• 조명전기설비학회논문지
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• 제26권10호
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• pp.81-88
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• 2012

Surge protective devices(SPDs) are widely used as a most effective means protecting the electrical and electronic equipment against overvoltages such as lightning and switching surges. When installing SPDs, it is essential that the voltage protection level provided by SPDs should be lower than the withstand voltage of the equipment being protected. But even the proper selection of SPDs are achieved, the voltage at the equipment terminal may be higher than the residual voltage of SPD due to the reflection and oscillation phenomena. This paper was focused on the investigations of the conditions for which the equipment is protected by an SPD taking into account the influences of the protective distance and type of load. The protective effects of SPD with voltage-limiting component were analyzed as functions of types of load and protective distance between the SPD and load. As a result, in the cases of long protective distances, capacitive loads and loads with high resistance, the voltage at the load terminal was significantly higher than the residual voltage of SPD. It was found that the proper installation of SPDs should be carried out by taking into account the protective distance and type of load to achieve reliable protection of electronic equipments against surges.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2005년도 춘계종합학술대회
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• pp.277-280
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• 2005

This paper dealt with the development of a surge protection device (SPD) that can protect high speed computer network devices from overvoltages caused by switching operations or lightning surges. The designed SPD is a form of hybrid circuit which is composed of a gas tube having large current diverting capability, high response bi-directional avalanche diodes, and fast recovery diodes to reduce insertion loss on high frequency domain. Surge protection and signal transmission characteristics of the fabricated SPD was tested according to the international standards, IEC 61000-4-5 and IEC 61643-21. From the test results, the SPD is satisfied with the international standards and the high cut-off frequency was 204MHz. Also, the SPD showed a good performance without an insertion loss on a field test of 100Mbps class Local Area Network

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권11호
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• pp.717-723
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• 1999

The transient characteristics of grounding systems play a major role in the protection of power equipments, electronic circuits and info-communication facilities against surges which arise from lightning or ground faults. Electronic devices are very weak against lightning surges injected from grounding systems and can be damaged. The malfunction and damage of electronic circuits bring about bad operation performances, a lot of economical losses, and etc. Therefore, in order to obtain the effective protection measure of electronic devices from overvoltages and lightning surges, the analysis of the transient grounding impedances in essential. One of this work is to examine the transient behaviors of grounding impedances under steplike currents for various grounding systems. And the other of this work is to evaluate the transient behaviors of a grid with rods under impulse currents and to investigate the effect of grounding lead wire. Transient grounding impedances of a grid with rods under impulse current waves have been measured as a parameter of the length of the grounding leads. Z-t, Z-i and V-i curves of transient grounding impedance under impulse current waveforms have been measured and analyzed. It was found that the grounding impedance gives the inductive, resistive and capacitive aspects under steplike current. Transient grounding impedance characteristics were very different with shapes, geometries of ground electrodes. Also, they were dependent on the waveform and magnitude of impulse current.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권1호
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• pp.42-46
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• 2003

Arresters are deteriorated by overvoltages or impulse currents, and the resistive leakage current of arresters increases as the deterioration of the arrester progresses, showing an increase in the 3$^{rd}$ harmonic component of the leakage current. In this reason, arrester diagnostic techniques based on the 3$^{rd}$ harmonic leakage current as a reference parameter of deterioration are widely used. The technique, however, includes an error due to the harmonics of power system voltage. Therefore, the influence of the harmonics on arrester diagnostics should be considered. In this paper, we designed a PSpice ZnO arrester model to simulate the influence of the voltage harmonics described above. A pure sinusoidal voltage and its the 3r harmonic voltage were applied to the model, and the leakage current components were analyzed. From the simulation results, it is confirmed that the peak value of resistive leakage current depends not only on the phase of the 3$^{rd}$ harmonic voltage but also on the magnitude of it. Consequently, the errors caused 1)y the harmonic voltage could be minimized by correcting the magnitude of leakage current upon analyzing the harmonics.cs.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 A
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• pp.48-50
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• 2004

The energization of high voltage transmission lines and transformers, that is an inevitable process in most countries as the first restorative action for wide-area blackout, may induce overvoltages such as sustained overvoltage, transient overvoltage and harmonic resonant overvoltage. And these may cause damages to power system equipments or failure of surge arresters. The harmonic resonant overvoltage originates in switching operations and nonlinear characteristics of equipments. Actually it is difficult to predict the occurrence of harmonic overvoltage, since they result from nonlinear characteristics of transformers and other equipments. This paper describes the analysis of domestic primary restorative transmission system using PSCAD/EMTDC. The harmonic resonance is verified and the solution to prevent harmonic resonance is proposed in this paper. As a result, the PSCAD/EMTBC simulation showed slightly conflictive results that had been presented by IEEE Power System Restoration Working Group report.

