SIST EN IEC 61400-24:2019

SLOVENSKI STANDARD
01-november-2019
Nadomešča:
SIST EN 61400-24:2010
Sistemi za proizvodnjo energije na veter - 24. del: Zaščita pred delovanjem strele
(IEC 61400-24:2019)
Wind energy generation systems - Part 24: Lightning protection (IEC 61400-24:2019)
Windenergieanlagen - Teil 24: Blitzschutz (IEC 61400-24:2019)
Systèmes de génération d’énergie éolienne - Partie 24 : Protection contre la foudre (IEC
61400-24:2019)
Ta slovenski standard je istoveten z: EN IEC 61400-24:2019
ICS:
27.180 Vetrne elektrarne Wind turbine energy systems
91.120.40 Zaščita pred strelo Lightning protection
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 61400-24

NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2019
ICS 27.180 Supersedes EN 61400-24:2010 and all of its
amendments and corrigenda (if any)
English Version
Wind energy generation systems - Part 24: Lightning protection
(IEC 61400-24:2019)
Systèmes de génération d’énergie éolienne - Partie 24 : Windenergieanlagen - Teil 24: Blitzschutz
Protection contre la foudre (IEC 61400-24:2019)
(IEC 61400-24:2019)
This European Standard was approved by CENELEC on 2019-08-07. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 61400-24:2019 E

European foreword
The text of document 88/709/FDIS, future edition 2 of IEC 61400-24, prepared by IEC/TC 88 "Wind
energy generation systems" was submitted to the IEC-CENELEC parallel vote and approved by
CENELEC as EN IEC 61400-24:2019.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2020-05-07
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2022-08-07
document have to be withdrawn
This document supersedes EN 61400-24:2010 and all of its amendments and corrigenda (if any).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Endorsement notice
The text of the International Standard IEC 61400-24:2019 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards
indicated:
IEC 60060-1:2010  NOTE  Harmonized as EN 60060-1:2010 (not modified)
IEC 60071 (series) NOTE Harmonized as EN 60071 (series)
IEC 60071-2:2018 NOTE Harmonized as EN IEC 60071-2:2018 (not modified)
IEC 60099-4 NOTE Harmonized as EN 60099-4
IEC 60099-5 NOTE Harmonized as EN IEC 60099-5
IEC 60204-1 NOTE Harmonized as EN 60204-1
IEC 60204-11 NOTE Harmonized as EN IEC 60204-11
IEC 60243 (series) NOTE Harmonized as EN 60243 (series)
IEC 60243-1 NOTE Harmonized as EN 60243-1
IEC 60243-3 NOTE Harmonized as EN 60243-3
IEC 60464-2 NOTE Harmonized as EN 60464-2
IEC 60587 NOTE Harmonized as EN 60587
IEC 62561 (series) NOTE Harmonized as EN IEC 62561 (series)
IEC 62561-1 NOTE Harmonized as EN 62561-1
IEC 62793 NOTE Harmonized as EN IEC 62793
IEC 62858 NOTE Harmonized as EN 62858

Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments)
applies.
NOTE 1  Where an International Publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
NOTE 2  Up-to-date information on the latest versions of the European Standards listed in this annex is available here:
www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60364-4-44 -  Low-voltage electrical installations - Part 4-HD 60364-4-442 -
44: Protection for safety - Protection
against voltage disturbances and
electromagnetic disturbances
IEC 60364-5-53 -  Low-voltage electrical installations -- Part- -
5-53: Selection and erection of electrical
equipment - Protection, isolation,
switching, control and monitoring
IEC 60364-5-54 -  Low-voltage electrical installations - Part 5-HD 60364-5-54 -
54: Selection and erection of electrical
equipment - Earthing arrangements and
protective conductors
IEC 60364-6 -  Low voltage electrical installations - Part 6: HD 60364-6 -
Verification
IEC 60664-1 -  Insulation coordination for equipment EN 60664-1 -
within low-voltage systems - Part 1:
Principles, requirements and tests
IEC 61000-1 series Electromagnetic compatibility (EMC) - PartE N 61000-1 series
1-2: General - Methodology for the
achievement of functional safety of
electrical and electronic systems including
equipment with regard to electromagnetic
phenomena
IEC 61000-4-5 -  Electromagnetic compatibility (EMC) - PartE N 61000-4-5 -
4-5: Testing and measurement techniques
- Surge immunity test
IEC 61000-4-9 -  Electromagnetic compatibility (EMC) – PartE N 61000-4-9 -
4-9: Testing and measurement techniques
– Impulse magnetic field immunity test
IEC 61000-4-10 -  Electromagnetic compatibility (EMC) – PartE N 61000-4-10 -
4-10: Testing and measurement
techniques – Damped oscillatory magnetic
field immunity test
Publication Year Title EN/HD Year
IEC 61400-23 -  Wind turbines - Part 23: Full-scale EN 61400-23 -
structural testing of rotor blades
IEC 61587-3 -  Mechanical structures for electronic EN 61587-3 -
equipment - Tests for IEC 60917 and IEC
60297 - Part 3: Electromagnetic shielding
performance tests for cabinets and
subracks
IEC 61643-11 -  Low-voltage surge protective devices - PartE N 61643-11 -
11: Surge protective devices connected to
low-voltage power systems - Requirements
and test methods
IEC 61643-12 -  Low-voltage surge protective devices - PartC LC/TS 61643-12 -
12: Surge protective devices connected to
low-voltage power distribution systems -
Selection and application principles
IEC 61643-21 -  Low voltage surge protective devices - Part- -
21: Surge protective devices connected to
telecommunications and signalling
networks - Performance requirements and
testing methods
IEC 61643-22 -  Low-voltage surge protective devices - PartC LC/TS 61643-22 -
22: Surge protective devices connected to
telecommunications and signalling
networks - Selection and application
principles
IEC 61936-1 -  Power installations exceeding 1 kV a.c. - EN 61936-1 -
Part 1: Common rules
IEC 62305-1 (mod) 2010 Protection against lightning - Part 1: EN 62305-1 2011
General principles
IEC 62305-2 (mod) 2010 Protection against lightning - Part 2: Risk EN 62305-2 2012
management
IEC 62305-3 (mod) 2010 Protection against lightning - Part 3: EN 62305-3 2011
Physical damage to structures and life
hazard
IEC 62305-4 (mod) 2010 Protection against lightning - Part 4: EN 62305-4 2011
Electrical and electronic systems within
structures
IEC/TR 60479-4 -  Effects of current on human beings and - -
livestock -- Part 4: Effects of lightning
strokes on human beings and livestock
IEC/TR 61000-5-2 -  Electromagnetic compatibility (EMC) - Part- -
5: Installation and mitigation guidelines -
Section 2: Earthing and cabling
IEC/TS 60479-1 -  Effects of current on human beings and - -
livestock - Part 1: General aspects
IEC/TS 61936-2 -  Power installations exceeding 1 kV a.c. - -
and 1,5 kV d.c. - Part 2: d.c.
ITU-T K.20 -  Resistibility of telecommunication - -
equipment installed in a telecommunication
centre to overvoltages and overcurrents
Publication Year Title EN/HD Year
ITU-T K.21 -  Resistibility of telecommunication - -
equipment installed in customer premises
to overvoltages and overcurrents

IEC 61400-24 ®
Edition 2.0 2019-07
INTERNATIONAL
STANDARD
colour
inside
Wind energy generation systems –

Part 24: Lightning protection
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.180 ISBN 978-2-8322-6599-4

