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Author: search.filters.author.Pattanadech, N.Subject: search.filters.subject.Mineral oil

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    Determination of water in transformer by water solubility and percent moisture by dry weight in comparison with ppm water value for justification transformer maintenance
    (2020-10-25)
    Wannapring, E.
    ;
    Sirisithichote, T.
    ;
    Pattanadech, N.
    ;
    Leelajindakrairerk, M.
    The measure of water content is to find water content in transformers. There are many ways that water can occur in the transformers, such as residual moisture in the paper insulation and oils during the manufacturing process, generating from the degradation of transformer paper insulation and oil, ingression into the transformer, etc. The water in the transformer resides in liquid insulation approximately 1% and in the solid paper insulation of roughly 99%. The status of water in oil and water in paper insulation is not stable; water in paper insulation moves into transformer oil and vice versa, depending on loads and temperature. Both waters in oil and water in paper insulation reduce the insulation property of the transformer. This paper aims to present the observations of total water content in the transformer (water in oil and water in paper insulation) compared to the PPM value directly from laboratory testing to understand the severity and manage proper transformer maintenance decisions.
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    Evaluation of loss factor of mineral oil and alternative fluids with temperature normalization
    (2020-07-01)
    Maneerot, S.
    ;
    Nimsanong, P.
    ;
    Pattanadech, N.
    This paper proposes the evaluation of loss factor of mineral oil and alternative fluids the natural ester (FR3) with temperature normalization. The oil samples (i.e., mineral oil, natural ester, and palm oil) were prepared for experiments. The oil samples were dried at 70 °C under 200 mbar in the controlled temperature oven and then cooled down to ambient temperature. The moisture contents of the oil samples were measured according to ASTM D1533. The test cell, according to IEC61620, was employed in these measurements. The polarization currents, ipol(t), of such oil samples under electric field stress of 0.2 kV/mm with a temperature range from 30 to 70 °C were measured, The test results are summarized in this paper. The step response measurement results were analyzed for conductivities, permittivity, and loss factor value. It was found that increasing temperature causes increasing conductivities but decreasing permittivity of oil samples.
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    Effect of different temperatures on AC breakdown voltage of mineral oil based nanofluids
    (2018-07-02)
    Muangpratoom, P.
    ;
    Kunakorn, A.
    ;
    Pattanadech, N.
    ;
    Vittayakorn, W.
    This study seeks to make improvements in the dielectric properties of transformer oil through the application of nanotechnology. In particular, two nanoparticles are examined experimentally: titanium dioxide (TiO<inf>2</inf>), and barium titanate (BaTiO<inf>3</inf>). Each has a mean diameter not exceeding 100 nm. The nanofluid samples comprised the nanoparticles mixed into the mineral oil through differing procedures. In the first case, the transformer oil was combined with 0.01% volume fraction of the nanoparticle; the second sample used 0.03% volume fraction of the nanoparticle volume fraction. A magnetic stirrer was then used for sample dispersal before an ultrasonic dispersant method was used on the prepared nanofluids so that sample homogeneity could be assured. The experimental process then recorded the AC breakdown voltage characteristics for the liquids through a range of temperatures from 35°C up to 90°C. The findings indicate that the AC breakdown voltages for mineral oils containing nanoparticles exceed those for unmodified mineral oils.
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    Dielectric properties of mineral oil compared with natural ester
    (2017-11-29)
    Jariyanurat, K.
    ;
    Nimsanong, P.
    ;
    Chaisiri, P.
    ;
    Maneerot, S.
    ;
    Kitcharoen, P.
    In this paper, dielectric properties of the mineral oil, ELECTROL A, and the natural ester, FR3, are comparatively investigated. AC breakdown voltages, dielectric dissipation factor, relative permittivity, partial discharge inception voltage and partial discharge of the mineral oil and of the natural ester are tested. In order to verify the capability in practical use of the mineral oil and the natural ester for transformer insulation systems, the impregnation of such liquids with pressboard insulation is performed. The impregnated pressboards are tested in the laboratory to measure the AC breakdown voltages. It is found that the natural ester shows superior dielectric properties to the mineral oil except the dielectric dissipation factor.
