• 한국전기전자재료학회논문지
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• 제20권4호
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• pp.374-380
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• 2007

In this paper a nobel optimum design method is presented for a shield in a vacuum interrupter which is equipped in switchgear to improve its electric insulation capability. The design of Taguchi experiment method which is based on the results by finite element method is used to find optimum design conditions. The important design factors are chosen at first and the concept of signal to noise ratio is applied to evaluate the vacuum interrupter performance, and the optimal values of each parameters are determined. From the results of various analyses, it is shown that the shield plate in circuit circuit breaker compartment of switchgear can reduce the concentration of electric field intensity. This method is very useful to design the construction of a shield in a short time. Consequently, the insulation capability of circuit breaker compartment in a gas insulated switchgear is improved by adopting an additional optimized shaped shield.

• 한국화재소방학회논문지
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• 제27권2호
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• pp.1-5
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• 2013

본 논문은 사고전압 감지형의 아크차단 제어회로에 대한 연구로써, 전기사고 발생 시 선간전압의 순간적인 전압감쇠를 감지하여 기존 차단기를 동작시키는 전압감지형 전기화재 예방장치이다. 현재 저압배전 계통에 사용중인 누전차단기, 배선용차단기 그리고 RCD 등은 전기화재의 주요 요인인 아크사고에 대해 보호능력이 없는 것으로 분석된다. 본 논문에서는 이러한 문제점들을 개선하기위하여 이전의 전류감지에 의한 아크사고 차단방식이 아닌 사고발생 시 전압파형의 왜곡을 이용한 새로운 전압감지형 아크차단 제어회로를 개발하여 전기화재를 예방하고자 한다. 제안한 아크차단 제어회로는 소형 경량으로 제작되는 장점과 다양한 동작분석을 통하여 그 실용성을 검증하였다.

• 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.

• 전기학회논문지
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• 제58권8호
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• pp.1532-1537
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• 2009

Nowadays the diversity and large-capacity of electric appliances are strong effect on electrical fires augment in an alarming way. But, as the inactive response characteristics of the existing RCD (Residual Current protective Device) used on low voltage power distribution lines, so control of overload and electric short circuit faults, major causes of electrical fires, are not enough. Therefore this paper is confirmed the unreliability of the existing RCD by electrical faults simulation and is proposed a auxiliary trip device of RCD by using a high precision current sensor (namely, reed switch) for the prevention of electrical disasters in low voltage power distribution lines caused by overload or electric short circuit faults. The sensitive reed switch in the proposed ATD (auxiliary trip device) exactly detects the increased magnetic flux with the overload or the short current caused by a number of electrical faults, and then rapidly cuts off the existing RCD. The proposed auxiliary trip device of RCD is confirmed the excellent characteristics in response velocity and accuracy in comparison with the conventional circuit breaker through various operation performance analysis. The proposed ATD can also prevent electrical disaster, like as electrical fires, which resulted from the malfunction and inactive response characteristics of the existing RCD.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.455-457
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• 2003

In the present IEC 60427(2000), reduced applied voltage can be used for synthetic short-circuit making current tests if the maximum pre-arcing time of the test circuit breaker is less than $1/{\omega}$. But in the near future IEC, only the making tests with full test voltage shall be allowed. To meet this trend, KERI is preparing synthetic making test facilities using step-up transformer, ITMC and plasma making switch. This paper presents analytical characteristics of KERI's synthetic short-circuit making test circuits. The results of this paper can be useful for effective and adequate tests.

• 대한기계학회논문집
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• 제6권2호
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• pp.133-139
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• 1982

One of factors that affect combustion in the cylinder of the engine is to keep a greater energy in the ignition system to minimize pollutant emissions and to increase its performance of the low temperature. This paper reviews theoretically the state and input variables of the ignition system from the state transition equation. Effects on characteristics of the system such as primary current, secondary available voltage and spark duration by reducing the pre-resistance from 3.5 to 0 ohm in 12V system is experimentally investigated when the ignition coil has a primary resistance of 1.5 ohms ad the dwell angle of the breaker point is 43.2 degrees (0.75 radian). Advantages and limitations for using the low resistance of the primary circuit are also presented to optimize the performance of the ignition system with the breaker point.

