SIST EN IEC 60071-2:2018

Insulation co-ordination - Part 2: Application guidelines (IEC 60071-2:2018)

This part of IEC 60071 constitutes application guidelines and deals with the selection of
insulation levels of equipment or installations for three-phase electrical 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 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 60071-1:2006. Clauses 4 to 7 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 (IEC 60071-2:2018)

Coordination de l'isolement - Partie 2: Lignes directrices en matière d'application (IEC 60071-2:2018)

NEW!IEC 60071-2:2018 est disponible sous forme de IEC 60071-2:2018 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.

L'IEC 60071-2:2018 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. 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. Il traite des réseaux triphasés de tension nominale supérieure à 1 kV. Il 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'annexe relative à la distance d'isolement dans l'air pour installation garantissant une tension de tenue aux chocs spécifiée est supprimée car cette annexe est déjà présente dans l'IEC 60071-1;
b) 4.2et 4.3relatifs aux parafoudres ont été mis à jour;
c) 4.3.5relatif aux surtensions à front très rapide a été révisé. L'Annexe J relative à la coordination de l'isolement pour les surtensions à front très rapide dans les postes UHT a été ajoutée;
d) l'Annexe H relative à la correction atmosphérique – correction de l'altitude a été ajoutée;
e) l'Annexe I relative à la méthode d'évaluation de la forme de la surtension de foudre non normalisée a été ajoutée.

Koordinacija izolacije - 2. del: Smernice za uporabo (IEC 60071-2:2018)

Ta del standarda IEC 60071 predstavlja smernice za uporabo in obravnava izbiro izolacijske stopnje opreme ali naprav za trifazne električne sisteme. Njegov namen je podati smernice za ugotavljanje naznačenih najvišjih vrednosti za razpona I in II standarda IEC 60071-1 ter utemeljiti povezavo med temi nazivnimi vrednostmi in standardizirano najvišjo napetostjo opreme.
Ta povezava je namenjena samo koordinaciji izolacije. Zahteve za varnost ljudi niso obravnavane v tem dokumentu.
Ta dokument zajema trifazne sisteme z nazivnimi napetostmi nad 1 kV. Vrednosti, izpeljane ali predlagane v tem dokumentu, se na splošno uporabljajo samo za tovrstne sisteme. Kljub temu pa predstavljeni koncepti veljajo tudi za dvofazne in enofazne sisteme.
Ta dokument zajema dozemno, medfazno in longitudinalno izolacijo.
Ta dokument ni namenjen obravnavi rutinskih preskusov. Te morajo določiti ustrezni tehnični odbori.
Vsebina tega dokumenta strogo sledi diagramu poteka za postopek koordinacije izolacije, ki je predstavljen na sliki 1 v standardu IEC 60071-1:2006. Točke 4 do 7 se ujemajo s kvadratki na tem diagramu in podajajo podrobne informacije o konceptih, ki veljajo za postopek koordinacije izolacije, s katerim se dosežejo zahtevane stopnje vzdržljivosti.
Ta dokument poudarja, da je že na samem začetku treba upoštevati vse izvore, vse razrede in vse vrste napetostnih obremenitev med delovanjem, ne glede na razpon najvišje napetosti opreme. Šele na koncu postopka, ko je treba izbrati standardne najvišje napetosti, se uporabi načelo, pri katerem se določi standardna najvišja napetost za posamezno napetostno obremenitev med delovanjem. Prav tako se pri tem zadnjem koraku dokument nanaša na korelacijo, navedeno v standardu IEC 60071-1, med standardnimi stopnjami izolacije in najvišjo napetostjo opreme.
Ta dodatek vsebuje primere in podrobne informacije, ki pojasnjujejo ali utemeljujejo koncepte, opisane v glavnem besedilu, ter navaja osnovne uporabljene analitske tehnike.

