• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.25 no.12
• /
• pp.88-93
• /
• 2011

When the ground current is injected into the adjacent ground electrode, the potential interference is caused between ground electrodes, the ground potential interferences have been largely studied with power frequency fault currents. Many attempts to find the frequency-dependent grounding impedance report that the high frequency grounding impedance is very different with the ground resistance. This paper presents experimental data on the frequency-dependent potential interference effects in the vicinity of ground rod. The ground potential rises around the test ground rod of 4 or 6[m] were measured and discussed. As a result, the ground potential rises and potential interference factor are decreased with decreasing the grounding impedance. It was found that the lowering of grounding impedance is critical to reduce the ground potential interference effects.

• Proceedings of the KIEE Conference
• /
• 2000.07c
• /
• pp.2068-2070
• /
• 2000

Ground potential rise is a vital part of personal safety, this paper presents the ground potential rise distribution induced by a ground rod. The experiments were conducted with the AC square wave currents according to the buried depth of ground rod. The ground potential is significantly varied in the vicinity of ground rod and the ground potential distribution is flat and few with increasing the buried depth of ground rod.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.2
• /
• pp.436-441
• /
• 2007

Background: As patients are positioned at insulated bed and practitioner are positioned at insulated floor or shoes, it could be a cause of lessening effect in acupuncture practice. We investigated how Ground connection could influence on the electrical meridian potential between practitioner and patient during acupuncture practice. Method: We treated 30 normal healthy subjects with acupuncture and measured changes in the electrical potential between the stomach meridian points ST-39 and ST-37 in response to light touch after insertion of a needle at ST-36. At first, we stimulated needle and measured electrical potentials for non ground, patient ground only, practitioner ground only, all ground, respectively. Result: All ground subject elicited positive mean potential $44.6{\pm}19.2{\mu}V$ and showed $181.4{\pm}59.7{\mu}V$ peak to peak potential. practitioner ground only showed negative mean potential $-51.5{\pm}9.3{\mu}V\;and\;367.4{\pm}27.8{\mu}V$ of peak to peak potential. Patient ground only revealed no mean potential as $2.9{\pm}1.3{\mu}V,\;16.4{\pm}11.9{\mu}V$ of peak to peak potential. All ground showed no mean potential as $1.6{\pm}0.7{\mu}V,\;3.3{\pm}1.9{\mu}V$ of peak to peak potential. respectively.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.12
• /
• pp.2243-2250
• /
• 2006

When a patient is positioned at insulated bed and practitioner is positioned at insulated floor, that condition could be a cause of lessening effect in acupuncture practice. We investigated how Ground connection and Insulation could influence on the electrical meridian potential between practitioner and patient during acupuncture practice. We treated 30 normal healthy subjects with acupuncture and measured changes in the electrical potential between the stomach meridian points ST-39 and ST-37 in response to light touch after insertion of a needle at ST-36. At first, we stimulated non-insulated needle and measured electrical potentials for non ground, patient ground only, practitioner ground only, all ground respectively. Then we used insulated needles and measured same as above. Non-insulated all ground subject elicited positive mean potential $44.6{\pm}19.2{\mu}V$ and showed $181.4{\pm}59.7{\mu}V$ peak to peak potential. Practitioner ground only showed negative mean potential of $51.5{\pm}9.3{\mu}V$ and $367.4{\pm}27.8{\mu}V$ of peak to peak potential. Patient ground only revealed no mean potential of $2.9{\pm}1.3{\mu}V$, $16.4{\pm}11.9{\mu}V$ of peak to peak potential. All ground showed no mean potential of $1.6{\pm}0.7{\mu}V$, $3.3{\pm}1.9{\mu}V$ of peak to peak potential. In case of Insulated condition, there elicited no mean potential. Non ground and Practitioner only showed weak value of peak to peak potential as $7.8{\pm}2.6{\mu}V$ and $8.4{\pm}2.5{\mu}V$ each. But patient only and all ground showed no potential as $4.7{\pm}2.2{\mu}V$, $3.4{\pm}2.2{\mu}V$, respectively. Therefore, Ground connection modulate the energy transfer course between practitioner and patient. Insulation block energy transfer but static electrical impulse between practitioner and patient.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.26 no.3
• /
• pp.53-60
• /
• 2012