• 한국산학기술학회논문지
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• 제16권5호
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• pp.3370-3377
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• 2015

전동차는 대용량 교통수단으로서 정시 운행 및 높은 안전성이 요구되기 때문에, 고장 분석을 체계적으로 수행하여 신뢰도를 향상시키기 위한 수단으로서 고장 영향의 심각도 및 치명도를 정량적으로 평가하는 FMECA (Failure Modes, Effects and Criticality Analysis) 기법이 적용되고 있다. 그러나, 아직까지 전동차에 특화된 FMECA 규격 및 절차는 정립되어 있지 않고 자동차 산업 등 다른 산업분야의 FMECA 규격을 그대로 적용하고 있기 때문에 전동차의 고유한 운영 및 유지보수 여건을 충분히 반영하지 못하고 있다. 본 논문에서는 산업계 각 분야에서 적용되고 있는 FMECA 규격에 대한 분석을 토대로, 전동차 분야에 적합한 FMECA 기법으로서 고장 영향 분석과 치명도 분석을 단계별로 나누어 수행하고 고장 영향의 심각도에 중점을 두어 치명도를 분석하는 기법을 제시하였다. 제안 기법을 전동차의 핵심 안전 장치인 고속차단기에 적용하여 도시철도 현장에서의 15년 동안의 전동차 유지보수 데이터를 이용하여 분석한 결과, 고속차단기 부품 중에서 특히 아크 슈트의 절손이 심각도 3등급, 치명도 5등급으로 위험도가 가장 높았으며, 뒤를 이어서 전자변 파손 및 접촉 불량, 실린더 파손 등이 심각도 3등급, 치명도 4등급으로 위험도가 높은 것으로 나타났다. 이상의 분석 결과는 전동차 고속차단기의 설계 및 유지보수 업무의 개선에 활용할 수 있다.

• 한국기계가공학회지
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• 제21권9호
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• pp.78-84
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• 2022

An air circuit breaker (ACB) is an electrical protection device that interrupts abnormal fault currents that result from overloads or short circuits in a low-voltage power distribution line. The ACB consists of a main circuit part for current flow, mechanism part for the opening and closing operation of movable conductors, and arc-extinguishing part for arc extinction during the breaking operation. The driving mechanism of the ACB is a spring energy charging type. The faster the contact opening speed of the movable conductors during the opening process, the better the breaking performance. However, there is a disadvantage that the durability of mechanism decreases in inverse proportion to the use of a spring capable of accumulating high energy to configure the breaking speed faster. Therefore, to simultaneously satisfy the breaking performance and mechanical endurance of the ACB, its driving mechanism must be optimized. In this study, a dynamic model of the ACB was developed using the MDO(Mechanism Dynamics Option) module of CREO, which is widely used in multibody dynamics analysis. To improve the opening velocity, the Taguchi design method was applied to optimize the design parameters of an ACB with many linkages. In addition, to evaluate the improvement in the operating characteristics, the simulation and experimental results were compared with the MDO model and improved prototype sample, respectively.

• 한국산업안전학회:학술대회논문집
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• 한국안전학회 1998년도 추계 학술논문발표회 논문집
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• pp.335-340
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• 1998

This paper presents a study on the electrical fire hazards of leakage current in a distribution circuit simulating a domestic circuit for low voltage. In this simulated circuits, total charges and energy of leakage current are calculated by a theoretical approach and compared with the results obtained from experiments, The approach and results become a cornerstone for studying and analyzing causes of electrical fires.

• KIEE International Transactions on Electrophysics and Applications
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• 제5C권6호
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• pp.233-241
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• 2005

The present model of a SF6 arc accounts for the copper vapour contamination from the electrodes inside a Laval nozzle of a circuit breaker. Steady state simulations have been done for the arc with electrode gap of 60mm and DC electric current of 500A, 1000A and 1500A for both cases with and without copper contamination. The effects of electrode polarity are considered for the arc current of 1000A. It was found out that evaporation of copper from the anode results in a cooling of the arc in a region close to the electrodes. The electrical potential across the electrodes is not sensitive to the presence of copper vapour, typically less than $4\%$ difference. Transient analysis has been done in order to obtain the arc properties at current zero. The arc current is increased linearly from -1000 to 0A when the upstream electrode is cathode with constant dI/dt of $27.0A/{\mu}s$ (or decreased linearly from 1000 to 0A when upstream electrode is anode). It has been predicted that the presence of copper vapour reduces the interruption capability of the breaker.