IEC 60099-5:2018

Surge arresters - Part 5: Selection and application recommendations

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: 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: 19-Jan-2018
• Completion Date: 22-Dec-2017

Relations

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

Overview

IEC 60099-5:2018 - "Surge arresters - Part 5: Selection and application recommendations" provides guidance for the selection, application and coordination of surge arresters used on three‑phase systems with nominal voltages above 1 kV. This third edition (2018) replaces the 2013 edition and incorporates a technical revision that aligns arrester selection practice with the new surge arrester classification introduced in IEC 60099‑4:2014.

Key topics and requirements

• Scope of arrester types: Gapless metal‑oxide arresters (IEC 60099‑4), combined series/parallel gapped arresters rated ≤ 52 kV (IEC 60099‑6), and metal‑oxide arresters with external series gap for overhead lines (EGLA, IEC 60099‑8). Annex J discusses older SiC gapped arresters.
• Insulation coordination: Procedures and application practices for line and substation insulation coordination, including selection workflows and coordination studies.
• Residual voltage: Emphasis on residual voltage as a primary selection parameter; typical maximum residual voltages are provided in Annex F.
• New classification guidance: Expanded comparison between the former line discharge classes and the newer charge/energy‑based classification; methods to estimate equivalent charges and energies are included (Annexes H and I).
• Application‑specific guidance: Selection for line surge arresters (LSA), cable protection, distribution systems, UHV, capacitor switching, transformer neutrals, phase‑to‑phase arrangements and parallel arrester applications.
• Modelling & diagnostics: Recommended arrester models for impulse and insulation studies (Annex C) and diagnostic/monitoring methods for MO arresters in service (Annex D).
• Asset management: Practical guidance on procurement data, commissioning, maintenance, monitoring, end‑of‑life, disposal and recycling (Annexes E, D and main text).

Practical applications and intended users

IEC 60099‑5 is essential for:

• Utility and transmission/distribution engineers specifying and procuring surge arresters
• Protection and insulation coordination engineers performing surge and switching studies
• Substation designers and consulting engineers defining arrester ratings and residual voltage limits
• Asset managers and maintenance teams implementing diagnostic programs and end‑of‑life strategies
• Manufacturers and testing laboratories preparing product data and compliance guidance

Use cases include selecting arresters for new installations, verifying coordination for system upgrades, estimating arrester cumulative energies during line switching, and defining maintenance/monitoring procedures.

Related standards

• IEC 60099‑4 - Metal‑oxide surge arresters (classification and test methods; 2014 revision relevant)
• IEC 60099‑6 - Surge arresters with series/parallel gapped structures (rated ≤ 52 kV)
• IEC 60099‑8 - Externally gapped line arresters (EGLA)

Keywords: selection and application of surge arrestors, surge arresters, nominal voltages above 1 kV, residual voltage, insulation coordination, IEC 60099‑5:2018.

Standards Content (Sample)

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

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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 manufacturer . 133
D.5 Summary of diagnostic methods . 135
Annex E (informative) Typical data needed from arrester manufacturers for proper
selection of surge arresters . 136
Annex F (informative) Typical maximum residual voltages for metal-oxide arresters
without gaps according to IEC 60099-4 . 137
Annex G (informative) Steepness reduction of incoming surge with additional line
terminal surge capacitance . 138
G.1 General . 138
G.2 Steepness reduction factor . 138
G.3 Equivalent capacitance associated with incoming surge fronts . 140
G.3.1 General . 140
G.3.2 Examples of incoming surge steepness change, f , using typical 550 kV
s
& 245 kV circuit parameters . 141
G.3.3 Change in coordination withstand voltage, U , with steepness
cw
reduction, f : . 142
s
G.4 EMTP & capacitor charging models for steepness change comparisons at
line open terminal . 142
G.5 Typical steepness (S = 1000 kV/µs), change comparisons with C & C . 143
0 0 s
G.6 Faster steepness (2000 kV/µs), change comparisons with C & C . 145
o s
Annex H (informative) Comparison of the former energy classification system based
on line discharge classes and the present classification system based on thermal
energy ratings for operating duty tests and repetitive charge transfer ratings for
repetitive single event energies. 147
H.1 General . 147
H.2 Examples . 150
Annex I (informative) Estimation of arrester cumulative charges and energies during
line switching . 155
I.1 Simplified method of estimating arrester line switching energies . 155
I.1.1 Introduction . 155
I.1.2 Simplified method calculation steps . 156
I.1.3 Typical line surge impedances with bundled conductors . 158
I.1.4 Prospective switching surge overvoltages . 158
I.1.5 Use of IEC 60099-4:2009 to obtain values for surge impedance and
prospective surge voltages . 159
I.2 Example of charge and energy calculated using line discharge parameters. 160
I.3 Arrester line switching energy examples . 164
I.3.1 General . 164
I.3.2 Case 1 – 145 kV . 167
I.3.3 Case 2 – 242 kV . 167
I.3.4 Case 3 – 362 kV . 167
I.3.5 Case 4 – 420 kV . 168
I.3.6 Case 5 – 550 kV . 168
Annex J (informative) End of life and replacement of old gapped SiC-arresters . 180
J.1 Overview. 180
J.2 Design and operation of SiC-arresters . 180

J.3 Failure causes and aging phenomena . 180
J.3.1 General . 180
J.3.2 Sealing problems . 180
J.3.3 Equalization of internal and external pressure and atmosphere . 181
J.3.4 Gap electrode erosion . 181
J.3.5 Ageing of grading components . 182
J.3.6 Changed system conditions . 182
J.3.7 Increased pollution levels . 182
J.4 Possibility to check the status of the arresters . 182
J.5 Advantages of planning replacements ahead . 182
J.5.1 General . 182
J.5.2 Improved reliability . 183
J.5.3 Cost advantages . 183
J.5.4 Increased safety requirements . 183
J.6 Replacement issues . 183
J.6.1 General . 183
J.6.2 Establishing replacement priority . 183
J.6.3 Selection of MO arresters for replacement installations . 184
Bibliography . 185

