volume | PIER Journals

Abstract

Different optimization strategies to reduce the earth resistance in a high resistivity soil are discussed in this work and illustrated with a practical example. Finite Element simulations reproducing real-world conditions in terms of structure design and soil profiles have been made to evaluate the improvements that should be adopted to minimize earth resistance. We analyze an example of an earthing system of an array of four identical telescopes installed on high resistivity (k¢m order) soils with two different behaviors. In the first one, current dissipation occurs in an uniform soil. In the second one, a terrain with four layers of different resistivities is considered. This situation corresponds to a real world case of an observatory constructed in a volcanic terrain. It was found that the best strategy in each case differs: extend horizontal electrodes as far as possible from the foundation in the first case and combine these electrodes with buried vertical electrodes that connect with deep high conductive layers in the second. The results are discussed in terms of the achieved improvements depending on the modifications introduced in the main structure.

1. International Electrotechnical Commission (IEC), , Protection against lightning — Part 1: General principles, IEC 62305-1, Ed 2.0 2010-12, 2010, https://webstore.iec.ch/preview/info iec62305-1%7Bed2.0%7Den.pdf.

2. International Electrotechnical Commission (IEC), , Protection against lightning — Part 2: Risk management, 2010, https://webstore.iec.ch/preview/info iec62305-2%7Bed2.0%7Den.pdf.

3. International Electrotecnical Commission, , Protection against lightning—Part 3: Physical damage to structures and life hazard, IEC 62305-3, 2010, https://webstore.iec.ch/publication/6795.

4. International Electrotecnical Commission "Protection against lightning — Part 4: Electrical and electronic systems within structures, IEC 62305-4,", 2010, https://webstore.iec.ch/searchform&q=IEC 62305-4. Google Scholar

5. ITC-BT-18, Ministerio de Ciencia y Tecnologia, 2018.

6. Ueng, T. T.-S., Y.-C. Lin, J.-C. Chang, and C.-K. Kuan, The ground testing of tps ground system, 2011, https://accelconf.web.cern.ch/ipac2011/papers/tups062.pdf (accessed: Jun. 06, 2020).

7. British Standards Institution, Code of practice for protective earthing of electrical installations BS 7430:2011, No. 1, 1–96, 2011, https://global.ihs.com/doc detail.cfm?document name=BS 7430&item s key=00131083&csf=TIA (accessed: Jun. 06, 2020).

8. Military handbook grounding, bonding and shielding for electronic equipments and facilities Volume I of II Volumes basic Theory, 1982, https://www.wbdg.org/FFC/NAVFAC/DMMHNAV/hdbk419a vol1.pdf (accessed: Jun. 06, 2020).

9. Electric Engineer Portal, Measurements and calculations of Earth electrode systems, https://electrical-engineering-portal.com/earth-electrode-systems#types-earth-electrodes (accessed: Jun. 06, 2020)..

10. IEEE Std 80 Guide for Safety In AC Substation Grounding, Vol. 2000, Feb. 2000.

11. Okyere, P. Y. and G. Eduful, "Reducing Earth electrode resistance by replacing soil in critical resistance area," J. Mod. Eng., 2006. Google Scholar

12. "IEC 62561-7:2018 Lightning protection system components (LPSC) — Part 7: Requirements for earthing enhancing compound,", International Standard, 2018, https://webstore.iec.ch/publication/33885 (accessed: Jun. 06, 2020). Google Scholar

13. Lindsay, T., "National electrical grounding research project, technical report,", 2007, https://www.nfpa.org/-/media/Files/News-and-Research/Archived-reports/negrpfinalreport.ashx ?la=en. Google Scholar

14. LST — Cherenkov telescope array, https://www.cta-observatory.org/project/technology/lst/ (accessed: Jun. 15, 2020).

15. Cortina, J. and M. Teshima, Status of the Cherenkov telescope array's large size telescopes, 2015, http://cta-observatory.org (accessed: Jun. 15, 2020).

16. Sabiha, N. A. and N. I. Elkalashy, Evaluation of grounding system design for wind farm using COMSOL, 2018, http://www.ripublication.com (accessed: Jun. 26, 2020).

17. Malanda, S. C., I. E. Davidson, E. Singh, and E. Buraimoh, "Analysis of soil resistivity and its impact on grounding systems design," 2018 IEEE PES/IAS PowerAfrica, PowerAfrica 2018, 324-329, Nov. 2018.
doi:10.6028/bulletin.282 Google Scholar

18. Wenner, F., "A Method of measuring Earth resistivity," Bull. Bur. Stand., Vol. 12, 469-478, 1916.
doi:10.4236/jemaa.2020.127008 Google Scholar

19. Ronda, S., O. Martinez, C. Oliver, P. Marquez, and J. M. Miranda, "Finite element analysis and experimental characterization of soil electrical resistivity at El roque de los muchachos observatory," Journal of Electromagnetic Analysis and Applications, Vol. 12, No. 7, 89-102, 2020. Google Scholar

20. De A. de Canarias, I. LIC-15-034: Construction of foundation of Telescope LST1, 10, Plataforma de Contrataci´on del Estado (Spain), 2015, https://contrataciondelestado.es/wps/wcm/connect/8e64f971-f3eb-41d1-a206-edca7ec9b590/DOC CD2015-229760.pdf?MOD=AJPERES (accessed: Jun. 15, 2020).

21. Ma, J., T. Del Pino, and S. P. Martı, NTP-1.084: Prevencion de riesgos laborales originados por la caıda de rayos, 2017.

22. UNE 21186:2011 Proteccion contra el rayo: Pararrayos con dispo, 2011, https://www.aenor.com/normas-y-libros/buscador-de-normas/une/?Tipo=N&c=N0048559 (accessed: Jun. 25, 2020).
doi:10.4018/978-1-5225-3853-0

23. El-Sayed Gouda, O., Design Parameters of Electrical Network Grounding Systems, IGI Global, 2018.

24. Zeng, R., J. He, Z. Wang, Y. Gao, W. Sun, and Q. Su, "Analysis on influence of long vertical grounding electrodes on grounding system for substation," PowerCon 2000 — 2000 International Conference on Power System Technology, Proceedings, Vol. 3, 1475-1480, 2000.
doi:10.4018/978-1-5225-3853-0 Google Scholar

25. El-Sayed Gouda, O., Design Parameters of Electrical Network Grounding Systems, IGI Global, 2018.
doi:10.1016/j.ijepes.2012.10.058

26. Lim, S. C., C. Gomes, and M. Z. A. Ab Kadir, "Electrical earthing in troubled environment," Int. J. Electr. Power Energy Syst., Vol. 47, No. 1, 117-128, May 2013. Google Scholar

27. Zeng, R., J. He, Z. Wang, Y. Gao, W. Sun, and Q. Su, "Analysis on influence of long vertical grounding electrodes on grounding system for substation," PowerCon 2000 — 2000 International Conference on Power System Technology, Proceedings, Vol. 3, 1475-1480, 2000. Google Scholar

28. Malanda, S. C., I. E. Davidson, E. Singh, and E. Buraimoh, "Analysis of soil resistivity and its impact on grounding systems design," 2018 IEEE PES/IAS PowerAfrica, PowerAfrica 2018, 324-329, Nov. 2018.
doi:10.1201/9780429329357 Google Scholar

29. Mitolo, M., Analysis of Grounding and Bounding Systems, CRC Press, 2020.

Miss Silvia Ronda

Dr. Clara Oliver

Dr. OIbar Martínez Vilchez

Dr. Patricia Márquez Paniagua

Dr. Jose Miguel Miranda