• 한국전기전자재료학회논문지
• /
• 제35권2호
• /
• pp.184-189
• /
• 2022

In this paper, the fault current limiting operations of three-phase transformer type superconducting fault current limiter (SFCL) using double quench, which consisted of E-I iron core with three legs wound by primary and secondary windings and two superconducting modules (SCMs), were analyzed according to three-phase ground fault types. To verify the effective operation of the three-phase transformer type SFCL using double quench, the test circuit for three-phase ground faults was constructed, and the fault current tests were carried out. Through analysis on the fault current test results, the different fault current limiting characteristics of three-phase transformer type SFCL using double quench from three-phase transformer type SFCL using three SCMs were discussed.

• 한국철도학회논문집
• /
• 제10권6호
• /
• pp.645-649
• /
• 2007

접지시스템은 고장전류를 대지로 방출시켜 대지전위상승을 억제하는 역할을 한다. 본 논문에서는 넓은 주파수 범위에서 접지임피던스를 분석하기 위하여 서지임피던스측정기를 설계 제작하였다. 본 측정기는 서지발생회로, 고속 샘플/홀드회로 및 주변 전자회로로 구성되어 있으며, 서지발생치고는 상승시간 $50ns\sim500ns$ 범위에서 최대 5kV까지 발생시킬 수 있다. 제작한 서지임피던스 측정기는 심타접지극으로 구성된 접지계에서 실질적 평가가 수행되었다. 실험 결과로부터 접지계의 서지임피던스는 인가전압의 상승시간에 따라 증가하는 경향을 나타내므로, 접지임피던스는 여러가지 고속의 서지파형으로 평가되어야함을 확인하였다.

• 조명전기설비학회논문지
• /
• 제23권8호
• /
• pp.86-92
• /
• 2009

접지임피던스의 측정에서는 교류의 전자유도결합을 최소화시키기 위해 보조전극을 직각으로 설치하며, 측정공간이 제한되는 경우 대안적 방법이 적용되고 있다 이때 접지임피던스의 측정에서는 교류 상호결합과 도전유도에 의한 측정오차를 검토할 필요가 있다. 본 논문에서는 수직 또는 수평으로 매설된 접지극의 접지임피던스를 측정할 때 전류와 전위보조전극의 위치에 따른 측정의 정확도에 관한 것으로 전자유도결합에 의한 측정오차를 평가하였다. 결과적으로 교류 전자유도의 영향을 수직 접지극보다 수평접지극의 경우 크게 나타났으며, 교류 전자유도결합에 의한 측정오차는 전류와 전위보조선이 평행하게 배치되는 경우 가장 크게 나타났으며, 결국 61.8[%]법은 접지임피던스측정에는 부적합하다. 이론적으로 전류와 전위보조전극을 90[^{\circ}]$로 배치하면 전자유도결합은 나타나지 않는다. 측정공간의 제한으로 전류와 전위보조전극을 90[^{\circ}]$로 배치할 수 없는 경우 전자유도에 의한 오차를 저감시키기 위해서는 보조전극을 예각보다는 둔각으로 배치하는 것이 바람직하다.

• 한국지진공학회논문집
• /
• 제24권2호
• /
• pp.111-119
• /
• 2020

Recently, some of the most destructive earthquakes have occurred in South Korea since earthquake observations began in 1978. In particular, the soil liquefactions have been reported in Pohang as a result of the ML 5.4 earthquake that occurred in November 2017. Liquefaction-induced ground deformations can cause significant damage to a wide range of buildings and infrastructures. Therefore, it is necessary to take practical steps to ensure safety during an earthquake. In the current seismic design in South Korea, the Hachinohe earthquake and Ofunato earthquake recorded in Japan, along with artificial earthquakes, have been generally used for input motions in dynamic analyses. However, such strong ground motions are only from Japan, and artificial earthquake ground motions are different from real ground motions. In this study, seven ground motions are selected, including those recorded in South Korea, while others are compatible to the current design spectra of South Korea. The effects of the newly selected ground motions on site response analyses and liquefaction analyses are evaluated.

