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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.
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    Dielectric Properties of Mineral Oil-based Nanofluids using Zinc Oxide Nano-composites for Power Transformer Application
    (2018-11-14)
    Muangpratoom, P.
    ;
    Kunakorn, A.
    ;
    Pattanadech, N.
    ;
    Vittayakorn, W.
    ;
    Thungsook, K.
    This research paper describes and analyzes various experiments designed to investigate the dielectric properties (at a series of pre-determined test temperatures and % moisture content) of mineral oil-based nanofluids produced by the incorporation of zinc oxide (ZnO) powder (of mean diameter less than 100nm) into a standard mineral oil, with the surfactant sorbitan mono-oleate (Span 80) added to modify the surface of the nanoparticles in all but the control sample. Five different nanofluid test samples (one control sample and four modified samples) based on the standard mineral oil were produced for testing: 1) a control sample containing no Span 80 and no ZnO, 2) a modified sample with Span 80, and ZnO volume fraction of 0.01 %, 3) a modified sample without Span 80, and ZnO volume fraction of 0.01 %, 4) a modified sample with Span 80, and ZnO volume fraction of 0.03%, and 5) a modified sample without Span 80, and ZnO volume fraction of 0.03 %. In addition, the five liquid samples above were tested to determine AC breakdown voltage at seven different temperatures in the range of 35°C to 90°C. The test circuit was set up in accordance with IEC 60156 using a sphere-sphere electrode configuration with gap spacing of 2.5 mm. Several significant results were obtained from the investigation. Firstly, ZnO nanoparticles had a positive effect on all the test solutions in which they were used. Second, a positive relationship was confirmed between breakdown voltages, temperature rise. Third, a negative correlation was established between higher concentration of ZnO nanoparticles and breakdown voltage. Fourth, the use of surfactant proved to have both positive and negative effects on breakdown voltages.
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    Dielectric breakdown strength of mineral oil based nanofluids
    (2016-11-28)
    Muangpratoom, Pichai
    ;
    Pattanadech, Norasage
    In this paper, the dielectric properties of the mineral oil-based nanofluids was studied. The aim of this research is to improve electrical property of the mineral oil by applying nanotechnology knowledge. Three types of nanoparticle i.e. Titanium dioxide (TiO<inf>2</inf>), Barium titanate (BaTiO<inf>3</inf>) and Zinc oxide (ZnO) with the mean diameter less than 100 nm were used in the experiment. The nanofluid samples, the mineral oil mixed with nanoparticle, were prepared in three processes. Firstly, the mineral oil was mixed with 0.01% of nanoparticle volume fraction of nanoparticle. Besides, the mineral oil was also mixed with 0.03% of nanoparticle volume fraction. Then it was dispersed by using a magnetic stirrer. Finally, the ultrasonic dispersant technique was applied for the prepared nanofluids to ensure the homogeneity of such liquid. To measure the AC breakdown voltages, an oil breakdown tester (FOSTER OTS 60AF) was used. The gap distance between electrodes was set to be 2.5 mm. The testing was carried out 6 times for each liquid test sample according to IEC 60156. The test results showed that the AC breakdown property of the modified liquid was strongly influenced by the type of the nanoparticles added. With the addition of nanoparticles, the AC breakdown voltage increased slightly above that of the mineral oil (37 kV). In case of 0.01% nanoparticle volume fraction, the AC breakdown voltage of the mineral oil with TiO<inf>2</inf>, the mineral oil with BaTiO<inf>3</inf> and the mineral oil with ZnO was 42 kV, 45 kV and 46 kV respectively. For 0.03% nanoparticle volume fraction, the AC breakdown voltage of the mineral oil with TiO<inf>2</inf>, the mineral oil with BaTiO<inf>3</inf> and the mineral oil with ZnO was 45 kV, 48 kV and 60 kV respectively. From these results, it is indicated that nanoparticles is a good candidate to develop mineral oil-based nanofluids for dielectric applications.