Figure 1 – Example of GIS arresters of three mechanical/one electrical column
(middle) and one column (left) design and current path of the three mechanical/one
electrical column design (right) . 29
Figure 2 – Typical deadfront arrester . 30
Figure 3 – Internally gapped metal-oxide surge arrester designs . 35
Figure 4 – Components of an EGLA acc. to IEC 60099-8 . 36
Figure 5 – Typical arrangement of a 420 kV arrester . 41
Figure 6 – Examples of UHV and HV arresters with grading and corona rings . 42
Figure 7 – Same type of arrester mounted on a pedestal (left), suspended from an
earthed steel structure (middle) or suspended from a line conductor (right . 43
Figure 8 – Installations without earth-mat (distribution systems) . 44
Figure 9 – Installations with earth-mat (high-voltage substations) . 45
Figure 10 – Definition of mechanical loads according to IEC 60099-4:2014 . 47
Figure 11 – Distribution arrester with disconnector and insulating bracket. 48
Figure 12 – Examples of good and poor connection principles for distribution arresters . 50
Figure 13 – Typical voltages and duration example for differently earthed systems . 54
Figure 14 – Typical phase-to-earth overvoltages encountered in power systems . 55
Figure 15 – Arrester voltage-current characteristics . 56
Figure 16 – Direct strike to a phase conductor with LSA . 61
Figure 17 – Strike to a shield wire or tower with LSA . 62
Figure 18 – Typical procedure for a surge arrester insulation coordination study . 69
Figure 19 – Flow diagrams for standard selection of surge arrester . 73
Figure 20 – Examples of arrester TOV capability . 74
Figure 21 – Flow diagram for the selection of NGLA . 87
Figure 22 – Flow diagram for the selection of EGLA . 91
Figure 23 – Common neutral configurations . 96

– 6 – IEC 60099-5:2018 © IEC 2018
Figure 24 – Typical configurations for arresters connected phase-to-phase and phase-
to-ground . 105
Figure A.1 – Earth fault factor k on a base of X /X , for R /X = R = 0 . 114
0 1 1 1 1
Figure A.2 – Relationship between R /X and X /X for constant values of earth fault
0 1 0 1
factor k where R = 0 . 115
Figure A.3 – Relationship between R0/X1 and X0/X1 for constant values of earth fault
factor k where R = 0,5 X . 115
1 1
Figure A.4 – Relationship between R /X and X /X for constant values of earth fault
0 1 0 1
factor k where R = X . 116
1 1
Figure A.5 – Relationship between R /X and X /X for constant values of earth fault
0 1 0 1
factor k where R = 2X . 116
1 1
Figure C.1 – Schematic sketch of a typical arrester installation . 119
Figure C.2 – Increase in residual voltage as function of virtual current front time . 120
Figure C.3 – Arrester model for insulation coordination studies – fast- front
overvoltages and preliminary calculation (Option 1) . 121
Figure C.4 – Arrester model for insulation coordination studies – fast- front
overvoltages and preliminary calculation (Option 2) . 121
Figure C.5 – Arrester model for insulation coordination studies – slow-front
overvoltages . 121
Figure D.1 – Typical leakage current of a non-linear metal-oxide resistor in laboratory
conditions . 124
Figure D.2 – Typical leakage currents of arresters in service conditions . 125
Figure D.3 – Typical voltage-current characteristics for non-linear metal-oxide resistors . 126
Figure D.4 – Typical normalized voltage dependence at +20 °C . 126
Figure D.5 – Typical normalized temperature dependence at U . 127
c
Figure D.6 – Influence on total leakage current by increase in resistive leakage current . 128
Figure D.7 – Measured voltage and leakage current and calculated resistive and
capacitive currents (V = 6,3 kV r.m.s) . 130
Figure D.8 – Remaining current after compensation by capacitive current at U . 131
c
Figure D.9 – Error in the evaluation of the leakage current third harmonic for different
phase angles of system voltage third harmonic, considering various capacitances and
voltage-current characteristics of non-linear metal-oxide resistors . 132
Figure D.10 – Typical information for conversion to "standard" operating voltage
conditions . 134
Figure D.11 – Typical information for conversion to "standard" ambient temperature
conditions . 134
Figure G.1 – Surge voltage waveforms at various distances from strike location
(0,0 km) due to corona . 139
Figure G.2 – Case 1: EMTP Model: Thevenin equivalent source, line (Z,c) & substation
bus (Z,c) & Cap(C ). 142
s
Figure G.3 – Case 2: Capacitor Voltage charge via line Z: u(t) = 2×U × (1 – exp[-
surge
t/(Z×C]) . 143
Figure G.4 – EMTP model . 143
Figure G.5 – Simulated surge voltages at the line-substation bus interface . 144
Figure G.6 – Simulated Surge Voltages at the Transformer . 145
Figure G.7 – EMTP model . 145
Figure G.8 – Simulated surge voltages at the line-substation bus interface . 146
Figure G.9 – Simulated surge voltages at the transformer . 146

