oSIST prEN IEC 60071-2:2022
(Main)Insulation co-ordination - Part 2: Application guidelines (Proposed horizontal standard)
Insulation co-ordination - Part 2: Application guidelines (Proposed horizontal standard)
This part of IEC 60071 constitutes application guidelines and deals with the selection of insulation levels of equipment or installations for three-phase a.c. systems. Its aim is to give guidance for the determination of the rated withstand voltages for ranges I and II of IEC 60071- 1 and to justify the association of these rated values with the standardized highest voltages for equipment.
This association is for insulation co-ordination purposes only. The requirements for human safety are not covered by this document.
This document covers three-phase a.c. systems with nominal voltages above 1 kV. The values derived or proposed herein are generally applicable only to such systems. However, the concepts presented are also valid for two-phase or single-phase systems.
This document covers phase-to-earth, phase-to-phase and longitudinal insulation.
This document is not intended to deal with routine tests. These are to be specified by the relevant product committees.
The content of this document strictly follows the flow chart of the insulation co-ordination process presented in Figure 1 of IEC 60071-1:2019. Clauses 5 to 8 correspond to the squares in this flow chart and give detailed information on the concepts governing the insulation coordination process which leads to the establishment of the required withstand levels.
This document emphasizes the necessity of considering, at the very beginning, all origins, all classes and all types of voltage stresses in service irrespective of the range of highest voltage for equipment. Only at the end of the process, when the selection of the standard withstand voltages takes place, does the principle of covering a particular service voltage stress by a standard withstand voltage apply. Also, at this final step, this document refers to the correlation made in IEC 60071-1 between the standard insulation levels and the highest voltage for equipment.
The annexes contain examples and detailed information which explain or support the concepts described in the main text, and the basic analytical techniques used.
Isolationskoordination – Teil 2: Anwendungsrichtlinie
Coordination de l'isolement - Partie 2: Lignes directrices en matière d'application
IEC 60071-2:2023 est disponible sous forme de IEC 60071-2:2023 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.
L'IEC 60071-2:2023 constitue des lignes directrices en matière d'application et concerne le choix des niveaux d'isolement des matériels ou des installations pour les réseaux triphasés en courant alternatif. Elle a pour objet de donner des recommandations pour la détermination des tensions de tenue assignées pour les plages I et II de l'IEC 60071-1 et de justifier l'association de ces valeurs assignées avec les valeurs normalisées des tensions les plus élevées pour le matériel. Cette association ne couvre que les besoins de la coordination de l'isolement. Les exigences relatives à la sécurité des personnes ne sont pas traitées dans le présent document. Le présent document traite des réseaux triphasés en courant alternatif de tension nominale supérieure à 1 kV. Le présent document traite de l'isolement phase-terre, entre phases et longitudinal. Le présent document a le statut d'une norme horizontale conformément au Guide 108 de l'IEC. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) l'Article 4, Concepts applicables à la coordination de l'isolement, a été ajouté;
lb) e 5.3 a été révisé et le 5.4, Simulation détaillée, a été ajouté, car la simulation est largement appliquée dans les récentes pratiques de coordination de l'isolement;
c) des points particuliers ont été ajoutés pour les câbles et pour les lignes de transport/barres blindées à isolation gazeuse à l'Article 9;
d) l'Annexe K (informative), Application d'une inductance shunt pour la limitation des TOV et des SFO dans les lignes de transport aériennes à haute tension, a été ajoutée;
e) l'Annexe L (informative), Calcul du taux de foudroiement et du taux de coupure due à la foudre, a été ajoutée.
Koordinacija izolacije - 2. del: Smernice za uporabo (predlagan horizontalni standard)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
oSIST prEN IEC 60071-2:2022
01-julij-2022
Koordinacija izolacije - 2. del: Smernice za uporabo (predlagan horizontalni
standard)
Insulation co-ordination - Part 2: Application guidelines (Proposed horizontal standard)
Coordination de l'isolement - Partie 2: Lignes directrices en matière d'application
Ta slovenski standard je istoveten z: prEN IEC 60071-2:2022ICS:
29.080.01 Električna izolacija na Electrical insulation in
splošno general
oSIST prEN IEC 60071-2:2022 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN IEC 60071-2:2022
99/356/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 60071-2 ED5
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2022-05-06 2022-07-29
SUPERSEDES DOCUMENTS:
99/319/CD, 99/352/CC
IEC TC 99 : INSULATION CO-ORDINATION AND SYSTEM ENGINEERING OF HIGH VOLTAGE ELECTRICAL POWER INSTALLATIONS ABOVE 1,0
KV AC AND 1,5 KV DCSECRETARIAT: SECRETARY:
Australia Ms Erandi Chandrasekare
OF INTEREST TO THE FOLLOWING COMMITTEES: PROPOSED HORIZONTAL STANDARD:
TC 8,TC 11,TC 14,TC 17,SC 17A,SC 17C,TC 20,TC
22,SC 22F,SC 22G,TC 33,TC 36,TC 37,TC 38,TC 42,TC
Other TC/SCs are requested to indicate their interest, if any, in
115,TC 122
this CDV to the secretary.
