접지임피던스의 주파수 의존성 측정기법

엄주홍(Ju-Hong Eom),이복희(Bok-Hee Lee) 한국정보통신설비학회 2004 한국정보통신설비학회 학술대회 Vol.2004 No.1

154kV XLPE 케이블 수명검증을 위한 파괴단말 가속열화 시험계 구축

엄주홍(Ju-Hong Eom),고현상(Hyeon-Sang Ko),강지원(Ji-Won Kang) 대한전기학회 2022 대한전기학회 학술대회 논문집 Vol.2022 No.7

선진국의 뇌해경감 대처 방안의 최근 동향

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.

SPD 접지방식에 따른 통신기기의 과도위험전압

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.

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[㎲].

열화상 분석을 통한 바리스터의 직렬과 병렬 조합의 안전성 평가

엄주홍,조성철,이태형,한후석,Eom, Ju-Hong,Cho, Sung-Chul,Lee, Tae-Hyung,Han, Hoo-Sek 한국조명전기설비학회 2006 조명·전기설비학회논문지 Vol.20 No.8

According to the recent revision of KS on the basis of the IEC, equipotential grounding systems has been come into focus and the use of surge protective devices(SPD) has been increased radically in order to operate the power system stably. $Z_nO$ varistor with non-linear resistance, which has an outstanding voltage-current(V-I) characteristic, is mainly used in power system to limit surge voltage and divert surge current. $Z_nO$ varistors are packaged several types based on the circuit assembly to be connected to a.c. power line. When the user assemble the $Z_nO$ varistors into parallel or series circuit package, there are my things to be taken into consideration including functions and thermal stability because they are directly related to the safety. We compare stabilities of each assembly type by measuring residual voltage, discharge current, leakage current and surface temperature concerned to the protection performances between a single device with a 40[kA] of current capacity and parallel or series circuits type of varistor package. IEC 규격을 기반으로 최근에 개정된 KS 규격에 따라 등전위 접지시스템이 중요하게 자리매김 하였으며, 전원시스템의 안정성을 위해 서지보호소자의 사용이 급격히 증가하고 있다. 내재된 비선형 저항성분으로 뛰어난 V-I 특성을 가지는 $Z_nO$ 바리스터는 서지전압을 제한하여 서지전류로 환류시키기 위해 전원용 보호기로 주로 사용되고 있다. 이러한 $Z_nO$ 바리스터는 교류 전원선에 접속하기 위해서 몇 가지 회로조합 형태로 구성되어 사용되는데, 사용자는 바리스터를 직렬 혹은 병렬로 조합하여 사용함에 있어서 안전에 직접적으로 관련된 기능이나 열적 안정성을 포함한 많은 것들을 고려하여야 한다. 본 논문에서는 40[kA]의 전류용량을 가지는 단일 바리스터 소자와 직렬 혹은 병렬 회로조합의 바리스터에 대하여 잔류전압, 방전전류, 누설전류, 표면온도를 측정하여 각각의 조합형태에 따라 안정성을 비교하였다.

세라믹 필터를 이용한 동축 서지어레스터의 잔류전압 저감

엄주홍,조성철,이태형,이영철,Eom, Ju-Hong,Cho, Sung-Chul,Lee, Tae-Hyung,Lee, Young-Chul 한국조명전기설비학회 2007 조명·전기설비학회논문지 Vol.21 No.2

현재 급속한 발전을 거듭하고 있는 이동통신 및 무선 멀티미디어 관련 서비스(W-CDMA, DMB, WiBro 등)의 확장은 이들 시스템을 구현하기 위한 수많은 기지국과 안테나 및 다수의 신호전송선로를 필요로 한다. 기지국 또는 중계시설의 안테나는 신호전송선로를 통하여 고가의 통신 네트워크 장비들과 결합되어 있으므로 주요 통신기기 시스템은 안테나를 통해 유입하는 직격뢰 및 유도뢰에 의한 순간적인 과전압의 위험에 항시 노출되어 있다. 현재 통신용 보호기로 사용되고 있는 가스방전튜브(GDT) 또는 협대역 스터브형 어레스터는 고속 광대역의 통신설비에 대한 뇌서지 보호수단으로서는 한계점이 드러나고 있다. 따라서 본 연구에서는 안테나를 통해 입사하는 뇌서지를 효과적으로 저감시켜주는 서지어레스터의 성능향상을 위해 세라믹 필터를 적용하였으며, 잔류전압 저감에 효과적임을 성능실험을 통해 입증하였다. Extension of the mobile communication and the rapidly developing services connected with wireless multimedia(W-CDMA, DMB, Wibro, and so on) need great many base station transceiver systems, antennas, and many signal transmission line to embody these services. The min communication appliances system is exposed always in danger of transient overvoltage by direct stroke or induced lightning surge flowing in through antenna because the antenna of base station transceiver system or relay equipment is combined with expensive communication network equipments through signal transmission line. Now, gas discharge tube(GDT) or narrow band stub arrestor which is used by the surge protector for communication use is exposing limitations as for lightning surge protective means of the communication facility with high speed and wide frequency band. Therefore, for improving performance of surge arrestor, we applied ceramic filter which can reduce lightning surge invading from antenna effectively, and proved that ceramic filter is effective in residual voltage reduction through the experimental research.