Figure H.1 – Specific energy in kJ per kV rating dependant on the ratio of switching
impulse residual voltage (U ) to the r.m.s. value of the rated voltage U of the arrester . 148
a r
Figure I.1 – Simple network used for Arrester Line Discharge Calculation and Testing
according to IEC 60099-4:2009 . 155
Figure I.2 – Linearized arrester equation in the typical line switching current range
(voltage values shown are for a 372 kV rated arrester used on a 420 kV system) . 156
Figure I.3 – Graphical illustration of linearized line switching condition and arrester
characteristic . 157
Figure I.4 – Range of 2 % slow-front overvoltages at the receiving end due to line
energization and re-energization . 159
Figure I.5 – Arrester class 2 & 3 voltages calculated by EMTP calculations: U and
ps2
U (V × 10 ) . 162
ps3
Figure I.6 – Class 2 & 3 arrester currents calculated by EMTP studies: I and I
ps2 ps3
(A) . 162
Figure I.7 – Arrester Class 2 & 3 cumulative charges calculated by EMTP simulation:
Q and Q (C) . 163
rs2 rs3
Figure I.8 – Arrester Class 2 & 3 cumulative absorbed energies calculated by EMTP
simulation: W and W (kJ/kV U ) . 163
s2 s3 r
Figure I.9 – Typical Line Reclosing Computer Simulation Network . 164
Figure I.10 – Typical 550 kV Reclose Switching Overvoltage Profile along 480 km Line . 165
Figure I.11 – IEC LD based charge transfer, Q with varying arrester protective ratios . 166
rs
Figure I.12 – IEC LD based switching energy, W with varying arrester protective
th
ratios . 166
Figure I.13 – U for 145 kV system simulation (V x 10 ) . 170
ps
Figure I.14 – I for 145 kV system simulation (A) . 170
ps
Figure I.15 – 1 Cumulative charge (Q ) for 145 kV system simulation (C) . 171
rs
Figure I.16 – Cumulative energy (W ) for 145 kV system simulation (kJ/kV U ) . 171
th r
Figure I.17 – U for 245 kV system simulation (V x 10 ) . 172
ps
Figure I.18 – I for 245 kV system simulation (A) . 172
ps
Figure I.19 – Cumulative charge (Q ) for 245 kV system simulation (C) . 173
rs
Figure I.20 – Cumulative energy (W ) for 245 kV system simulation (kJ/kV U ) . 173
th r
Figure I.21 – U for 362 kV system simulation (V x 10 ) . 174
ps
Figure I.22 – I for 362 kV system simulation (A) . 174
ps
Figure I.23 – Cumulative charge (Q ) for 362 kV system simulation (C) . 175
rs
Figure I.24 – Cumulative energy (W ) for 362 kV system simulation (kJ/kV U ) . 175
th r
Figure I.25 – U for 420 kV system simulation (V x 10 ) . 176
ps
Figure I.26 – I for 420 kV system simulation (A) . 176
ps
Figure I.27 – Cumulative charge (Q ) for 420 kV system simulation (C) . 177
rs
Figure I.28 – Cumulative energy (W ) for 420 kV system simulation (kJ/kV U ) . 177
th r
Figure I.29 – U for 550 kV system simulation (V x 10 ) . 178
ps
Figure I.30 – I for 550 kV system simulation (A) . 178
ps
Figure I.31 – Cumulative charge (Q ) for 550 kV system simulation (C) . 179
rs
Figure I.32 – Cumulative energy (W ) for 550 kV system simulation (kJ/kV U ) . 179
th r
Figure J.1 – Internal SiC-arrester stack . 181

Table 1 – Minimum mechanical requirements (for porcelain-housed arresters) . 46

– 8 – IEC 60099-5:2018 © IEC 2018
Table 2 – Arrester classification . 78
Table 3 – Definition of factor A in formulas (14 and 15) for various overhead lines . 82
Table 4 – Examples for protective zones calculated by formula (16) for open-air
substations . 83
Table 5 – Example of the condition for calculating lightning current duty of EGLA in
77 kV transmission lines . 90
Table 6 – Probability of insulator flashover in Formula (18) . 93
Table D.1 – Summary of diagnostic methods . 135
Table D.2 – Properties of on-site leakage current measurement methods . 135
Table E.1 – Arrester data needed for the selection of surge arresters . 136
Table F.1 – Residual voltages for 20 000 A and 10 000 A arresters in per unit of rated
voltage . 137
Table F.2 – Residual voltages for 5 000 A, and 2 500 A arresters in per unit of rated
voltage . 137
Table G.1 – C impact on steepness ratio f and steepness S . 141
s s n
Table G.2 – Change in coordination withstand voltage, U . 142
cw
Table H.1 – Peak currents for switching impulse residual voltage test . 147
Table H.2 – Parameters for the line discharge test on 20 000 A and 10 000 A arresters. 148
Table H.3 – Comparison of the classification system according to IEC 60099-4:2009

and to IEC 6099-4 2014 . 149
Table I.1 – Typical Arrester Switching (U vs I ) Characteristics . 156
ps ps
Table I.2 – Typical line surge impedances (Z ) with single and bundled conductors . 158
s
Table I.3 – Line Parameters Prescribed by IEC 60099-4:2009 Line Discharge Class
Tests . 159
Table I.4 – Line surge impedances and prospective surge voltages derived from line
discharge tests parameters of IEC 60099-4:2009 for different system voltages and
arrester ratings . 160
Table I.5 – Comparison of energy and charge calculated by simplified method with
values calculated by EMTP simulation – Base parameters from Table I.4, used for
simplified method and for EMTP simulation . 161
Table I.6 – Comparison of energy and charge calculated by simplified method with

values calculated by EMTP simulation – Calculations using simplified method . 161
Table I.7 – Comparison of energy and charge calculated by simplified method with
values calculated by EMTP simulation – I.5.(c) Results from EMTP studies . 161
Table I.8 – Results of calculations using the ndifferent methods described for different
system voltages and arrester selection . 169

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SURGE ARRESTERS –
Part 5: Selection and application recommendations

FOREWORD
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International Standard IEC 60099-5 has been prepared by IEC technical committee 37: Surge
arresters.
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

– 10 – IEC 60099-5:2018 © IEC 2018
The text of this standard is based on the following documents:
FDIS Report on voting
37/437/FDIS 37/439/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 60099 series, published under the general title Surge arresters,
can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC website under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
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IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
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understanding of its contents. Users should therefore print this document using a
colour printer.
SURGE ARRESTERS –
Part 5: Selection and application recommendations

1 Scope
This part of IEC 60099 provides information, guidance, and recommendations for the
selection and application of surge arresters to be
...