The fall-of-potential method is commonly used in measuring the ground resistance of large-scaled grounding system and the current and potential auxiliary electrodes are horizontally arranged. Because the distances between the ground grid to be tested and auxiliary electrodes are limited in downtown areas, it is very difficult to measure accurately the ground resistance of large-scaled grounding system. In this paper, the fall-of-potential method of measuring the ground resistance with the vertically-placed current and potential auxiliary electrodes was examined and discussed. The validity and good accuracy of the proposed method of measuring the ground resistance were confirmed through various simulations and actual tests carried out in uniform and two-layer soil structures.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.21 no.1
• /
• pp.142-147
• /
• 2007

This paper presents the distributions of ground surface potential rises as functions of soil structure and buried depth of ground rod. To propose fundamental data relevant to the reduction of electric shock of human beings due to ground surface rise, the ground surface potential rises near the ground rod were computed and measured. Ground surface potential rises near ground rod strongly depend on the soil structure, and an increase of the buried depth of ground rod results in a decrease of the ground surface potentials. The maximum ground surface potential appeared at the just above point of ground rod. Also, the measured results were in reasonably agreement with the data computered by grounding analysis program.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.25 no.12
• /
• pp.107-112
• /
• 2011

Multiple ground rods are commonly used to obtain the low ground impedance, but they will not reduce the ground impedance unless the spacings between the ground rods are sufficient. This paper presents the experimental results of frequency-dependent resultant ground impedance of two ground rods in parallel. The resultant ground impedance of two ground rods in parallel were measured as functions of the spacing and length of ground rods and the frequency of test currents and were discussed based on the potential interferences. As a consequence, the frequency-dependent ground impedance of single ground rod and two combined ground rods give capacitive. It was found that the effect of potential interference on the ground impedance is directly associated with the frequency-dependent ground impedance and is strong in low frequency. Also, in order to reduce the increasing rate of resultant ground impedance of two ground rods due to potential interference to within 10(%), two ground rods in parallel will be placed over one rod length apart.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.26 no.2
• /
• pp.99-105
• /
• 2012

This paper deals with the experimental results of the frequency-dependent resultant ground impedance of vertical ground electrodes installed with a regular n-polygon. In order to propose an effective method of installing the vertically-driven multiple ground electrodes used to obtain the low ground impedance, the resultant ground impedance of ground electrodes installed with a regular n-polygon were measured as functions of the number of ground electrodes and the frequency of test currents and the results were discussed based on the potential interferences among ground electrodes. As a consequence, the effect of potential interference on the resultant ground impedance of vertical ground electrodes is frequency-dependent and it is significant in the low frequency of a few hundreds [Hz]. The resultant ground impedance of multiple vertical ground electrodes is not decreased in linearly proportion to the number of ground electrodes due to the overlapped potential interferences. Also the distributed-parameter circuit model considering the potential interference, the frequency-dependent relative permittivity and resistivity of soil was proposed. The simulated results of the frequency-dependent resultant ground impedance of multiple vertical ground electrodes are in good agreement with the measured data.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.24 no.12
• /
• pp.208-213
• /
• 2010

This paper deal with an analysis of the ground surface potential profiles using a hemispherical scaled-model. Because it is very difficult to draw valid conclusions concerning a general grounding problem from actual field data, scale model tests can be used to determine the ground surface potential profile around the grounding electrodes according to the configuration of grounding electrodes. In this work, a hemispherical vessel with a diameter of 1,100 [mm] was employed to simulate uniform soil and CDEGS program was employed to compare the measured and simulated results. As a result, the ground surface potential around the grounding electrode was significantly raised and the ground surface potential at the just upper point of ground electrode particularly was higher than other points. The ground surface potential of counterpoise was higher than other grounding electrodes such as mesh and grounding rods and the ground surface potential strongly depends on the frequency responses of grounding electrodes. Also the results measured with the small-sized model were in reasonably agreement with the data obtained from simulation.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.51 no.8
• /
• pp.347-353
• /
• 2002

This paper presents an accurate method for measuring the ground resistance in powered grounding system. Most of substations and electric power equipments are interconnected to an extensive grounding network of overhead ground wires, neutral conductors of transmission lines, cable shields, and etc. The parasitic effects due to circulating ground currents and ground potential rise make a significant error in measuring the ground resistance. The test current transition method was proposed to reduce the effects of stray ground currents, ground potential rise and harmonic components in measurements of the ground resistance for powered grounding systems. The instrumental error of the test current transition method is decreased as the ratio of the test current signal to noise(S/N) increases. It was found from the test results that the proposed measuring method of the ground resistance is more accurate than the conventional fall-of-potential method or low-pass filter method, and the measuring error was less than 3[%]when S/N is 10.