General Information

• Status: Published
• Publication Date: 14-May-2018
• ICS: 29.080.01 - Electrical insulation in general
• Technical Committee: IIZS - Insulating materials and systems
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 11-May-2018
• Due Date: 16-Jul-2018
• Completion Date: 15-May-2018
• Ref Project: EN IEC 60071-2:2018 - Insulation co-ordination - Part 2: Application guidelines

Relations

• Revised: SIST EN 60071-2:2001 - Insulation co-ordination -- Part 2: Application guide
• Effective Date: 07-Feb-2017
• Replaces: SIST EN 60071-2:2001 - Insulation co-ordination -- Part 2: Application guide
• Effective Date: 08-May-2018
• Revised: SIST EN IEC 60071-2:2023 - Insulation co-ordination - Part 2: Application guidelines (Proposed horizontal standard)
• Effective Date: 06-Jul-2021

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN IEC 60071-2:2018
01-julij-2018
1DGRPHãþD
SIST EN 60071-2:2001
Koordinacija izolacije - 2. del: Smernice za uporabo (IEC 60071-2:2018)
Insulation co-ordination - Part 2: Application guidelines (IEC 60071-2:2018)
Isolationskoordination - Teil 2: Anwendungsrichtlinie (IEC 60071-2:2018)
Coordination de l'isolement - Partie 2: Lignes directrices en matière d'application (IEC
60071-2:2018)
Ta slovenski standard je istoveten z: EN IEC 60071-2:2018
ICS:
29.080.01 (OHNWULþQDL]RODFLMDQD Electrical insulation in
VSORãQR general
SIST EN IEC 60071-2:2018 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN IEC 60071-2:2018

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SIST EN IEC 60071-2:2018


EUROPEAN STANDARD EN IEC 60071-2

NORME EUROPÉENNE

EUROPÄISCHE NORM
May 2018
ICS 29.080 Supersedes EN 60071-2:1997
English Version
Insulation co-ordination - Part 2: Application guidelines
(IEC 60071-2:2018)
Coordination de l'isolement - Partie 2: Lignes directrices en Isolationskoordination - Teil 2: Anwendungsrichtlinie
matière d'application (IEC 60071-2:2018)
(IEC 60071-2:2018)
This European Standard was approved by CENELEC on 2018-04-20. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden,
Switzerland, Turkey and the United Kingdom.


European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2018 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
 Ref. No. EN IEC 60071-2:2018 E

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SIST EN IEC 60071-2:2018
EN IEC 60071-2:2018 (E)
European foreword
The text of document 28/255/FDIS, future edition 4 of IEC 60071-2, prepared by IEC/TC 28 "Insulation
co-ordination" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
EN IEC 60071-2:2018.

The following dates are fixed:
(dop) 2019-01-20
• latest date by which the document has to be
implemented at national level by
publication of an identical national
standard or by endorsement
• latest date by which the national (dow) 2021-04-20
standards conflicting with the
document have to be withdrawn

This document supersedes EN 60071-2:1997.

Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.

Endorsement notice
The text of the International Standard IEC 60071-2:2018 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:

IEC 60099-4:2014 NOTE Harmonized as EN 60099-2014 (not modified).
IEC 60099-5 NOTE Harmonized as EN IEC 60099-5.
IEC 60099-8 NOTE Harmonized as EN IEC 60099-8.
IEC 60507 NOTE Harmonized as EN 60507.
IEC 62271-1:2017 NOTE Harmonized as EN 62271-1:2017 (not modified).
IEC 62271-100:2008 NOTE Harmonized as EN 62271-100:2009 (not modified).
2

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SIST EN IEC 60071-2:2018
EN IEC 60071-2:2018 (E)
Annex ZA
(normative)

Normative references to international publications
with their corresponding European publications

The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments)
applies.

NOTE 1  Where an International Publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.

NOTE 2  Up-to-date information on the latest versions of the European Standards listed in this annex is available here:
www.cenelec.eu.