FUNCTIONS CONCERNED:
EMC ENVIRONMENT QUALITY ASSURANCE SAFETY
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
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CENELEC, is drawn to the fact that this Committee Draft for
Vote (CDV) is submitted for parallel voting.
The CENELEC members are invited to vote through the
CENELEC online voting system.
This document is still under study and subject to change. It should not be used for reference purposes.
Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.TITLE:
Insulation co-ordination - Part 2: Application guidelines (Proposed horizontal standard)
PROPOSED STABILITY DATE: 2027NOTE FROM TC/SC OFFICERS:
Copyright © 2022 International Electrotechnical Commission, IEC. All rights reserved. It is permitted to download this
electronic file, to make a copy and to print out the content for the sole purpose of preparing National Committee positions. You
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oSIST prEN IEC 60071-2:2022
IEC 60071-2/Ed5/CDV @ IEC (E) – 2 – 99/356/CDV
1 CONTENTS
3 FOREWORD ........................................................................................................................... 9
4 1 Scope ............................................................................................................................ 11
5 2 Normative references .................................................................................................... 11
6 3 Terms, definitions, abbreviated terms and symbols ........................................................ 12
7 3.1 Terms and definitions ............................................................................................ 12
8 3.2 Abbreviated terms ................................................................................................. 12
9 3.3 Symbols ................................................................................................................ 12
10 4 Concepts governing the insulation co-ordination ............................................................ 17
11 5 Representative voltage stresses in service .................................................................... 18
12 5.1 Origin and classification of voltage stresses .......................................................... 18
13 5.2 Characteristics of overvoltage protection devices .................................................. 19
14 5.2.1 General remarks ............................................................................................ 19
15 5.2.2 Metal-oxide surge arresters without gaps (MOSA) ......................................... 19
16 5.2.3 Line surge arresters (LSA) for overhead transmission and distribution17 lines .............................................................................................................. 21
18 5.3 General approach for the determination of representative voltages and19 overvoltages ......................................................................................................... 22
20 5.3.1 Continuous (power-frequency) voltage ........................................................... 22
21 5.3.2 Temporary overvoltages ................................................................................ 22
22 5.3.3 Slow-front overvoltages ................................................................................. 25
23 5.3.4 Fast-front overvoltages .................................................................................. 31
24 5.3.5 Very-fast-front overvoltages ........................................................................... 35
25 5.4 Determination of representative overvoltages by detailed simulations ................... 36
26 5.4.1 General overview ........................................................................................... 36
27 5.4.2 Temporary overvoltages ................................................................................ 36
28 5.4.3 Slow-front overvoltages ................................................................................. 37
29 5.4.4 Fast-front overvoltages .................................................................................. 38
30 5.4.5 Very-fast-front Overvoltages .......................................................................... 42
31 6 Co-ordination withstand voltage ..................................................................................... 43
32 6.1 Insulation strength characteristics ......................................................................... 43
33 6.1.1 General ......................................................................................................... 43
34 6.1.2 Influence of polarity and overvoltage shapes ................................................. 44
35 6.1.3 Phase-to-phase and longitudinal insulation .................................................... 45
36 6.1.4 Influence of weather conditions on external insulation ................................... 45
37 6.1.5 Probability of disruptive discharge of insulation ............................................. 46
38 6.2 Performance criterion ............................................................................................ 47
39 6.3 Insulation co-ordination procedures ...................................................................... 48
40 6.3.1 General ......................................................................................................... 48
41 6.3.2 Insulation co-ordination procedures for continuous (power-frequency)42 voltage and temporary overvoltage ................................................................ 49
43 6.3.3 Insulation co-ordination procedures for slow-front overvoltages ..................... 49
44 6.3.4 Insulation co-ordination procedures for fast-front overvoltages ...................... 54
45 6.3.5 Insulation co-ordination procedures for very-fast-front overvoltages .............. 55
46 7 Required withstand voltage ............................................................................................ 55
47 7.1 General remarks ................................................................................................... 55
48 7.2 Atmospheric correction ......................................................................................... 55
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49 7.2.1 General remarks ............................................................................................ 55
50 7.2.2 Altitude correction .......................................................................................... 56
51 7.3 Safety factors........................................................................................................ 57
52 7.3.1 General ......................................................................................................... 57
