prEN IEC 60071-11:2022
(Main)Insulation co-ordination - Part 11：Definitions, principles and rules for HVDC system
Insulation co-ordination - Part 11：Definitions, principles and rules for HVDC system
Isolationskoordination – Teil 11: Begriffe, Grundsätze und Anforderungen für HVDC Systeme
Coordination de l'isolement - Partie 11: Définitions, principes et règles relatifs au réseau CCHT
Koordinacija izolacije - 11. del: Definicije, načela in pravila za visokonapetostni enosmerni (HVDC) sistem
General Information
Standards Content (sample)
SLOVENSKI STANDARD
oSIST prEN IEC 60071-11:2022
01-marec-2022
Koordinacija izolacije - 11. del: Definicije, načela in pravila za visokonapetostni
enosmerni (HVDC) sistemInsulation co-ordination - Part 11：Definitions, principles and rules for HVDC system
Ta slovenski standard je istoveten z: prEN IEC 60071-11:2022ICS:
29.080.30 Izolacijski sistemi Insulation systems
oSIST prEN IEC 60071-11:2022 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN IEC 60071-11:2022
99/353/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 60071-11 ED1
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2022-01-07 2022-04-01
SUPERSEDES DOCUMENTS:
99/322/CD, 99/350/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,SC 22F,TC 115
Other TC/SCs are requested to indicate their interest, if any,
in this CDV to the secretary.
FUNCTIONS CONCERNED:
EMC ENVIRONMENT QUALITY ASSURANCE SAFETY
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
Attention IEC-CENELEC parallel votingThe attention of IEC National Committees, members of
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 11：Definitions, principles and rules for HVDC system
PROPOSED STABILITY DATE: 2026NOTE FROM TC/SC OFFICERS:
Copyright © 2021 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 may not copy or "mirror" the file or printed version of the document, or any part of it, for any other purpose without
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2 CONTENTS
4 FOREWORD ........................................................................................................................... 4
5 1 Scope .............................................................................................................................. 7
6 1.1 General ................................................................................................................... 7
7 1.2 Additional background ............................................................................................ 7
8 2 Normative references ...................................................................................................... 7
9 3 Terms and definitions ...................................................................................................... 8
10 4 Symbols and abbreviations ............................................................................................ 14
11 4.1 General ................................................................................................................. 14
12 4.2 Subscripts ............................................................................................................. 14
13 4.3 Letter symbols ...................................................................................................... 14
14 4.4 Abbreviations ........................................................................................................ 14
15 5 Principles of insulation co-ordination ............................................................................. 15
16 5.1 General ................................................................................................................. 15
17 5.2 Essential differences between AC and DC systems............................................... 15
18 5.3 Insulation co-ordination procedure ........................................................................ 16
19 5.4 Differences of withstand voltage selection in AC and DC systems ......................... 16
20 6 Design procedure of insulation co-ordination ................................................................. 18
21 6.1 General ................................................................................................................. 18
22 6.2 Arrester characteristics ......................................................................................... 18
23 6.3 Insulation characteristics ...................................................................................... 18
24 6.4 Determination of the representative overvoltages (U ) .......................................... 19
25 6.5 Determination of the co-ordination withstand voltages (Ucw) .................................. 19
26 6.6 Determination of the required withstand voltages (U ) .......................................... 19
27 6.7 Determination of the specified withstand voltage (Uw) ........................................... 21
28 7 Requirements for withstand voltage tests ...................................................................... 21
29 8 Creepage distances ....................................................................................................... 21
30 8.1 General ................................................................................................................. 21
31 8.2 Base voltage for creepage distance ...................................................................... 21
32 8.3 Creepage distance for outdoor insulation under DC voltage .................................. 22
33 8.4 Creepage distance for indoor insulation under DC or mixed voltage ...................... 22
34 8.5 Creepage distance of AC insulators ...................................................................... 22
35 9 Clearances in air ........................................................................................................... 23
36 Annex A (informative) Typical HVDC converter station schemes .......................................... 24
37 Annex B (informative) Example of air clearances calculation ................................................ 27
38 Annex C (normative) Example of typical DC voltages with possible insulation levels
39 and corresponding air clearances .................................................................................. 30
40 Annex D (informative) Typical arrester characteristics.......................................................... 34
41 Bibliography .......................................................................................................................... 35
43 Figure 1 –Comparison of the selection between withstand voltages for AC equipment
44 and HVDCconverter station equipment ................................................................................. 17
