2014 KSR2014S186

Seasonal Variation of Ground Impedance for a Copper-rods and a Carbon-block *, *, *, *

Sun-Jae Kim*, Gi-Woo Jeong*, Guoming Wang*, Gyung-Suk Kil*

Abstract This paper described the seasonal variation of ground impedance for a copper-rods and a carbon block buried in the ground. Ground impedance was measured by the fall of potential method specified in IEEE Std. 81 and by the application of a fast-rise step impulse, a 8/20us standard lightning impulse and a square waveform for 2 years periodically. Comparatively, ground impedance as ages showed no difference for the last 2 years, and ground impedance of the carbon block was lower at the square waveform and was higher at the fast-rise step impulse than that of the copper-rods.

Keywords : Copper-rods, Carbon-block, Ground impedance, Fall of potential method, Seasonal variation

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Fig. 1 Definition of ground impedance to impulse

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Fig. 2 Photographs of ground electrodes

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Fig. 3 Configuration of the experimental setup

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(a) Fast-rise step impulse (b) Standard lightning impulse (c) Square waveform

Fig. 5 Typical waveforms of applied current and potential rise for the carbon-block

Table 1 .

Table 1 Ground impedance against applied current

Ground electrode

Current source Copper-rods () Carbon-block ()

Fast-rise step impulse 152.63 154.12

Standard lightning impulse 71.43 64.71

Square waveform 94.29 78.57

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International Conference and Exhibition on Optimization of Electrical and Electronic Equipments(OPTIM98), pp.171~174

[2] Chien-Hsing Lee, A. P. Sakis Meliopoulos (1999) A Comparison of IEC 479-1 and IEEE Std. 80 on Grounding Safety Criteria, Proc. Natl. Sci. Counc. ROC(A), 23(5), pp.612~621.

[3] A. Geri, 1999, Behaviour of Grounding Systems Excited by High Impulse Currents: the Model and Its Validation, IEEE Trans. On Power Delivery, Vol.14, No.3, pp.1008~1017.

[4] G. Vijayaraghavan, Mark Brown and Malcolm Barnes, 2004, Grounding, Bonding, Shielding and Surge Protection, Butterworth-Heinemann, United Kingdom, pp.62~78

[5] , , (1997) , , pp.203~218. [6] Ralph Morrison, Warren H. Lewis (1990) GROUNDING AND SHIELDING IN FACILITIES, John

Wiley & Sons, pp.44~45. [7] I. F. Gonos, F. V. Topalis, I. A. Stathopulos (1999) Transient Impedance of Grounding Rods, High

Voltage Engineering Symposium, 2(467), pp.272~275.

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