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The Behavior of Dissolved Gas in Mineral Oil with TiO2 and Three Types of Insulation Paper at 150 Degree Celsius
(2024-01-01)
Jongvilaikasem, Korraya
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Bunlaksananusorn, Chanin
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Vittayakorn, Wanwilai
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Pattanadech, Norasage
The main electrical insulation in oil-immersed transformers is liquid insulation and paper insulation. Liquid insulation is generally used mineral oil. However, improvements in the quality of liquid insulation are continually being made for better efficiency i.e. adding various additives such as inhibitors and nanoparticles. Nanoparticles are a solid substance used in research for many years. TiO<inf>2</inf> is a type of nano that is commonly used in research to increase the efficiency of mineral oil. This research experimented by preparing dry transformer oil mixed with 0.03% TiO<inf>2</inf>. The test vessels consisted of 3 main components: 1) 35 ml of MO with 0.03% TiO<inf>2</inf>, 2) 1 gram of paper with three types of insulation including pressboard, kraft, and diamond dot paper, and 3) two types of coils including copper and aluminum with size 1∗2.5 cm. The sample vessels were aged at 150 C for 72 hours in the vacuum oven. After aging, oil samples were analyzed by dissolved gas analysis (DGA). From the DGA test results, it was found that similar weights of different types of paper produced different gas-generating results.
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The Behavior of Dissolved Gas in Difference Liquid Insulation With ZnO Under Thermal Ageing Condition
(2024-01-01)
Jongvilaikasem, Korraya
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Bunlaksananusorn, Chanin
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Vittayakorn, Wanwilai
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Pattanadech, Norasage
Mineral oil is a commercial product that has been widely used as a dielectric liquid in transformers. However, alternative liquids have been developed to gradually replace mineral oil because of some better liquid insulating properties in the point of safety aspect and environmentally friendly. This paper represented the behavior of Dissolved Gas in different types of liquid insulations mixed with nanoparticles under thermal aging conditions. Various types of liquid insulation including mineral oil, natural ester, and palm oil added with a 0.03% concentration of zinc oxide (ZnO) and sorbitan mono-oleate surfactant (Span 80) underwent thermal stress aging at 90, 110, 130, and 150 degrees Celsius with 200 mbar for 72 hours in a vacuum oven. Then, the concentration of dissolved gas in the stressed samples was investigated by the Dissolved Gas Analysis (DGA) technique. From the test results, it was discovered that distinct liquid insulations and aging temperatures produced diverse dissolved gas generation behaviors. Besides, the dielectric liquid with Nanofluids or Nanofluids mixed with span 80 seems to have no different dissolved gas generation behaviors.
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Physical and chemical properties’ comparison of natural ester and palm oil used in a distribution transformer
(2023-03-01)
Kittikhuntharadol, Yannaphol
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Pattanadech, Norasage
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Maneerot, Sakda
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Jongvilaikasem, Korraya
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Jariyanurat, Kittipod
Because of its low cost and suitable qualities, mineral oil (MO) has been commonly employed in transformers. Alternative liquid insulations with great characteristics have recently been presented. Natural ester (NE) and palm oil (PO) are considered alternative liquid insulations. This paper aims to study the physical and chemical properties of NE and PO which were used in a transformer for 21 months. All of the liquid insulation test specimens were sampled every 3 months. Physical properties of the liquid insulation, i.e., interfacial tension (IFT), viscosity, and particles count, were examined. Chemical properties of the liquid insulation, i.e., moisture content, acidity, corrosive sulfur, and furanic compound (2-FAL), were investigated. IFT, particles count, moisture content, acidity, and 2-FAL test results indicated deterioration of liquid insulations of the used liquid insulation; however, there is no observation change for particles amount and acidity of NE. The other test results were not found significantly change.
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The Comparison of DGA Interpretation Techniques Application for Actual Failure Transformer Inspections Including Experience from Power Plants in Thailand
(2022-03-01)
Jongvilaikasem, Korraya
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Pattanadech, Norasage
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Wattakapaiboon, Wilasinee
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Kando, Masaaki
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Maneerot, Sakda
Dissolve gas analysis (DGA) is a diagnostic test technique applied for transformer condition evaluation. The interpretation of the dissolved gas results is a significant procedure to classify the incipient fault types in transformers. A variety of dissolved gas interpretation methods utilized for the same investigation case may give different fault type results. This paper investigates the performance of dissolved gas interpretation methods, including Doernenburg Ratio, Roger Ratio, IEC Ratio, Müller-Schlliesing and Soldner Method, Duval Triangle, and Duval Pentagon. The twenty-four failure transformer cases are used to evaluate the performance of the dissolved gas interpretation methods. The test result shows that the Duval pentagon interpretation technique shows the highest consistency interpretation. Besides, the Duval pentagon method demonstrates the ability to identify a normal aging problem of the transformer insulation.