45 Figure A.1 – Possible arrester locations in a pole with two 12-pulse converters in
46 series of LCC converter station ............................................................................................. 25
47 Figure A.2–Possible arrester locations in one pole of bipolar of VSC converter stations ........ 25
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48 Figure A.3 –Possible arrester locations in symmetrical monopole VSC converter
49 stations ................................................................................................................................. 26
51 Table 1 – Classes and shapes of overvoltages, Standard voltage shapes and Standard
52 withstand voltage tests ........................................................................................................... 9
53 Table 2 – Comparison the insulation coordination procedure of AC and DC systems ............ 16
54 Table 3 – Indicative values of ratios of required impulse withstand voltage to impulse
55 protective level ..................................................................................................................... 20
56 Table A.1– Symbol description .............................................................................................. 26
57 Table C.1– Typical DC voltages and switching/lightning impulse withstand voltage ............... 31
58 Table C.2– Correlation between presumed rated switching impulse withstand voltages
59 and minimum phase-to-earth air clearances .......................................................................... 32
60 Table C.3– Correlation between presumed rated lightning impulse withstand voltages
61 and minimum phase-to-earth air clearances .......................................................................... 33
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64 INTERNATIONAL ELECTROTECHNICAL COMMISSION
65 ____________
67 INSULATION CO-ORDINATION –
69 Part 11: Definitions, principles and rules for HVDC system
73 FOREWORD
74 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
75 all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
76 international co-operation on all questions concerning standardization in the electrical and electronic fields. To
77 this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
78 Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
79 Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
80 in the subject dealt with may participate in this preparatory work. International, governmental and non-
81 governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
82 with the International Organization for Standardization (ISO) in accordance with conditions determined by
83 agreement between the two organizations.84 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
85 consensus of opinion on the relevant subjects since each technical committee has representation from all
86 interested IEC National Committees.87 3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
88 Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
89 Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
90 misinterpretation by any end user.91 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
92 transparently to the maximum extent possible in their national and regional publications. Any divergence
93 between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
94 the latter.95 5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
96 assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
97 services carried out by independent certification bodies.98 6) All users should ensure that they have the latest edition of this publication.
99 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
100 members of its technical committees and IEC National Committees for any personal injury, property damage or
101 other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
102 expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
103 Publications.104 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
105 indispensable for the correct application of this publication.106 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
107 patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
108 IEC 60071-11 has been prepared by IEC technical committee 99: Insulation co-ordination and
109 system engineering of high voltage electrical power installations above 1,0 kV AC and 1,5 kV
110 DC. It is an International Standard.111 This International Standard and IEC 60071-12 'Application guidelines for LCC HVDC converter
112 stations' jointly replace IEC 60071-5 published in 2014.113 The sections arrangement of this standard and corresponding sections of IEC 60071-5:2014 are as
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IEC 60071-11 IEC 60071-5:2014
1 Scope 1
1.1 General 1.1
1.2 Additional background 1.2
2 Normative references 2
3 Terms and definitions 3
4 Symbols and abbreviations 4
4.1 General 4.1
4.2 Subscripts 4.2
4.3 Letter symbols 4.3
4.4 Abbreviations 4.4
5 Principles of insulation co-ordination 6
5.1 General 6.1
5.2 Essential differences between AC and DC systems 6.2
5.3 Insulation co-ordination procedure 6.3
5.4 Differences of withstand voltage selection in AC and DC 6.4
systems
6 Design procedure of insulation co-ordination 9
6.1 General 9.1
6.2 Arrester characteristics 8.1
6.3 Insulation characteristics 9.3
6.4 Determination of the representativeovervoltages (U ) 9.4
6.5 Determination of the co-ordination withstand voltages (U ) 9.5
6.6 Determination of the required withstand voltages (U ) 9.6
6.7 Determination of the specified withstand voltage (U ) 9.7
7 Requirements for withstand voltage tests -
8 Creepage distances 11
8.1 General 11.1
8.2 Base voltage for creepage distance 11.2
8.3 Creepage distance for outdoor insulation under DC voltage 11.3
8.4 Creepage distance for indoor insulation under DC or mixed 11.4
voltage
8.5 Creepage distance of AC insulators 11.5
9 Clearances in air 12
Annex A (informative)
Typical HVDC converter station arrester protection schemes
Annex B (informative)
Example of air clearances calculation
Annex C (normative)
Example of typical DC voltages with possible insulation levels
and corresponding air clearances
Annex D (informative)
Annex D
Typical arrester characteristics
115
116 The text of this International Standard is based on the following documents:
Draft Report on voting
XX/XX/FDIS XX/XX/RVD
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117
118 Full information on the voting for its approval can be found in the report on voting indicated in
119 the above table.120 The language used for the development of this International Standard is English.
