• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
• /
• pp.57-60
• /
• 2001

CATV is the abbreviation for Cable Television. General CATV is a way of multi-channel sending images, voices and music including stillness image as well as characters to public receivers through electrical cable communication system. In the beginning, master antennas were people can not receive TV signal well. TV programs were received from master antennas to TVs in each house. Ground connection began by experimenting lightning with the use of a kite and it means electric appliances, communication equipments, measuring instruments and so on connecting the Earth in order to flow away overcharged electricity. There are two kinds of earth connection: Power Ground and Signal Ground. Power Ground is for preventing an electric shock and in general there's no current in the connector. However in an accident, there's a quick flow of electricity out to the Earth. Signal Ground is not only for the safety of appliances but also for the safety of equipment operation. This paper is about connection for noise and interference reduce in order to prevent wrong operation and distortion of signal in the electrical appliances which can take place in CATV.

• 조명전기설비학회논문지
• /
• 제26권5호
• /
• pp.58-64
• /
• 2012

In electric power supply systems, an earthing system determines the electric potential of the conductors related to that of the Earth's surface. The choice of earthing system has implications for the safety of the power supply systems. There are considerably different regulations for earthing (grounding) systems in each country. A protective earth(PE) conductor ensures that all exposed conductive surfaces are at the same electric potential as the earth surface. This paper deals with that when PEN conductor of TN-C-S system is disconnected, dangerous touch voltage causes personnel body to be harmed and human being's property to be damaged seriously. For this reason, this paper explains how serious problems can occur when the fault current flows. As a consequence, we can understand how we can design earthing system properly to ensure the personnel safety against earth faults. The result shows the way that TN-C-S system can be applied safely in Korea.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 추계학술대회 논문집
• /
• pp.57-60
• /
• 2001

CATV is the abbreviation for Cable Television. General CATV is a way of multi-channel sending images, voices and music including stillness image as well as characters to public receivers through electrical cable communication system. In the beginning, master antennas were people can not receive TV signal well. TV programs were received from master antennas to TVs in each house. Ground connection began by experimenting lightning with the use of a kite and it means electric appliances, communication equipments, measuring instruments and so on connecting the Earth in order to flow away overcharged electricity. There are two kinds of earth connection: Power Ground and Signal Ground. Power Ground is for preventing an electric shock and in general there's no current in the connector. However in an accident, there's a quick flow of electricity out to the Earth. Signal Ground is not only for the safety of appliances but also for the safety of equipment operation. This paper is about connection for noise and interference reduce in order to prevent wrong operation and distortion of signal in the electrical appliances which can take place in CATV.

• 조명전기설비학회논문지
• /
• 제12권4호
• /
• pp.55-61
• /
• 1998

일반적으로 접지시스템에서 접지저항계산은 저주파수의 전원이 대지에 인가될 때 발새외는 대지전위상승을 측정하여 계산한다. 그러나 뇌격과 써지 엄펄스와 같은 고주파수에 해당하는 전원에 대해서는 현재의 접지 시스템에서 고려하고 있지 않기 때문에 전기설비에 매우 큰 영향을 미칠 우려가 있다. 그래서 이 논문에 서는 뇌격이 전극봉에 인가되었을 때 발생되는 접지 임피던스의 과도현상을 실험하였다. 그리고 이 실험 결과는 이론적 해석과 잘 일치하였으며 지중방전현상이 임펄스 임피던스 저감에 영향올 미친다는 사실을 확인 할 수 있었다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 하계학술대회 논문집 C
• /
• pp.1674-1676
• /
• 2003

The factors affecting the accuracy of lightning current measuring system are figured out the materials and length of down-conductor, and impedance matching between grounding resistance and characteristic impedance of cable. The cable with the low characteristic impedance used to transfer the lightning current from the top of the tower is too long to measure the waveform of lightning current, exactly. Especially, the height of the tower can cause the change of front time and magnitude of lightning stroke current. Basically, in this experiment. It was found that the magnitude and rise time of the lightning current are extremely dependant in the length of down-conductor in lightning current measuring system.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2005년도 추계종합학술대회
• /
• pp.693-696
• /
• 2005

국내의 통신망은 효율적인 유지보수를 위하여 도로를 따라 기반시설이 구축되고 있기 때문에 전력망과 통신망의 교차와 병행이 가속화되고 있다. 전력망은 전력유도를 발생시킬 뿐만 아니라, 낙뢰와 같은 전기적 과도현상으로부터 그 자체가 전송매체로 되기 때문에 전력망 지중 접지체와 통신망 지중 접지체간을 통하여 낙뢰서지 및 지락선 과도 현상이 통신망에 유도되어 악영향을 초래한다. 본 연구에서는 통신망의 보호대책으로 지중접지체간의 이격거리를 통한 귀로전류의 차단과 양쪽 단자의 유휴심선을 접지하여 전력유도전압을 차폐하는 방법이 우수한 효과를 나타냄을 확인 할 수 있었다.

