• 조명전기설비학회논문지
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• 제29권10호
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• pp.54-59
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• 2015

In this paper, we evaluate safety of grounding system which is designed according to IEC standards. Safety assessment of construction site and grounding system of building is needed before construction for the safety of human in building. Until now, in case of domestic field, design of grounding system is proceeded based on methods which are proposed in IEEE Std. 80. In other words, it is not in the situation that grounding system is designed based on IEC standards. Therefore, we propose a method which designs grounding system and evaluates safety of it according to IEC standards. We measure ground resistance of construction site using measuring equipment of ground resistance. Using this value, soil structure and ground resistivity are obtained through program analysis. CDEGS program of SES company is used for simulation analysis.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.2064-2067
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• 2000

In our country, most region is composed of mountains and people have recently been displeased with the construction of the substations in their vicinity so the substations newly built are mainly constructed with GIS system in the small area that has high soil resistivity near mountain. Therefore, nowadays the design of substation grounding system has been difficult, and the additional considerations are needed. UC substation was also difficult to design the grounding system because of so small substation area and high soil resistivity. This paper shows the examples of reducing the grounding system resistance reasonably by using several ways. Designing the ground grid electrode in the access road, deep electric earth probe, changing the substation soil with the law level resistivity soil. This report deals with the computer simulation of the grounding system resistance about the ways illustrated above.

• 대한전기학회논문지:전력기술부문A
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• 제49권1호
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• pp.19-25
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• 2000

This paper describes the sheath induced voltage in underground transmission cable system which will be operated with cable cover protection unit(CCPU). Simulation was carried out to analyze the sheath induced voltage in the real cable system which was installed by 154㎸ CV cable in the case with and without CCPU. The sheath induced voltage will be also analyzed according to the change of grounding method, fault resistance and fault angle. Simulation was performed using EMTP and ATP Draw, the simulation results show whether the CCPU in necessary or not in underground transmission power cable system.

• 조명전기설비학회논문지
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• 제20권3호
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• pp.28-35
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• 2006

최근들어 빌딩내에 있는 많은 전기 전자 통신설비들은 기기 보호 및 안전을 위하여 반드시 접지를 필요로 하며, 고장 전류가 같은 빌딩내에 있는 어떤 접지 시스템으로 흐를 때, 이 전류에 의한 전위상승에 영향을 받아 다른 접지시스템의 전위 상승을 유도할 수 있다. 이러한 전위간섭은 접지극의 표면전위에 의해 영향을 받으며, 전각의 형상과 깊은 관련이 있다. 본 논문에서의 기본적 공식은 전위간섭을 받는 접지극과 전위간섭의 원천이 되는 두 접지극의 표면 전위에 기초하여 추론되었으며, 다중 접지극에 있어서의 전위간섭의 정도는 미리 간단한 모델을 이용하여 시뮬레이션을 실시하였다. 이는 대지위에 설치되는 건조물의 접지저항을 추정하기 위한 것이며, 실제의 현장에서 측정한 접지 저항값과 추정값과의 일치성을 입증하기 위하여 반구형 수조에서 모의 접지시스템의 축적 모델로 실험을 행한 결과, 확실한 메쉬접지극의 접지저항을 얻을 수 있었다. 따라서 수조 모델 실험을 통하여 메쉬접지각의 접지저항을 추정할 수 있음을 보여주고 있다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1482-1504
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• 2007

철도시스템은 열차견인을 위한 고전압시스템, 열차제어를 위한 저전압시스템을 사용하며, 철도를 구성하는 시스템이 지형적으로 광범위하게 분포되어 있다. 철도시스템에서 전차선의 지락에 의한 과대한 고장전류, 낙뢰 등에 의한 이상 고전압이 발생되어 사람의 사상 및 기기의 고장이 발생할 수 있는데, 지락에 의한 고장전류, 낙뢰에 의한 고전압으로부터 기기를 보호하기 위해서 접지를 설치한다. 각 시스템에 대한 단독접지를 하는 경우에는 기기 상호가 폐회로가 형성되어 이상전류가 흐르게 되어 기기를 정상적으로 작동시키지 못하는 경우가 있다. 따라서 이러한 해결책으로 등전위 접지시스템을 채용한다. 이러한 등전위 접지시스템은 매우 낮은 접지저항을 확보하여야 한다. 본 논문에서는 철도시스템에서 기존의 단독접지시스템에서 현재의 공통접지시스템으로의 변화 및 두 시스템의 시뮬레이션 비교분석과 앞으로의 새로운 접지시스템에 대한 방향에 대해 제시하였다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2005년도 학술대회 논문집
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• pp.111-114
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• 2005