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Dissolved Gas Behavior in Natural Ester under Corona, Surface, and Internal Discharges
(2020-10-25)
Jongvilaikasem, Korraya
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Pattanadech, Norasage
The normal operating transformers encounter various kinds of stresses such as thermal stress, electrical stress, mechanical stress, and ambient effect that can expedite the deterioration process. Partial discharge occurs normally in high voltage equipment under high electric field. For a natural-immersed transformer, partial discharge can be detected by the dissolved gas analysis technique. This paper presents the patterns of dissolved gas generation in natural ester under partial discharge conditions. Besides, the existence of acidity number is also reported. Various types of partial discharge, including corona discharge, surface discharge, and the FR3 impregnated pressboard internal discharge, were simulated. A needle-plane electrode was used to simulate corona discharge, a needle-plane electrode with the impregnated pressboard was used to simulate surface discharge, whereas the plane electrode with pressboards was used to simulate the internal discharge. Each experiment was simulated in the test vessel under 24 kV test voltage for 3000 hours. The natural ester and the pressboards were heated at 80°C for 12 hours. before filled in the test vessel. Each test vessel was contained two identical plane electrodes with a 32 mm gap spacing. The impregnated pressboard was fit-inserted between such electrodes. The high voltage electrode was subjected to 24 kV whereas another plane electrode was grounded. Then, the natural ester were sampled from the vessel after operating for 350, 1000, and 3000 hours respectively. Dissolved gas analysis of the natural ester in this work followed ASTM D3612; the acidity number of aging natural ester was also tested according to ASTM D664. From the test results, it was found that different types of partial discharges generated various patterns of dissolved gas generation. Besides, the experiment with non-impregnated pressboards couldn't survive in this condition.
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Dissolved Gas Analysis of Palm Oil Compared with Mineral Oil from Different Types of Breakdown Voltage
(2020-10-25)
Suksagoolpanya, Suthat
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Jongvilaikasem, Korraya
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Jariyanurat, Kitipod
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Banthoengjai, Thanpilin
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Jeenmuang, Siwakorn
Natural products are required instead of chemical materials for saving the environment. Nowadays, the palm oil is a new alternative liquid insulation that may be used in a transformer. Normally, the characteristics of liquid insulation can be investigated and analyzed by various methods. One of the diagnosis methods widely used is a dissolved gas analysis technique (DGA). The propose of this paper is to study the interpretation of dissolved gases in the palm oil compared with that of in the mineral oil which is caused by different kinds of breakdown phenomena, i.e. AC breakdown, positive lightning impulse breakdown, and negative lightning impulse breakdown. An AC breakdown voltage test according to IEC 60156 was performed by using 3 difference gap spacing which were 1.0, 1.5, and 2.0 mm. For lightning impulse tests, the test cell was contained needle-sphere electrodes with 10, 15, and 20 mm gap different spacing. The lightning impulse tests were performed in accordance with IEC 60897. Each experiment was performed for 5, 10, and 15 times. For a material preparation, the mineral oil and the palm oil was heated at 80oC for 12 hours. Then, it was naturally cooled before filling into the test cell to perform AC and lightning impulse breakdown tests. After that, the mineral oil and the palm oil was sampled out of the test cell to perform the DGA experiment. The dissolved gases from the mineral oil and the palm oil were interpreted by applying IEC and IEEE gas interpretation techniques. It was found that the breakdown voltages of the palm oil were less than the mineral oil but the palm oil generates more dissolved gases than the mineral oil. Moreover, Duval pentagon for natural ester fluid seemed to be the most suitable method to interpret dissolved gases in the palm oil compared with the IEC ratio, Doernenburg ratio, Roger ratio, and Duval triangle.
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Dissolved gas analysis of liquid insulation under ac and impulse breakdown voltage tests
(2019-07-01)
Pattanadech, Norasage
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Lukin, Kanchanaporn
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Samerpak, Chantapapa
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Chumninuan, Nattakrit
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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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Comparison of dissolved gases in natural ester under partial discharges
(2019-06-01)
Jongvilaikasem, Korraya
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Maneerot, Sakda
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Jariyanurat, Kittipod
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Pattanadech, Norasage
Currently, natural ester is alternative liquid insulation applied for both distribution and power transformers. Generally, transformers are expected to operate stably and reliably. However, their functions may fail during operation. Dissolved gases analysis is one of the worldwide accepted diagnostic techniques to examine the insulation integrity of the transformers. This paper presents the analysis of dissolved gases generated from partial discharge (PD) experiments i.e. corona discharge, surface discharge and internal discharge which were conducted in the test cell filled with natural ester (FR3). To simulate corona discharge, a needle electrode with a tip radius of 10, 20, and 40 micrometers was used as high voltage electrode and the plane electrode with a diameter of 45 mm was used as a grounded electrode. The gap distance was fixed at 32 mm. The corona discharge experiment was performed for 2 hours at the test voltage level of 35, 40, 45 kV respectively. In case of surface discharge, the pressboard samples i.e. non-impregnated pressboards, 8-hour impregnated pressboards, and 16-hour impregnated pressboards were inserted between the 20-micrometer tip radius needle and grounded plane. Then, the test voltage of 25 kV was applied to the electrode system for 1 hour. Besides, the surface discharge was tested at 35 and 45 kV respectively. For internal discharge, the pressboard samples i.e. non-impregnated pressboards, 8-hour impregnated pressboards, and 16-hour impregnated pressboards were inserted between the plane-plane electrodes. Then the test voltage of 25 kV was applied to the electrode system for 1 hour. Moreover, the internal discharge was tested also at 35 and 45 kV. Their natural ester samples were sampling from the test cell for each experiment and the dissolved gases were measured and analyzed. From the test results, it was found that the types and quantity of dissolved gases depended strongly on the type of discharge and material samples.

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