53 7.3.2 Ageing ........................................................................................................... 58
54 7.3.3 Production and assembly dispersion .............................................................. 58
55 7.3.4 Inaccuracy of the withstand voltage ............................................................... 58
56 7.3.5 Recommended safety factors (K ) ................................................................. 58
57 8 Standard withstand voltage and testing procedures ....................................................... 58
58 8.1 General remarks ................................................................................................... 58
59 8.1.1 Overview ....................................................................................................... 58
60 8.1.2 Standard switching impulse withstand voltage ............................................... 59
61 8.1.3 Standard lightning impulse withstand voltage ................................................. 59
62 8.2 Test conversion factors ......................................................................................... 60
63 8.2.1 Range I.......................................................................................................... 60
64 8.2.2 Range II ........................................................................................................ 60
65 8.3 Determination of insulation withstand by type tests ............................................... 61
66 8.3.1 Test procedure dependency upon insulation type .......................................... 61
67 8.3.2 Non-self-restoring insulation .......................................................................... 61
68 8.3.3 Self-restoring insulation ................................................................................. 61
69 8.3.4 Mixed insulation ............................................................................................. 61
70 8.3.5 Limitations of the test procedures .................................................................. 63
71 8.3.6 Selection of the type test procedures ............................................................. 63
72 8.3.7 Selection of the type test voltages ................................................................. 63
73 9 Special considerations for apparatus and transmission line ........................................... 64
74 9.1 Overhead line ....................................................................................................... 64
75 9.1.1 General ......................................................................................................... 64
76 9.1.2 Insulation co-ordination for operating voltages and temporary77 overvoltages .................................................................................................. 64
78 9.1.3 Insulation co-ordination for slow-front overvoltages ....................................... 65
79 9.1.4 Insulation co-ordination for fast-front overvoltages ......................................... 65
80 9.2 Cable line ............................................................................................................. 66
81 9.2.1 General ......................................................................................................... 66
82 9.2.2 Insulation co-ordination for operating voltages and temporary83 overvoltages .................................................................................................. 67
84 9.2.3 Insulation co-ordination for slow-front overvoltages ....................................... 67
85 9.2.4 Insulation co-ordination for fast-front overvoltages ......................................... 67
86 9.2.5 Overvoltage protection of cable lines ............................................................. 68
87 9.3 GIL (gas insulated transmission line) / GIB (Gas-insulated busduct) ..................... 68
88 9.3.1 General ......................................................................................................... 68
89 9.3.2 Insulation co-ordination for operating voltages and temporary90 overvoltages .................................................................................................. 68
91 9.3.3 Insulation co-ordination for slow-front overvoltages ....................................... 69
92 9.3.4 Insulation co-ordination for fast-front overvoltages ......................................... 69
93 9.3.5 Overvoltage protection of GIL/GIB lines ......................................................... 69
94 9.4 Substation ............................................................................................................ 69
95 9.4.1 General ......................................................................................................... 69
96 9.4.2 Insulation co-ordination for overvoltages........................................................ 71
97 Annex A (informative) Determination of temporary overvoltages due to earth faults ............. 73
98 Annex B (informative) Weibull probability distributions ......................................................... 77
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99 B.1 General remarks ................................................................................................... 77
100 B.2 Disruptive discharge probability of external insulation ........................................... 78
101 B.3 Cumulative frequency distribution of overvoltages ................................................. 80
102 Annex C (informative) Determination of the representative slow-front overvoltage due
103 to line energization and re-energization ......................................................................... 83
104 C.1 General remarks ................................................................................................... 83
105 C.2 Probability distribution of the representative amplitude of the prospective
106 overvoltage phase-to-earth ................................................................................... 83
107 C.3 Probability distribution of the representative amplitude of the prospective
108 overvoltage phase-to-phase .................................................................................. 85
109 C.4 Insulation characteristic ........................................................................................ 86
110 C.5 Numerical example ............................................................................................... 89
111 Annex D (informative) Transferred overvoltages in transformers .......................................... 94
112 D.1 General remarks ................................................................................................... 94
113 D.2 Transferred temporary overvoltages ...................................................................... 95
