IEC 60099-5:2018

Surge arresters - Part 5: Selection and application recommendations

IEC 60099-5:2018 is available as IEC 60099-5:2018 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.
IEC 60099-5:2018 provides information, guidance, and recommendations for the selection and application of surge arresters to be used in three-phase systems with nominal voltages above 1 kV. It applies to gapless metal-oxide surge arresters as defined in IEC 60099-4, to surge arresters containing both series and parallel gapped structure – rated 52 kV and less as defined in IEC 60099-6 and metal-oxide surge arresters with external series gap for overhead transmission and distribution lines (EGLA) as defined in IEC 60099-8. In Annex J, some aspects regarding the old type of SiC gapped arresters are discussed. Surge arrester residual voltage is a major parameter to which most users have paid a lot of attention to when selecting the type and rating. Typical maximum residual voltages are given in Annex F. It is likely, however, that for some systems, or in some countries, the requirements on system reliability and design are sufficiently uniform, so that the recommendations of the present standard may lead to the definition of narrow ranges of arresters. The user of surge arresters will, in that case, not be required to apply the whole process introduced here to any new installation and the selection of characteristics resulting from prior practice may be continued. Annexes H and I present comparisons and calculations between old line discharge classification and new charge classification. This third edition cancels and replaces the second edition published in 2013. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition regarding the new surge arrester classification introduced in IEC 60099-4:2014:
a) Expanded discussion of comparison between the old and new classification and how to calculate or estimate the corresponding charge for different stresses.
b) New annexes dealing with:
- Comparison between line discharge classes and charge classification
- Estimation of arrester cumulative charges and energies during line switching
Keywords: selection and application of surge arrestors, nominal voltages above 1 kV

Parafoudres - Partie 5: Recommandations pour le choix et l'utilisation

IEC 60099-5:2018 comporte des informations et des recommandations pour le choix et l'utilisation des parafoudres à utiliser sur des réseaux triphasés de tensions nominales supérieures à 1 kV. Elle concerne les parafoudres à oxyde métallique sans éclateur définis dans l'IEC 60099-4, les parafoudres qui contiennent des structures avec éclateur en série et en parallèle, de tension assignée inférieure ou égale à 52 kV, tels que définis dans l'IEC 60099-6, et les parafoudres à oxyde métallique à éclateur extérieur en série pour les lignes aériennes de transmission ou de distribution (EGLA) tels que définis dans l'IEC 60099-8. L'Annexe J traite de quelques aspects concernant les anciens parafoudres au carbure de silicium (SiC) avec éclateur. La tension résiduelle des parafoudres représente un paramètre essentiel dont la plupart des utilisateurs tiennent dûment compte lors du choix du type et des caractéristiques assignées d'un parafoudre. Les tensions résiduelles maximales types sont données à l'Annexe F. Il est probable, cependant, que pour certains réseaux, ou pour certains pays, les exigences de fiabilité et de conception des réseaux soient assez uniformes pour que les recommandations de la présente norme puissent se traduire par la définition de plages limitées de parafoudres. L'utilisateur de parafoudres n'est alors pas tenu de reprendre pour chaque nouvelle installation toute la démarche exposée dans le présent document et le choix des caractéristiques relevant de la pratique antérieure peut perdurer. Les Annexes H et I comparent l'ancienne classification de décharge de ligne et la nouvelle classification des charges, et présentent les méthodes de calculs. Cette troisième édition annule et remplace la deuxième édition parue en 2013. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente, qui concernent la nouvelle classification des parafoudres introduite dans l'IEC 60099-4:2014:
a) comparaison détaillée entre l'ancienne et la nouvelle classification, et présentation détaillée de la méthode de calcul ou d'estimation de la charge correspondante pour les différentes contraintes;
b) nouvelles annexes portant sur:
- la comparaison entre les classes de décharge de ligne et la classification des charges;
- l'estimation des charges et des énergies cumulées des parafoudres lors d'une manœuvre de ligne.

