• Title/Summary/Keyword: transformer oil

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Overload Criterion of Mineral-Oil-immersed Distribution Transformers Rated 100kVA and Less Using the Characteristics of Top-Oil Temperature Rising (최상부 유온 상승 특성을 이용한 100kVA 이하 유입식 배전용 변압기의 과부하 판정 기준)

  • Yun, Sang-Yun;Kim, Jae-Chul;Park, Chang-Ho
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.51 no.11
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    • pp.559-567
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    • 2002
  • This paper presents the general recommendations for the overload criterions of mineral-oil-immersed distribution transformers rated 100kVA and less. For this purpose, we analyze the characteristics of top-oil temperature rising for mineral-oil-immersed power distribution transformer rated 100kVA and less, manufactured in Korea, In order to analyze the characteristics of top-oil temperature rising due to the distribution transformer loading, we performed experiments at KERI (Korea Electrical Research Institute) from December 2000 to May 2001. The restraint of ambient temperatures for the experiment results is solved using the results of foreign standards. Finally, we present the overload criterions of distribution transformer for summer and winter season, respectively.

Analyses on Electrical-Mechanical Characteristics of Environment-friendly Transformer Insulating Material by Accelerated Thermal Aging (가속 열 열화에 따른 환경친화형 변압기 절연물의 전기적-기계적 특성 분석)

  • Shim, Myeong-Seop;An, Jung-Sik;Choi, Sun-Ho;Jeong, Jung-Il;Lee, Tae-Ho;Huh, Chang-Su
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.10
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    • pp.1832-1838
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    • 2010
  • Aging of transformer insulating material in natural ester insulating oil is compared to that in conventional transformer oil. Aging of insulating paper and insulating oil have been studied by performing accelerated thermal aging test. Sealed aging test vessels containing cooper, laminated core, Kraft paper and insulating oil(natural oil or mineral oil) were aged at $140^{\circ}C$ for 500, 1000, 1500 and 2000 hours. Insulating oils after aging are investigated with total acid number, breakdown voltage and viscosity. Also, degradation of insulating paper after aging is determined using breakdown voltage and mechanical strength. Accelerated aging studies demonstrate a slower aging rate for natural ester insulating oil compared to the rate for conventional mineral oil.

Copper Particle Effect on the Breakdown Strength of Insulating Oil at Combined AC and DC Voltage

  • Wang, You-Yuan;Li, Yuan-Long;Wei, Chao;Zhang, Jing;Li, Xi
    • Journal of Electrical Engineering and Technology
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    • v.12 no.2
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    • pp.865-873
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    • 2017
  • Converter transformer is the key equipment of high voltage direct current transmission system. The solid suspending particles originating from the process of installation and operation of converter transformer have significant influence on the insulation performance of transformer oil, especially in presence of DC component in applied voltage. Under high electric field, the particles easily lead to partial discharge and breakdown of insulating oil. This paper investigated copper particle effect on the breakdown voltage of transformer oil at combined AC and DC voltage. A simulation model with single copper particle was established to interpret the particle effect on the breakdown strength of insulating oil. The experimental and simulation results showed that the particles distort the electric field. The breakdown voltage of insulating oil contaminated with copper particle decreases with the increase of particle number, and the breakdown voltage and the logarithm of particle number approximately satisfy the linear relationship. With the increase of the DC component in applied voltage, the breakdown voltage of contaminated insulating oil decreases. The simulation results show that the particle collides with the electrode more frequently with more DC component contained in the applied voltage, which will trigger more discharge and decrease the breakdown voltage of insulating oil.

Study on Aging Characteristics and Chemical Composition of Hydrogenated Transformer Oil

  • Qian, Yi-Hua;Huang, Yi-Bin;Fu, Qiang;Zhong, Zhen-Sheng
    • Journal of Electrical Engineering and Technology
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    • v.8 no.3
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    • pp.588-594
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    • 2013
  • Under the condition of Baader aging, the chemical composition variation and the influence of transformer oil aging on electrical properties such as dielectric loss factor and physic-chemical properties such as interfacial tension were studied in the aging precess. Moreover, the correlation between hydrogenated transformer oil electrical and physic-chemical properties and its chemical composition variation were also investigated. The results show that these parameters of physic-chemical and electrical properties of hydrogenated transformer oil relate to each other and have closed correlation with chemical composition.

Breakdown Properties for Insulation Design of the Environment-Friendly Pole Transformer using the Vegetable Insulating Oil (식물성절연유를 사용한 친환경 주상변압기 설계를 위한 절연파괴 특성)

  • Kwag, Dong-Soon
    • Journal of the Korean Society of Safety
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    • v.26 no.6
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    • pp.7-12
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    • 2011
  • In recent years, environmental concerns have been raised on the use of poorly biodegradable fluids in electrical apparatus in regions where spills from leaks and equipment failure could contaminate the surroundings. The newly invented vegetable insulating oil is highly biodegradable and have negligible impact on the environment, human health and the ecosystem. For development of the environmental-friendly pole transformer using vegetable insulating oil, the dielectric constructions of the pole transformer were discussed in this paper. Depending on the dielectric constructions, the AC breakdown characteristics of the Nomex insulating papers and the vegetable insulating oil were studied by simulated electrode systems. Based on the experimental results, the maximum design stress($E_{max}$) for insulation design of the environmental-friendly pole transformer were suggested.