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

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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 arrester manufacturer . 145
D.5 Summary of diagnostic methods . 147
Annex E (informative) Typical data needed from arrester manufacturers for proper
selection of surge arresters . 148
Annex F (informative) Typical maximum residual voltages for metal-oxide arresters
without gaps according to IEC 60099-4 . 149
Annex G (informative) Steepness reduction of incoming surge with additional line
terminal surge capacitance . 150
G.1 General . 150
G.2 Basic formula Steepness reduction factor . 150
G.3 Equivalent capacitance associated with incoming surge fronts . 152
G.3.1 General . 152
G.3.2 Examples of incoming surge steepness change, f , using typical 550 kV
s
& 245 kV circuit parameters . 156
G.3.3 Change in coordination withstand voltage, U , with steepness
cw
reduction, f : . 157
s
G.4 EMTP & capacitor charging models for steepness change comparisons at
line open terminal . 158
G.5 Typical steepness (S = 1000 kV/µs), change comparisons with C & C . 159
0 0 s
G.6 Faster steepness (2000 kV/µs), change comparisons with C & C . 161
o s
Annex H (informative) Comparison of the former energy classification system based
on line discharge classes and the present classification system based on thermal
energy ratings for operating duty tests and repetitive charge transfer ratings for
repetitive single event energies. 163
H.1 General . 163
H.2 Examples . 166
Annex I (informative) Estimation of arrester cumulative charges and energies during
line switching . 171
I.1 Simplified method of estimating arrester line switching energies . 171
I.1.1 Introduction . 171
I.1.2 Simplified method calculation steps . 172
I.1.3 Typical line surge impedances with bundled conductors . 174
I.1.4 Prospective switching surge overvoltages . 174
I.1.5 Use of IEC 60099-4:2009 to obtain values for surge impedance and
prospective surge voltages . 175
I.2 Example of charge and energy calculated using line discharge parameters. 176
I.3 Arrester line switching energy examples . 180
I.3.1 General . 180
I.3.2 Case 1 – 145 kV . 183
I.3.3 Case 2 – 242 kV . 183
I.3.4 Case 3 – 362 kV . 183
I.3.5 Case 4 – 420 kV . 184
I.3.6 Case 5 – 550 kV . 184
Annex J (informative) End of life and replacement of old gapped SiC-arresters . 196
J.1 Introduction Overview . 196
J.2 Design and operation of SiC-arresters . 196

J.3 Failure causes and aging phenomena . 196
J.3.1 General . 196
J.3.2 Sealing problems . 196
J.3.3 Equalization of internal and external pressure and atmosphere . 197
J.3.4 Gap electrode erosion . 197
J.3.5 Ageing of grading components . 198
J.3.6 Changed system conditions . 198
J.3.7 Increased pollution levels . 198
J.4 Possibility to check the status of the arresters . 198
J.5 Advantages of planning replacements ahead . 198
J.5.1 General . 198
J.5.2 Improved reliability . 199
J.5.3 Cost advantages . 199
J.5.4 Increased safety requirements . 199
J.6 Replacement issues . 199
J.6.1 General . 199
J.6.2 Establishing replacement priority . 199
J.6.3 Selection of MO arresters for replacement installations . 200
Bibliography . 201

Figure 1 – Example of GIS arresters of three mechanical/one electrical column
(middle) and one column (left) design and current path of the three mechanical/one
electrical column design (right) . 30
Figure 2 – Typical deadfront arrester . 31
Figure 3 – Internally gapped metal-oxide surge arrester designs . 37
Figure 4 – Components of an EGLA acc. to IEC 60099-8 . 38
Figure 5 – Typical arrangement of a 420 kV arrester . 43
Figure 6 – Examples of UHV and HV arresters with grading and corona rings . 44
Figure 7 – Same type of arrester mounted on a pedestal (left), suspended from an
earthed steel structure (middle) or suspended from a line conductor (right . 45
Figure 8 – Installations without earth-mat (distribution systems) . 46
Figure 9 – Installations with earth-mat (high-voltage substations) . 47
Figure 10 – Definition of mechanical loads according to IEC 60099-4:2014 . 49
Figure 11 – Distribution arrester with disconnector and insulating bracket. 50
Figure 12 – Examples of good and poor earthing connection principles for distribution
arresters . 53
Figure 13 – Typical voltages and duration example for an efficiently differently earthed
systems . 58
Figure 14 – Typical phase-to-earth overvoltages encountered in power systems . 60
Figure 15 – Arrester voltage-current characteristics . 60
Figure 16 – Direct strike to a phase conductor with LSA . 65
Figure 17 – Strike to a shield wire or tower with LSA . 66
Figure 18 – Typical procedure for a surge arrester insulation coordination study . 74
Figure 19 – Flow diagrams for standard selection of surge arrester . 78
Figure 20 – Examples of arrester TOV capability . 79
Figure 21 – Flow diagram for the selection of NGLA . 96
Figure 22 – Flow diagram for the selection of EGLA . 100

