiment. The PDC characteristics of the pressboard that had been subjected to thermal stress were discovered to be slightly different when compared with the same impregnation time of the pressboard.
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    AC Breakdown Characteristics of Different Moisture Content Pressboards Impregnated with Natural Ester
    (2021-04-01)
    Pattanadech, Norasage
    ;
    Kittikhuntharadol, Yannaphol
    ;
    Pannil, Pittaya
    Biodegradable materials are necessary for saving the environment. Natural ester is alternative liquid insulation that can be biodegraded and used in a transformer. Insulation system in a transformer, liquid insulation cooperates with solid insulation such as cellulose. Pressboard is the main kind of cellulose used in the transformers. Normally, the characteristics of solid insulation can be investigated and analyzed by diverse methods. This paper represents the study of AC breakdown voltage of non-impregnation, 8-hours, and 16-hours impregnated pressboard with natural ester with different moisture content. To vary the moisture content of the pressboards, they were heated at 100 degrees Celsius for 12 hours and 24 -hours in a vacuum oven. After that, the Coulometric Karl Fischer method was used to determine the moisture content. Before impregnation, the natural ester was heated at 100 degrees Celsius for 12-hours in another vacuum oven. To investigate AC breakdown voltage, electrode configuration and test circuit were set-ups according to IEC 60243-1. From the test result, higher' moisture content caused clearly lower AC breakdown voltage of the pressboards.
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    The Polarization and Depolarization Current Characteristics of Natural Ester Stressed by Partial Discharge
    (2020-10-25)
    Maneerat, Noppadol
    ;
    Makmork, Kawee
    ;
    Kittikhuntharadol, Yannaphol
    ;
    Suksai, Nattapat
    ;
    Chusang, Thanapat
    This paper represents the polarization and depolarization current (PDC) of the natural ester stressed by partial discharge (PD). The needle-plane electrode was used to simulate corona discharge in natural ester. Besides, the needle electrode as a high voltage electrode placed on the 8 hours natural ester impregnated pressboards and the plane electrode as a grounded electrode were used to simulate the surface discharge. To simulate the internal discharge, the plane-plane electrode inserted with various condition impregnated pressboards were experimented. PD phenomena were simulated in the natural ester container for 1, 3, and 6 months. Then the PD-stressed natural ester was used as the liquid specimen for polarization and depolarization current measurement. It was found that the PDC characteristics of natural ester undergone with various PD types were obviously different.
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    Dielectric Properties of Natural Ester Mixed with Nanoparticles under Thermal Stress
    (2020-10-25)
    Kittikhuntharadol, Yannaphol
    ;
    Vittayakorn, Wanwilai
    ;
    Pattanadech, Norasage
    This paper aim to study of the dielectric properties of thermal stressed natural ester mixed with TiO2, and ZnO. Polarization and depolarization current (PDC) along with dielectric loss factor (tanδ) of the test specimens were investigated. The test specimens comprised of unmodified natural ester and natural ester mixed with different volume concentration, i.e., 0.01%, and 0.03% of TiO2, and ZnO. After preparing the natural ester and the natural ester nanofluid specimen, such specimens were undergone with thermal stress at 110 degree Celsius for 72 hours in vacuum oven. Then, a PDC-Analyser-1MOD was utilized for PDC measurement of the test samples. For tanδ measurement, test circuit was set-up according to IEC 60247 and the C and tanδ meter with the liquid electrode were used. From the test result, thermal stress strongly affects the PDC and tanδ characteristics of the liquid samples. Besides, natural ester mixed with 0.01% of TiO2 concentration shows the high potential dielectric liquids compared with other specimens.
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    AC Breakdown and Resistivity of Natural Ester Based Nanofluids
    (2020-10-25)
    Maneerat, Noppadol
    ;
    Makmork, Kawee
    ;
    Kittikhuntharadol, Yannaphol
    ;
    Suksai, Nattapat
    ;
    Chusang, Thanapat
    In this paper, AC breakdown including resistivity of natural ester and natural ester mixed with nanoparticles were studied. Two types of nanoparticles i.e. Barium titanate (BaTiO3) and Titanium dioxide (TiO2) which have their diameter less than 100 nm were used in experiment. For the nanofluid samples, three concentration of nanoparticles including 0.01%, 0.03% and 0.05% were prepared in five processes. Firstly, the natural ester mixed was with 0.01%, 0.03% and 0.05% of volume fraction of nanoparticles. Second, a magnetic stirrer was used to diffuse them evenly over the liquid later, ultrasonic dispersion was also used to ensure that the prepared nanofluids were homogeneous. Then, the nanofluid liquid was heated at 80 degree Celsius in vacuum oven for 15 hours. Finally, this liquid was dispersed by using magnetic stirrer again. Besides, the mixed liquid sample was heated at 110, and 130 degree Celsius for 72 hours to simulated thermal stress. To measure the AC breakdown voltage, a dielectric breakdown testing device was used. The test circuit was set up according to ASTM D1816. The gap distance between electrode was set at 2.0 mm. Furthermore, the test cell for liquid insulation testing (Model DAC-OBE-2: SOKEN) was used for polarization and depolarization current (PDC) experiment. The PDC test result was then used to calculated the resistivity of the liquid samples. The test results show that the AC breakdown voltages of the natural ester mixed with nanoparticles is higher than unmodified natural ester. Additionally, Barium titanate nanoparticles and Titanium dioxide nanoparticles enhance the breakdown strength and the resistivity of the ester nanofluid tested. According to the results, it concluded that nanoparticles were an good alternative to enhance the dielectric properties of natural ester for dielectric application.