• Title/Summary/Keyword: transformer oil

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Thermal Analysis of Vegetable Insulation Oil for Hermetically Sealed Wind Turbine Transformer (풍력발전기용 밀폐형 변압기의 식물성 절연유에 대한 열적특성 연구)

  • Lee, Sung-Won;Lee, Joon-Yeob;Kim, Jun-Su;Woo, Jae-Hi;Kim, Dong-Hae
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.36 no.1
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    • pp.97-102
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    • 2012
  • A hermetically sealed oil transformer is designed by applying expanding function of the tank due to the volume changes of the insulation oil according to the temperature rises. When the insulation oil expands, an increase in the volume of the corrugated fin prevents a pressure rise of the transformer. For a wind turbine transformer, a vegetable-oil-immersed transformer has the advantages of excellent biodegradation and fire-resistant properties like an exceptionally high fire point. When vegetable oil is substituted for mineral oil, however, the maximum winding temperature rises because of the decrease in the internal circulation flow rate resulting from the variations of the oil's physical characteristics, such as density and viscosity. The purpose of this study is to develop a hermetically sealed vegetable oil transformer that can be applied in a wind turbine and to analyze the thermal stability of the active part of the transformer to deal with pressure variations due to the temperature changes. In addition, thermal tests for the vegetable oil transformer have been performed, and the measured values are compared with the analysis results.

Analysis of Insulation Characteristics for Transformer Insulating Materials According to Thermal Degradation (열 열화에 따른 변압기 절연물의 절연특성 분석)

  • Lee, Min-Gu;Shim, Jae-Myung;Lim, Kyung-Bum;Lee, Dae-Dong
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.10
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    • pp.1688-1693
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    • 2016
  • In this study shall investigate the influence upon the electrical property of transformer oil due to the heat among accelerated heat degradation experiment for a constant hour in the typical insulation oils of mineral base oil, silicon base oil and vegetable oil. In addition, the electric insulation performance of insulation materials in transformer shall be evaluated through the electric property analysis according to the heat degradation of epoxy insulation material, which has been used for electric facilities such as a molded transformer.

Review on the Relationship of Dissolved Gas Analysis and Internal Inspection of Transformer (변압기 절연재료 분석과 내부점검 결과와의 상관성 연구)

  • Park, Hyun-Joo;Nam, Chang-Hyun;Jung, Nyun-Ho
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.10
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    • pp.1869-1873
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    • 2010
  • For reliable operation of oil-filled electrical equipment, monitoring and maintenance of insulating oil is essential. Dissolved gas analysis(DGA) is widely used for monitoring faults in high voltage electrical equipment in service. Therefore, oil analysis should be monitored regularly during its service life. KEPCO has investigated thousands of dissolved gas analysis data since 1985, and conducted studies on the relationship of gas in oil analysis and internal inspection results of transformer. As the results, KEPCO revised criteria for transformer diagnosis and has applied it since 2008. Almost of 100 cases of internal inspection results since 2001 have been investigated. This paper presents the correlation of the fault-identifying gases with faults found in actual transformers and how should we approach to internal inspection of transformer by dissolved gas analysis.

Gas detection charracteristic of Transformer Oil Gas Detector (변압기 절연유중 가스 검출장치의 가스 감지 특성)

  • 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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    • 2005.11a
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    • pp.323-324
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    • 2005
  • To found out the degradation characteristic of transformer insulation, insulation materials and electrodes are deposited into transformer oil. They used to heated and make flashover. Due to the thermal and electrical stress added to insulation materials, the density of carbon dioxide and hydrogen included in transformer oil was increased. The gas density can measured by using the gas density detection equipment of gas sensor and air circulation method.

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A Study on the Streaming Electrification in the Super-high Voltage Model Transformer (초고압 대용량 모델변압기의 유동대전 현상에 관한 연구(전압무인가))

  • 이덕출;박재윤
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.40 no.6
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    • pp.619-625
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    • 1991
  • Phenomena of streaming electrification of insulting oil(T.O) is studied where the oil is contacted with solid insulating materials when it is pumped through a circulating system in a large power transformer. The leakage current, the electrical potential at the neutral terminal point of the transformer and the surface electrical potential of the oil are investigated. And the leakage current from the neutral terminal point is measured as a function of a bias polarity applied to a transformer case to investigate the polarty of ion which is absorbed in the case at the interface between the case and oil. As a result, it is found that insulating materials, and it is suggested that the leakage current is the sum of the relaxation current by positive charge from insulating oil to the neutral terminal point and by electrification current from negative charge electrified by the contact with solid insulating materials.

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A new method for measuring the degradation level of transformer insulating oil in use (변압기 절연유의 열화 검출에 관한 연구)

  • Bae, Jin-Ho;Chon, Young-Kap;Kang, Young-Ku
    • Proceedings of the KIEE Conference
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    • 1988.11a
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    • pp.214-219
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    • 1988
  • Aging process in transformer insulating oil is studied by measuring the leakage current in ceramic sensor. the current of a sensor developed if this paper shows a close relationship with the acid value and the breakdown voltage of the transformer oil. The sensor has excellent physico-chemical reaction to the oil and stable adsorption of conductive impurities. Therefore the experimental data show good reproducibility. From the detailed analysis of the leakage current, it may be proposed that the condition of transformer insulating oil in service can be checked portably.

