Pattanadech, Norasage

Preferred name

Alternative Name

Pattanadech, N.

Main Affiliation

School of Engineering

norasage.pa@kmitl.ac.th

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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.
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Dissolved gas analysis of liquid insulation under ac and impulse breakdown voltage tests
(2019-07-01)
Pattanadech, Norasage
;
Lukin, Kanchanaporn
;
Samerpak, Chantapapa
;
Chumninuan, Nattakrit
;
Piyapatamin, Nadpakul
This paper represents the study of dissolved gas analysis in mineral oil compared with natural ester (FR3) under AC and impulse breakdown voltage tests. Liquid insulation was heated at 60°C with 200 mbar for 12 hours. Liquid test samples were divided into three groups. The first group was tested with AC voltage using the spherical electrodes with the gap distance of 1.0, 1.5, and 2.0 mm. The AC test procedure was in accordant with IEC 60156. The second and the third group of liquid samples was tested with standard positive lightning impulse and standard negative lightning impulse voltage using the needle - sphere electrode with the distance of 10, 15, and 20 mm. The impulse test procedure was according to IEC 60897. Testing experiments were performed 5, 10, and 15 times consecutively for each test sample. Then dissolved gas analysis of each test sample was performed. From the test results, the type of breakdown voltage and the number of breakdowns effected on the quantity of the dissolved gas in the liquid insulation.
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Dielectric properties of mineral oil compared with natural ester
(2017-11-29)
Jariyanurat, K.
;
Nimsanong, P.
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Chaisiri, P.
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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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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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Comments on PDIV testing procedure according to IEC 61294
(2017-11-29)
Pattanadech, Norasage
;
Muhr, Michael
—In this paper, partial discharge inception voltage (PDIV) and partial discharge (PD) activity of mineral oil with water content of 4 ppm are investigated. The PDIV test procedure was performed according to IEC 61294. Then, the PDactivitywas recorded for 1 minute at 1.1 PDIV level. The investigation wasconducted with a needle – plane electrode and a needle –sphere electrode by which different tip radius needles, plane electrodes, and various diameter sphere electrodes were used for the experiments. The PDIV and PD activity test results are reported in this paper. It was found that PDIV strongly depends on the electrode configuration and the gap distance. From the experiments,PDIV values of some electrode systems were not obtained due to the problems of breakdown events occurring during the experiments.Theparticular patterns for PDIV testing to explain the possibility PD and breakdown events which may occur during PDIV testing in accordance with IEC 61294 are developed. The particular patterns for PDIV testingare divided into four cases as the followings: The first PD pulse coexisting with PDIV, the low risk of breakdown for PDIV experiment, the medium risk of breakdown for PDIV experiment and the high risk of breakdown for PDIV experiment. In case of the very simple case PDIV and the lower risk of breakdown for PDIV experiment, the PDIV can be detected without breakdown occur. However, in the case of the medium risk of breakdown for PDIV experiment breakdown may take place before or after the PDIV is detected. In the case of high risk of breakdown for PDIV measurement, breakdown takes place easily during performing the PDIV experiment.Therefore, the exact PDIV valuesare not be obtained for such cases. To avoid the breakdown events which may occur during PDIV experimentaccording to IEC 61294 was performed, the combined PDIV measurement was recommended. Besides, PDIV testing with the combined PDIV method provided the lower PDIVwhich was closer to the theoretical PDIV compared with testing in accordance with IEC61294.
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Dissolved gas analysis caused by electrical breakdown of liquid impregnated pressboards
(2019-07-01)
Pattanadech, Norasage
;
Luk-In, Kanchanaporn
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Samerpak, Chantapapa
;
Chumninuan, Nattakrit
;
Piyapatamin, Nadpakul
The aim of this paper is to analyze the dissolved gases in dielectric liquid caused by electrical breakdown of liquid-impregnated pressboards. The pressboards were prepared with dimension of 100 x 100 x 3.2 mm (W x L x H). First of all, each liquid insulation, mineral oil and natural ester (FR3), was heated at 60°C with 200 mbar for 12 hours. Second, pressboards were heated at 80°C with 200 mbar for 12 hours. Then the heated pressboards were impregnated with the dielectric liquid at 60°C with 200 mbar for 12 hours. The impregnated pressboards were divided into three groups. The first group was tested with AC voltage. The second and third group was tested with positive and negative lightning impulse voltages respectively. From the test results, the type and quantity of generated gases caused by breakdown phenomena is dependent on the type and the number of breakdowns.
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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.
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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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Dielectric Response Analysis of Mineral Oil Immersed Transformer Insulation during Manufacturing Process
(2019-06-01)
Nganpitak, Tritod
;
Nimsanong, Phethai
;
Maneerot, Sakda
;
Pattanadech, Norasage
Polarization and Depolarization current (PDC) method is one of non-destructive insulation testing methods that can be used for diagnosis the insulation conditions of high voltage equipment. This paper presents the PDC analysis of an oil immersed distribution transformer measured during the manufacturing process. A 22 kV, 30 kVA single phase transformer was designed and constructed. During manufacturing process, the polarization current and depolarization current of the transformer insulation were measured for 6 case studies as follows: 1) paper insulation between iron core and low voltage (LV) windings before dry and vacuum in the oven, 2) paper insulation between LV and high voltage (HV) windings before dry and vacuum in the oven, 3) paper insulation between iron core and LV windings after dry and vacuum in the oven, 4) paper insulation between LV and HV windings after dry and vacuum in the oven, 5) oilpaper insulation between iron core and LV windings after dry and impregnation process and 6) oil-paper insulation between LV and HV windings after dry and impregnation process. Then, PDC test results were analyzed. It was found that the moisture content in the paper insulation clearly affected the capacitance at power frequency, and PDC shapes. Besides, the impregnation process had a good effect on the capacitance ratio and dielectric dissipation factor. Moreover, the current difference of dry paper insulation between HV and LV windings presented the nonlinear characteristic both before and after impregnation process.
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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.

Pattanadech, Norasage

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