• 전기학회논문지
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• 제60권2호
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• pp.301-308
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• 2011

This paper deals with the coupled electromagnetic-mechanical field analysis for short-circuit electromagnetic force of the dry-type transformer. The short-circuit currents are calculated using external circuit in accordance with short-circuit test equipment. According to short-circuit current, the generated magnetic leakage flux density in dry-type transformer model is calculated by finite element method. The radially-directed electromagnetic forces in windings are calculated using electromagnetic field analysis and then axially-directed electromagnetic forces in windings are calculated using electromagnetic-mechanical field analysis. The calculated axially-directed electromagnetic forces in high voltage winding are compared to those of measured ones and showed good agreement with experimental results.

• 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.

• Journal of Magnetics
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• 제20권4호
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• pp.400-404
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• 2015

Various kinds of winding arrangements can be used to enable fault current limiters (FCL) to tolerate higher forces without resulting in a substantial increase in construction and fabrication costs. In this paper, a distributed winding arrangement is investigated in terms of its effects on the short-circuit forces in a three-phase FCL. The force magnitudes of the AC supplied windings are calculated by employing a finite element-based model in the time stepping procedure. The leakage flux and radial and axial force magnitudes obtained from the simulation are compared to those obtained from a conventional winding arrangement. The comparison shows that the distributed winding arrangement significantly reduces the radial and, especially, the axial force magnitudes.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.101-101
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• 2010

Power distribution system requires the transformer with higher capacity than ever, but this ever, but this may be the cause of the increasing of short circuit current in contrast to conventional one when short-circuit accident is occurred. Therefore molded case circuit breaker improved in aspects of interrupting capacity of short circuit current in this system is needed. The arrangement and quality of the material of grids in arc quenching room are also designed optimally by the analysis of arc driving forces.

• 조명전기설비학회논문지
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• 제21권7호
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• pp.84-93
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• 2007

주상변압기는 고객에게 직접 전력을 공급하는 설비로서 전력공급의 안정성확보를 위한 중요한 기자재 중 하나이다. 하지만 제조결함에 의한 3년 이내의 초기고장 또는 13년이 초과 사용한 후의 열화고장이 빈번히 발생하고 있어 변압기 품질분석을 통한 신뢰성이 개선된 주상변압기 개발이 필요하다. 본 논문에서는 열적, 기계적, 전기적으로 성능이 향상된 새로운 모델의 혼합절연 주상변압기를 개발하였다. 변압기의 기계적, 열적특성을 향상시키기 위한 혼합절연 방식에 대한 설계 및 제작방법을 제시하고 과부하시험을 시행하여 순간최대부하에 대응할 수 있도록 과부하내량 160[%] 까지 증가시킬 수 있음을 확인하였다. 또한 본 논문에서는 100[kVA] 1대를 시제품으로 제작하여 단락강도시험과 변압기 관련 절연시험을 시행하여 전자기계력의 분석과 단락강도설계 향상 방안에 대하여 설명하고 이와 관련하여 연구한 결과에 대해 논하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.942-945
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• 2002

A garter spring, which is a long. special, close-coiled extension spring with its ends joined to form a ring, is used in connection between vacuum circuit breaker and bus bar in switchgear. To carry short-time current and resist welding at the contact surface in the connection, the garter spring must transmits an uniform contact force to the contact surface through the contact chips arranged in the circumference of bus bar. In this paper, the system for measurement of the contact force by the garter spring is developed. Using the developed measurement system, the design of the connection structure including the garter spring is reviewed to obtain the uniform contact forces in all of contact chips.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 연구회
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• pp.51-54
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• 2001

This Paper is described basic principles of arc quenching in Molded Case Circuit Breaker. We analyzed magnetic blowout forces acting on the arc in contact system when circuit breakers interrupt fault currents in different three models by 3-D FEM(Finite Element Method). The interrupting time simulated is compared with that of short circuit tests. The results of this study derive valid of the simulation method and present the techniques to improve arc quenching performance.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.394-394
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• 2009

Owing to the increasing number of intelligent homes(or called Smart home), the corresponding cost is much higher. Low voltage circuit breakers are widely used in the intelligent homes to interrupt fault current rapidly and to assure the reliability of the power supply. The distribution of magnetic field induced by arc current in the contact system of molded case circuit breaker(hereafter MCCB) depends on the shape, arrangement, and kinds of material of arc runner. This paper is focused on understanding the interrupting capability, more specifically of the arc runner, based on the shape of the contact system in the current MCCB. The magnetic driving force was calculated by using the flux densities induced by the arc current, which are obtained by three-dimensional finite element method. There is a need to assure that the optimum design required to analyze the electromagnetic forces of the contact system generated by current and the flux density be present. This is paper present our computational analysis on contact system in MCCB.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1451_1452
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• 2009

Owing to the increasing number of intelligent homes(or called Smart home), the corresponding cost is much higher. Low voltage circuit breakers are widely used in the intelligent homes to interrupt fault current rapidly and to assure the reliability of the power supply. The distribution of magnetic field induced by arc current in the contact system of molded case circuit breaker depends on the shape, arrangement, and kinds of material of grids. This paper is focused on understanding the interrupting capability, more specifically of the grid and the arc runner, based on the shape of the contact system in the current MCCB. The magnetic driving force was calculated by using the flux densities induced by the arc current, which are obtained by three-dimensional finite element method. There is a need to assure that the optimum design required to analyze the electromagnetic forces of the contact system generated by current and the flux density be present. This is paper present our computational analysis on contact system in MCCB.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.329-330
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• 2006

The research and development of an actuator are accelerating in the robotics industry. The electricity polymer and SMA actuator are designed simply and are produced a lot of forces per unit volume. Their motions are similar to human's motion, But the repeatability of the electricity polymer actuator is lower. The reaction velocity of the SMA actuator is slow and the travel is short. In this paper, the dynamic characteristic of the segmented SMA is studied. The SMA wire is divided by using the Thermo-electric module(TEM) to control each of segments independently. The MOSFET circuit is used to supply constant currents fer the Thermo-electric module(TEM). The hysteresis and displacement of the SMA wire according to load are measured.