114 D.3 Capacitively transferred surges ............................................................................. 95
115 D.4 Inductively transferred surges ............................................................................... 97
116 Annex E (informative) Determination of lightning overvoltages by simplified method .......... 101
117 E.1 General remarks ................................................................................................. 101
118 E.2 Determination of the limit distance (X ) ............................................................... 101
119 E.2.1 Protection with arresters in the substation ................................................... 101
120 E.2.2 Self-protection of substation ........................................................................ 102
121 E.3 Estimation of the representative lightning overvoltage amplitude......................... 103
122 E.3.1 General ....................................................................................................... 103
123 E.3.2 Shielding penetration ................................................................................... 103
124 E.3.3 Back flashovers ........................................................................................... 104
125 E.4 Simplified approach ............................................................................................ 106
126 E.5 Assumed maximum value of the representative lightning overvoltage ................. 108
127 Annex F (informative) Calculation of air gap breakdown strength from experimental
128 data ............................................................................................................................. 109
129 F.1 General ............................................................................................................... 109
130 F.2 Insulation response to power-frequency voltages ................................................ 109
131 F.3 Insulation response to slow-front overvoltages .................................................... 110
132 F.4 Insulation response to fast-front overvoltages ..................................................... 111
133 Annex G (informative) Examples of insulation co-ordination procedure .............................. 115
134 G.1 Overview............................................................................................................. 115
135 G.2 Numerical example for a system in range I (with nominal voltage of 230 kV) ....... 115
136 G.2.1 General ....................................................................................................... 115
137 G.2.2 Part 1: no special operating conditions ........................................................ 116
138 G.2.3 Part 2: influence of capacitor switching at station 2 ...................................... 123
139 G.2.4 Part 3: flow charts related to the example of Clause G.2 .............................. 125
140 G.3 Numerical example for a system in range II (with nominal voltage of 735 kV) ...... 130
141 G.3.1 General ....................................................................................................... 130
142 G.3.2 Step 1: determination of the representative overvoltages –143 values of U ............................................................................................... 130
144 G.3.3 Step 2: determination of the co-ordination withstand voltages –145 values of U .............................................................................................. 131
146 G.3.4 Step 3: determination of the required withstand voltages – values of147 U .............................................................................................................. 132
148 G.3.5 Step 4: conversion to switching impulse withstand voltages (SIWV) ............. 133
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149 G.3.6 Step 5: selection of standard insulation levels ............................................. 134
150 G.3.7 Considerations relative to phase-to-phase insulation co-ordination .............. 134
151 G.3.8 Phase-to-earth clearances ........................................................................... 135
152 G.3.9 Phase-to-phase clearances ......................................................................... 136
153 G.4 Numerical example for substations in distribution systems with U up to154 36 kV in range I .................................................................................................. 136
155 G.4.1 General ....................................................................................................... 136
156 G.4.2 Step 1: determination of the representative overvoltages –157 values of U ............................................................................................... 137
158 G.4.3 Step 2: determination of the co-ordination withstand voltages –159 values of U .............................................................................................. 137
160 G.4.4 Step 3: determination of required withstand voltages – values of U .......... 138
161 G.4.5 Step 4: conversion to standard short-duration power-frequency and162 lightning impulse withstand voltages ............................................................ 139
163 G.4.6 Step 5: selection of standard withstand voltages .......................................... 140
164 G.4.7 Summary of insulation co-ordination procedure for the example of165 Clause G.4 .................................................................................................. 140
166 Annex H (informative) Atmospheric correction – Altitude correction application
167 example ....................................................................................................................... 142
168 H.1 General principles ............................................................................................... 142
169 H.1.1 Atmospheric correction in standard tests ..................................................... 142
170 H.1.2 Task of atmospheric correction in insulation co-ordination ........................... 143
171 H.2 Atmospheric correction in insulation co-ordination .............................................. 145
172 H.2.1 Factors for atmospheric correction ............................................................... 145
173 H.2.2 General characteristics for moderate climates ............................................. 145
174 H.2.3 Special atmospheric conditions .................................................................... 146
175 H.2.4 Altitude dependency of air pressure ............................................................. 147
176 H.3 Altitude correction ............................................................................................... 148