– 2 – IEC 61400-24:2019 © IEC 2019
CONTENTS
FOREWORD . 11
1 Scope . 13
2 Normative references . 13
3 Terms and definitions . 15
4 Symbols and units . 21
5 Abbreviated terms . 24
6 Lightning environment for wind turbine . 25
6.1 General . 25
6.2 Lightning current parameters and lightning protection levels (LPL) . 25
7 Lightning exposure assessment . 26
7.1 General . 26
7.2 Assessing the frequency of lightning affecting a single wind turbine or a
group of wind turbines . 28
7.2.1 Categorization of lightning events . 28
7.2.2 Estimation of average number of lightning flashes to a single or a group
of wind turbines . 28
7.2.3 Estimation of average annual number of lightning flashes near the wind
turbine (N ) . 31
M
7.2.4 Estimation of average annual number of lightning flashes to the service
lines connecting the wind turbines (N ) . 32
L
7.2.5 Estimation of average annual number of lightning flashes near the
service lines connecting the wind turbine (N ) . 32
I
7.3 Assessing the risk of damage . 33
7.3.1 Basic equation . 33
7.3.2 Assessment of risk components due to flashes to the wind turbine (S1) . 34
7.3.3 Assessment of the risk component due to flashes near the wind turbine
(S2) . 34
7.3.4 Assessment of risk components due to flashes to a service line
connected to the wind turbine (S3) . 35
7.3.5 Assessment of risk component due to flashes near a service line
connected to the wind turbine (S4) . 35
8 Lightning protection of subcomponents . 36
8.1 General . 36
8.1.1 Lightning protection level (LPL) . 36
8.1.2 Lightning protection zones (LPZ) . 37
8.2 Blades . 37
8.2.1 General . 37
8.2.2 Requirements . 37
8.2.3 Verification . 38
8.2.4 Protection design considerations . 38
8.2.5 Test methods . 41
8.3 Nacelle and other structural components . 42
8.3.1 General . 42
8.3.2 Hub . 42
8.3.3 Spinner . 42
8.3.4 Nacelle . 43
8.3.5 Tower . 43
8.3.6 Verification methods . 44

IEC 61400-24:2019 © IEC 2019 – 3 –
8.4 Mechanical drive train and yaw system . 44
8.4.1 General . 44
8.4.2 Bearings . 44
8.4.3 Hydraulic systems . 45
8.4.4 Spark gaps and sliding contacts . 46
8.4.5 Verification . 46
8.5 Electrical low-voltage systems and electronic systems and installations . 46
8.5.1 General . 46
8.5.2 Equipotential bonding within the wind turbine . 50
8.5.3 LEMP protection and immunity levels . 51
8.5.4 Shielding and line routing . 52
8.5.5 SPD protection . 53
8.5.6 Testing methods for system immunity tests . 57
8.6 Electrical high-voltage (HV) power systems . 57
9 Earthing of wind turbines . 59
9.1 General . 59
9.1.1 Purpose and scope . 59
9.1.2 Basic requirements . 59
9.1.3 Earth electrode arrangements . 59
9.1.4 Earthing system impedance . 60
9.2 Equipotential bonding . 60
9.2.1 General . 60
9.2.2 Lightning equipotential bonding for metal installations . 60
9.3 Structural components . 61
9.3.1 General . 61
9.3.2 Metal tubular type tower . 61
9.3.3 Metal reinforced concrete towers . 61
9.3.4 Lattice tower . 61
9.3.5 Systems inside the tower . 62
9.3.6 Concrete foundation . 62
9.3.7 Rocky area foundation . 62
9.3.8 Metal mono-pile foundation . 63
9.3.9 Offshore foundation . 63
9.4 Electrode shape dimensions . 63
9.5 Execution and maintenance of the earthing system . 64
10 Personal safety . 64
11 Documentation of lightning protection system . 66
11.1 General . 66
11.2 Documentation necessary during assessment for design evaluation. 66
11.2.1 General . 66
11.2.2 General documentation . 66
11.2.3 Documentation for rotor blades . 66
11.2.4 Documentation of mechanical systems . 67
11.2.5 Documentation of electrical and electronic systems . 67
11.2.6 Documentation of earthing and bonding systems . 67
11.2.7 Documentation of nacelle cover, hub and tower lightning protection
systems . 67
11.3 Site-specific information . 68
11.4 Documentation to be provided in the manuals for LPS inspections . 68