121 This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
122 accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement,
123 available at www.iec.ch/members_experts/refdocs. The main document types developed by
124 IEC are described in greater detail at http://www.iec.ch/standardsdev/publications.
125 The committee has decided that the contents of this document will remain unchanged until the
126 stability date indicated on the IEC website under webstore.iec.ch in the data related to the
127 specific document. At this date, the document will be128 • reconfirmed,
129 • withdrawn,
130 • replaced by a revised edition, or
131 • amended.
132
133
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134 INSULATION CO-ORDINATION–
135
136 Part 11: Definitions, principles and rules for HVDC system
137
138
139
140 1 Scope
141 1.1 General
142 This standard applies to High-voltage direct current (HVDC) systems. It specifies the
143 principles on the procedures for the determination of the specified withstand voltages,
144 creepage distance and air clearances for the equipment and the installations of these systems.
145 This standard gives the insulation co-ordination principles related to line commutated
146 converter (LCC) and voltage sourced converters (VSC) HVDC systems. The main principles of
147 this standard also apply to other special converter configurations of LCC, such as the
148 capacitor commutated converter (CCC) as well as the controlled series compensated
149 converter (CSCC) etc.150 This standard applies to insulation co-ordination of equipment connected between the
151 converter AC bus (including the AC harmonic filters, the converter transformer, the circuit
152 breakers) and the DC line side. The line and cable terminations in so far as they influence the
153 insulation co-ordination of converter station equipment are also covered.154 This standard applies only for HVDC applications in power systems and not for industrial
155 conversion equipment. Principles and guidance given are for insulation co-ordination
156 purposes only. The requirements for human safety are not covered by this standard.
157 This horizontal standard is primarily intended for use by technical committees in the
158 preparation of standards in accordance with the principles laid down in IEC Guide 108.
159 One of the responsibilities of a technical committee is, wherever applicable, to make use of
160 horizontal standards in the preparation of its publications. The contents of this horizontal
161 standard will not apply unless specifically referred to or included in the relevant publications.
162 1.2 Additional background163 The use of power semi-conductor device in a series and/or parallel arrangement, along with
164 the unique control and protection strategies employed in the conversion process, has
165 ramifications requiring particular consideration of overvoltage protection of equipment in
166 converter stations compared with substations in AC systems.167 The basic principles and design objectives of insulation co-ordination of converter stations, in
168 so far as they differ from normal AC system practice, are described.169 NOTE In IEC 60071-12, Application guidelines, all rules for insulation co-ordination given in this standard are
170 justified in detail, in particular the association of the specified withstand voltages with the rated voltage for
171 equipment, and arrester configuration.172 2 Normative references
173 The following documents are referred to in the text in such a way that some or all of their
174 content constitutes requirements of this document. For dated references, only the edition
175 cited applies. For undated references, the latest edition of the referenced document (including
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177 IEC 60060-1, High-voltage test techniques – Part 1: General definitions and test requirements
178 IEC 60071-1:2019, Insulation co-ordination – Part 1: Definitions, principles and rules
179 IEC 60071-2:2018, Insulation co-ordination – Part 2: Application guidelines180 IEC 60099-4:2014, Surge arresters – Part 4: Metal-oxide surge arresters without gaps for a.c.
