Measurement and Analysis of Risk Voltages by Various Current Sources in Grounding System

다양한 전류원에 대한 접지시스템의 위험전압 측정과 분석

  • 길경석 (한국해양대 전기전자공학부) ;
  • 문병두 (한국해양대 전기전자공학부) ;
  • 김황국 (한국해양대 전기전자공학부) ;
  • 박대원 (한국해양대 전기전자공학부) ;
  • 길형준 (한국전기안전연구원)
  • Published : 2009.01.01

Abstract

Grounding systems set the reference voltage level of electric circuits and suppress the Ground Potential Rise (GPR) by flowing fault currents to the ground safely. There are several parameters which evaluate the performance of grounding systems as ground resistance, touch voltage and step voltage. The touch and step voltages, which is called "risk voltage", are especially important to ensure the safety of human body. This paper dealt with the influence of current sources with the different frequency components on the touch and the step voltages. Three types of current sources as commercial frequency, square wave, and surge with the fast risetime of $50\;ns{\sim}500\;ns$ were used to analyze the risk voltages in a grounding system. The risk voltages showed remarkable difference in the same current amplitude depending on the current sources, and increased linearly with the current amplitude in the same current source. From the experimental results, it was confirmed that the risk voltages can be evaluated by a small current application in large-scale grounding systems and the possible largest risk voltage can be calculated by a surge current with the risetime of 200 ns or a current source with the same frequency component as the surge current.

References

  1. Ronald P. O Riley, 'Electrical Grounding: Bringing Grounding Back to Earth', DELMAR, pp.40-43, 2002
  2. Chien-Hsing Lee, A.P Sakis Meliopoulos, 'A Comparison of IEC 479-1 and IEEE Std. 80 on Grounding Safety Criteria', Proc. Natl. Sci. Counc. ROC(A), Vol. 23, No.5, pp.612-621, 1999
  3. A. Geri, '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, 1999 https://doi.org/10.1109/61.772347
  4. A.P. Sakis Meliopoulos, 'Power System Grounding and Transient : An Introduction', Marcel Dekker, INC., 1988
  5. Romuald Kosztaluk, Dinkar Mukhedkar, Yvon Gervais, 'Field Measurements of Touch and Step Voltages', IEEE Trans. on Power Apparatus and Systems, Vol. PAS-103, No. 11, pp.3286-3294, 1984 https://doi.org/10.1109/TPAS.1984.318571
  6. A.P. Sakis Meliopoulos, George Cokkinides 'A PC Based Ground Impedance Measurement Instrument', IEEE Trans. on Power Delivery, Vol. 8, No.3, pp.1095-1106, 1993 https://doi.org/10.1109/61.252636
  7. H. Zhao, H. Gruffiths, A Haddad, A. Ainsley, F. Ainslie, D. Frame, 'Error in Step and Touch Voltage Measurements at Large Substations' XIVth International Symposium on High Voltage Engineering, B-18, 2005
  8. Tony Mitton, Robin Watson, 'Practical Testing of Grounding Systems by Current Injection', CDEGS User Meeting, pp. 1-8, 2005
  9. 최홍규, 최병숙, 송영주, '접지설비 및 설계', 성안당, pp. 223-229, 2007
  10. 길경석, 류길수, 김일권, 문병두, 김황국, 박찬용, Design and Fabrication of a Surge Impedance Meter', 한국철도학회 논문집, 제10권, 제6호, pp.645-649, 2007
  11. IEEE Std 81.2, 'IEEE Guide for measurement of Impedance and Safety characteristics of Large, Extended or Interconnected Grounding Systems,' pp.51-55, 1991 https://doi.org/10.1109/IEEESTD.1992.106970
  12. IEEE Std 80, 'IEEE Guide for safety in AC Substation Grounding,' pp.43-48, 1986 https://doi.org/10.1109/IEEESTD.1986.81070
  13. G. Parise, U. Grasselli, R. Iaconelli, 'Measurements of touch and step voltages adopting multi current auxiliary electrodes', Industry Applications Conference, vol. 5, pp.3187-3193, 8-12 Oct. 2000
  14. Y. L. Chow, M. M. A. Salama, G. Djogo, 'Thevenin source resistances of the touch, transferred and step voltages of a grounding system', Generation, Proceedings of IEE Transmission and Distribution, Volume 146, Issue 2, pp.107-114, March 1999 https://doi.org/10.1049/ip-gtd:19990038