• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.5
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• pp.62-69
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• 2010

This paper presents the dependances of transient grounding impedances of counterpoises on the soil structures and the injected point of impulse currents. The transient and conventional grounding impedances of the 25 and 50[m] counterpoises buried in the soil with different resistivity were measured and analyzed as a function of the rise time of impulse currents. As a result, the transient grounding impedances give an inductive behavior, and the trend of the conventional grounding impedances is similar to that of the transient grounding impedances. The ground resistance of counterpoises is irrespective to the injected of impulse current, but the transient and conventional grounding impedances in a short time range especially depend on the soil resistivity and position of the injected point of impulse currents.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.5
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• pp.54-60
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• 2011

This paper presents characteristics of frequency-dependent grounding impedance and transient grounding impedance for the carbon compound grounding electrode used in the installation of computerized electronic equipment and lightning protection system. The frequency-dependent grounding impedances were measured by applying sinusoidal currents in the frequency range from 100 [Hz] to 10[MHz], and the transient grounding impedances were examined by subjecting the impulse current with the front-time between 1~80[${\mu}s$]. As a result, the ground resistance of the carbon compound grounding electrode is less than that of another type grounding electrodes. The transient grounding impedance is relatively low and the conventional grounding impedance is rather lower than the ground resistance. The frequency-dependent grounding impedance of the carbon compound grounding electrode is capacitive and the grounding impedance is decreased with increasing the frequency of injected currents. Therefore in the case that the carbon compound grounding electrode is jointly used with large-scaled grounding electrodes, it is possible to reduce the high frequency grounding impedance of the integrated grounding electrode system.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.328-331
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• 2009

This paper presents the behaviors of transient and conventional grounding impedances of a 30m counterpoise according to the injection point of lightning impulse currents. As a result, the trend of the conventional grounding impedances measured as a function of risetime of impulse current is similar to the transient grounding impedance of counterpoise. The injection point of impulse current greatly influences on the transient grounding impedance characteristics of counterpoise. The transient grounding impedances strongly depend on the injection point and the rising time of impulse current and the soil characteristics.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.6
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• pp.66-71
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• 2009

This paper presents the grounding impedance behaviors of counterpoise exposed to impulse currents. The transient and conventional grounding impedances of three counterpoises having the length of 10, 30 and 50[m] were measured and analyzed as a function of the injection point of impulse currents. As a result, the trend of the conventional grounding impedances measured as a function of injection of impulse current is similar to the transient grounding impedance of counterpoise. The injection point of impulse current has great influence on the transient grounding impedance characteristics of counterpoise. The transient grounding impedance characteristics in a short time range are strongly dependent on the length of counterpoise. The transient characteristics of grounding impedance of 10[m] counterpoise subjected to the impulse current was capacitive behavior, on the other hand, those of 30[m] and 50[m] counterpoises were inductive behavior. It is found that the grounding conductor should be connected to the central point of counterpoise.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.69-72
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• 2008

This paper presents the transient and conventional grounding impedance behaviors of large grid grounding system associated with the injection point of impulse current The measurement methods consider two possible errors in the grounding-system impedances: (1) ground mutual resistance due to current flow through ground from the ground electrode to be measured to the current auxiliary, (2) ac mutual coupling between the current test lead and the potential test lead The test circuit was set to reduce the error factors. The transient grounding impedance depends on the rise time and injection point of impulse current It is effective that grounding conductor is connected to the center of the large grid grounding system.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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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.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.6
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• pp.298-306
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• 2002

We performed an safety evaluation on constructing of a common grounding system for electrical railway in view of its efficacy and technical fit. In order to compare the conventional grounding method, which has been individually conducted, with the common grounding with all ground wires connected in common to the counterpoise buried below the surface of the earth in parallel with rail, we set up scenarios with several cases of fault and load conditions in Chungbuk railway sections with the common grounding system. Based on models for railway conductors including the grounded system, line Parameters of railway power system are computed. The circuit model for power system with up and down lines, auto-transformers and railway substations is used to compute impedances of counterpoise and substation ground net. For each scenario with faults and operation conditions of railway, the induced potentials on signal and communication lines are also computed. It is shown that the common grounding for Chungbuk railway is superior experimentally to the conventional method in three respects: (1) the lower rail potentials during operation of railway in line, (2) the lower rail potentials for short-circuit faults between catenary and rail, and (3) the lower stress voltages on signal and communication lines for short-circuit or ground faults. The analysis results confirm that the grounding system for electric railway is required to be built by the common grounding and be evaluated on its safety in design.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.4
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• pp.117-123
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• 2011

Lightning and switching surges propagating through the grounding conductors lead to transient overvoltages, and electronic circuits in information technology systems are very susceptible to damage or malfunction from the electrical surges. Surge damages or malfunctions of electrical and electronic equipment may be caused by potential rises. To solve these problems, it is very important to evaluate the ground surface potential rises and hazardous voltages such as touch and step voltages at or near the grounding systems energized by electrical surges. In this paper, the performance of grounding systems against the surge current containing high frequency components on the basis of the actual-sized tests is presented. The ground surface potential rises and hazardous voltages depending on impulse currents for vertical or horizontal grounding electrodes are measured and analyzed. Also the touch and step voltages caused by the impulse currents are investigated. As a result, the ground surface potential rises, the touch and step voltages near the grounding electrodes are raised and the conventional grounding impedances are increased as the front time of the injected impulse currents is getting faster.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.8
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• pp.94-100
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• 2010

Grounding system insures a reference potential point for electric devices and also provides a low impedance path for fault currents or transient currents in the earth. The ground impedance as function of frequency is necessary for determining its performance since fault currents could contain a wide range of frequencies. In this paper, the grounding resistance, grounding impedance and transient grounding impedance are measured by using 3-point fall-of-potential method in order to analyse grounding characteristics of the stainless-steel plate grounding electrode. An equivalent transfer function model of the grounding impedance and transient grounding impedance are identified from the measured values by using ARMA method and evaluated by comparing conventional grounding impedances.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.10
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• pp.1861-1868
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• 2009

A ground electrode subjected to lightning surge current shows the transient impedance behaviors. The ground electrode for protection against lightning should be evaluated in view of the transient grounding impedance and conventional grounding impedance, not ground resistance. The transient impedance characteristics of ground electrodes are influenced by the shape of ground electrode and the soil characteristics, as well as the waveform of lightning surge current. In order to propose a simulation method of analyzing the transient impedance characteristics of the grounding system in practical use, this paper suggests a theoretical analysis method of distributed parameter circuit model to simulate the transient impedance characteristics of counterpoise subjected to lightning surge current. EMTP and Matlab programs were employed to compute the transient grounding impedances of three counterpoises with different lengths. As a consequence, the simulated results using the proposed distributed parameter circuit model are in good agreement with the measured results.