• E2M - 전기 전자와 첨단 소재
• /
• 제9권8호
• /
• pp.806-812
• /
• 1996

I-V characteristics of ground electrode fabricated using an aluminium scrap are presented. We fabricated several shapes of aluminium scraps and aluminium electrodes. The results show that the current of aluminium electrode increased linearly by the voltage increase. AC breakdown voltage of copper plate electrode was higher than that of aluminium electrode. AC breakdown current of aluminium electrode was higher than that of copper plate electrode. As applied voltage increased, grounding resistance of aluminum electrode decreased linearly.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
• /
• pp.2283-2285
• /
• 2005

Electrical conduction in soils depends on the grain site, compactness, humidity and etc. When a high current is injected into the soil, and the breakdown phenomenon occurs and electrical behaviors in the vicinity of grounding electrodes may be changed. In the present work, electrical behaviors in the vicinity of ground rod due to the injection of impulse current were investigated. Spark-over phenomena at the tip of ground rod depend on the grain size and kinds of soils.

• 전기학회논문지P
• /
• 제59권2호
• /
• pp.191-196
• /
• 2010

The electricity distribution system in Korea is adopting a multi-grounding system. Protection of this distribution system against lightning is performed by installing overhead ground wires over the high voltage wires, and connecting the overhead ground wires to the ground every 200 m. The ground resistance in this system is limited not to exceed $50\Omega$ and overhead ground wire and neutral wire are multiple parallel lines. Although overhead ground wire and neutral wire are installed in different locations on the same pole, this circuit configuration has duplicated functions of providing a return path for unbalanced currents and protecting the distribution system against induced lightning. Therefore, the purpose of this study is to analyze the induced lightning shielding effect according to the neutral wire installation structure of a 22.9kV distribution line in order to present a new 22.9kV distribution line structure model and characteristics. This study calculated induced lightning voltage by performing numerical analysis when an overhead ground wire is present in the multi-grounding type 22.9kV distribution line structure, and calculated the induced lightning shielding effect based on this calculated induced lightning voltage. In addition, this study proposed and analyzed an improved distribution line model allowing the use of both overhead wire and neutral wire to be installed in the current distribution lines. The result of MATLAB simulation using the conditions applied by Yokoyama showed almost no difference between the induced lightning voltage developed in the current line and that developed in the proposed line. This signifies that shielding the induced lightning voltage through overhead wire makes no difference between current and proposed distribution line structures. That is, this study found that the ground resistance of the overhead wire had an effect on the induced lightning voltage, and that the induced lightning shielding effect of overhead wire is small.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
• /
• pp.3099-3103
• /
• 2011

In measurement of risk voltages; the step and touch voltage, the distance between the current electrode and the ground electrode recedes up to several hundred meters as the scale of grounding system increases. This paper dealt with the measurement method of risk voltage in a restricted space. The risk voltage was analyzed depending on the distance and the direction of the current electrode from the ground electrode in a $10[m]{\times}10[m]$ mesh grounding system. The average value of risk voltages measured at a point 20 [m] away from the current electrode was deviated below 5 [%] from that measured at 100 [m] point. Consequently, the evaluation of risk voltage of a large-scale grounding system buried in a spatially restricted place is available if the current electrode is installed in symmetry to the ground electrode.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제48권4호
• /
• pp.161-166
• /
• 1999

We have performed an EMTDC simulation for the current limiting effects of a superconducting fault current limiter (SFCL). The fault currents in the 154 kV transmission line between the arbitrary S1 and S2 substations increased up to 39 kA during the single and double line-to-ground faults, respectively. The SFCL in the transmission line is sufficient.

• 전기의세계
• /
• 제29권5호
• /
• pp.303-311
• /
• 1980

The hazards of electrical shock are well known, but the conventional ground fault circuit breakers did not provide the statis factory safety for human body. Thus this paper considers the standards of performance that they must meet, and describes the new tripping mechanism the operations and the improvements. The experiment at new G.F.C.I. indicates maximum tripping time 25msec minimum sensitive leakage current 25mA and maximum nonaperation leakage current 15mA.