Publication Year Title EN/HD Year
IEC 60060-1 2010 High-voltage test techniques -- Part 1: EN 60060-1 2010
General definitions and test requirements
IEC 60071-1 2006 Insulation co-ordination -- Part 1: EN 60071-1 2006
Definitions, principles and rules
+ A1 2010  + A1 2010
IEC 60505 2011 Evaluation and qualification of electrical EN 60505 2011
insulation systems
IEC/TS 60815-1 -  Selection and dimensioning of high-voltage - -
insulators intended for use in polluted
conditions - Part 1: Definitions, information
and general principles
ISO 2533 1975 Standard Atmosphere - -



3

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SIST EN IEC 60071-2:2018

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SIST EN IEC 60071-2:2018




IEC 60071-2

®


Edition 4.0 2018-03




INTERNATIONAL



STANDARD




NORME



INTERNATIONALE
colour

inside



HORIZONTAL STANDARD

NORME HORIZONTALE




Insulation co-ordination –

Part 2: Application guidelines




Coordination de l'isolement –

Partie 2: Lignes directrices en matière d'application
















INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE


INTERNATIONALE




ICS 29.080.30 ISBN 978-2-8322-5405-9



Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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SIST EN IEC 60071-2:2018
– 2 – IEC 60071-2:2018  IEC 2018
CONTENTS
FOREWORD . 8
1 Scope . 10
2 Normative references . 10
3 Terms, definitions, abbreviated terms and symbols . 11
3.1 Terms and definitions . 11
3.2 Abbreviated terms . 11
3.3 Symbols . 11
4 Representative voltage stresses in service . 16
4.1 Origin and classification of voltage stresses . 16
4.2 Characteristics of overvoltage protection devices . 17
4.2.1 General remarks . 17
4.2.2 Metal-oxide surge arresters without gaps (MOSA) . 17
4.2.3 Line surge arresters (LSA) for overhead transmission and distribution
lines . 19
4.3 Representative voltages and overvoltages . 19
4.3.1 Continuous (power-frequency) voltage . 19
4.3.2 Temporary overvoltages . 20
4.3.3 Slow-front overvoltages . 23
4.3.4 Fast-front overvoltages . 29
4.3.5 Very-fast-front overvoltages [13] . 33
5 Co-ordination withstand voltage . 34
5.1 Insulation strength characteristics . 34
5.1.1 General . 34
5.1.2 Influence of polarity and overvoltage shapes . 35
5.1.3 Phase-to-phase and longitudinal insulation . 36
5.1.4 Influence of weather conditions on external insulation . 36
5.1.5 Probability of disruptive discharge of insulation . 37
5.2 Performance criterion . 38
5.3 Insulation co-ordination procedures . 39
5.3.1 General . 39
5.3.2 Insulation co-ordination procedures for continuous (power-frequency)
voltage and temporary overvoltage . 40
5.3.3 Insulation co-ordination procedures for slow-front overvoltages . 40
5.3.4 Insulation co-ordination procedures for fast-front overvoltages . 45
6 Required withstand voltage . 46
6.1 General remarks . 46
6.2 Atmospheric correction . 46
6.2.1 General remarks . 46
6.2.2 Altitude correction . 46
6.3 Safety factors. 48
6.3.1 General . 48
6.3.2 Ageing . 48
6.3.3 Production and assembly dispersion . 48
6.3.4 Inaccuracy of the withstand voltage . 48
6.3.5 Recommended safety factors (K ) . 49
s
7 Standard withstand voltage and testing procedures . 49