Transformer diagnosis using characteristics of corona in Oil (변압기의 고장검출을 위한 유중 코로나 특성 연구)

  • 권태원;곽희로;김재철;김응상;박민규
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 1989.10a
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    • pp.65-70
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    • 1989
  • This paper presents resarch results on the use of a corona detector and a pulse counter in order to diagnose for oil transformers. Using these experimental apparatus, tests were carried out on a typical transformer oil containing different carbonized paper and various moisture contents to measure the picocoulomb val-ues and pulse count. Through the result of this study it was found that the picocoulomb values and pulse count of corona were depended on the getting stained in transformer oil. The amplitude of the partial discharge amount and the number of pulse were decreased up to 70 [。c] and then was increased as the oil temperature goes up. It was concluded that the determinati-on level for diagnosis of oil transform-er was taken into account the temperatu-er of transformer oil, The use of pulse counter method, which have been taken the same property of voltage and temperature variation for the corona measurement mothod, considera-bly increase insulator avilability.

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Electrical Breakdown Properties of Insulating Oils for oil-immersed transformer (유입변압기용 절연유의 절연파괴특성)

  • 이인성;신현택;이종필;이수원;홍진웅
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.11a
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    • pp.605-608
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    • 2001
  • With the intention of investigating the breakdown properties of oil-immersed transformer oils in temperature range of 20∼100[$^{\circ}C$], we are made researches AC breakdown in the gap of 500∼2,500[$\mu\textrm{m}$]. The classification for the physical properties of oil for oil-immersed transformer by FTH and $^1$H-NMR experiments was confirmed to type of mineral oils. As the dependance of breakdown properties due to electrode gap length variation, breakdown voltage was found increasing according to the increase of gap, while dielectric strength was decreasing. As a result the characteristics for AC breakdown, It goes to prove that the breakdown voltage was increased to 90[$^{\circ}C$] but decreased over 90[$^{\circ}C$] in the temperature range. Also, breakdown voltage was found increasing in the increase of gap and the rising of temperature according to Weibull distribution.

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Gas detection of transformer oil according to degradation characteristic of insulation material (절연물의열화에 의한 변압기유의 가스분석)

  • Hwang, Kyu-Hyun;Seo, Ho-Joon;Lee, Suck-Woo;Rhie, Dong-Hee
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.07a
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    • pp.574-574
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    • 2005
  • To found out the degradation characteristic of transformer insulation, insulation material was depisited into transformer oil and heated. Due to the thermal stress which added to insulation, the density of carbon dioxide which included in transformer oil was mesured by using the gas density detection equipment of gas sensor and air circulation method. As a result, it didn't match with the transformer supervision standard. But it was found that as thermal stress increased, the density of carbon dioxide propertionally increased.

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Analysis on the Temperature Distribution Characteristics of Insulating oil of Transformer Using the Vegetable oil and Mineral oil (식물성 절연유와 광유가 사용된 유입변압기의 온도분포 특성)

  • An, Jung-Sik;Shim, Meoung-Seop;Jung, Joong-Il;Kim, Nam-Ryul;Huh, Chang-Su
    • Proceedings of the KIEE Conference
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    • 2009.07a
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    • pp.1215_1216
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    • 2009
  • Most transformer use insulating and cooling fluids derived from petroleum crude oil, but mineral oil is some possibility of environmental pollution and fire with explosion. vegetable oil fluids extracted from seed has superior biodegradation and fire-resistant properties including an exceptionally high fire point enhancing fire safety. In this study, it is aimed at the practicality of substituting natural ester dielectric fluid for mineral oil in liquid insulation system of transformers. As a rise in coil winding temperature has a direct influence on transformer life time, it is important to evaluate the temperature rise of coil winding in vegetable oil in comparison with mineral oil. Three transformers for the test are designed with 10KVA, 13.2KV, one phase unit. The temperature are directly measured in insulating oil of these transformers with the two sorts of natural ester and mineral oil dielectric fluid respectively. Temperature of vegetable oil transformers was similar to temperature of mineral oil transformer in the same design at 80% load and above.

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Experimental Study on the Dielectric Breakdown Voltage with the Addition of Magnetic Nanoparticles in a Transformer Oil (변압기 오일에 자성나노입자 첨가에 따른 절연파괴전압 특성변화에 관한 실험적 연구)

  • Seo, Hyun-Seok;Lee, Won-Ho;Lee, Se-Hee;Lee, Jong-Chul
    • Proceedings of the KIEE Conference
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    • 2011.07a
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    • pp.1538-1539
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    • 2011
  • In this study, we have investigated the dielectric breakdown by measuring AC (60Hz) breakdown strength of the fluids in accordance with IEC 156 standard and have compared the results with references. It was found that the dielectric breakdown voltage of pure transformer oil is around 12 [kV] with the gap distance of 1.5mm between electrodes. In case of our transformer oil based magnetic fluids with 0.1% < ${\Phi}$(volume concentration of magnetic particles) <0.6%, the dielectric breakdown voltage shows above 30 [kV], which is 2.5 times higher than that of pure transformer oil. It can be explained by the changed ionization process by adding nanoparticles in pure transformer oil, which is due to trapped fast electrons and slow negative nanoparticles. Moreover, in case of the fluid with applied magnetic field, the dielectric breakdown voltage increases above 40 [kV], which is 3.3 times higher than that of pure transformer oil.

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