• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.3
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• pp.175-179
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• 2022

Magnetic arc extinguishing technology is effective as an extinguishing device for low-voltage direct current (DC) circuit breakers with a resistive load of ≤4 kW. The separation distance between the magnet and the electrical contact must be shortened to increase the magnetic arc extinguishing force. However, if the magnet is installed too close to the electrical contact points, the magnet is exposed to high temperatures due to the arc current generated when the load current is cut off and the magnetism is lost. To solve this problem, the effective magnetic flux density at the electrical contact can be maintained high by placing the arc extinguishing magnet in a tandem structure with the electrical contact point between them, and the proper separation distance between the contact points and the magnet can be maintained. In addition, an electric arc extinguishing technology that emits arc energy using a series circuit of diode and resistor is used to suppress the continuous arc voltage generated by the inductive load. For the proposed circuit breaker, the breaking characteristics are analyzed through the breaking test for the DC load of the 760 V level, the load power of 4 kW, and the time constant of 5 ms, and an appropriate arc extinguishing design guideline is proposed.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.6
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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.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.304-305
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• 2017

AC 그리드에 비해 DC 그리드는 전류의 영교차점이 없으므로 사고전류를 신속하게 차단하지 못 한다면 아크나 스파크에 의한 전기화재가 발생하여 큰 피해가 따른다. 본 연구에서는 신속한 차단과 전류 커패시터를 쉽게 충전할 수 있는 구조가 간단한 새로운 DC SSCB를 제안한다. 제안하는 DC SSCB는 단락사고를 모의하여 시뮬레이션 및 실험을 통해 동작특성을 검증한다. 본 논문에서 연구한 DC SSCB는 향후 DC 그리드 시스템의 설계 및 구현에 활용될 것으로 기대된다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.6
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• pp.123-128
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• 2021

As the spread of DC power distribution systems increases, the occurrence of failures and fire accidents are also increasing. In particular, the ESS fire accident, which is a component of the smart grid, and the fire accident of the solar power system, which is a direct current system, are caused by problems in the electrical connection between system components as the supply of new and renewable energy rapidly increases and old facilities increase. An arc that can cause a direct fire by releasing the induced light and heat has been pointed out as one of the causes of fire. Therefore, the problem of such an arc defect is that it is impossible to block an arc accident in advance with the existing overcurrent circuit breaker and earth leakage circuit breaker. In this paper, we intend to develop a test equipment that satisfies international standardization and to develop a DC arc generator to protect against failure and fire caused by arcing.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.71-72
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• 2006

This paper introduces the results of the development of a new mobile Digital DC-arc Welding Machine (DDWM). A simple PI controller is applied to the DDWM to control the output welding current tracking the constant setting current. Furthermore, a hot-start function, an anti-stuck function, a standby mode and an intelligential circuit breaker (ICB) are included in the DDWM. The DDWM increases welding quality and saves more power energy than a conventional welding machine. Because the DDWM is changed from ready mode into the standby mode automatically after 2 minutes interval from this unload start. Then the DDWM is changed into ready mode automatically since it is reused to weld. Mover, the DDWM increases welding qualify, productivity and reduces costs of welding. So, the DDWM can have a great of contribution to the mobile welding industries. The effectiveness of the DDWM was proven by the experimental results and durable test.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.471-472
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• 2017

DC 전력전송은 송전선로의 원거리화 및 절연내력의 저감과 같은 장점이 있으나, 전류 차단 시 큰 아크로 인하여 고속 차단기 구성이 어렵다는 큰 단점이 있다. 최근 소용량 DC 전력전송에 있어서 큰 과제인 고속차단을 위해 전자식 차단기에 대한 연구가 이루어지고 있다. 본 연구에서는 변압기와 결합한 SCR을 이용한 새로운 전자식 차단기를 제안한다. 제안된 방식은 SCR 오프시 변압기를 이용하여 SCR에 역전압을 인가하므로 전류를 소호하는 방식이다. 또한 Psim을 이용한 시뮬레이션을 통하여 제안된 방식의 타당성 검증하였다.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.996-998
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• 2005

전기철도나 지하철 분야에 사용되고 있는 고속 DC 차단기의 조작부는 solenoid actuator 방식이나 motor charging 방식을 주로 채택하고 있으나 구조가 복잡하고 부품수가 많아 부피가 크다는 단점이 있다. 이에 반해 magnetic actuator 방식은 동작시간과 제어가 용이하고 부품수가 감소하여 신뢰성과 반복성이 뛰어나다. 본 논문에서는 고속 DC 차단기 조작부를 영구자석 엑추에이터(PMA)방식으로 적용하고자 영구자석(PM)의 개략적 설계 및 이를 이용한 PMA 설계를 하였고, 유한요소 해석을 통해 이들의 동작특성을 해석하였다.

• Journal of the Korean Society of Safety
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• v.32 no.3
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• pp.15-20
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• 2017

This study presented the strength of the materials and parts for smart distribution board fabrication, and developed a work operation process chart for smart distribution board fabrication. This work operation process chart for smart distribution board fabrication complied with SPS-KEMC regulations, and the applicable range and object are less than 1,000 V and 1,000 Hz for the AC distribution board and less than 1,500 V for the DC distribution board. The power supply is 3 phase 4 wires ($3{\Phi}$ 4W), divided into a single phase circuit and a 3 phase circuit. In addition, the circuit was configured so that the leakage current flowing through the distribution line of the load could be monitored in real time by using the sensor module installed at the rear end of the circuit breaker. Therefore, the administrator can easily find the risk factor of the load since engineer can check the leakage current of each distribution line. In addition, if a leakage current greater than standard value flows, it is possible to generate an alarm against a short circuit and cut off the leakage current. The work operation process chart for the smart distribution board fabrication consists of the following steps: raw and subsidiary materials, sheet metal work, tube making, welding, painting, busbar fabrication, assembly and wiring, product inspection, shipment, etc. Moreover, symbols, ${\Delta}$, ${\nabla}$, ${\bigcirc}$, ${\Rightarrow}$, etc. were used according to the type of work and work progress so that workers can easily understand the progress of the work.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.728_729
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• 2009

최근 태양광 발전설비 및 신재생에너지 보급이 확대됨에 따라 저압 직류차단기가 설치되고 있는 실정이다. 본 논문에서는 저압 직류차단기의 성능이 교류차단기와 어떻게 다른가를 분석하고, 더 나아가 국내 직류차단기에 대한 시험 기반구축의 현실과 향후 필요한 대책을 제시하였다.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.67-69
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• 2002

This paper presents the statistical analysis of the circuit breaker's making current in large sacle industrical loads using EMTDC. Typically, the making current includes DC components as the phase angel of making instances varies and represents as a instantaneous valus not rms. Consequently, in this paper, the statistical analysis results of making current and steady state fault current for typical industrial loads presents.