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A Simplified Unified Model for Predicting the Dielectrophoretic Aactivity of Magnetic Nanoparticles Aimed at Enhancing the Dielectric Characteristics of Transformer Oil

  • Lee, Jong-Cheol;Jeon, Hong-Pil
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.431.2-431.2
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    • 2014
  • The dielectric breakdown voltage (DBV) is a measure of an insulating fluids ability to withstand a high electric field stress without breaking down. Conventionally, the presence of water or particulate matter in a dielectric fluid comprises the liquid's breakdown strength. However, the addition of magnetic nanoparticles (MNPs) in the base oil can increase the dielectric breakdown voltage of the fluid reversely, if the condition of the added particles in the fluid is in balance with that of keeping down the initiation and propagation of electrical streamers. In this study, we developed a mathematical model by a set of coupled, nonlinear equations using the COMSOL multiphysics finite element simulation suite and calculated the dielectrophoretic activity of magnetic nanoparticles suspended in the presence of electric field, which is the behavior responsible for enhancing the dielectric characteristics of transformer oil, in order to examine how the activity differ in a transformer oil-based magnetic fluid.

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PD Signal Time-Frequency Map and PRPD Pattern Analysis of Nano SiO2 Modified Palm Oil for Transformer Insulation Applications

  • Arvind Shriram, R.K.;Chandrasekar, S.;Karthik, B.
    • Journal of Electrical Engineering and Technology
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    • v.13 no.2
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    • pp.902-910
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    • 2018
  • In recent times, development of nanofluid insulation for power transformers is a hot research topic. Many researchers reported the enhancement in dielectric characteristics of nano modified mineral oils. Considering the drawbacks of petroleum based mineral oil, it is necessary to understand the dielectric characteristics of nanofluids developed with natural ester based oils. Palm oil has better insulation characteristics comparable to mineral oil. However very few research reports is available in the area of nanofluids based on palm oil. Partial discharge (PD) is one of the major sources of insulation performance degradation of transformer oil. It is essential to understand the partial discharge(PD) characteristics by collecting huge data base of PD performance of nano modified palm oil which will increase its confidence level for power transformer application. Knowing these facts, in the present work, certain laboratory experiments have been performed on PD characteristics of nano $SiO_2$ modified palm oil at different electrode configurations. Influence of concentration of nano filler material on the PD characteristics is also studied. Partial discharge inception voltage, Phase resolved partial discharge (PRPD) pattern, PD signal time-frequency domain characteristics, PD signal equivalent timelength-bandwidth mapping, Weibull distribution statistical parameters of PRPD pattern, skewness, repetition rate and phase angle variations are evaluated at different test conditions. From the results of the experiments conducted, we came to understand that PD performance of palm oil is considerably enhanced with the addition of $nano-SiO_2$ filler at 0.01%wt and 0.05%wt concentration. Significant reduction in PD inception voltage, repetition rate, Weibull shape parameter and PD magnitude are noticed with addition of $SiO_2$ nanofillers in palm oil. These results will be useful for recommending nano modified palm oil for power transformer applications.

Analysis of Aging Characteristics in Oil Immerged Pole Transformer (과부하 및 경년 변압기 절연유 열화 특성 분석 연구)

  • Lee, Byung-Sung;Song, Il-Keun;Lee, Jae-Bong;Park, Dong-Bea;Han, Sang-Ok
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.05c
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    • pp.203-207
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    • 2002
  • In order to evaluate the aging of mineral oil immersed distribution transformers, it gathered some insulation oil in over loaded and long time(exceed their service life, 13yrs.) aged transformers in the field, we measured moisture content, acid number, dielectric strength of the oil as defined in KS C 2101 standard. And also, it had been measured dielectric constant, specific resistant, $tan{\delta}$ on aged transformer oil at from $10^{\circ}C$ to $130^{\circ}C$. These results are compared with a new mineral oil. From this study, it can be considered that the analysis of mineral oil may be suitable for evaluation of life expectancy in distribution transformers

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Research of Flow Velocity and BTA According to the Streaming Electrification of Vegetable Insulating Oils (식물성 절연유의 유속과 BTA에 따른 유동대전 현상 연구)

  • Choi, Sun-Ho;Bang, Jeong-Ju;Huh, Chang-Su
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.25 no.10
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    • pp.791-797
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    • 2012
  • Mineral insulating oils are an important insulating materials in oil-filled transformer. However, the mineral oil is the cause of the environmental problem. The vegetable oils are substitutes for mineral oil because of its biodegradability characteristic. As large size and high rating of the transformer increases, the losses increase at a faster rate. So insulating oil is forced circulation in the oil-filled transformer by using oil pumps. The flow electrification occurs when insulating oil was forced to be circulated. To check the flow electrification, had conducted experiments varying factors. As a result, the streaming electrification could see the changes according to flow velocity, oil temperature and insulation materials.