– 6 – IEC 60099-5:2018 RLV © IEC 2018
Figure 23 – Common neutral configurations . 106
Figure 24 – Typical configurations for arresters connected phase-to-phase and phase-
to-ground . 116
Figure A.1 – Earth fault factor k on a base of X /X , for R /X = R = 0 . 126
0 1 1 1 1
Figure A.2 – Relationship between R /X and X /X for constant values of earth fault
0 1 0 1
factor k where R = 0 . 127
Figure A.3 – Relationship between R0/X1 and X0/X1 for constant values of earth fault
factor k where R = 0,5 X . 127
1 1
Figure A.4 – Relationship between R /X and X /X for constant values of earth fault
0 1 0 1
factor k where R = X . 128
1 1
Figure A.5 – Relationship between R /X and X /X for constant values of earth fault
0 1 0 1
factor k where R = 2X . 128
1 1
Figure C.1 – Schematic sketch of a typical arrester installation . 131
Figure C.2 – Increase in residual voltage as function of virtual current front time . 132
Figure C.3 – Arrester model for insulation coordination studies – fast- front
overvoltages and preliminary calculation (Option 1) . 133
Figure C.4 – Arrester model for insulation coordination studies – fast- front
overvoltages and preliminary calculation (Option 2) . 133
Figure C.5 – Arrester model for insulation coordination studies – slow-front
overvoltages . 133
Figure D.1 – Typical leakage current of a non-linear metal-oxide resistor in laboratory
conditions . 136
Figure D.2 – Typical leakage currents of arresters in service conditions . 137
Figure D.3 – Typical voltage-current characteristics for non-linear metal-oxide resistors . 138
Figure D.4 – Typical normalized voltage dependence at +20 °C . 138
Figure D.5 – Typical normalized temperature dependence at U . 139
c
Figure D.6 – Influence on total leakage current by increase in resistive leakage current . 140
Figure D.7 – Measured voltage and leakage current and calculated resistive and
capacitive currents (V = 6,3 kV r.m.s) . 142
Figure D.8 – Remaining current after compensation by capacitive current at U . 143
c
Figure D.9 – Error in the evaluation of the leakage current third harmonic for different
phase angles of system voltage third harmonic, considering various capacitances and
voltage-current characteristics of non-linear metal-oxide resistors . 144
Figure D.10 – Typical information for conversion to "standard" operating voltage
conditions . 146
Figure D.11 – Typical information for conversion to "standard" ambient temperature
conditions . 146
Figure G.1 – Surge voltage waveforms at various distances from strike location
(0,0 km) due to corona . 152
Figure G.2 – Case 1: EMTP Model: Thevenin equivalent source, line (Z,c) & substation
bus (Z,c) & Cap(C ). 158
s
Figure G.3 – Case 2: Capacitor Voltage charge via line Z: u(t) = 2×U × (1 – exp[-
surge
t/(Z×C]) . 159
Figure G.4 – EMTP model . 159
Figure G.5 – Simulated surge voltages at the line-substation bus interface . 160
Figure G.6 – Simulated Surge Voltages at the Transformer . 161
Figure G.7 – EMTP model . 161
Figure G.8 – Simulated surge voltages at the line-substation bus interface . 162

Figure G.9 – Simulated surge voltages at the transformer . 162
Figure H.1 – Specific energy in kJ per kV rating dependant on the ratio of switching
impulse residual voltage (U ) to the r.m.s. value of the rated voltage U of the arrester . 164
a r
Figure I.1 – Simple network used for Arrester Line Discharge Calculation and Testing
according to IEC 60099-4:2009 . 171
Figure I.2 – Linearized arrester equation in the typical line switching current range
(voltage values shown are for a 372 kV rated arrester used on a 420 kV system) . 172
Figure I.3 – Graphical illustration of linearized line switching condition and arrester
characteristic . 173
Figure I.4 – Range of 2 % slow-front overvoltages at the receiving end due to line
energization and re-energization . 175
Figure I.5 – Arrester class 2 & 3 voltages calculated by EMTP calculations: U and
ps2
U (V × 10 ) . 178
ps3
Figure I.6 – Class 2 & 3 arrester currents calculated by EMTP studies: I and I
ps2 ps3
(A) . 178
Figure I.7 – Arrester Class 2 & 3 cumulative charges calculated by EMTP simulation:
Q and Q (C) . 179
rs2 rs3
Figure I.8 – Arrester Class 2 & 3 cumulative absorbed energies calculated by EMTP
simulation: W and W (kJ/kV U ) . 179
s2 s3 r
Figure I.9 – Typical Line Reclosing Computer Simulation Network . 180
Figure I.10 – Typical 550 kV Reclose Switching Overvoltage Profile along 480 km Line . 181
Figure I.11 – IEC LD based charge transfer, Q with varying arrester protective ratios . 182
rs
Figure I.12 – IEC LD based switching energy, W with varying arrester protective
th
ratios . 182
Figure I.13 – U for 145 kV system simulation (V x 10 ) . 186
ps
Figure I.14 – I for 145 kV system simulation (A) . 186
ps
Figure I.15 – 1 Cumulative charge (Q ) for 145 kV system simulation (C) . 187
rs
Figure I.16 – Cumulative energy (W ) for 145 kV system simulation (kJ/kV U ) . 187
th r
Figure I.17 – U for 245 kV system simulation (V x 10 ) . 188
ps
Figure I.18 – I for 245 kV system simulation (A) . 188
ps
Figure I.19 – Cumulative charge (Q ) for 245 kV system simulation (C) . 189
rs
Figure I.20 – Cumulative energy (W ) for 245 kV system simulation (kJ/kV U ) . 189
th r
Figure I.21 – U for 362 kV system simulation (V x 10 ) . 190
ps
Figure I.22 – I for 362 kV system simulation (A) . 190
ps
Figure I.23 – Cumulative charge (Q ) for 362 kV system simulation (C) . 191
rs
Figure I.24 – Cumulative energy (W ) for 362 kV system simulation (kJ/kV U ) . 191
th r
Figure I.25 – U for 420 kV system simulation (V x 10 ) . 192
ps
Figure I.26 – I for 420 kV system simulation (A) . 192
ps
Figure I.27 – Cumulative charge (Q ) for 420 kV system simulation (C) . 193
rs
Figure I.28 – Cumulative energy (W ) for 420 kV system simulation (kJ/kV U ) . 193
th r
Figure I.29 – U for 550 kV system simulation (V x 10 ) . 194
ps
Figure I.30 – I for 550 kV system simulation (A) . 194
ps
Figure I.31 – Cumulative charge (Q ) for 550 kV system simulation (C) . 195
rs
Figure I.32 – Cumulative energy (W ) for 550 kV system simulation (kJ/kV U ) . 195
th r
Figure J.1 – Internal SiC-arrester stack . 197

