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엄주홍(Ju-Hong Eom),조성철(Sung-Chul Cho),유양우(Yang-Woo Yoo),이태형(Tae-Hyung Lee) 대한전기학회 2009 대한전기학회 학술대회 논문집 Vol.2009 No.7
This paper shows the latest trend of coping plan for mitigating lightning damage in advanced countries. The mitigation measures were investigated in following fields: the organization of government and warning system, education and publicity, support program and concerned service. In results of investigations, the USA and Japan have been organized with the latest technology of warning system and the effective management of organization. So government-level mitigation measures based on the small-scaled lightning warning system need to be considered for reducing the damage of lightning in our country.
전류 및 전위 측정선간 상호유도가 접지임피던스에 미치는 영향
嚴柱弘(Ju-Hong Eom),趙成哲(Sung-Chul Cho),李泰炯(Tae-Hyung Lee) 대한전기학회 2008 전기학회논문지 Vol.57 No.7
While a high frequency source is used for measuring the ground impedance, there are several factors having an effect on the measured value. A primary factor of the measurement error is the ac mutual coupling between current and potential test leads. The mutual coupling causes the test current to induce a voltage into the potential test lead that adds to the actual ground potential rise and produces a significant measurement error as the length of the test leads paralleled is prolonged. In order to avoid the mutual coupling, it is recommended that the ground impedance be measured by angled arrangement of test leads. The mutual impedance due to the inductive coupling with an angle of 90° was calculated at 0° by Campbell/Foster Method. With an angle of 180°, the mutual impedance was calculated large value enough to introduce a fairly large margin of error, however, the measured value of ground impedance was close to the value at 90°.
Step-up 방식에 의한 송전용 XLPE 모델케이블의 가속열화 수명분석 고찰
엄주홍(Ju Hong Eom),김동규(Dong Kyu Kim),정연하(Yeon Ha Jung),강연욱(Yeon Woog Kang),강지원(Ji Won Kang) 대한전기학회 2021 대한전기학회 학술대회 논문집 Vol.2021 No.10
A new Step-up stress acceleration method, which complements the shortcomings of the constant stress method, was proposed in the stress-life experimental analysis area for power transmission cables, and it was verified that a number of failure data can be obtained and statistical life by stress level is calculated through simulation results.
가변주파수 및 임펄스 전류를 이용한 과도접지임피던스 분석
엄주홍(Ju-Hong Eom),조성철(Sung-Chul Cho),이태형(Tae-Hyung Lee) 한국조명·전기설비학회 2008 조명·전기설비학회논문지 Vol.22 No.6
접지전극의 형태, 크기, 재질 및 임펄스전류의 형상에 따라 변화하는 과도접지임피던스는 접지시스템의 성능에 중요한 영향을 미친다. 본 논문은 기존의 실효임펄스임피던스가 실제 과도접지임피던스를 얼마나 효과적으로 나타내고 있는가에 대한 분석과 보다 효과적인 과도접지임피던스 평가방법에 대하여 실험적인 결과를 제시하였다. 실험에 사용된 접지전극은 저항성분과 인덕턴스를 포함한 모의 접지전극과 1[m] 탄소접지봉, 9[m] 일반동봉 그리고 40[m] 매설지선이며, 가변주파수 전류와 임펄스전류에 의한 접지임피던스를 각각 측정하였다. 각각의 값을 비교 했을 때 기존의 실효임펄스임피던스의 값보다는 전압의 최대값과 전류의 최대값을 이용하여 과도접지임피던스를 구한 임피던스 값(Z₁)이 등가주파수에 해당하는 가변주파수 전류에 의해 구해진 접지임피던스에 근접함을 확인하였다. The transient ground impedance depending on configuration, size, and material of grounding electrodes as well as the shapes of impulse currents, has a significant affect on the performance of the grounding system. This paper presents experimental results in regard to the analysis method of transient ground impedance using the lightning impulse and variable frequency currents. Also a new estimation method to replace the effective surge impedance for transient ground impedance was proposed. The ground electrodes used in this experiment are virtual ground electrodes including both resistance and inductance components, carbon ground electrode with 1[m] length, copper electrode with 9[m] length and counterpoise with 40[m] length. Ground impedances using the proposed method were measured respectively. Comparing with the ground impedance using variable frequency current, the conventional ground impedance(Z₁) calculated from the peak values of impulse voltage and impulse current is observed more correct method for evaluating the performance of ground electrode than the effective surge impedance.
Crowbar 장치를 이용한 최초 단시간뇌격전류 발생기술 및 뇌격전류발생기 개발
엄주홍(Ju-Hong Eom),이태형(Tae-Hyung Lee),권기량(Ki-Ryang Kwon),조성철(Sung-Chul Cho) 한국조명·전기설비학회 2011 조명·전기설비학회논문지 Vol.25 No.1
This paper presents a technical study for the first short stroke lightning current generator using a crowbar device. The so-called crowbar-technology is most common to make 10/350[㎲] impulse currents with high amplitude, and the lightning current generator with crowbar device has an economic advantage than the nominal RLC current generator. But both the operating efficiency and the operating reliability of crowbar spark gap are very important to design the current generator. So, the peaking circuit which consists of small capacitors and a spark gap is applied. And the multi-step coil for controlling the circuit constant at the different test conditions is used. The presented test facility is designed to perform impulse tests with amplitudes up to 50[㎄] of 10/350[㎲].
엄주홍(Ju-Hong Eom),이태형(Tae-Hyung Lee),조성철(Sung-Chul Cho) 한국조명·전기설비학회 2008 조명·전기설비학회논문지 Vol.22 No.4
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 입사 하는 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. The tendency of lightning surge to propagate is appeared variously depend on the power system and subject equipment of protection. However, looking into the subject equipment with the lightning surge, the invasion route of lightning surge can be divided in between the two lines of power, between the power line and the ground, the power line and the PE conductor, between the neutral line and the ground and the like. In addition, in the event of the communication equipment, there exists the route of lightning surge incoming from between the communication lines, the communication line and the ground in addition to the power lines. In this study, the tendency of propagation of lightning surge penetrated on to the subject equipment is analyzed through the empirical experiment in accordance with the ground method by using the independent ground, common ground and bypass arrester ground for safety improvement in power lines.
엄주홍(Ju-hong Eom),조성철(Sung-chul Cho) 한국조명·전기설비학회 2005 한국조명·전기설비학회 학술대회논문집 Vol.2005 No.11월
Surge protective devices can be divided into three categories based on the circuit assembly: a parallel circuit type that considers the surge current amount within the device, a series circuit type that considers the voltage and single circuit type that uses a single element. However, when assembling SPDs, there are many things including function and safety to be taken into consideration because they are directly related to the performance and safety of the device. In this paper, we executed an experimental comparative study of performance and thermal stability of each SPD type using lightning surge generator and thermal image camera.