Browse > Article
http://dx.doi.org/10.5207/JIEIE.2011.25.6.068

Analysis of Electric Shock Hazards due to Touch Current According to Soil Resistivity Ratio in Two-layer Earth Model  

Lee, Bok-Hee (인하대학교 IT공과대학 전기공학부)
Kim, Tae-Ki (인하대 대학원 전기공학과)
Cho, Yong-Seung (인하대 대학원 전기공학과)
Choi, Jong-Hyuk (인하대 대학원 전기공학과)
Publication Information
Journal of the Korean Institute of Illuminating and Electrical Installation Engineers / v.25, no.6, 2011 , pp. 68-74 More about this Journal
Abstract
The touch or step voltages which exist in the vicinity of a grounding electrode are closely related to the earth structure and resistivity and the ground current. The grounding design approach is required to determine the grounding electrode location where the hazardous voltages are minimized. In this paper, in order to propose a method of mitigating the electric shock hazards caused by the ground surface potential rise in the vicinity of a counterpoise, the hazards relevant to touch voltage were evaluated as a function of the soil resistivity ratio $\rho_2/\rho_1$ for several practical values of two-layer earth structures. The touch voltage and current on the ground surface just above the test electrode are calculated with CDEGS program. As a consequence, it was found that burying a grounding electrode in the soil with low resistivity is effective to reduce the electric shock hazards. In the case that the bottom layer soil where a counterpoise is buried has lower resistivity than the upper layer soil, when the upper layer soil resistivity is increased, the surface potential is slightly raised, but the current through the human body is reduced with increasing the upper layer soil resistivity because of the greater contact resistance between the earth surface and the feet. The electric shock hazard in the vicinity of grounding electrodes is closely related to soil structure and resistivity and are reduced with increasing the ration of the upper layer resistivity to the bottom layer resistivity in two-layer soil.
Keywords
Soil Resistivity; Touch Voltage; Two-Layer Earth Model; Counterpoise; Ground Surface Potential Rise;
Citations & Related Records
연도 인용수 순위
  • Reference
1 International Standard IEC 61936-1, “Power installations exceeding 1 kV a.c. - Part 1: Common rules”, 2nd ed. pp.84-88, 2010.
2 IEEE. Standard Board, “IEEE Guide for Measuring Earth Resistivity. Ground Impedence, and Earth Surface Potentials of a Ground System”, IEEE Std 81, pp.24-26. 1983.
3 IEEE. Standard Board, “IEEE Guide for safety in AC Substation Grounding”. IEEE Std 80, pp.16-29. 2000.
4 KS C IEC 62305-3, “피뢰시스템 - 제3부 : 구조물의 물 리적 손상 및 인명위험”, pp.249-268, 2007.
5 이복희, 이승칠, “접지의 핵심 기초 기술”, 도서출판 의제, pp.27-64, 1999.
6 F. P. Dawalibi and D. Mukhedkar, "Optimum design of substation grounding in two-layer earth structure - Part I, Analytical study", IEEE Trans. PAS, Vol.94, No.2, pp.252-261, 1975.   DOI
7 Kostic, M.B. “Parametric analysis of foundation grounding systems surrounded by two-layer soil”, IEEE Trans. Power Del., Vol.9, No.3, pp.1406-1411, 1994.   DOI
8 Kosztaluk, R., Mukhedkar, R. Gervais, Y., “Field Measurements of Touch And Step Voltages”, IEEE Trans. on PAS, Vol 103, No. 11, pp.3286-3294, 1984.   DOI
9 Chow, Y.L., Salama, M.M.A., Djogo, G., “Thevenin source resistances of the touch, transferred and step voltages of a grounding system”, IEE PGTD, Vo. 146, No. 2, pp.107-114, 1999.
10 IEEE. Standard Board, “IEEE Guide for Measurement of Impedence and Safety Characteristics of Large, Extended or Interconnected Grounding System”, IEEE Std 81-2, pp.51-56. 1991.
11 European Committee for Electrotechnical Standardization, “Power installations exceeding 1 kV a.c.”, HD 637 S1, pp.75-85, 1999.