General Information

• Status: Published
• Publication Date: 18-Jan-2018
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 29.120.50 - Fuses and other overcurrent protection devices
• ICS: 29.240.10 - Substations. Surge arresters
• Technical Committee: TC 37 - Surge arresters
• Drafting Committee: MT 10 - TC 37/MT 10
• Current Stage: PPUB - Publication issued
• Start Date: 22-Dec-2017
• Completion Date: 19-Jan-2018

Relations

• Revises: IEC 60099-5:2013 - Surge arresters - Part 5: Selection and application recommendations
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 60099-5 ®
Edition 3.0 2018-01
INTERNATIONAL
STANDARD
colour
inside
Surge arresters –
Part 5: Selection and application recommendations

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.: [phone]
3, rue de Varembé [e-mail]
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: [e-mail].
IEC 60099-5 ®
Edition 3.0 2018-01
INTERNATIONAL
STANDARD
colour
inside
Surge arresters –
Part 5: Selection and application recommendations

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.120.50; 29.240.10 ISBN 978-2-8322-5075-4

– 2 – IEC 60099-5:2018 © IEC 2018
CONTENTS
FOREWORD . 9
1 Scope . 11
2 Normative references . 11
3 Terms and definitions . 12
4 General principles for the application of surge arresters . 21
5 Surge arrester fundamentals and applications issues . 22
5.1 Evolution of surge protection equipment . 22
5.2 Different types and designs and their electrical and mechanical
characteristics . 23
5.2.1 General . 23
5.2.2 Metal-oxide arresters without gaps according to IEC 60099-4 . 24
5.2.3 Metal-oxide surge arresters with internal series gaps according to
IEC 60099-6 . 34
5.2.4 Externally gapped line arresters (EGLA) according to IEC 60099-8. 36
5.2.5 Application considerations . 39
6 Insulation coordination and surge arrester applications. 52
6.1 General . 52
6.2 Insulation coordination overview . 52
6.2.1 General . 52
6.2.2 IEC insulation coordination procedure . 53
6.2.3 Overvoltages . 53
6.2.4 Line insulation coordination: Arrester Application Practices . 59
6.2.5 Substation insulation coordination: Arrester application practices . 64
6.2.6 Insulation coordination studies. 68
6.3 Selection of arresters . 70
6.3.1 General . 70
6.3.2 General procedure for the selection of surge arresters . 70
6.3.3 Selection of line surge arresters, LSA . 84
6.3.4 Selection of arresters for cable protection . 93
6.3.5 Selection of arresters for distribution systems – special attention . 95
6.3.6 Application and coordination of disconnectors . 96
6.3.7 Selection of UHV arresters . 98
6.4 Standard and special service conditions . 99
6.4.1 Standard service conditions . 99
6.4.2 Special service conditions . 99
7 Surge arresters for special applications . 103
7.1 Surge arresters for transformer neutrals . 103
7.1.1 General . 103
7.1.2 Surge arresters for fully insulated transformer neutrals . 103
7.1.3 Surge arresters for neutrals of transformers with non-uniform insulation . 103
7.2 Surge arresters between phases . 104
7.2.1 General . 104
7.2.2 6-arrester arrangement . 104
7.2.3 4-arrester (Neptune) arrangement . 104
7.3 Surge arresters for rotating machines . 105
7.4 Surge arresters in parallel . 106

7.4.1 General . 106
7.4.2 Combining different designs of arresters . 107
7.5 Surge arresters for capacitor switching . 107
7.6 Surge arresters for series capacitor banks . 109
8 Asset management of surge arresters . 110
8.1 General . 110
8.2 Managing surge arresters in a power grid . 110
8.2.1 Asset database . 110
8.2.2 Technical specifications . 110
8.2.3 Strategic spares . 110
8.2.4 Transportation and storage . 111
8.2.5 Commissioning . 111
8.3 Maintenance . 111
8.3.1 General . 111
8.3.2 Polluted arrester housing . 112
8.3.3 Coating of arrester housings . 112
8.3.4 Inspection of disconnectors on surge arresters . 112
8.3.5 Line surge arresters . 112
8.4 Performance and diagnostic tools . 112
8.5 End of life . 113
8.5.1 General . 113
8.5.2 GIS arresters . 113
8.6 Disposal and recycling . 113
Annex A (informative) Determination of temporary overvoltages due to earth faults . 114
Annex B (informative) Current practice . 118
Annex C (informative)  Arrester modelling techniques for studies involving insulation
coordination and energy requirements . 119
C.1 Arrester models for impulse simulations . 119
C.2 Application to insulation coordination studies . 120
C.3 Summary of proposed arrester models to be used for impulse applications . 120
Annex D (informative) Diagnostic indicators of metal-oxide surge arresters in service . 122
D.1 General . 122
D.1.1 Overview . 122
D.1.2 Fault indicators . 122
D.1.3 Disconnectors . 122
D.1.4 Surge counters . 122
D.1.5 Monitoring spark gaps . 123
D.1.6 Temperature measurements . 123
D.1.7 Leakage current measurements of gapless metal-oxide arresters . 123
D.2 Measurement of the total leakage current . 128
D.3 Measurement of the resistive leakage current or the power loss. 129
D.3.1 General . 129
D.3.2 Method A1 – Using the applied voltage signal as a reference . 129
D.3.3 Method A2 – Compensating the capacitive component using a voltage
signal . 130
D.3.4 Method A3 – Compensating the capacitive component without using a
voltage signal . 131
D.3.5 Method A4 – Capacitive compensation by combining the leakage
current of the three phases . 131