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SIST EN IEC 60071-2:2018
IEC 60071-2:2018  IEC 2018 – 3 –
7.1 General remarks . 49
7.1.1 Overview . 49
7.1.2 Standard switching impulse withstand voltage . 49
7.1.3 Standard lightning impulse withstand voltage . 50
7.2 Test conversion factors . 50
7.2.1 Range I. 50
7.2.2 Range II . 51
7.3 Determination of insulation withstand by type tests . 51
7.3.1 Test procedure dependency upon insulation type . 51
7.3.2 Non-self-restoring insulation . 52
7.3.3 Self-restoring insulation . 52
7.3.4 Mixed insulation . 52
7.3.5 Limitations of the test procedures . 53
7.3.6 Selection of the type test procedures . 54
7.3.7 Selection of the type test voltages . 54
8 Special considerations for overhead lines . 55
8.1 General remarks . 55
8.2 Insulation co-ordination for operating voltages and temporary overvoltages . 55
8.3 Insulation co-ordination for slow-front overvoltages . 55
8.3.1 General . 55
8.3.2 Earth-fault overvoltages . 56
8.3.3 Energization and re-energization overvoltages . 56
8.4 Insulation co-ordination for lightning overvoltages . 56
8.4.1 General . 56
8.4.2 Distribution lines . 56
8.4.3 Transmission lines . 57
9 Special considerations for substations . 57
9.1 General remarks . 57
9.1.1 Overview . 57
9.1.2 Operating voltage . 57
9.1.3 Temporary overvoltage . 57
9.1.4 Slow-front overvoltages . 58
9.1.5 Fast-front overvoltages . 58
9.2 Insulation co-ordination for overvoltages . 58
9.2.1 Substations in distribution systems with U up to 36 kV in range I . 58
m
9.2.2 Substations in transmission systems with U between 52,5 kV and
m
245 kV in range I . 59
9.2.3 Substations in transmission systems in range II . 60
Annex A (informative) Determination of temporary overvoltages due to earth faults . 61
Annex B (informative) Weibull probability distributions . 65
B.1 General remarks . 65
B.2 Disruptive discharge probability of external insulation . 66
B.3 Cumulative frequency distribution of overvoltages . 68
Annex C (informative) Determination of the representative slow-front overvoltage due
to line energization and re-energization . 71
C.1 General remarks . 71
C.2 Probability distribution of the representative amplitude of the prospective
overvoltage phase-to-earth . 71

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SIST EN IEC 60071-2:2018
– 4 – IEC 60071-2:2018  IEC 2018
C.3 Probability distribution of the representative amplitude of the prospective
overvoltage phase-to-phase . 71
C.4 Insulation characteristic . 73
C.5 Numerical example . 75
Annex D (informative) Transferred overvoltages in transformers . 81
D.1 General remarks . 81
D.2 Transferred temporary overvoltages . 82
D.3 Capacitively transferred surges . 82
D.4 Inductively transferred surges . 84
Annex E (informative) Lightning overvoltages . 88
E.1 General remarks . 88
E.2 Determination of the limit distance (X ) . 88
p
E.2.1 Protection with arresters in the substation . 88
E.2.2 Self-protection of substation . 89
E.3 Estimation of the representative lightning overvoltage amplitude. 90
E.3.1 General . 90
E.3.2 Shielding penetration . 90
E.3.3 Back flashovers . 91
E.4 Simplified method . 93
E.5 Assumed maximum value of the representative lightning overvoltage . 95
Annex F (informative) Calculation of air gap breakdown strength from experimental
data . 96
F.1 General . 96
F.2 Insulation response to power-frequency voltages . 96
F.3 Insulation response to slow-front overvoltages . 97
F.4 Insulation response to fast-front overvoltages . 98
Annex G (informative) Examples of insulation co-ordination procedure . 102
G.1 Overview. 102
G.2 Numerical example for a system in range I (with nominal voltage of 230 kV) . 102
G.2.1 General . 102
G.2.2 Part 1: no special operating conditions . 103
G.2.3 Part 2: influence of capacitor switching at station 2 . 110
G.2.4 Part 3: flow charts related to the example of Clause G.2 . 112
G.3 Numerical example for a system in range II (with nominal voltage of 735 kV) . 117
G.3.1 General . 117
G.3.2 Step 1: determination of the representative overvoltages –
values of U . 117
rp
G.3.3 Step 2: determination of the co-ordination withstand voltages –
values of U . 118
cw
G.3.4 Step 3: determination of the required withstand voltages – values of
U . 119
rw
G.3.5 Step 4: conversion to switching impulse withstand voltages (SIWV) . 120
G.3.6 Step 5: selection of standard insulation levels . 120
G.3.7 Considerations relative to phase-to-phase insulation co-ordination . 121
G.3.8 Phase-to-earth clearances . 122
G.3.9 Phase-to-phase clearances . 122
G.4 Numerical example for substations in distribution systems with U up to
m
36 kV in range I . 123
G.4.1 General . 123