– 8 – IEC 60099-5:2018 RLV © IEC 2018
Table 1 – Minimum mechanical requirements (for porcelain-housed arresters) . 48
Table 2 – Arrester classification for surge arresters . 83
Table 3 – Definition of factor A in formulas (14 and 15) for various overhead lines . 90
Table 4 – Examples for protective zones calculated by formula (16) for open-air
substations . 91
Table 5 – Example of the condition for calculating lightning current duty of EGLA in
77 kV transmission lines . 99
Table 6 – Probability of insulator flashover in Formula (18) . 102
Table D.1 – Summary of diagnostic methods . 147
Table D.2 – Properties of on-site leakage current measurement methods . 147
Table E.1 – Arrester data needed for the selection of surge arresters . 148
Table F.1 – Residual voltages for 20 000 A and 10 000 A arresters in per unit of rated
voltage . 149
Table F.2 – Residual voltages for 5 000 A and 2 500 A and 1 500 A arresters in per
unit of rated voltage . 149
Table G.1 – C impact on steepness ratio f and steepness S . 155
s s n
Table G.2 – Change in coordination withstand voltage, U . 157
cw
Table H.1 – Peak currents for switching impulse residual voltage test . 163
Table H.2 – Parameters for the line discharge test on 20 000 A and 10 000 A arresters. 164
Table H.3 – Comparison of the classification system according to IEC 60099-4:2009
and to IEC 6099-4 2014 . 165
Table I.1 – Typical Arrester Switching (U vs I ) Characteristics . 172
ps ps
Table I.2 – Typical line surge impedances (Z ) with single and bundled conductors . 174
s
Table I.3 – Line Parameters Prescribed by IEC 60099-4:2009 Line Discharge Class
Tests . 175
Table I.4 – Line surge impedances and prospective surge voltages derived from line
discharge tests parameters of IEC 60099-4:2009 for different system voltages and
arrester ratings . 176
Table I.5 – Comparison of energy and charge calculated by simplified method with
values calculated by EMTP simulation – Base parameters from Table I.4, used for
simplified method and for EMTP simulation . 177
Table I.6 – Comparison of energy and charge calculated by simplified method with
values calculated by EMTP simulation – Calculations using simplified method . 177
Table I.7 – Comparison of energy and charge calculated by simplified method with
values calculated by EMTP simulation – I.5.(c) Results from EMTP studies . 177
Table I.8 – Results of calculations using the ndifferent methods described for different
system voltages and arrester selection . 185

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SURGE ARRESTERS –
Part 5: Selection and application recommendations

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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6) All users should ensure that they have the latest edition of this publication.
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This redline version of the official IEC Standard allows the user to identify the changes
made to the previous edition. A vertical bar appears in the margin wherever a change
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– 10 – IEC 60099-5:2018 RLV © IEC 2018
International Standard IEC 60099-5 has been prepared by IEC technical committee 37: Surge
arresters.
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
The text of this standard is based on the following documents:
FDIS Report on voting
37/437/FDIS 37/439/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 60099 series, published under the general title Surge arresters,
can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC website under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

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

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

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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 . 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 . 132
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 manufacturer . 133
D.5 Summary of diagnostic methods . 135
Annex E (informative) Typical data needed from arrester manufacturers for proper
selection of surge arresters . 136
Annex F (informative) Typical maximum residual voltages for metal-oxide arresters
without gaps according to IEC 60099-4 . 137
Annex G (informative) Steepness reduction of incoming surge with additional line
terminal surge capacitance . 138
G.1 General . 138
G.2 Steepness reduction factor . 138
G.3 Equivalent capacitance associated with incoming surge fronts . 140
G.3.1 General . 140
G.3.2 Examples of incoming surge steepness change, f , using typical 550 kV
s
& 245 kV circuit parameters . 142
G.3.3 Change in coordination withstand voltage, U , with steepness
cw
reduction, f : . 142
s
G.4 EMTP & capacitor charging models for steepness change comparisons at
line open terminal . 142
G.5 Typical steepness (S = 1000 kV/µs), change comparisons with C & C . 144
0 0 s
G.6 Faster steepness (2000 kV/µs), change comparisons with C & C . 146
o s
Annex H (informative) Comparison of the former energy classification system based
on line discharge classes and the present classification system based on thermal
energy ratings for operating duty tests and repetitive charge transfer ratings for
repetitive single event energies. 149
H.1 General . 149
H.2 Examples . 152
Annex I (informative) Estimation of arrester cumulative charges and energies during
line switching . 157
I.1 Simplified method of estimating arrester line switching energies . 157
I.1.1 Introduction . 157
I.1.2 Simplified method calculation steps . 158
I.1.3 Typical line surge impedances with bundled conductors . 160
I.1.4 Prospective switching surge overvoltages . 160
I.1.5 Use of IEC 60099-4:2009 to obtain values for surge impedance and
prospective surge voltages . 161
I.2 Example of charge and energy calculated using line discharge parameters. 162
I.3 Arrester line switching energy examples . 166
I.3.1 General . 166
I.3.2 Case 1 – 145 kV . 169
I.3.3 Case 2 – 242 kV . 169
I.3.4 Case 3 – 362 kV . 169
I.3.5 Case 4 – 420 kV . 170
I.3.6 Case 5 – 550 kV . 170
Annex J (informative) End of life and replacement of old gapped SiC-arresters . 182
J.1 Overview. 182