– 4 – IEC 60099-5:2018 © IEC 2018
D.3.6 Method B1 – Third order harmonic analysis . 132
D.3.7 Method B2 – Third order harmonic analysis with compensation for
harmonics in the voltage . 133
D.3.8 Method B3 – First order harmonic analysis . 133
D.3.9 Method C – Direct determination of the power losses . 133
D.4 Leakage current information from the arrester manufac
...

IEC 60099-5 ®
Edition 3.0 2018-01
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Surge arresters –
Part 5: Selection and application recommendations

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.: [phone]
3, rue de Varembé [e-mail]
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: [e-mail].
IEC 60099-5 ®
Edition 3.0 2018-01
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Surge arresters –
Part 5: Selection and application recommendations

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.120.50; 29.240.10 ISBN 978-2-8322-5314-4

– 2 – IEC 60099-5:2018 RLV © IEC 2018
CONTENTS
FOREWORD . 9
1 Scope . 11
2 Normative references . 11
3 Terms and definitions . 12
4 General principles for the application of surge arresters . 21
5 Surge arrester fundamentals and applications issues . 22
5.1 Evolution of surge protection equipment . 22
5.2 Different types and designs and their electrical and mechanical
characteristics . 23
5.2.1 General . 23
5.2.2 Metal-oxide arresters without gaps according to IEC 60099-4 . 24
5.2.3 Metal-oxide surge arresters with internal series gaps according to
IEC 60099-6 . 36
5.2.4 Externally gapped line arresters (EGLA) according to IEC 60099-8. 38
5.2.5  Installation considerations for arresters Application considerations . 41
6 Insulation coordination and surge arrester applications. 55
6.1 General . 55
6.2 Insulation coordination overview . 56
6.2.1 General . 56
6.2.2 IEC insulation coordination procedure . 56
6.2.3 Overvoltages . 56
6.2.4 Line insulation coordination: Arrester Application Practices . 63
6.2.5 Substation insulation coordination: Arrester application practices . 68
6.2.6 Insulation coordination studies. 72
6.3 Selection of arresters . 74
6.3.1 General . 74
6.3.2 General procedure for the selection of surge arresters . 75
6.3.3 Selection of line surge arresters, LSA . 92
6.3.4 Selection of arresters for cable protection . 102
6.3.5 Selection of arresters for distribution systems – special attention . 104
6.3.6 Application and coordination of disconnectors . 106
6.3.7 Selection of UHV arresters . 108
6.4  Normal Standard and abnormal special conditions . 110
6.4.1 Normal Standard service conditions . 110
6.4.2 Abnormal Special service conditions . 110
7 Surge arresters for special applications . 113
7.1 Surge arresters for transformer neutrals . 113
7.1.1 General . 113
7.1.2 Surge arresters for fully insulated transformer neutrals . 114
7.1.3 Surge arresters for neutrals of transformers with non-uniform insulation . 114
7.2 Surge arresters between phases . 114
7.2.1 General . 114
7.2.2 6-arrester arrangement . 115
7.2.3 4-arrester (Neptune) arrangement . 115
7.3 Surge arresters for rotating machines . 116
7.4 Surge arresters in parallel . 117

