• Journal of electromagnetic engineering and science
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• 제15권1호
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• pp.26-30
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• 2015

In this paper, a simple equivalent circuit model for a defected ground structure (DGS) microstrip line with stepped impedance slot-lines in the ground plane is presented. In addition, an analytic expression for the resonance frequency of the proposed structure is derived. In equivalent circuit modeling, the capacitance and the inductance of the resonance circuit are evaluated from the dimensions of the etched pattern in the ground plane. The resonance frequencies calculated from the proposed method are compared with those obtained with an electromagnetic (EM) simulation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1418_1419
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• 2009

This paper presents the transient impedance when high current impulse up to 5 kA is applied to a scaled grounding grid in test field. For a realistic analysis of transient impedance on the high current impulse in the ground systems, grounding electrode installed outdoors and impulse current generator was used. The results were discussed based on its voltage and current trace, impulse impedance and V-I curve.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1589-1591
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• 1998

This paper presents experimental results of transient impedance characteristics investigated on the site of a large-scale grounding system using impulse current. The ground potential rise was measured while injecting an impulse current and the transient impedance was determined. As a results, the transient impedance was significantly greater than the stationary grounding resistance due to high inductance of ground conductors and leads.

• 조명전기설비학회논문지
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• 제18권3호
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• pp.120-127
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• 2004

스위칭 모드 전원 공급 장치와 같은 비선형 부하의 증가로, 3상 4선식 배전계통을 채용하는 중성선에 많은 고조파 전류가 흐른다. 중성선은 접지 시스템과 연결되어 있기 때문에 접지 임피던스는 중성선 고조파 전류에 영향을 끼친다고 알려져 있다. 현장에서 실측한 고조파 전류와 전압으로 고조파 해석용 3상 등가 회로를 구성하였다. 실측한 값과 MATLAB으로 시뮬레이션 한 값을 수치와 파형으로 비교 검토하였다. 또한 본 논문에서는 중성선 고조파 전류와 접지 임피던스와의 관계를 시뮬레이션을 통해 검증하였다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권11호
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• pp.717-723
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• 1999

The transient characteristics of grounding systems play a major role in the protection of power equipments, electronic circuits and info-communication facilities against surges which arise from lightning or ground faults. Electronic devices are very weak against lightning surges injected from grounding systems and can be damaged. The malfunction and damage of electronic circuits bring about bad operation performances, a lot of economical losses, and etc. Therefore, in order to obtain the effective protection measure of electronic devices from overvoltages and lightning surges, the analysis of the transient grounding impedances in essential. One of this work is to examine the transient behaviors of grounding impedances under steplike currents for various grounding systems. And the other of this work is to evaluate the transient behaviors of a grid with rods under impulse currents and to investigate the effect of grounding lead wire. Transient grounding impedances of a grid with rods under impulse current waves have been measured as a parameter of the length of the grounding leads. Z-t, Z-i and V-i curves of transient grounding impedance under impulse current waveforms have been measured and analyzed. It was found that the grounding impedance gives the inductive, resistive and capacitive aspects under steplike current. Transient grounding impedance characteristics were very different with shapes, geometries of ground electrodes. Also, they were dependent on the waveform and magnitude of impulse current.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 춘계학술대회 논문집
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• pp.297-300
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• 2008

This paper presents the behaviors of transient and conventional grounding impedances of a deep-driven ground rods associated with the injection point of lightning impulse currents. The transient impedance of deep-driven ground rods under lightning impulse currents were higher than the static ground resistance. The transient grounding impedances strongly depend on the injection point and size of grounding electrodes and the rising time of impulse current. Reduction of ground system inductance is an important factor to lightning surge protection.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권5호
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• pp.248-252
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• 2004

Since DC ground resistance, which is a good index of the performance of a grounding system in low frequency. does not show the performance in transient state. We measured ground impedances in frequency domain ranging from 0.1 Hz to 900 KHz maximum to quantify the transient grounding performance of 4 types of grounding system. Transfer function was derived from the measured frequency-dependant ground impedance of a grounding grid. A simulation has been performed to verify the transfer function using EMTP (Electro-Magnetic Transient Program).

• 한국안전학회지
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• 제28권3호
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• pp.56-62
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• 2013

The occurrence of the ventricular fibrillation is directly dependent on the magnitude and duration of the current. The current which flows through the human body is proportional to the touch voltage applied across the body and is in inverse proportion to the impedances in the circuit. The circuit impedances consist of human body impedance, line impedance, equipment impedance, earth terminal impedance and impedance of shoes which a person put on. The impedance of shoes greatly affect the severity of the electric accidents. The human body impedances relevant to the contact areas, contact conditions, current paths and touch voltages are already determined in the IEC 60479-1. However, the impedance of shoes is ignored or substituted by a simple value because of the absence of the sufficient data. For example, the impedance of shoes plus ground contact resistance is postulated to be $1,000{\Omega}$ in the IEC 61200-612. In IEEE 80, the shoe resistance plus ground contact resistance is assumed to be bare foot with ${\rho}/4b{\Omega}$. In this paper, we measured and analyzed the impedance of shoes with respect to conditions such as applied weight, environment variables and voltages. The results showed that the impedance of shoes is dependent on environment variables regardless of the types of shoes. Most of shoes showed the correlation with the applied force, whereas a few shoes showed characteristics related to the applied voltage. In terms of severity of electric shock, one thirds of test samples indicated to be dangerous in saltwater conditions.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 D
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• pp.1000-1002
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• 1997

In this paper we proposes a scheme which can improve the detecting capability of the high impedance fault of the conventional distance relaying. It utilizes the directional ground overcurrent relay called HIFR together with the distance relay in order to secure the security and selectivity.

• 한국재난정보학회 논문집
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• 제18권1호
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• pp.19-28
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• 2022

연구목적: 전기로 인한 화재·폭발·감전 등의 재해를 예방하기 위한 방법 중의 하나가 접지를 시행하는 것이다. 접지전류가 높은 주파수 성분을 포함하는 경우에는 접지저항보다는 접지임피던스를 측정하는 것이 바람직하다. 본 연구에서는 수 kHz 이상의 주파수 성분을 가지는 접지전류에 의한 대지전위상승을 억제하기 위한 접지임피던스를 줄이는 방안을 제시하고자 한다. 연구방법: 대지에 접지동봉과 접지침봉을 매설하여 각각 접지저항과 접지임피던스를 측정하였고, 주파수에 따른 접지임피던스의 특성을 파악하였다. 연구결과: 접지동봉과 접지침봉의 접지저항 측정 결과는 거의 차이가 없었다. 62.5kHz 보다 낮은 주파수 영역에서는 접지동봉이나 접지침봉의 접지임피던스 측정 결과는 거의 차이가 없었으며, 62.5kHz 보다 높은 주파수 영역에서는 접지침봉의 접지임피던스가 접지동봉의 접지임피던스보다 약 15% 정도의 저감효과가 있었다. 결론: 상용주파수 영역에서 접지저항 값을 낮추기 위하여 다수의 접지극을 공통으로 접지하는 것이 효과적이고, 접지임피던스가 낮은 접지침봉을 설치하는 경우 수 kHz 이상의 주파수 성분을 가지는 접지전류에 의한 대지전위상승을 효과적으로 억제할 수 있을 것으로 보인다.