• 조명전기설비학회논문지
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• 제22권4호
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• pp.130-138
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• 2008

뇌서지 전압이 전파되는 양상은 대상 전원계통과 기기별로 차이를 보인다. 하지만 뇌서지가 유입되는 대상기기를 중심으로 보면 뇌서지 침입경로는 전원선의 두 선간, 전원선과 대지간, 전원선과 PE도체, 중성선과 대지 간 등으로 구분되어진다. 또한 통신기기에서 전원측에서 들어오는 뇌서지 외에 통신선의 선간, 통신선과 대지 간으로 입사하는 경로가 존재한다. 이 논문은 각각의 경로를 통하여 대상기기에 침입하는 뇌서지에 대해 SPD를 사용한 전원계통의 안전향상 기법 중 독립접지, 공통접지, 바이패스 어레스터를 이용한 접지의 뇌서지 양상을 실증실험을 통하여 분석한 결과를 기술하고 있다.

• 조명전기설비학회논문지
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• 제16권4호
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• pp.8-14
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• 2002

현대의 뇌보호시스템은 낙뢰로 인한 감전이나 건축물, 전기·전자기기의 파손과 같은 위험성을 제거하는 것이 요구되지만 종래의 뇌보호설비는 단지 인명의 피해나 건축물을 보호하는 것이 주된 역할이었다. 오늘날 컴퓨터, 정보통신설비 등을 효과적으로 보호할 수 있는 뇌보호설비가 필수적 요건으로 대두되었다. 본 논문에서는 뇌과전압으로부터 컴퓨터와 전자장비를 보호할 수 있는 기술을 개발할 목적으로 인하도선의 종류와 설치기법에 따라서 인하도선에 유도되는 전위상승 억제에 대한 연구를 수행하였다. 그 결과 인하도선의 전위상승에 의한 측면방전과 위험성을 줄이기 위해서는 인하도선으로 낮은 특성임피던스를 가지는 동축케이블이 적당하며, 인하도선과 금속관을 상단과 하단에서 본딩하는 방법이 효과가 높게 나타났다.

• 한국정보통신학회논문지
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• 제9권6호
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• pp.1253-1259
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• 2005

본 논문은 외부의 서지로부터 컴퓨터 네트워크회로의 보호를 위한 서지방호장치에 대하여 기술하였다. 서지방호장치는 동작속도가 빠른 아발란시 다이오드와 에너지 내량이 큰 가스튜브의 하이브리드형으로 구성하였으며, 고주파 대역에서의 삽입손실을 줄이기 위하여 고속회복 다이오드를 사용하였다. 제안한 서지전압 차단장치의 성능 평가를 위하여 국제규격 IEC 61000-4-5 및 IEC 61643-21에 따라 서지차단특성과 신호전송 특성평가를 수행하였다. 실험결과로부터 본 서지차단장치는 국제규격에 제시된 서지차단특성을 만족하였으며, -3dB의 고역차단 주파수가 204 MHz로 100 Mbps급 근거리 통신네트워크에 적합한 특성을 나타내었다.

• 조명전기설비학회논문지
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• 제22권1호
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• pp.141-148
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• 2008

본 논문에는 22.9 kV-Y 배전계통의 1선 지락고장이 인체의 안전 및 저압설비의 보호에 대한 실험적 결과를 기술하였다. 새로이 제정된 KS C IEC 60364 규격군에 따른 고압 충전도체가 대지에 접촉되는 지락고장에 의한 위험전압과 저압기기의 스트레스전압을 평가하기 위해서 22.9[kV] 중성점 다중접지계통에 대한 실증실험을 수행하였다. 실험결과로부터 KS C IEC 60364 규격군을 기존의 국내배전계통에 적용할 때 부합되지 않는 중대한 문제점을 도출하였으며, 22.9 kV-Y 다중접지와 수용가설비접지를 공용하는 공통접지계통에서 발생하는 지락고장에 의한 일시적 과전압에 대한 효과적인 보호대책을 제시하였다. 결국 22.9 kV-Y계통과 저압설비를 공통접지로 하는 경우 인체와 저압설비의 안전을 위한 효과적인 보호대책의 구현에는 등전위본딩이 중요한 필수적 요건임이 밝혀졌다.

• Journal of Power Electronics
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• 제11권6호
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• pp.880-889
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• 2011

In this paper, a novel Active Voltage Quality Regulator (AVQR) topology with a thyristor rectifier and an adaptive dclink voltage control strategy are proposed. The proposed AVQR can efficiently mitigate the long duration variations (e.g. undervoltages/overvoltages), voltage imbalances and voltage harmonics. Compared with conventional AVQRs, it can regulate the load voltage very well with a much lower dc-link voltage. This is accomplished by replacing the diode rectifier with a thyristor rectifier. Moreover, its dc-link voltage can vary with the deviations of the supply voltage through the proposed adaptive dc-link voltage control strategy. All of these contribute to its significantly higher efficiency for online operating, which is very important and attractive for many applications. The proposed topology and control strategy are theoretically analyzed in detail. Simulation results are also provided in the paper. Finally, the feasibility and effectiveness of the proposed method are verified by means of experimental results from a 2kVA prototype. Both of the simulation and experimental results show that the proposed AVQR can achieve a much higher efficiency and similar regulation performance when compared with the conventional ones.