• Title, Summary, Keyword: Transformer

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The Safety Survey Analysis and Consideration of Small Transformer (소형 변압기 안전성 실태 분석 및 고찰)

  • Kim, Sung-Sam
    • Journal of the Korean Society of Safety
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    • v.29 no.2
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    • pp.1-6
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    • 2014
  • In this paper, safety certification products and safety condition of small transformer is analyzed in industries field and educational facilities. In transformer of 50places, absolute majority is step down transformer to measure of instrument. Most transformers were below 5kVA and 1~3kVA capacity was the mainstream. In industries field, 5 transformers were found without safety certification according to the Electrical Appliances Safety Control Act as cheap product prefer and lack of safety consciousness. Mark & number, voltage, date of manufacture of safety certification must show item of certification. However date of manufacture showed in product of 18%, 9places. As result of thermal imaging camera, running temperature of transformer was showed in below of target temperature. However as a narrow space of transformer and wall, power cable was touched on a ventilating flue in transformer. It was simple carelessness case that surface fouling and temperature ageing of transformer accelerate. Power poor connection, neglect of transformer in production equipment, fall damage by setup incongruity and ground omission were found in case of illogicality item of transformer.

Analysis of the Contactless Power Transfer System Using Modeling and Analysis of the Contactless Transformer

  • Ryu Myung-Hyo;Kim Jong-Hyun;Baek Ju-Won;Cha Hon-Nyong
    • Journal of Electrical Engineering and Technology
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    • v.1 no.3
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    • pp.351-358
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    • 2006
  • In this paper, the electrical characteristics of the contactless transformer is presented using the conventional coupled inductor theory. Compared with the conventional transformer, the contactless transformer has a large airgap, long primary wire and multi-secondary wire. As such, the contactless transformer has a large leakage inductance, small magnetizing inductance and poor coupling coefficient. Therefore, large magnetizing currents flow through the entire primary system due to small magnetizing inductance, resulting in low overall system efficiency. In high power applications, the contactless transformer is so bulky and heavy that it needs to be split by some light and small transformers. So, the contactless transformer needs several small transformer modules that are connected in series or parallel to transfer the primary power to the secondary one. This paper shows the analysis and measurement results of each contactless transformer module and comparison results between the series- and parallel-connection of the contactless transformer. The results are verified on the simulation based on the theoretical analysis and the 30kW experimental prototype.

Development and Characteristics of Detector for Open of Current Transformer Secondary Terminal (변류기 2차측 개방 보호장치 개발 및 특성)

  • Choi, Sang-Won;Song, Ki-Chan
    • Journal of the Korean Society of Safety
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    • v.22 no.4
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    • pp.20-25
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    • 2007
  • Instrument transformers are a safe measurement device designed to measure high voltage and large current. A current transformer(CT) is a type of instrument transformer designed to provide a current in its secondary winding proportional to the current flowing in its primary. It is commonly used in metering and protective relaying in the electrical power industry where it facilitates the safe measurement of large current. But, care must be taken that the secondary of a current transformer is not disconnected from its load while current is flowing in the primary, as this will produce a dangerously high voltage across the open secondary, and may permanently affect the accuracy of the transformer. Especially, industrial disaster such as an electric shock and/or a burn accident occurs occasionally by disregard of warning or attention. In this paper, we developed the detector for open of current transformer secondary terminal, and which was tested by the Korea Electrotechnology Research Institute. Test results show that Current Transformer secondary Open Detector(CTOD) interrupted within one second electronically when the 2nd terminal of current transformer opened.

Review of the measurement uncertainty of Tr no-load loss measuring system (변압기철손 측정시스템의 측정 불확도)

  • Kang, T.S.
    • Proceedings of the KIEE Conference
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    • pp.139-141
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    • 2005
  • For the reliable evaluation of the distribution and power transformer no-load loss measurement, measurement uncertainty of the transformer measuring system, consisted of current transformer, potential transformer and power metering equipment is required. In this paper, we describe the uncertainty of transformer measuring system based on ANSI/IEEE C57.12.90.

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Flux Saturation Modeling of Matching Transformer for Dynamic Voltage Restore (동적전압보상기를 구성하기 위한 정합변압기의 자속포화현상 모델링)

  • Kim Wang-Rae;Kang Ho-Hyun;Jeon Hee-Jong;Han Woon-Dong;Oh Joong-Min
    • Proceedings of the KIPE Conference
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    • pp.428-431
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    • 2006
  • Matching transformer in Dynamic Voltage Compensator is needed for grid connection and isolation. Flux saturation in transformer will be occurred by voltage of transformer from inverter and DC offset voltage and flux saturation makes over current in transformer. In this paper, mathematical modeling of matching transformer is proposed for flux saturation simulation of Dynamic Voltage Compensator.

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Conceptual Design of Single Phase 10MVA HTS Transformer (단상 10MVA 고온초전도 변압기 개념설계)

  • 석복렬;최명준
    • Progress in Superconductivity and Cryogenics
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    • v.4 no.2
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    • pp.42-46
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    • 2002
  • This research is conducted with the object of Piling up the foundation of design technologies for high temperature superconducting (HTS) power transformer which is thought to be as a powerful power transformer of next generation. In this study, not only the theoretical design of high temperature superconducting (HTS) transformer but also the arrangements of superconducting tape and the cooling method have been conducted. Moreover, electromagnetic analyses using finite element method (FEM) were conducted to confirm the efficiency of the designed transformer.

Forward Converter using Planar transformer and Lossless Snubber (Planar 변압기와 무손실 스너버를 사용한 포워드 컨버터)

  • 박경수;이재학;김춘삼;김윤호
    • Proceedings of the KIPE Conference
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    • pp.480-484
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    • 1999
  • In this paper, a design technique of SMPS using plannar transformer is described. The application of plannar transformer can solve the space problem which occurs when it is installed on PCB since plannar transformer has low profile. In addition a lossless snubber circuit added to reduce the device stress and to improve the system efficiency. The designed system is verifed by simulation and experiment with comparison of efficiency between the system using conventional transformer and the system using plannar transformer.

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Transformer Differential Relay by Using Neural-Fuzzy System

  • Kim, Byung Whan;Masatoshi, Nakamura
    • 제어로봇시스템학회:학술대회논문집
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    • pp.157.2-157
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    • 2001
  • This paper describes the synergism of Artificial Neural Network and Fuzzy Logic based approach to improve the reliability of transformer differential protection, the conventional transformer differential protection commonly used a harmonic restraint principle to prevent a tripping from inrush current during initial transformer´s energization but such a principle can not performs the best optimization on tripping time. Furthermore, in some cases there may be false operation such as during CT saturation, high DC offset or harmonic containing in the line. Therefore an artificial neural network and fuzzy logic has been proposed to improve reliability of the transformer protection relay. By using EMTP-ATP the power transformer is modeled, all currents flowing ...

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A Transformer Design and Magnetic Analysis Model for the High-Speed EMU (동력분산형 고속철도용 변압기 설계 및 자계해석 모델)

  • Park, Byoung-Gun;Hyun, Dong-Seok
    • Proceedings of the KSR Conference
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    • pp.517-524
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    • 2009
  • This paper proposes a magnetic analysis model and design method of transformer for the high-speed EMU. It has a many part of the consideration in design because the transformer in high-speed train has the multiple output. Also the output characteristic, weight, and size of transformer is an important factor. This research proposes a design method of transformer in high-speed EMU. And it is easy to design by using the analysis model in design the transformer through the establishment of the magnetic analysis model.

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