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    Partial discharge characteristics of mineral oil compared with natural ester
    (2017-10-19)
    Pattanadech, N.
    ;
    Jariyanurat, K.
    ;
    Maneerot, S.
    ;
    Nimsanong, P.
    In this paper, partial discharge inception voltage (PDIV) and partial discharge (PD) characteristics of mineral oil compared with natural ester were studies. Three typical PD types, corona discharge of the liquid insulations, surface discharge and internal discharge of the liquid impregnated pressboards were investigated. In case of corona discharge, both corona discharges from high voltage side and from low voltage side were simulated by using the needle-plane electrode configuration. The needle with the tip radius of 10μm, 20μm, 40μm respectively was used as high voltage electrode while the brass plane electrode with 45 mm diameter was used as the grounded electrode for simulation the corona discharge at high voltage side, and vice versa, for simulation corona discharge at low voltage side. The gap distance was fixed for 30 mm. Moreover, the mineral oil and natural ester were used to impregnate the pressboards which were 1.6 mm thick. Then, the impregnated pressboards were selected to experiment for surface discharge and internal discharge respectively. The surface discharge experiment was performed with the 40μm tip radius needle as high voltage electrode put on the ten pieces of 12 hour impregnated pressboards stuck together as a single insulation and the plane electrode with 45 mm diameter as grounded electrode. In case of the internal discharge, ten pieces of 6 hour impregnated pressboards were stuck together as a single insulation. A cylindrical void with 5 mm diameter and a height of 3.2 mm was simulated at the middle of the insulation. Then, the insulation was placed between the mentioned plane electrodes for the internal discharge experiment. PD test circuit was prepared following to IEC 60270. PDIV was examined by applying the step voltage to the high voltage electrode with the increase rate of 1 kV per step for the step duration of 1 minute until observing the PDIV. Then, PD activity was examined and recorded for 1 minute at 110% PDIV level. Form the test results, the natural ester and pressboards impregnated with natural ester provide higher PDIV than mineral oil and the mineral oil impregnated pressboards. Consequently, the PD amplitude at 1.1 PDIV of natural ester and natural ester impregnated pressboards are higher than that of mineral oil and mineral oil impregnated pressboards.
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    Electrical characteristic comparison of mineral oil and natural ester for transformer applications
    (2017-10-19)
    Pattanadech, N.
    ;
    Jariyanurat, K.
    ;
    Maneerot, S.
    ;
    Nimsanong, P.
    In this paper, the electrical characteristics of mineral oil compared with natural ester were studies. AC breakdown strength, dielectric dissipation factor, and permittivity of both liquids were investigated. Both new liquids were heated in the oven at 60°C with 200 mbar for 6 hours before starting all investigation, the water contents of mineral oil and natural ester were 18 and 178 ppm respectively. Moreover, the mineral oil and natural ester were used to impregnate the pressboards which were 1.6 mm and 3.2 mm thick respectively. These pressboards were impregnated for 3-12 hours. Then, the AC breakdown voltage of the impregnated pressboards was examined. AC breakdown strength of the liquid insulations was tested according to IEC 60156. The dielectric dissipation factor and permittivity of the liquids with the temperature of from 35°C - 100°C were investigated as well. Moreover, the breakdown voltage strength of the impregnated pressboards was examined with the electrodes in accordance with IEC 60243-1. From the test results, mineral oil sample provided lower AC breakdown voltage than natural ester sample. However, mineral oil generated approximately 77 times lower dielectric dissipation factor compared with the natural ester. Besides, natural ester impregnated pressboards had a bit higher breakdown strength than mineral oil impregnated pressboards. Furthermore, breakdown strength of the liquid impregnated pressboard depended clearly the function of time and the pressboard thickness.