• 전기전자학회논문지
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• 제26권3호
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• pp.445-455
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• 2022

본 논문에서는 90W급 LED-TV용 DC-DC Flyback 컨버터에 사용되고 있는 소형화 및 권선 자동화에 적합한 사출형 평면 동판 권선 방식의 Flyback 변압기 최적화 설계에 대해서 나타낸다. 또한 본 논문에서는 수동권선방식의 기존 양산 Flyback 변압기에 비해 권선 자동화, Trans 체적 저감 및 전기적 특성 동질성 향상이 가능한 사출형 평면 동판 권선 방식의 Flyback 변압기를 제안한다. 특히 본 논문에서 제안한 사출형 평면 동판 권선 변압기는 권선 자동화를 위하여 수직형 권선 방식으로 구성한다. 본 논문 제안한 사출형 평면 동판 권선 방식의 Flyback 변압기의 1차측과 2차측 권선은 각각 기존 권선, 3중 절연 권선 및 사출형 평면 동판권선을 사용하였다. 최종적으로 Maxwell 2D 및 3D Tool을 이용한 시뮬레이션 결과를 토대로 본 논문에서 제안한 소형화 및 권선 자동화에 적합한 사출형 평면 동판 권선 방식의 Flyback 변압기 최적화 설계를 수행하였다.

• Progress in Superconductivity
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• 제7권2호
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• pp.162-166
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• 2006

We have proposed a 3 phase, 100 MVA, 154 kV class HTS transformer substituting for a 60 MVA conventional transformer. The power transformer of 154 kV class has a tertiary winding besides primary and secondary windings. So the HTS transformer should have the 3rd superconducting winding. In this paper, we designed conceptually the structure of the superconducting windings of a single phase 33 MVA transformer. The electrical characteristics of the HTS transformer such as % impedance and AC loss vary with the arrangement of the windings and gaps between windings. We analyzed the effects of the winding parameters, evaluated the cost of each design, and proposed a suitable HTS transformer model for future power distribution system.

• 전기전자학회논문지
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• 제24권3호
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• pp.828-837
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• 2020

본 논문에서는 10W급 Tablet용 AC to DC Adapter의 소형화 및 슬림형에 적합한 평면 Flyback 변압기 최적화 설계에 대해서 나타낸다. 또한 본 논문에서는 수동권선의 기존 양산 Flyback 변압기에 비해 자동권선, Trans 크기 저감 및 누설 인덕턴스(L_k) 저감이 가능한 Hybrid형 사출 권선 변압기와 Drum형 사출 권선 변압기를 제안한다. 특히 본 논문에서 제안한 Drum형 사출 권선 변압기는 Hybrid형 사출 권선 변압기 2차측의 동판 사출 권선 접속 문제를 해결하기 위하여 변압기를 수평으로 눕힌 형태로 구성하였다. 본 논문에서 제안한 Hybrid형 사출 권선 변압기와 Drum형 사출 권선 변압기의 1차측과 2차측 권선은 각각 기존 권선과 동판 사출 권선을 사용하였다. 본 논문에서 제안한 Hybrid형 사출 권선 변압기와 Drum형 사출권선 변압기에 대해 Maxwell 2D 및 3D Tool을 이용하여 소형화 및 슬림형에 적합한 평면 Flyback 변압기 최적화 설계를 수행하였다.

• 대한전기학회논문지:전력기술부문A
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• 제52권3호
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• pp.173-178
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• 2003

This paper proposes a three-winding transformer protective relaying algorithm based on the ratio of the induced voltages (RIV). The RIV of the two windings is the same as the turn ratio for all operating conditions except an internal fault. For a single phase and a three-phase transformer containing the wye-connected windings, the induced voltages of the windings are estimated. For a three-phase transformer containing the delta-connected windings, the induced voltage differences are estimated using the line currents, because the winding currents are practically unavailable. The algorithm can identify the faulted phase and winding if a fault occurs on one phase of a winding. The test results clearly show that the algorithm successfully discriminates internal winding faults from magnetic inrush. The algorithm not only does not require hysteresis data but also can reduce the operating time of a relay.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.983-989
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• 2015

Power transformer is one of the major and key apparatus in electric power system. Monitoring and diagnosis of transformer fault is necessary for improving the life period of transformer. The failures caused by short circuits are one of the causes of transformer outages. The short circuit currents induce excessive forces in the transformer windings which result in winding deformation affecting the mechanical and electrical characteristics of the winding. In the present work, a transformer producing only the radial flux under short circuit is considered. The corresponding axial displacement profile of the windings is computed using Finite Element Method based transient structural analysis and thus obtained displacements are compared with the experimental result. The change in inter disc capacitance and mutual inductance of the deformed windings due to different short circuit currents are computed using Finite Element Method based field analyses and the corresponding Sweep Frequency Responses are computed using the modified electrical equivalent circuit. From the change in the first resonant frequency, the winding movement can be quantified which will be useful for estimating the mechanical withstand capability of the winding for different short circuit currents in the design stage itself.