181 systems182 IEC 60633, Terminology for high-voltage direct current (HVDC) transmission
183 IEC 60700-1:2015, Thyristor valves for high voltage direct current (HVDC) power transmission
184 – Part 1 Electrical testing185 IEC TS 60815-1:2008, Selection and dimensioning of high-voltage insulators intended for use
186 in polluted conditions – Part 1: Definitions, information and general principles
187 IEC TS 60815-2:2008, Selection and dimensioning of high-voltage insulators intended for use
188 in polluted conditions – Part 2: Ceramic and glass insulators for a.c. systems
189 IEC TS 60815-3:2008, Selection and dimensioning of high-voltage insulators intended for use
190 in polluted conditions – Part 3: Polymer insulators for a.c. systems191 IEC TS 60815-4:2016, Selection and dimensioning of high-voltage insulators intended for use
192 in polluted conditions – Part 4: Insulators for d.c. systems.193 3 Terms and definitions
194 For the purposes of this document, the following terms and definitions apply.
195 ISO and IEC maintain terminological databases for use in standardization at the following
196 addresses:197 • IEC Electropedia: available at http://www.electropedia.org/
198 • ISO Online browsing platform: available at http://www.iso.org/obp
199 NOTE Many of the following definitions refer to insulation co-ordination concepts (IEC 60071-1), or to arrester
200 parameters (IEC 60099-4).201 3.1
202 insulation co-ordination
203 selection of the dielectric strength of equipment in relation to the operating voltages and
204 overvoltages which can appear on the system for which the equipment is intended and taking
205 into account the service environment and the characteristics of the available preventing and
206 protective devices207 [SOURCE: IEC 60071-1: 2019, 3.1]
208 3.2
209 nominal DC voltage
210 mean value of the DC voltage required to transmit nominal power at nominal current
211 3.3212 highest DC voltage
213 highest value of DC voltage for which the equipment is designed to operate continuously, in
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215 3.4
216 overvoltage
217 voltage having a value exceeding the corresponding highest steady state voltage of the
218 system219 Note 1 to entry: Table 1 presents (as per IEC 60071-1) the classification of these voltages which are defined in
220 3.4.1 to 3.4.2.3.221
222 Table 1 – Classes and shapes of overvoltages, Standard voltage shapes
223 and Standard withstand voltage tests
Low frequency Transient
Class
Continuous Temporary Slow-front Fast-front Very-fast-front
1/f
1/f
1/f
Voltage or
over-
voltage
1/f
shapes T
t 1/f
Tt 2
T≤ 100 ns
10 Hz Range of
0,3 MHz T≥3 600s 1
t 20 µs f = 50 Hz or
p 1
500 Hz
voltage or
100 MHz
60 Hz
5 000 µs 20 µs
over- 1/T = f = 0 Hz
t 1
voltage 0,02 s ≤T≤ 30 kHz t 2
T≥3 600s
T ≤ 20 ms T ≤ 300 µs
2 2
f <2 500 Hz
shapes
3 600 s 300 kHz
1/f
1/f
un+Δu
un-Δu
Standard
voltage T Tp T
Tt t 1
shapes
f = 50 Hz
48 Hz ≤f≤
≤ 3%
T = 250 µs T = 1,2 µs
p 1
or 60 Hz
U 62 Hz
T = 2 500 µs T = 50 µs
2 2
T T = 60 s
T t t
Standard Short-duration
DC voltage Switching impulse Lightning impulse
withstand power a
test test test
voltage test frequency test
To be specified by the relevant apparatus committees.
Unless otherwise specified by the relevant Technical Committees, standard voltage shapes should be in accordance with IEC
60060-1.224
225 3.4.1
226 temporary overvoltage
227 overvoltages of relatively long duration (ranging from 0,02 to 3 600 s as per IEC 60071-1)
228 Note 1 to entry: The overvoltage may be undamped or weakly damped.229 3.4.2
230 transient overvoltage
231 short-duration overvoltage of a few millisecond or less, oscillatory or non-oscillatory, usually
232 highly damped233 [SOURCE: IEC 60071-1: 2019, 3.17.3]
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234 3.4.2.1
235 slow-front overvoltage
236 transient overvoltage, usually unidirectional, with time to peak 20 μs < T ≤ 5 000 μs, and
237 tail duration T ≤ 20 ms238 Note 1 to entry: For the purpose of insulation co-ordination, slow-front overvoltages are classified according to
239 their shape, regardless of their origin. Although considerable deviations from the standard shapes occur on actual
240 systems, in this standard it is considered sufficient in most cases to describe such overvoltages by their
241 classification and peak value.242 3.4.2.2
243 fast-front overvoltage
244 overvoltage at a given location on a system, due to a lightning discharge or other cause, the
245 shape of which can be regarded, for insulation co-ordination purposes, as similar to that of
246 the standard impulse (IEC 60060-1) used for lightning impulse tests247 Note 1 to entry: Fast-front overvoltage is defined as transient overvoltage, usually unidirectional, with time to peak
248 0,1 μs < T ≤ 20 μs, and tail duration T ≤ 300 μs in IEC 60071-1:2019, 3.17.3.2.