J.2 Design and operation of SiC-arresters . 182
J.3 Failure causes and aging phenomena . 182
J.3.1 General . 182
J.3.2 Sealing problems . 182
J.3.3 Equalization of internal and external pressure and atmosphere . 183
J.3.4 Gap electrode erosion . 183
J.3.5 Ageing of grading components . 184
J.3.6 Changed system conditions . 184
J.3.7 Increased pollution levels . 184
J.4 Possibility to check the status of the arresters . 184
J.5 Advantages of planning replacements ahead . 184
J.5.1 General . 184
J.5.2 Improved reliability . 185
J.5.3 Cost advantages . 185
J.5.4 Increased safety requirements . 185
J.6 Replacement issues . 185
J.6.1 General . 185
J.6.2 Establishing replacement priority . 185
J.6.3 Selection of MO arresters for replacement installations . 186
Bibliography . 187

Figure 1 – Example of GIS arresters of three mechanical/one electrical column
(middle) and one column (left) design and current path of the three mechanical/one
electrical column design (right) . 29
Figure 2 – Typical deadfront arrester . 30
Figure 3 – Internally gapped metal-oxide surge arrester designs . 35
Figure 4 – Components of an EGLA acc. to IEC 60099-8 . 36
Figure 5 – Typical arrangement of a 420 kV arrester . 41
Figure 6 – Examples of UHV and HV arresters with grading and corona rings . 42
Figure 7 – Same type of arrester mounted on a pedestal (left), suspended from an
earthed steel structure (middle) or suspended from a line conductor (right . 43
Figure 8 – Installations without earth-mat (distribution systems) . 44
Figure 9 – Installations with earth-mat (high-voltage substations) . 45
Figure 10 – Definition of mechanical loads according to IEC 60099-4:2014 . 47
Figure 11 – Distribution arrester with disconnector and insulating bracket. 48
Figure 12 – Examples of good and poor connection principles for distribution arresters . 50
Figure 13 – Typical voltages and duration example for differently earthed systems . 54
Figure 14 – Typical phase-to-earth overvoltages encountered in power systems . 56
Figure 15 – Arrester voltage-current characteristics . 56
Figure 16 – Direct strike to a phase conductor with LSA . 61
Figure 17 – Strike to a shield wire or tower with LSA . 62
Figure 18 – Typical procedure for a surge arrester insulation coordination study . 69
Figure 19 – Flow diagrams for standard selection of surge arrester . 73
Figure 20 – Examples of arrester TOV capability . 74
Figure 21 – Flow diagram for the selection of NGLA . 87
Figure 22 – Flow diagram for the selection of EGLA . 91

– 6 – IEC 60099-5:2018 © IEC 2018
Figure 23 – Common neutral configurations . 96
Figure 24 – Typical configurations for arresters connected phase-to-phase and phase-
to-ground . 105
Figure A.1 – Earth fault factor k on a base of X /X , for R /X = R = 0 . 114
0 1 1 1 1
Figure A.2 – Relationship between R /X and X /X for constant values of earth fault
0 1 0 1
factor k where R = 0 . 115
Figure A.3 – Relationship between R0/X1 and X0/X1 for constant values of earth fault
factor k where R = 0,5 X . 115
1 1
Figure A.4 – Relationship between R /X and X /X for constant values of earth fault
0 1 0 1
factor k where R = X . 116
1 1
Figure A.5 – Relationship between R /X and X /X for constant values of earth fault
0 1 0 1
factor k where R = 2X . 116
1 1
Figure C.1 – Schematic sketch of a typical arrester installation . 119
Figure C.2 – Increase in residual voltage as function of virtual current front time . 120
Figure C.3 – Arrester model for insulation coordination studies – fast- front
overvoltages and preliminary calculation (Option 1) . 121
Figure C.4 – Arrester model for insulation coordination studies – fast- front
overvoltages and preliminary calculation (Option 2) . 121
Figure C.5 – Arrester model for insulation coordination studies – slow-front

overvoltages . 121
Figure D.1 – Typical leakage current of a non-linear metal-oxide resistor in laboratory
conditions . 124
Figure D.2 – Typical leakage currents of arresters in service conditions . 125
Figure D.3 – Typical voltage-current characteristics for non-linear metal-oxide resistors . 126
Figure D.4 – Typical normalized voltage dependence at +20 °C . 126
Figure D.5 – Typical normalized temperature dependence at U . 127
c
Figure D.6 – Influence on total leakage current by increase in resistive leakage current . 128
Figure D.7 – Measured voltage and leakage current and calculated resistive and
capacitive currents (V = 6,3 kV r.m.s) . 130
Figure D.8 – Remaining current after compensation by capacitive current at U . 131
c
Figure D.9 – Error in the evaluation of the leakage current third harmonic for different
phase angles of system voltage third harmonic, considering various capacitances and
voltage-current characteristics of non-linear metal-oxide resistors . 132
Figure D.10 – Typical information for conversion to "standard" operating voltage
conditions . 134
Figure D.11 – Typical information for conversion to "standard" ambient temperature
conditions . 134
Figure G.1 – Surge voltage waveforms at various distances from strike location
(0,0 km) due to corona . 140
Figure G.2 – Case 1: EMTP Model: Thevenin equivalent source, line (Z,c) & substation
bus (Z,c) & Cap(C ). 143
s
Figure G.3 – Case 2: Capacitor Voltage charge via line Z: u(t) = 2×U × (1 – exp[-
surge
t/(Z×C]) . 144
Figure G.4 – EMTP model . 144
Figure G.5 – Simulated surge voltages at the line-substation bus interface . 145
Figure G.6 – Simulated Surge Voltages at the Transformer . 146

