IEC 60071-2:2018
(Main)Insulation co-ordination - Part 2: Application guidelines
Insulation co-ordination - Part 2: Application guidelines
IEC 60071-2:2018 constitutes application guidelines and deals with the selection of insulation levels of equipment or installations for three-phase electrical systems. It gives 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. It covers three-phase systems with nominal voltages above 1 kV. This edition includes the following significant technical changes with respect to the previous edition:
a) the annex on clearance in air to assure a specified impulse withstand voltage installation is deleted because the annex in IEC 60071-1 is overlapped;
b) 4.2 and 4.3 on surge arresters are updated;
c) 4.3.5 on very-fast-front overvoltages is revised. Annex J on insulation co-ordination for very-fast-front overvoltages in UHV substations is added;
d) Annex H on atmospheric correction – altitude correction is added.
e) Annex I on evaluation method of non-standard lightning overvoltage shape is added.
It has the status of a horizontal standard in accordance with IEC Guide 108.
Coordination de l'isolement - Partie 2: Lignes directrices en matière d'application
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. 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.
Elle a le statut de norme horizontale conformément au Guide IEC 108.
General Information
Relations
Standards Content (Sample)
IEC 60071-2 ®
Edition 4.0 2018-03
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
HORIZONTAL STANDARD
Insulation co-ordination –
Part 2: Application guidelines
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.
IEC Central Office Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.
About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.
IEC Catalogue - webstore.iec.ch/catalogue Electropedia - www.electropedia.org
The stand-alone application for consulting the entire The world's leading online dictionary of electronic and
bibliographical information on IEC International Standards, electrical terms containing 21 000 terms and definitions in
Technical Specifications, Technical Reports and other English and French, with equivalent terms in 16 additional
documents. Available for PC, Mac OS, Android Tablets and languages. Also known as the International Electrotechnical
iPad. Vocabulary (IEV) online.
IEC publications search - webstore.iec.ch/advsearchform IEC Glossary - std.iec.ch/glossary
The advanced search enables to find IEC publications by a 67 000 electrotechnical terminology entries in English and
variety of criteria (reference number, text, technical French extracted from the Terms and Definitions clause of
committee,…). It also gives information on projects, replaced IEC publications issued since 2002. Some entries have been
and withdrawn publications. collected from earlier publications of IEC TC 37, 77, 86 and
CISPR.
IEC Just Published - webstore.iec.ch/justpublished
Stay up to date on all new IEC publications. Just Published IEC Customer Service Centre - webstore.iec.ch/csc
details all new publications released. Available online and If you wish to give us your feedback on this publication or
also once a month by email. need further assistance, please contact the Customer Service
Centre: sales@iec.ch.
IEC 60071-2 ®
Edition 4.0 2018-03
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
HORIZONTAL STANDARD
Insulation co-ordination –
Part 2: Application guidelines
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.080.30 ISBN 978-2-8322-5498-1
– 2 – IEC 60071-2:2018 RLV IEC 2018
CONTENTS
FOREWORD . 9
General .
1 Scope . 11
2 Normative references . 11
3 Terms, definitions, abbreviated terms and symbols . 12
3.1 Terms and definitions . 12
3.2 Abbreviated terms . 12
3.3 Symbols . 13
4 Representative voltage stresses in service . 18
4.1 Origin and classification of voltage stresses . 18
4.2 Characteristics of overvoltage protective protection devices. 18
4.2.1 General remarks . 20
4.2.2 Metal-oxide surge arresters without gaps (MOSA) . 21
Spark gaps .
4.2.3 Line surge arresters (LSA) for overhead transmission and distribution
lines . 22
4.3 Representative voltages and overvoltages . 23
4.3.1 Continuous (power-frequency) voltage . 23
4.3.2 Temporary overvoltages . 23
4.3.3 Slow-front overvoltages . 27
4.3.4 Fast-front overvoltages . 33
4.3.5 Very-fast-front overvoltages [13] . 37
5 Co-ordination withstand voltage . 38
5.1 Insulation strength characteristics . 38
5.1.1 General . 38
5.1.2 Influence of polarity and overvoltage shapes . 40
5.1.3 Phase-to-phase and longitudinal insulation . 40
5.1.4 Influence of weather conditions on external insulation . 41
5.1.5 Probability of disruptive discharge of insulation . 41
5.2 Performance criterion . 43
5.3 Insulation co-ordination procedures . 43
5.3.1 General . 43
5.3.2 Insulation co-ordination procedures for continuous (power-frequency)
voltage and temporary overvoltage . 44
5.3.3 Insulation co-ordination procedures for slow-front overvoltages . 46
5.3.4 Insulation co-ordination procedures for fast-front overvoltages . 51
6 Required withstand voltage . 52
6.1 General remarks . 52
6.2 Atmospheric correction . 52
6.2.1 General remarks . 52
6.2.2 Altitude correction . 52
6.3 Safety factors. 54
6.3.1 General . 54
6.3.2 Ageing . 54
6.3.3 Production and assembly dispersion . 54
6.3.4 Inaccuracy of the withstand voltage . 54
6.3.5 Recommended safety factors (K ) . 55
s
7 Standard withstand voltage and testing procedures . 55
7.1 General remarks . 55
7.1.1 Overview . 55
7.1.2 Standard switching impulse withstand voltage . 55
7.1.3 Standard lightning impulse withstand voltage . 56
7.2 Test conversion factors . 56
7.2.1 Range I. 56
7.2.2 Range II . 57
7.3 Determination of insulation withstand by type tests . 57
7.3.1 Test procedure dependency upon insulation type . 57
7.3.2 Non-self-restoring insulation . 58
7.3.3 Self-restoring insulation . 58
7.3.4 Mixed insulation . 58
7.3.5 Limitations of the test procedures . 59
7.3.6 Selection of the type test procedures . 60
7.3.7 Selection of the type test voltages . 60
8 Special considerations for overhead lines . 61
8.1 General remarks . 61
8.2 Insulation co-ordination for operating voltages and temporary overvoltages . 61
8.3 Insulation co-ordination for slow-front overvoltages . 61
8.3.1 General . 61
8.3.2 Earth-fault overvoltages . 62
8.3.3 Energization and re-energization overvoltages . 62
8.4 Insulation co-ordination for lightning overvoltages . 62
8.4.1 General . 62
8.4.2 Distribution lines . 62
8.4.3 Transmission lines . 63
9 Special considerations for substations . 63
9.1 General remarks . 63
9.1.1 Overview . 63
9.1.2 Operating voltage . 63
9.1.3 Temporary overvoltage . 63
9.1.4 Slow-front overvoltages . 64
9.1.5 Fast-front overvoltages . 64
9.2 Insulation co-ordination for overvoltages . 64
9.2.1 Substations in distribution systems with U up to 36 kV in range I . 64
m
9.2.2 Substations in transmission systems with U between 52,5 kV and
m
245 kV in range I . 65
9.2.3 Substations in transmission systems in range II . 66
Annex (normative) Clearances in air to assure a specified impulse withstand voltage
installation .
Annex A (informative) Determination of temporary overvoltages due to earth faults . 71
Annex B (informative) Weibull probability distributions . 75
B.1 General remarks . 75
B.2 Disruptive discharge probability of external insulation . 76
B.3 Cumulative frequency distribution of overvoltages . 78
Annex C (informative) Determination of the representative slow-front overvoltage due
to line energization and re-energization . 81
– 4 – IEC 60071-2:2018 RLV IEC 2018
C.1 General remarks .
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.