1 2249 Note 2 to entry: For the purpose of insulation co-ordination, fast-front overvoltages are classified according to their
250 shape, regardless of their origin. Although considerable deviations from the standard shapes occur on actual
251 systems, in this standard it is considered sufficient in most cases to describe such overvoltages by their
252 classification and peak value.253 3.4.2.3
254 very-fast-front overvoltage
255 transient overvoltage, usually unidirectional, with time to peak T < 0,1 μs, and with or without
256 superimposed oscillations at frequency 30 kHz < f < 100 MHz257 [SOURCE: IEC 60071-1:2019, 3.17.3.3]
258 3.4.2.4
259 steep-front overvoltage
260 transient overvoltage classified as a kind of fast-front overvoltage with time to peak3 ns < T <
261 1,2 μs262 Note 1 to entry: A steep-front impulse voltage for test purposes is defined in IEC 60700-1.
263 Note 2 to entry: The front time is decided by means of system studies.264 3.4.2.5
265 combined overvoltage
266 overvoltage consisting of two voltage components simultaneously applied between each of
267 the two-phase terminals of a phase-to-phase (or longitudinal) insulation and earth
268 Note 1 to entry: Combined overvoltage can include temporary, slow-front, fast-front or very-fast front overvoltages.
269 Note 2 to entry: It is classified by the component of higher peak value.270 3.5
271 representative overvoltages
272 U
273 overvoltages assumed to produce the same dielectric effect on the insulation as overvoltages
274 of a given class occurring in service due to various origins275 Note 1 to entry: In this standard it is generally assumed that the representative overvoltages are characterized by
276 their assumed or obtained maximum values.277 [SOURCE: IEC 60071-1:2019, 3.19]
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278 3.5.1
279 representative slow-front overvoltage
280 RSFO
281 voltage value between terminals of an equipment having the shape of a standard switching
282 impulse283 3.5.2
284 representative fast-front overvoltage
285 RFFO
286 voltage value between terminals of an equipment having the shape of a standard lightning
287 impulse288 3.5.3
289 representative steep-front overvoltage
290 RSTO
291 voltage value with a standard shape having a time to crest less than that of a standard
292 lightning impulse, but not less than that of a very-fast-front overvoltage as defined by IEC
293 60071-1294 Note 1 to entry: A steep-front impulse voltage for test purposes is defined in Figure 1 of IEC 60700-1:2015. The
295 front time is decided by means of system studies.296 3.6
297 co-ordination withstand voltage
298 U
299 for each class of voltage, value of the withstand voltage of the insulation configuration, in
300 actual service conditions, that meets the performance criterion301 [SOURCE: IEC 60071-1:2019, 3.24]
302 3.7
303 required withstand voltage
304 U
305 test voltage that the insulation must withstand in a standard withstand voltage test to ensure
306 that the insulation will meet the performance criterion when subjected to a given class of
307 overvoltages in actual service conditions and for the whole service duration. The required
308 withstand voltage has the shape of the co-ordination withstand voltage, and is specified with
309 reference to all the conditions of the standard withstand voltage test selected to verify it
310 [SOURCE: IEC 60071-1:2019, 3.27]311 3.8
312 specified withstand voltage
313 U
314 test voltage suitably selected equal to or above the required withstand voltage (U )
315 Note 1 to entry: For AC equipment, values of withstand voltages U are standardized as per IEC 60071-1. For
316 HVDC equipment, the specified withstand voltages are rounded up to convenient practical values.
317 Note 2 to entry: The standard impulse shapes used for withstand tests on equipment as well as the test procedures
318 are defined in IEC 60060-1 and IEC 60071-1. For some DC equipment (e.g. the thyristor valves), the standard
319 impulse shapes may be modified in order to more rea...
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