• 한국산학기술학회논문지
• /
• 제21권4호
• /
• pp.39-48
• /
• 2020

2017년 8월에 발생한 고창 전력시험센터를 시작으로, 현재까지 총 29건의 전기저장장치 화재가 발생하여 많은 재산피해가 보고되고 있다. 이에 대한 원인은 아직 정확하게 규명되지 않았으나, ESS(energy storage system)와 전력변환장치뿐만 아니라, 계통측 불평형 문제도 하나의 원인으로 고려되어야 할 것으로 보인다. 특히, 연계용변압기측의 순환전류가 자화전류에 영향을 미쳐, 의도치 않게 변압기의 철심이 포화되고 서지전압이 발생하여 ESS에 영향을 줄 수 있다. 따라서, 본 논문에서는 부하불평형에 의한 불평형전류 발생시, ESS 연계용변압기로 순환전류의 유입과 변압기 포화로 인한 서지전압 발생 현상을 해석하기 위하여, PSCAD/EMTDC를 이용한 배전용변전소, 연계용변압기 및 수용가부하로 구성된 배전계통의 모델링을 수행한다. 또한, 이러한 문제를 해결하기 위하여, 중성점 접지 저항기(neutral grounding resistor, NGR)를 통해 순환전류의 크기를 일정 값 이내로 저감시키는 방안을 제시하였다. 이를 바탕으로 시뮬레이션을 수행한 결과, 연계용변압기의 결선방식 및 철심구조에 따라 일정 값(10[A]) 이상의 순환전류가 발생하여, ESS에 전기적인 위해 요인이 될 수 있음을 알 수 있었고, 변압기 포화로 인해 2차측에 최대 3[pu]의 서지전압이 발생될 수 있음을 확인하였다.

• 한국전기전자재료학회논문지
• /
• 제18권9호
• /
• pp.851-855
• /
• 2005

We investigated the unbalanced characteristics of the superconducting fault current limiters (SFCLs) based on YBCO thin films with a single line-to-ground fault. When a single line-to-ground fault occurred, the short circuit current of a fault phase increased about 6 times of transport currents after the fault onset but was effectively limited to the designed current level within 2 ms by the resistance development of the SFCL. The fault currents of the sound phases almost did not change because of their direct grounding system. The unbalanced rates of a fault phase were distributed from 6.4 to 1.4. It was found that the unbalanced rates of currents were noticeably improved within one cycle after the fault onset. We calculated the zero phase currents for a single line-to-ground fault using the balanced component analysis. The positive sequence resistance was reduced remarkably right after the fault onset but eventually approached the balanced positive resistance component prior to the system fault. This means that the system reaches almost the three-phase balanced state in about 60 ms after the fault onset at the three-phase system.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2009년도 제40회 하계학술대회
• /
• pp.1420_1422
• /
• 2009

Lightning currents are one of major influences on the dynamic performance of counterpoise. High lightning current causes the dynamic grounding performance of counterpoise due to very fast fronted pulses. The previous analysis has often been based on quasi-static approximation that can not be applicable to very fast fronted pulses. To extend the analysis for fast fronted pulses in this paper, the full-wave analysis method based on the rigorous electromagnetic-field theory approach is used and the effects of the ionization of the soil are disregarded. Based on the simulation results, the empirical formulas applicable for slow and fast fronted lightning current pulses are reviewed; therefore, the validity of the theoretical approach is verified through comparison between the calculated and measured results.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2000년도 추계학술대회 논문집
• /
• pp.704-711
• /
• 2000

This study is carried out using a circuit model approach. First, the self and shunt impedances of all the conductors in the rail system and the mutual impedances between different conductors are computed. Then, a circuit representing the both rail systems at interfaces including the rails, feeders, protection wires, contact wires, ground wires is built. Auto-transformers in the system are also represented in the circuit model. The circuit model is then 1]recessed using a circuit solver based on a double-elimination method. Several different scenarios are analyzed, including the load conditions and a few fault conditions with different fault locations. The effect of the buried ground wires is also analyzed by comparing the results with and without the presence of the ground wires. The analysis procedure presented in the paper demonstrated an accurate way of computing fault current distribution and EMC at interfaces between both systems. The results presented in the paper can be used as a reference for estimating interference levels in similar rail systems.