Figure G.7 – EMTP model . 146
Figure G.8 – Simulated surge voltages at the line-substation bus interface . 147
Figure G.9 – Simulated surge voltages at the transformer . 148
Figure H.1 – Specific energy in kJ per kV rating dependant on the ratio of switching
impulse residual voltage (U ) to the r.m.s. value of the rated voltage U of the arrester . 150
a r
Figure I.1 – Simple network used for Arrester Line Discharge Calculation and Testing
according to IEC 60099-4:2009 . 157
Figure I.2 – Linearized arrester equation in the typical line switching current range
(voltage values shown are for a 372 kV rated arrester used on a 420 kV system) . 158
Figure I.3 – Graphical illustration of linearized line switching condition and arrester
characteristic . 160
Figure I.4 – Range of 2 % slow-front overvoltages at the receiving end due to line
energization and re-energization . 161
Figure I.5 – Arrester class 2 & 3 voltages calculated by EMTP calculations: U and
ps2
U (V × 10 ) . 164
ps3
Figure I.6 – Class 2 & 3 arrester currents calculated by EMTP studies: I and I
ps2 ps3
(A) . 164
Figure I.7 – Arrester Class 2 & 3 cumulative charges calculated by EMTP simulation:
Q and Q (C) . 165
rs2 rs3
Figure I.8 – Arrester Class 2 & 3 cumulative absorbed energies calculated by EMTP
simulation: W and W (kJ/kV U ) . 165
s2 s3 r
Figure I.9 – Typical Line Reclosing Computer Simulation Network . 166
Figure I.10 – Typical 550 kV Reclose Switching Overvoltage Profile along 480 km Line . 167
Figure I.11 – IEC LD based charge transfer, Q with varying arrester protective ratios . 168
rs
Figure I.12 – IEC LD based switching energy, W with varying arrester protective
th
ratios . 168
Figure I.13 – U for 145 kV system simulation (V x 10 ) . 172
ps
Figure I.14 – I for 145 kV system simulation (A) . 172
ps
Figure I.15 – 1 Cumulative charge (Q ) for 145 kV system simulation (C) . 173
rs
Figure I.16 – Cumulative energy (W ) for 145 kV system simulation (kJ/kV U ) . 173
th r
Figure I.17 – U for 245 kV system simulation (V x 10 ) . 174
ps
Figure I.18 – I for 245 kV system simulation (A) . 174
ps
Figure I.19 – Cumulative charge (Q ) for 245 kV system simulation (C) . 175
rs
Figure I.20 – Cumulative energy (W ) for 245 kV system simulation (kJ/kV U ) . 175
th r
Figure I.21 – U for 362 kV system simulation (V x 10 ) . 176
ps
Figure I.22 – I for 362 kV system simulation (A) . 176
ps
Figure I.23 – Cumulative charge (Q ) for 362 kV system simulation (C) . 177
rs
Figure I.24 – Cumulative energy (W ) for 362 kV system simulation (kJ/kV U ) . 177
th r
Figure I.25 – U for 420 kV system simulation (V x 10 ) . 178
ps
Figure I.26 – I for 420 kV system simulation (A) . 178
ps
Figure I.27 – Cumulative charge (Q ) for 420 kV system simulation (C) . 179
rs
– 8 – IEC 60099-5:2018 © IEC 2018
Figure I.28 – Cumulative energy (W ) for 420 kV system simulation (kJ/kV U ) . 179
th r
Figure I.29 – U for 550 kV system simulation (V x 10 ) . 180
ps
Figure I.30 – I for 550 kV system simulation (A) . 180
ps
Figure I.31 – Cumulative charge (Q ) for 550 kV system simulation (C) . 181
rs
Figure I.32 – Cumulative energy (W ) for 550 kV system simulation (kJ/kV U ) . 181
th r
Figure J.1 – Internal SiC-arrester stack . 183

Table 1 – Minimum mechanical requirements (for porcelain-housed arresters) . 46
Table 2 – Arrester classification . 78
Table 3 – Definition of factor A in formulas (14 and 15) for various overhead lines . 82
Table 4 – Examples for protective zones calculated by formula (16) for open-air
substations . 83
Table 5 – Example of the condition for calculating lightning current duty of EGLA in

77 kV transmission lines . 90
Table 6 – Probability of insulator flashover in Formula (18) . 93
Table D.1 – Summary of diagnostic methods . 135
Table D.2 – Properties of on-site leakage current measurement methods . 135
Table E.1 – Arrester data needed for the selection of surge arresters . 136
Table F.1 – Residual voltages for 20 000 A and 10 000 A arresters in per unit of rated
voltage . 137
Table F.2 – Residual voltages for 5 000 A, and 2 500 A arresters in per unit of rated
voltage . 137
Table G.1 – C impact on steepness ratio f and steepness S . 141
s s n
Table G.2 – Change in coordination withstand voltage, U . 142
cw
Table H.1 – Peak currents for switching impulse residual voltage test . 149
Table H.2 – Parameters for the line discharge test on 20 000 A and 10 000 A arresters. 150
Table H.3 – Comparison of the classification system according to IEC 60099-4:2009

and to IEC 6099-4 2014 . 151
Table I.1 – Typical Arrester Switching (U vs I ) Characteristics . 158
ps ps
Table I.2 – Typical line surge impedances (Z ) with single and bundled conductors . 160
s
Table I.3 – Line Parameters Prescribed by IEC 60099-4:2009 Line Discharge Class
Tests . 161
Table I.4 – Line surge impedances and prospective surge voltages derived from line
discharge tests parameters of IEC 60099-4:2009 for different system voltages and
arrester ratings . 162
Table I.5 – Comparison of energy and charge calculated by simplified method with
values calculated by EMTP simulation – Base parameters from Table I.4, used for
simplified method and for EMTP simulation . 163
Table I.6 – Comparison of energy and charge calculated by simplified method with

values calculated by EMTP simulation – Calculations using simplified method . 163
Table I.7 – Comparison of energy and charge calculated by simplified method with
values calculated by EMTP simulation – I.5.(c) Results from EMTP studies . 163
Table I.8 – Results of calculations using the ndifferent methods described for different
system voltages and arrester selection . 171

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SURGE ARRESTERS –
Part 5: Selection and application recommendations

FOREWORD
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