This paper presents a comparison of experimental value by hemispherical grounding simulation system and calculated value by CDEGS program for ground potential rise of structure. When a test current flowed through structure grounding electrodes, ground potential rise was measured and analyzed for types of structure using the hemispherical grounding simulation system in real time, and was computed by means of CDEGS program. The model structures were designed and fabricated with two types on a scale of one-one hundred sixty. When the experimental data were compared with the theoretical values, the similar profile was shown. Therefore, the confidence of measurement was obtained. The distributions of ground surface potential are dependent on the resistivity and absorption percentage in concrete attached to structure.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.736-741
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• 2005

This paper presents electric characteristics analysis and safe configuration for extension power supply between existent 6.6kV ungrounded distribution system and establishment and improvement 22.9kV direct grounding distribution system. For this, we model 6.6kV ungrounded and 22.9kV direct grounding distribution system of urban underground, ground region. and rural electrical, unelectrical region using PSCAD/EMTDC and analyze voltage drop, charging current, ground and short fault through simulation. To analyze electric characteristics of extension power supply, we simulate extension power supply of overhead line of 6.6kV ungrounded system and underground line of 22.9kV direct grounding system of rural electrical region and propose operation condition for safe extension power supply through result of analysis. Characteristics of voltage drop, charging current, ground and short fault appear almost similarly with electrical characteristic of direct power supply. However, because unbalance of phases may cause relay's malfunction of ungrounded system and ground fault current of direct grounding system may demage facilities of ungrounded system, we propose safe system configuration such as impedance grounding system of neutral point.

• 전기학회논문지
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• 제63권3호
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• pp.331-337
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• 2014

The Korean distribution system consists of overhead ground wire (OHGW), phase conductors and neutral wire. Especially, OHGW is installed over the phase conductors to protect distribution system from the lightning surge. The flashover rate and the magnitude of lightning overvoltage on distribution system can be affected by grounding condition of OHGW such as grounding resistance and grounding interval. In this paper, we conduct an analysis of lightning overvoltage and flashover rate according to the grounding condition of OHGW. The distribution system and lightning surge are modeled by using ElectroMagnetic Transient Program (EMTP). Also, the Monte Carlo method is applied to consider random characteristics of lightning, and the flashover rate is calculated based on IEEE std. 1410. The simulations are performed by changing the grounding resistance and interval of OHGW and the simulation results are analyzed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1948-1949
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• 2007

This paper presents the characteristics and effects of grounding resistor and impedance. In grounding system, Grounding resistor is governed neutral currents and voltage. It seems that, grounding resistor has 0 value, then circuit has no faults. While if grounding resistor has large value, then neutral current has large value of fault current and it is made a damage to the utility. In order to analyze the grounding impedance characteristic, EMTP simulation has been used. The grounding impedance characteristic has been analyzed and tested for various grounding arrangements and electrode circuit shapes.

• 대한전기학회논문지:전력기술부문A
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• 제50권8호
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• pp.359-364
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• 2001

This paper presents the influence of the lightning overvoltage and the shielding effect of lightning arresters and overhead grounding wires on the DC railroad systems. Modeling of railroad system is established in ATPDraw to perform the simulation and the line constants of railroad were calculated using ATP_LCC. When a direct lightning strikes to the DC railroad, the result of simulation reveals that the shielding effect of arresters is reduced at messenger, trolly-wire, and the shielding effects of overhead grounding wire is over 90% than the case which does not include it. Therefore it is evaluated that overhead grounding wires should be installed in the DC railroad line.