177 H.3.1 Definition of the altitude correction factor ..................................................... 148
178 H.3.2 Principle of altitude correction ..................................................................... 149
179 H.3.3 Altitude correction for standard equipment operating at altitudes up to
180 1 000 m ....................................................................................................... 150
181 H.3.4 Altitude correction for standard equipment operating at altitudes above
182 1 000 m ....................................................................................................... 151
183 H.4 Selection of the exponent m ................................................................................ 151
184 H.4.1 General ....................................................................................................... 151
185 H.4.2 Derivation of exponent m for switching impulse voltage ............................... 152
186 H.4.3 Derivation of exponent m for critical switching impulse voltage .................... 154
187 Annex I (informative) Evaluation method of non-standard lightning overvoltage shape
188 for representative voltages and overvoltages ............................................................... 157
189 I.1 General remarks ................................................................................................. 157
190 I.2 Lightning overvoltage shape ............................................................................... 157
191 I.3 Evaluation method for GIS .................................................................................. 157
192 I.3.1 Experiments ................................................................................................ 157
193 I.3.2 Evaluation of overvoltage shape .................................................................. 158
194 I.4 Evaluation method for transformer ...................................................................... 158
195 I.4.1 Experiments ................................................................................................ 158
196 I.4.2 Evaluation of overvoltage shape .................................................................. 158
197 Annex J (informative) Insulation co-ordination for very-fast-front overvoltages in UHV
198 substations .................................................................................................................. 165
199 J.1 General ............................................................................................................... 165
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200 J.2 Influence of disconnector design ......................................................................... 165
201 J.3 Insulation co-ordination for VFFO ....................................................................... 166
202 Annex K (informative) Application of shunt reactors to limit TOV and SFO of high
203 voltage overhead transmission line .............................................................................. 168
204 K.1 General remarks ................................................................................................. 168
205 K.2 Limitation of TOV and SFO ................................................................................. 168
206 K.3 Application of the neutral grounding reactor to limit resonance overvoltage
207 and secondary arc current .................................................................................. 168
208 K.4 SFO and Beat frequency overvoltage limited by neutral arrester ......................... 169
209 K.5 SFO and FFO due to SR de-energization ............................................................ 170
210 K.6 Limitation of TOV by Controllable SR .................................................................. 170
211 K.7 Insulation coordination of the SR and neutral grounding reactor .......................... 170
212 K.8 Self-excitation TOV of synchronous generator .................................................... 170
213 Annex L (informative) Calculation of lightning stroke rate and lightning outage rate ........... 171
214 L.1 Introduction ......................................................................................................... 171
215 L.2 Description in CIGRE [38] ................................................................................... 171
216 L.3 Flash program in IEEE [51] ................................................................................. 172
217 L.4 [Case Study] Calculation of Lightning Stroke Rate and Lightning Outage Rate
218 (Appendix D in CIGRE TB 839 [38]) .................................................................... 172
219 L.4.1 Basic flow of calculation method ........................................................................... 172
220 L.4.2 Comparison of Calculation Results with Observations .......................................... 174
221 L.4.2.1 Calculations on Lightning Strokes to Phase Conductor ................................... 174
222 L.4.2.2 Calculations on Lightning Outage Rate ........................................................... 175
223 Bibliography ........................................................................................................................ 177
224225 Figure 1 – Range of 2 % slow-front overvoltages at the receiving end due to line
226 energization and re-energization [28] .................................................................................... 27
227 Figure 2 – Ratio between the 2 % values of slow-front overvoltages phase-to-phase
228 and phase-to-earth [29], [30] ................................................................................................. 28
229 Figure 3 – Diagram for surge arrester connection to the protected object .............................. 35
230 41231 Figure 4 – Modelling of transmission lines and substations/power stations ............................ 41
232 Figure 5 – Distributive discharge probability of self-restoring insulation described on a
233 linear scale ........................................................................................................................... 50
234 Figure 6 – Disruptive discharge probability of self-restoring insulation described on a
235 Gaussian scale ..................................................................................................................... 50
236 Figure 7 – Evaluation of deterministic co-ordination factor K ............................................. 51
237 Figure 8 – Evaluation of the risk of failure ............................................................................. 52
238 Figure 9 – Risk of failure of external insulation for slow-front overvoltages as a fun
...
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