• 전력전자학회논문지
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• 제20권3호
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• pp.255-261
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• 2015

An analysis of the interleaving effect for the secondary winding distribution of a toroidal transformer is presented in this paper. The equations to calculate the leakage inductance of the toroidal transformer are derived using MMF diagrams for the different secondary winding distributions. The simulation and experimental results are provided to show the validity of the theoretical calculation.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권3호
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• pp.101-106
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• 2003

The high temperature superconductor transformers gain interests from the industries. This paper described construction and test results of 10㎸A HTS transformer Three phase transformer with double pancake windings were constructed. To reduce the leakage magnetic field, secondary coil were placed between the two primary coils. BSCCO-2223 wire. silicon sheet steel core and FRP cryostats were used to construct the transformer. Three coils were stacked in one cryostat. Two double pancake coils were connected in series for the primary coil and one double pancake coil was used for the secondary coil. Total number of turns of the primary winding and the secondary winding were 112turns and 98urns, respectively, The rated voltages of each winding were 440/220V. The rated currents of each winding were 13.1/26.2A. After the tests of basic properties of the three phase HTS transformer using no-load test, short-circuit test and full-load test, continuous operation of 100 hours with pure resistive load has been carried out. Test results proved over-load capability and reliability of the HTS transformer.

• 산업경영시스템학회지
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• 제31권3호
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• pp.117-124
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• 2008

Ultra-high voltage transformer industry has characteristic of small quantity batch production system by other order processing unlike general mass production systems. In this industry, observance of time deadline is very important in market competitive power security and company continued existence. The transformer winding is a process that rolls a coil is coated with an electric insulation material in order to generate the required voltage using the voltage fluctuation. The winding process is very important production process in the extra-high voltage transformer manufacturing industry because winding process is core process that occupy weight about half of whole process and is process that decide current ratio of transformer. This paper proposes a statistical calculation and control method of planned leadtime on the basis of real data and informations for the A company in transformer winding process. Moreover, we develop unit process scheduling system.

• 한국전기전자재료학회논문지
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• 제21권12호
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• pp.1111-1117
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• 2008

A transformer type superconducting fault current limiter (SFCL) is one of the fault current limiters which have been proposed to reduce the fault current in the transmission lines. This paper proposes the new circuit configuration of a transformer type SFCL and also investigates the operating characteristics of the transformer type SFCL containig the resistor in the tertiary winding. The proposed SFCL contains the resistor in the tertiary winding. The newly inserted resistor can divert the power which the High-Tc superconducting has to bear. Because the resistor in the tertiary winding relieves the power of the High-Tc superconducting, it is possible that the proposed transformer type SFCL can decrease the more larger fault current than the conventional SFCL with the same High-Tc superconducting. And the cost of the proposed transformer type SFCL can be reduced.

• 전기학회논문지
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• 제60권6호
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• pp.1274-1279
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• 2011

The purpose of this paper is to present the manufacturing defect and damage pattern of a 3 phase 22.9/3.3kV oil immersed transformer, as well as to present an objective basis for the prevention of a similar accident and to secure data for the settlement of PL related disputes. It was found that in order to prevent the occurrence of accidents to transformers, insulating oil analysis, thermal image measurement, and corona discharge diagnosis, etc., were performed by establishing relevant regulation. The result of analysis performed on the external appearance of a transformer to which an accident occurred, the internal insulation resistance and protection system, etc., showed that most of the analysis items were judged to be acceptable. However, it was found that the insulation characteristics between the primary winding and the enclosure, those between the ground and the secondary winding, and those between the primary and secondary windings were inappropriate due to an insulating oil leak caused by damage to the pressure relief valve. From the analysis of the acidity values measured over the past 5 years, it is thought that an increase in carbon dioxide (CO2) caused an increase in the temperature inside the transformer and the increase in the ethylene gas increased the possibility of ignition. Even though 17 years have passed since the transformer was installed, it was found that the system's design, manufacture, maintenance and management have been performed well and the insulating paper was in good condition, and that there was no trace of public access or vandalism. However, in the case of transformers to which accidents have occurred, a melted area between the upper and the intermediate bobbins of the W-phase secondary winding as well as between its intermediate and lower bobbins. It can be seen that a V-pattern was formed at the carbonized area of the transformer and that the depth of the carbonization is deeper at the upper side than the lower side. In addition, it was found that physical bending and deformation occurred inside the secondary winding due to non-uniform pressure while performing transformer winding work. Therefore, since it is obvious that the accident occurred due to a manufacturing defect (winding work defect), it is thought that the manufacturer of the transformer is responsible for the accident and that it is lawful for the manufacture to investigate and prove the concrete cause of the accident according to the Product Liability Law (PLL).