Insulation Coordination of a UHV AC Transmission Line Considering the Switching Overvoltage Waveshape


A. Ramchandra Reddy


This paper presents the determination of insulation coordination for phase-to-ground switching over voltages by a practical method in which the effect of the switching overvoltage waveshape, especially the impact of the time to crest on insulation strength is considered. This work is carried out on the world’s first 1200 kV transmission line by modelling it in PSCAD.


How to Cite
Reddy, A. R. . (2023). Insulation Coordination of a UHV AC Transmission Line Considering the Switching Overvoltage Waveshape. Power Research - A Journal of CPRI, 18(2), 93–99.


  1. CIGRE Working Group 13.05. The calculation of switching surges- II. Network representation for energization and re-energization studies on lines fed by an inductive source. Electra N° 32; 1974. p. 17-42.
  2. IEC 60071-2, Insulation coordination- Part 2: Application guide; 1996.
  3. Hileman AR. Insulation coordination for power systems. New York: Marcel Dekker; 1999. DOI:
  4. Oprea L, Velicescu C. Switching overvoltages on 400 and 750 kV Romanian transmission lines. International Conference on Power System Transients (IPST), Budapest, Hungary; 1999 Jun. p. 142-146.
  5. Arabani MP, Fathi AF. Effect of line configuration changes on its insulation coordination. CIGRE Session, Paris; 2002. P. 33-103.
  6. Hamza AH, Ghania SM, Emam AM, Shafy AS. Failure risk analysis under switching surges in power transmission systems. Electric Power Systems Research. 2019 Jan; 166:190-8. DOI:
  7. Nunes RR, Boaventura WDC. Insulation coordination considering the switching overvoltage waveshape - Part I: Methodology. IEEE Transactions on Power Delivery. 2009 Oct; 24(4):2434-40. TPWRD.2009.2028477 DOI:
  8. Li Y. He J, Yuan J. Li C, Hu J, Zeng R. Failure risk of UHV AC transmission line considering the statistical characteristics of switching overvoltage waveshape. IEEE Transactions on Power Delivery. 2013 Jul; 28(3): 1731-9. DOI:
  9. Nayak RN, Bhatnagar MC, De Bhowmick BN, Tyagi. RK. 1200 kV transmission system and status of development of substation equipment/transmission line material in India. Second International Symposium on Standards for Ultra High Voltage Transmission. New Delhi, India; 2009 Jan.
  10. PSCAD® Software. Rep. Version 4.6.0; 2018 May.
  11. IEC 60071-4, Insulation co-ordination- Part 4: Computational Guide to Insulation co-ordination and modelling of electrical networks; 2004.
  12. Ibrahim AI, Dommel HW. A knowledge base for switching surge transients. International Conference on Power Systems Transients (IPST-2005). Montreal, QC, Canada; 2005 Jun.
  13. CIGRE Technical Brochure 362. Technical requirements for substations exceeding 800 kV. CIGRE WG A3.22; 2008 Dec.
  14. Bhurat P, Meera KS, Vasudev N. Application of line surge arresters for switching over-voltages in UHV transmission systems. Power Research. 2020 Jul-Dec; 16(2):87-93. DOI:
  15. CIGRE working group 13.02. Switching overvoltages in EHV and UHV systems with special reference to closing and reclosing transmission lines. Electra N° 30. 1973. p. 70-122.
  16. Lings RJ. EPRI AC transmission line reference book- 200 kV and above. 3rd ed. Palo Alto, CA: Electric Power Research Institute; 2005. ch.3. 5.
  17. Martinez JA, Natarajan R, Camm E. Comparison of statistical switching results using gaussian, uniform and systematic switching approaches. Power Engineering Society Summer Meeting Seattle, WA, USA. 2000 Jul; 2: 884-889.
  18. Jardini JA, Saiki GY, Bassini MT, Nicola GLC, Graham JF. Electromagnetic transients in a 1000 kV System: Part II- Line energization, reclosing and insulation coordination. 2016 IEEE PES Transmission and Distribution Conference and Exposition Latin America (T&D LA), Morelia; 2016 Sept. p. 21-23. DOI:
  19. CIGRE Technical Brochure 336. Changing network conditions and system requirements. CIGRE WG A3.13; 2007 Dec.
  20. CIGRE technical brochure 400. Technical requirements for substations exceeding 800 kV. CIGRE WG B3.22; 2009 Dec.
  21. Gela G. Air gap sparkover and gap factors - analysis of published data. EPRI TR-104437, Project 3787. Final Report; 1994 Dec.
  22. Kishizima I, Matsumoto K, Watanabe Y. New facilities for phase-to-phase switching impulse tests and some test results. IEEE Transactions on Power Apparatus and Systems. 1984 Jun; PAS-103(6):1211-6. DOI:
  23. Ramakrishna V, Nayak RN, Bhatnagar MC, De Bhowmick BN, Tyagi RK. 1200 kV transmission network and development status of 1200 kV technology in India. CIGRE Session, Paris; 2010. p. A3-105.
  24. Thione L. Evaluation of switching impulse strength of external insulation. Electra No 94. 1983. p. 77-95.
  25. IEEE Standard 1862. IEEE recommended practice for overvoltage and insulation coordination of transmission systems at 1000 kV AC and above; 2014.