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SIST EN IEC 60071-2:2018
IEC 60071-2:2018  IEC 2018 – 5 –
G.4.2 Step 1: determination of the representative overvoltages –
values of U . 123
rp
G.4.3 Step 2: determination of the co-ordination withstand voltages –
values of U . 124
cw
G.4.4 Step 3: determination of required withstand voltages – values of U . 125
rw
G.4.5 Step 4: conversion to standard short-duration power-frequency and
lightning impulse withstand voltages . 126
G.4.6 Step 5: selection of standard withstand voltages . 126
G.4.7 Summary of insulation co-ordination procedure for the example of
Clause G.4 . 127
Annex H (informative) Atmospheric correction – Altitude correction . 129
H.1 General principles . 129
H.1.1 Atmospheric correction in standard tests . 129
H.1.2 Task of atmospheric correction in insulation co-ordination . 130
H.2 Atmospheric correction in insulation co-ordination . 132
H.2.1 Factors for atmospheric correction . 132
H.2.2 General characteristics for moderate climates . 132
H.2.3 Special atmospheric conditions . 133
H.2.4 Altitude dependency of air pressure . 134
H.3 Altitude correction . 135
H.3.1 Definition of the altitude correction factor . 135
H.3.2 Principle of altitude correction . 136
H.3.3 Standard equipment operating at altitudes up to 1 000 m . 137
H.3.4 Equipment operating at altitudes above 1 000 m . 137
H.4 Selection of the exponent m . 138
H.4.1 General . 138
H.4.2 Derivation of exponent m for switching impulse voltage . 138
H.4.3 Derivation of exponent m for critical switching impulse voltage . 141
Annex I (informative) Evaluation method of non-standard lightning overvoltage shape
for representative voltages and overvoltages . 144
I.1 General remarks . 144
I.2 Lightning overvoltage shape . 144
I.3 Evaluation method for GIS . 144
I.3.1 Experiments . 144
I.3.2 Evaluation of overvoltage shape . 145
I.4 Evaluation method for transformer . 145
I.4.1 Experiments . 145
I.4.2 Evaluation of overvoltage shape . 145
Annex J (informative) Insulation co-ordination for very-fast-front overvoltages in UHV
substations . 152
J.1 General . 152
J.2 Influence of disconnector design . 152
J.3 Insulation co-ordination for VFFO . 153
Bibliography . 155

Figure 1 – Range of 2 % slow-front overvoltages at the receiving end due to line
energization and re-energization . 25
Figure 2 – Ratio between the 2 % values of slow-front overvoltages phase-to-phase
and phase-to-earth . 26
Figure 3 – Diagram for surge arrester connection to the protected object . 33

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SIST EN IEC 60071-2:2018
– 6 – IEC 60071-2:2018  IEC 2018
Figure 4 – Distributive discharge probability of self-restoring insulation described on a
linear scale . 41
Figure 5 – Disruptive discharge probability of self-restoring insulation described on a
Gaussian scale . 41
Figure 6 – Evaluation of deterministic co-ordination factor K . 42
cd
Figure 7 – Evaluation of the risk of failure . 43
Figure 8 – Risk of failure of external insulation for slow-front overvoltages as a function
of the statistical co-ordination factor K . 45
cs
Figure 9 – Dependence of exponent m on the co-ordination switching impulse
withstand voltage . 47
Figure 10 – Probability P of an equipment to pass the test depen
...