7.4.1 General . 117
7.4.2 Combining different designs of arresters . 118
7.5 Surge arresters for capacitor switching . 118
7.6 Surge arresters for series capacitor banks . 120
8 Asset management of surge arresters . 121
8.1 General . 121
8.2 Managing surge arresters in a power grid . 121
8.2.1 Asset database . 121
8.2.2 Technical specifications . 121
8.2.3 Strategic spares . 121
8.2.4 Transportation and storage . 122
8.2.5 Commissioning . 122
8.3 Maintenance . 122
8.3.1 General . 122
8.3.2 Polluted arrester housing . 123
8.3.3 Coating of arrester housings . 123
8.3.4 Inspection of disconnectors on surge arresters . 123
8.3.5 Line surge arresters . 124
8.4 Performance and diagnostic tools . 124
8.5 End of life . 124
8.5.1 General . 124
8.5.2 GIS arresters . 124
8.6 Disposal and recycling . 124
Annex A (informative) Determination of temporary overvoltages due to earth faults . 126
Annex B (informative) Current practice . 130
Annex C (informative)  Arrester modelling techniques for studies involving insulation
coordination and energy requirements . 131
C.1 Arrester models for impulse simulations . 131
C.2 Application to insulation coordination studies . 132
C.3 Summary of proposed arrester models to be used for impulse applications . 132
Annex D (informative) Diagnostic indicators of metal-oxide surge arresters in service . 134
D.1 General . 134
D.1.1 Introduction Overview . 134
D.1.2 Fault indicators . 134
D.1.3 Disconnectors . 134
D.1.4 Surge counters . 134
D.1.5 Monitoring spark gaps . 135
D.1.6 Temperature measurements . 135
D.1.7 Leakage current measurements of gapless metal-oxide arresters . 135
D.2 Measurement of the total leakage current . 140
D.3 Measurement of the resistive leakage current or the power loss. 141
D.3.1 General . 141
D.3.2 Method A1 – Using the applied voltage signal as a reference . 141
D.3.3 Method A2 – Compensating the capacitive component using a voltage
signal . 142
D.3.4 Method A3 – Compensating the capacitive component without using a
voltage signal . 143
D.3.5 Method A4 – Capacitive compensation by combining the leakage
current of the three phases . 143

– 4 – IEC 60099-5:2018 RLV © IEC 2018
D.3.6 Method B1 – Third order harmonic analysis . 144
D.3.7 Method B2 – Third order harmonic analysis with compensation for
harmonics in the voltage . 145
D.3.8 Method B3 – First order harmonic analysis . 145
D.3.9 Method C – Direct determination of the power losses . 145
D.4 Leakage current information from the
...

IEC 60099-5 ®
Edition 3.0 2018-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Surge arresters –
Part 5: Selection and application recommendations

Parafoudres –
Partie 5: Recommandations pour le choix et l'utilisation

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.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite ni
utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie et
les microfilms, sans l'accord écrit de l'IEC ou du Comité national de l'IEC du pays du demandeur. Si vous avez des
questions sur le copyright de l'IEC ou si vous désirez obtenir des droits supplémentaires sur cette publication, utilisez
les coordonnées ci-après ou contactez le Comité national de l'IEC de votre pays de résidence.

IEC Central Office Tel.: [phone]
3, rue de Varembé [e-mail]
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 corrigendum or an amendment might have been published.

IEC publications search - webstore.iec.ch/advsearchform IEC online collection - oc.iec.ch
The advanced search enables to find IEC publications by a Discover our powerful search engine and read freely all the
variety of criteria (reference number, text, technical publications previews. With a subscription you will always have
committee, …). It also gives information on projects, replaced access to up to date content tailored to your needs.
and withdrawn publications.
Electropedia - www.electropedia.org
IEC Just Published - webstore.iec.ch/justpublished
The world's leading online dictionary on electrotechnology,
Stay up to date on all new IEC publications. Just Published
containing more than 22 000 terminological entries in English
details all new publications released. Available online and once
and French, with equivalent terms in 18 additional languages.
a month by email.
Also known as the International Electrotechnical Vocabulary

(IEV) online.
IEC Customer Service Centre - webstore.iec.ch/csc
If you wish to give us your feedback on this publication or need
further assistance, please contact the Customer Service
Centre: [e-mail].
A propos de l'IEC
La Commission Electrotechnique Internationale (IEC) est la première organisation mondiale qui élabore et publie des
Normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.

A propos des publications IEC
Le contenu technique des publications IEC est constamment revu. Veuillez vous assurer que vous possédez l’édition la
plus récente, un corrigendum ou amendement peut avoir été publié.

Recherche de publications IEC - Découvrez notre puissant moteur de recherche et consultez
webstore.iec.ch/advsearchform gratuitement tous les aperçus des publications. Avec un
La recherche avancée permet de trouver des publications IEC abonnement, vous aurez toujours accès à un contenu à jour
en utilisant différents critères (numéro de référence, texte, adapté à vos besoins.
comité d’études, …). Elle donne aussi des informations sur les
projets et les publications remplacées ou retirées. Electropedia - www.electropedia.org

Le premier dictionnaire d'électrotechnologie en ligne au monde,
IEC Just Published - webstore.iec.ch/justpublished
avec plus de 22 000 articles terminologiques en anglais et en
Restez informé sur les nouvelles publications IEC. Just
français, ainsi que les termes équivalents dans 16 langues
Published détaille les nouvelles publications parues.
additionnelles. Egalement appelé Vocabulaire
Disponible en ligne et une fois par mois par email.
Electrotechnique International (IEV) en ligne.

