1. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 1 - Overvoltage Protection and Insulation Coordination in Power Systems Prof. Dr.-Ing. Volker Hinrichsen Dipl.-Ing. Thomas Rettenmaier Technische Universität Darmstadt High Voltage Laboratories © Siemens

2. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 2 - What is Insulation Coordination? Definition in IEC 60071-1 Definition in IEEE 1313.1

3. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 3 - Fundamentals of Insulation Coordination Time duration of (over-)voltage Possible voltages without arresters Voltages limited by arresters Withstand voltage of equipment Lightning overvoltages (Microseconds) Switching overvoltages (Milliseconds) Temporary overvoltages (Seconds) Highest voltage of equipment (Continuously) Magnitude of (over-)voltage / p.u. 1 2 3 4 0 5

4. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 4 - What is Insulation Coordination? Procedure of insulation coordination [THI-01] Three elements are involved in the insulation coordination discipline, namely: the study of the "stresses", both electrical and environmental, acting on the equipment insulation. This is usually performed by calculations or field measurements; the study of the "strength" (dielectric withstand characteristics) of the insulation (both new and aged) when submitted to such stresses, taking into account, when applicable, the effect of the environmental stresses (pollution, rain, snow, ice, atmospheric conditions at large altidudes), including the study of the "test and measurement techniques" which are employed to assess such strength. The strength is determined by calculations, based on suitable discharge models, and/or by laboratory/factory tests, on-site tests and in-service measurements (diagnostics); the assessment of the insulation performance (usually expressed in terms of risk of failure) in the considered situation of stresses and strength, including the selection and application of "protective devices and techniques", to establish the final insulation design fulfilling the specified requirements. This may be based on "deterministic" or "statistical" approach. Three elements are involved in the insulation coordination discipline, namely: the study of the "stresses", both electrical and environmental, acting on the equipment insulation. This is usually performed by calculations or field measurements; the study of the "strength" (dielectric withstand characteristics) of the insulation (both new and aged) when submitted to such stresses, taking into account, when applicable, the effect of the environmental stresses (pollution, rain, snow, ice, atmospheric conditions at large altidudes), including the study of the "test and measurement techniques" which are employed to assess such strength. The strength is determined by calculations, based on suitable discharge models, and/or by laboratory/factory tests, on-site tests and in-service measurements (diagnostics); the assessment of the insulation performance (usually expressed in terms of risk of failure) in the considered situation of stresses and strength, including the selection and application of "protective devices and techniques", to establish the final insulation design fulfilling the specified requirements. This may be based on "deterministic" or "statistical" approach.

5. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 5 - Literature (1) [BAL-04-1]G. Balzer Power Systems, Part 2 Chapter 4: Insulation coordination Script TU Darmstadt, 2004 [BAL-04-2]G. Balzer Elektrische Energieversorgung, Teil 2 Kapitel 4: Isolationskoordination Skript der TU Darmstadt, 2004 [CIG-73]CIGRE W.G. 13-02 Switching overvoltages in EHV and UHV systems with special reference to closing and reclosing transmission lines ELECTRA 30 (1973) pp. 70-122 [CIG-79-1]CIGRE WG 33.02 Phase-to-phase Insulation Co-ordination: Part 1: Switching overvoltages in three-phase systems ELECTRA 64 (1979) pp. 138-158 [CIG-79-2]CIGRE WG 33.03 Phase-to-phase Insulation Co-ordination Part 2: Switching impulse strength of phase-to-phase external insulation ELECTRA 64 1979, pp. 158-181

6. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 6 - Literature (2) [CIG-79-3]CIGRE WG 33.06 Phase-to-phase Insulation Co-ordination Part 3: Design and testing of phase-to-phase insulation ELECTRA 64 1979, pp. 182-210 [CIG-79-4]CIGRE TF 33-03.03 Phase-to-phase Insulation Co-ordination Part 4: The influence of non-standard conditions on the switching impulse strength of phase-to-phase insulation ELECTRA 64 1979, pp. 211-230 [CIG-91]CIGRE WG 33.01 Guide to procedures for estimating the lightning performance of transmission lines, CIGRE technical brochure No. 63, 1991 buch_020.pdf [CIG-92]CIGRE WG 33-07 Guidelines for the evaluation of the dielectric strength of external insulation, CIGRE technical brochure No. 72, 1992 buch_019.pdf [DOR-81]H. Dorsch Überspannungen und Isolationsbemessung bei Drehstrom-Hochspannungsanlagen Siemens AG, Erlangen, 1981 (ISBN 3-8009-1325-9)

7. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 7 - Literature (3) [ERI-88]A.J. Eriksson, K.-H. Weck Simplified procedures for determining representative substation impinging lightning overvoltages, CIGRE report 33-16, 1988 [ETG-93]ETG-Fachbericht 49 ETG-Tage '93: Isolationskoordination in Hoch- und Mittelspannungsanlagen vde-Verlag GmbH Berlin, Offenbach (ISBN 0341-3934) [FGH-78]FGH Technischer Bericht 1-240 Isolationskoordination auf der Grundlage der neuen DIN/VDE-Bestimmung 0111 FGH, Mannheim, Juli 1978 [HIL-99]A. R. Hileman Insulation Coordination for Power Systems Marcel Dekker, Inc., New York, Basel, 1999 [HIN-00]V. Hinrichsen Metalloxidableiter: Grundlagen Siemens AG Berlin, 1. Auflage 2000 AbleiterBuch.pdf [HIN-01]V. Hinrichsen Metalloxidableiter: Grundlagen Siemens AG Berlin, Edition 1, 2001 ArresterBook.pdf

8. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 8 - [HIN-03]V. Hinrichsen Latest Designs and Service Experience with Station-Class Polymer Housed Surge Arresters World Conference on Insulators, Arresters & Bushings Marbella (Málaga), Spain, November 16-19, 2003, Proceedings pp. 85-96 pub_048.pdf [KIN-05]V. Hinrichsen Latest Testing Requirements and Emerging Standards for Transmission Line Arresters World Conference on Insulators, Arresters & Bushings Hong Kong, November 27-30, 2005 inmr_2005_paper.pdf [KIS-84]I. Kishizima, K. Matsumoto, Y. Watanabe, New facilities for phase switching impulse tests and some test results, IEEE PAS TO3 No. 6, June 1984 pp. 1211-1216. [KOE-93-1]D. König, Y. N. Rao Teilentladungen in Betriebsmitteln der Energietechnik vde-Verlag, Berlin, Offenburg, 1993, ISBN 3-8007-1764-6 [KOE-93-2]D. König, Y. N. Rao Partial discharges in Power Apparatus vde-Verlag, Berlin, Offenburg, 1993, ISBN 3-8007-1760-3 Literature (4)

9. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 9 - [PAR-68]L. Paris, R. Cortina Switching and lightning impulse discharge characteristics of large air gaps and long insulation strings, IEEE Trans on PAS, vol 87, No. 4, April 1968, p. 947-957 [ RUD-99-1]R. Rudolph, B. Richter Dimensioning, testing and application of metal oxide surge arresters in medium voltage networks 3rd Edition, 1999, ABB Switzerland, 26 pages (also available in German) application_guide_medium_voltage_networks.pdf [RUD-99-2]R. Rudolph, B. Richter Bemessung, Prüfung und Einsatz von Metalloxid-Ableitern in Mittelspannungsnetzen ABB Schweiz AG, Wettingen (CH), 3. Auflage 1999 Anwendungsrichtlinien_Mittelspannung.pdf [THI-01]L. Thione Insulation coordination in electrical power systems – theory and application Tutorial, ALPI, Milan, 2001 (www.alpiass.com)www.alpiass.com buch_018.pdf Literature (5)

10. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 10 - [WEC-07] K.-H. Weck Standardization of insulation withstand levels for UHV systems in IEC TC 28 „Insulation co-ordination” IEC/CIGRE UHV Symposium Beijing 18-21 July 2007, report 5-4 5-4_KHWeck.pdf Overview on CIGRE publications (very interesting!): Cigré Catalogue of Publications 01/07/2005 CATALOGUE_PUBLICATIONS_2005.pdf Literature (6)

11. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 11 - IEC 60071-1, Edition 8.0 (2006-01) + Amendment 1 (2009-09) Insulation co-ordination – Part 1: Definitions, principles and rules IEC 60071-2, Third Edition (1996-12) Insulation co-ordination – Part 2: Application guide IEC/TR 60071-4, First Edition (2004-06) Insulation co-ordination - Part 4: Computational guide to insulation co-ordination and modelling of electrical networks IEC 60099-4, Ed. 2.1, 2006-07 Surge arresters – Part 4: Metal-oxide surge arresters without gaps for a.c. systems IEC 60099-5, Ed. 1.1, 2000-03 Surge arresters – Part 5: Selection and application recommendations DIN EN 60071-1, 1996-07 Isolationskoordination - Teil 1: Begriffe, Grundsätze und Anforderungen (IEC 60071-1:1993); Deutsche Fassung EN 60071-1:1995 DIN EN 60071-2, 1997-09 Isolationskoordination - Teil 2: Anwendungsrichtlinie (IEC 60071-2:1996); Deutsche Fassung EN 60071-2:1997 IEEE 1313.1-1996 IEEE Standard for Insulation Coordination—Definitions, Principles, and Rules Standards (1)

12. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 12 - IEEE 1313.2-1999 IEEE Guide for the Application of Insulation Coordination IEEE C62.11-2005 IEEE Standard for Metal-Oxide Surge Arresters for AC Power Circuits (> 1 kV) IEEE C62.22-1997 IEEE Guide for the Application of Metal-Oxide Surge Arresters for Alternating-Current Systems Standards (2)

13. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 13 - Organization 115.10.200912:30-14:00Lecture 1Introduction 222.10.200914:00-15:30Lecture 2 Voltage stresses in power systems 329.10.200914:00-15:30Lecture 3 45.11.200914:00-15:30Lecture 4 512.11.200914:00-15:30Lecture 5 Traveling waves 19.11.2009Cancelled 626.11.200914:00-15:30Lecture 6 Overvoltage protection by surge arresters 73.12.200914:00-15:30Lecture 7 810.12.200914:00-15:30Lecture 8 Dielectric strength (incl. gap factors, pollution, rain, parallel insulation, aging) 917.12.200914:00-15:30Lecture 9 24.12.2009 Christmas holidays 31.12.2009 7.1.2010 1014.01.201014:00-15:30Lecture 10 Insulation coordination 1121.01.201014:00-15:30Lecture 11 1228.01.201014:00-15:30Lecture 12 Calculation Examples 1304.02.201014:00-15:30Lecture 13 UHV systems; test procedures; condition monitoring (partial discharges, non-conventional approaches) 1411.02.201014:00-15:30Lecture 14

14. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 14 - Organization Examination Exclusively oral Exercises None; but calculation examples in the lecture Script Slides will be available for download www.hst.tu-darmstadt.de User: PW:

15. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 15 - Insulation Coordination - Principles Environment System System voltages Dielectric strength Equipment Overvoltage protection devices stress versus strength

16. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 16 - Insulation Coordination - Principles Voltages of the system –Nominal voltage U n »rounded value for characterizing the system »10 kV - 20 kV - 110 kV - 220 kV - 380 kV –System voltage »voltage at which the system is being operated »around the nominal value, but not constant –Highest system voltage U s »highest operating voltage between phases under normal conditions »12 kV - 24 kV - 123 kV - 245 kV - 420 kV (IEC 60038) Voltages of equipment –Highest voltage for equipment U m »highest voltage between phases for which the insulation is designed »12 kV - 24 kV - 123 kV - 245 kV - 420 kV (IEC 60071-1)

17. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 17 - Insulation Coordination - Principles Overvoltages –voltages exceeding the peak value of the highest system voltage –various amplitudes and shapes depending on »system configuration (grid size, degree of meshing, etc.) »origin of overvoltage (failure, switching, lightning strike etc.) Dielectric strength of insulation –verified by type test in the laboratory with the help of »standardized test voltages (shape, amplitude) »specified test setups »specified environmental conditions Insulation coordination –Determination of interdependence between voltages and overvoltages of the system and necessary test voltages for the equipment in the laboratory

18. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 18 - Insulation Coordination - Principles Equipment in the laboratory Equipment in the laboratory Equipment in the system Equipment in the system Variety of amplitudes and shapes of overvoltages Variety of amplitudes and shapes of overvoltages Standardized amplitudes and shapes of test voltages Standardized amplitudes and shapes of test voltages Variety of operating conditions and age Variety of operating conditions and age Standardized setups and conditions Standardized setups and conditions Variety of environmental conditions Variety of environmental conditions Standardized environmental conditions Standardized environmental conditions

19. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 19 - Insulation Coordination - Principles line bb 1 bb 2 busbar disconnectors Insulation phase - ground stressed by voltages between one phase and ground 1 Insulation phase - phase stressed by voltages between two phases 2 Longitudinal insulation stressed by voltages between same phases of two different systems 3 2 3 1

20. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 20 - Insulation Coordination according to IEC 60071-1 (and 60071-2)

21. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 21 - Insulation Coordination according to IEC 60071-1 (and 60071-2)

22. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 22 - Insulation Coordination according to IEC 60071-1 (and 60071-2) Procedure for insulation coordination = 10 pages! Procedure for insulation coordination = 10 pages!...39 pages in sum

23. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 23 - Insulation Coordination according to IEC 60071-1 (and 60071-2)

24. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 24 - Insulation Coordination according to IEC 60071-1 (and 60071-2)

25. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 25 - Insulation Coordination according to IEC 60071-1 (and 60071-2)

26. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 26 - Insulation Coordination according to IEC 60071-1 (and 60071-2)

27. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 27 - Insulation Coordination according to IEC 60071-1 (and 60071-2)

28. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 28 - Insulation Coordination according to IEC 60071-1 (and 60071-2)...125 pages in sum

29. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 29 - Procedure for Insulation Coordination - General The procedure for insulation coordination consists of the selection of a set of standard withstand voltages which characterize the insulation of the equipment. Range IRange II

30. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 30 - Procedure for Insulation Coordination - General Basic difference between ranges I and II withstand voltage time duration of stress peak gap spacing 3 m gap spacing 0.5 m [FGH-78] Minimum of withstand voltage for switching overvoltage Withstand voltage continuously decreasing with time duration of stress Range I Range II

31. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 31 - Procedure for Insulation Coordination in Four Steps Determination of the representative overvoltages U rp The representative overvoltages are derived from real service conditions, but have just standardized shapes. They are determined in amplitude, shape and duration by system analysis, taking into account overvoltage limiting devices. [IEC 60071-1]

32. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 32 - Determination of the coordination withstand voltages U cw The coordination withstand voltages are the lowest values of withstand voltages of each overvoltage class, for which the expected low failure rate of the equipment is not exceeded over its full lifetime. Derived from the representative overvoltages U rp by the coordination factor K c. [IEC 60071-1] Procedure for Insulation Coordination in Four Steps Typical for Germany: 0.1% per year  1 failure in 1000 years

33. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 33 - Procedure for Insulation Coordination in Four Steps Deterministic approach Statistical approach Assumed maximum of representative overvoltage Assumed maximum of representative overvoltage Multiplication by coordination factor based on operating experience Multiplication by coordination factor based on operating experience Statistical distribution of representative overvoltages Statistical distribution of representative overvoltages Determination of failure probability of insulation Determination of failure probability of insulation Calculation of failure risk depending on assumed coordination withstand voltage Calculation of failure risk depending on assumed coordination withstand voltage Coordination withstand voltage Assumed conventional U cw (0% value) Statistical U cw (10% value) Coordination withstand voltage Assumed conventional U cw (0% value) Statistical U cw (10% value)

34. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 34 - Determination of the required withstand voltages U rw The required withstand voltages are determined by converting the coordination withstand voltages to appropriate standard test conditions. Usually different from the coordination withstand voltages. Derived from the coordination withstand voltages U cw by the safety factor K s and the atmospheric correction factor K t or the altitude correction factor K a. [IEC 60071-1] Procedure for Insulation Coordination in Four Steps

35. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 35 - [IEC 60071-1] Procedure for Insulation Coordination in Four Steps Influences covered by the safety factor K s Differences in equipment assembly Dispersion in product quality Quality of installation Aging of the installation during expected lifetime Other unknown influences

36. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 36 - Determination of the required withstand voltages U rw The required withstand voltages are determined by converting the coordination withstand voltages to appropriate standard test conditions. Usually different from the coordination withstand voltages. Derived from the coordination withstand voltages U cw by the safety factor K s and/or the altitude correction factor K a. [IEC 60071-1] Procedure for Insulation Coordination in Four Steps

37. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 37 - Selection of the rated and of the standard insulation level (set of standard rated withstand voltages U w ) Most economical set of standard withstand voltages U w of the insulation to prove that all the required withstand voltages are met. For each range (I or II) a combination of only two withstand voltages defined: Range I:standard lightning impulse withstand voltage standard short-duration power-frequency withstand voltage Range II:standard switching impulse withstand voltage standard lightning impulse withstand voltage For range I, only phase-to-earth standard withstand voltages are defined, which have to cover phase-to-earth, phase-to-phase and longitudinal insulation. Procedure for Insulation Coordination in Four Steps

38. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 38 - [IEC 60071-1] Procedure for Insulation Coordination in Four Steps Definitions

39. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 39 - Procedure for Insulation Coordination in Four Steps Examples for…... non-self-restoring insulation (power transformers, instrument transformers *) ) *) mixed insulation... self-restoring insulation (disconnectors, insulators)

40. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 40 - [IEC 60071-1:2006/FprA1:2008] Procedure for Insulation Coordination in Four Steps List of standard short-duration power-frequency withstand voltages (r.m.s. values in kV) 1020283850 7095115140185 230275325360395 460510570630680 2040607595125145170200250325 3804505506507508509501050117513001425 15501675180019502100225024002550270029003100 List of standard impulse withstand voltages (peak values in kV) 710790830880960 975105011001200 Standardized: Under consideration:

41. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 41 - The standard voltage values are all the same for phase-to-earth-, phase-to-phase-, longitudinal insulation! Range I: U m = 1 kV up to and including U m = 245 kV Procedure for Insulation Coordination in Four Steps [IEC 60071-1]

42. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 42 - Range II: U m above 245 kV Different standard voltage values for phase-to-earth-, phase-to-phase-, longitudinal insulation! Procedure for Insulation Coordination in Four Steps [IEC 60071-1]

43. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 43 - Procedure for Insulation Coordination in Four Steps [IEC 60071-1, Amendment 1: 2009-09] New with Amendment 1, 2009

44. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 44 - Procedure for Insulation Coordination in Four Steps Outcome of insulation coordination –For three types of insulation »phase to ground »phase to phase »longitudinal –and for 4 values each of required withstand voltages U rw »required continuous operating voltage »required short-duration power-frequency withstand voltage »required switching impulse withstand voltage »required lightning impulse withstand voltage  Standardization of tests for equipment –Reduction of these 12 values to a necessary minimum number of withstand voltages U w of the insulation –Determination of necessary withstand voltages from tables for two ranges of highest voltage for equipment twelve voltages

45. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 45 - [IEC 60071-1] Procedure for Insulation Coordination in Four Steps - Summary Flow chart acc. to IEC 60071-1 (Figure 1) continued next slide

46. Fachgebiet Hochspannungstechnik Overvoltage Protection and Insulation Coordination / Chapter 1- 46 - [IEC 60071-1] Procedure for Insulation Coordination in Four Steps - Summary Flow chart acc. to IEC 60071-1 (Figure 1) (continued)