Service Clients - webstore.iec.ch/csc
Si vous désirez nous donner des commentaires sur cette
publication ou si vous avez des questions contactez-nous:
[e-mail].
IEC online collection - oc.iec.ch

IEC 60099-5 ®
Edition 3.0 2018-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Surge arresters –
Part 5: Selection and application recommendations

Parafoudres –
Partie 5: Recommandations pour le choix et l'utilisation

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.120.50; 29.240.10 ISBN 978-2-8322-9360-7

– 2 – IEC 60099-5:2018 © IEC 2018
CONTENTS
FOREWORD . 9
1 Scope . 11
2 Normative references . 11
3 Terms and definitions . 12
4 General principles for the application of surge arresters . 21
5 Surge arrester fundamentals and applications issues . 22
5.1 Evolution of surge protection equipment . 22
5.2 Different types and designs and their electrical and mechanical
characteristics . 23
5.2.1 General . 23
5.2.2 Metal-oxide arresters without gaps according to IEC 60099-4 . 24
5.2.3 Metal-oxide surge arresters with internal series gaps according to
IEC 60099-6 . 34
5.2.4 Externally gapped line arresters (EGLA) according to IEC 60099-8. 36
5.2.5 Application considerations . 39
6 Insulation coordination and surge arrester applications. 52
6.1 General . 52
6.2 Insulation coordination overview . 52
6.2.1 General . 52
6.2.2 IEC insulation coordination procedure . 52
6.2.3 Overvoltages . 53
6.2.4 Line insulation coordination: Arrester Application Practices . 59
6.2.5 Substation insulation coordination: Arrester application practices . 64
6.2.6 Insulation coordination studies. 68
6.3 Selection of arresters . 69
6.3.1 General . 69
6.3.2 General procedure for the selection of surge arresters . 70
6.3.3 Selection of line surge arresters, LSA . 84
6.3.4 Selection of arresters for cable protection . 93
6.3.5 Selection of arresters for distribution systems – special attention . 95
6.3.6 Application and coordination of disconnectors . 96
6.3.7 Selection of UHV arresters . 98
6.4 Standard and special service conditions . 99
6.4.1 Standard service conditions . 99
6.4.2 Special service conditions . 99
7 Surge arresters for special applications . 103
7.1 Surge arresters for transformer neutrals . 103
7.1.1 General . 103
7.1.2 Surge arresters for fully insulated transformer neutrals . 103
7.1.3 Surge arresters for neutrals of transformers with non-uniform insulation . 104
7.2 Surge arresters between phases . 104
7.2.1 General . 104
7.2.2 6-arrester arrangement . 104
7.2.3 4-arrester (Neptune) arrangement . 104
7.3 Surge arresters for rotating machines . 105
7.4 Surge arresters in parallel . 106

7.4.1 General . 106
7.4.2 Combining different designs of arresters . 107
7.5 Surge arresters for capacitor switching . 107
7.6 Surge arresters for series capacitor banks . 109
8 Asset management of surge arresters . 110
8.1 General . 110
8.2 Managing surge arresters in a power grid . 110
8.2.1 Asset database . 110
8.2.2 Technical specifications . 110
8.2.3 Strategic spares . 110
8.2.4 Transportation and storage . 111
8.2.5 Commissioning . 111
8.3 Maintenance . 111
8.3.1 General . 111
8.3.2 Polluted arrester housing . 112
8.3.3 Coating of arrester housings . 112
8.3.4 Inspection of disconnectors on surge arresters . 112
8.3.5 Line surge arresters . 112
8.4 Performance and diagnostic tools . 112
8.5 End of life . 113
8.5.1 General . 113
8.5.2 GIS arresters . 113
8.6 Disposal and recycling . 113
Annex A (informative) Determination of temporary overvoltages due to earth faults . 114
Annex B (informative) Current practice . 118
Annex C (informative)  Arrester modelling techniques for studies involving insulation
coordination and energy requirements . 119
C.1 Arrester models for impulse simulations . 119
C.2 Application to insulation coordination studies . 120
C.3 Summary of proposed arrester models to be used for impulse applications . 120
Annex D (informative) Diagnostic indicators of metal-oxide surge arresters in service . 122
D.1 General . 122
D.1.1 Overview .
...