– 4 – IEC 61400-24:2019 © IEC 2019
11.5 Manuals . 68
12 Inspection of lightning protection system . 68
12.1 Scope of inspection . 68
12.2 Order of inspections . 68
12.2.1 General . 68
12.2.2 Inspection during production of the wind turbine . 69
12.2.3 Inspection during installation of the wind turbine . 69
12.2.4 Inspection during commissioning of the wind turbine and periodic
inspection . 69
12.2.5 Inspection after dismantling or repair of main parts . 70
12.3 Maintenance . 71
Annex A (informative) The lightning phenomenon in relation to wind turbines . 72
A.1 Lightning environment for wind turbines . 72
A.1.1 General . 72
A.1.2 The properties of lightning . 72
A.1.3 Lightning discharge formation and electrical parameters . 72
A.1.4 Cloud-to-ground flashes . 73
A.1.5 Upward initiated flashes. 79
A.2 Lightning current parameters relevant to the point of strike . 82
A.3 Leader current without return stroke. 83
A.4 Lightning electromagnetic impulse, LEMP, effects . 83
Annex B (informative) Lightning exposure assessment . 84
B.1 General . 84
B.2 Methodology to estimate the average annual flashes or strokes to the wind
turbines of a wind farm and upward lightning activity in wind turbines . 84
B.2.1 General . 84
B.2.2 Methodology to determine average annual flashes to turbines of a wind
farm estimation by increase of the location factor to consider upward
lightning from wind turbines . 84
B.2.3 Upward lightning percentage in wind farms . 88
B.3 Explanation of terms . 88
B.3.1 Damage and loss . 88
B.3.2 Composition of risk . 90
B.3.3 Assessment of risk components . 90
B.3.4 Frequency of damage . 91
B.3.5 Assessment of probability, P , of damage . 92
X
B.4 Assessing the probability of damage to the wind turbine . 93
B.4.1 Probability, P , that a lightning flash to a wind turbine will cause
AT
dangerous touch and step voltage . 93
B.4.2 Probability, P , that a lightning flash to the wind turbine will cause
AD
injury to an exposed person on the structure . 94
B.4.3 Probability, P , that a lightning flash to the wind turbine will cause
B
physical damage . 94
B.4.4 Probability, P , that a lightning flash to the wind turbine will cause
C
failure of internal systems . 96
B.4.5 Probability, P , that a lightning flash near the wind turbine will cause
M
failure of internal systems . 96
B.4.6 Probability, P , that a lightning flash to a service line will cause injury
U
to human beings owing to touch voltage . 96
B.4.7 Probability, P , that a lightning flash to a service line will cause
V
physical damage . 97

IEC 61400-24:2019 © IEC 2019 – 5 –
B.4.8 Probability, P , that a lightning flash to a service line will cause failure
W
of internal systems . 97
B.4.9 Probability, P , that a lightning flash near an incoming service line will
Z
cause failure of internal systems . 98
B.4.10 Probability P that a person will be in a dangerous place . 99
P
B.4.11 Probability P that equipment will be exposed to damaging event . 99
e
B.5 Assessing the amount of loss L in a wind turbine . 99
X
B.5.1 General . 99
B.5.2 Mean relative loss per dangerous event . 99
Annex C (informative) Protection methods for blades . 101
C.1 General . 101
C.1.1 Types of blades and types of protection methods for blades . 101
C.1.2 Blade damage mechanism . 102
C.2 Protection methods . 103
C.2.1 General . 103
C.2.2 Lightning air-termination systems on the blade surface or embedded in
the surface . 104
C.2.3 Adhesive metallic tapes and segmented diverter strips . 104
C.2.4 Internal down conductor systems . 105
C.2.5 Conducting surface materials . 105
C.3 CFRP structural components . 106
C.4 Particular concerns with conducting components . 107
C.5 Interception efficiency . 108
C.6 Dimensioning of lightning protection systems . 109
C.7 Blade-to-hub connection . 111
C.8 WTG blade field exposure . 111
C.8.1 General . 111
C.8.2 Application . 112
C.8.3 Field exposure . 112
Annex D (normative) Test specifications . 113
D.1 General . 113
D.2 High-voltage strike attachment tests . 113
D.2.1 Verification of air termination system effectiveness . 113
D.2.2 Initial leader attachment test . 113
D.2.3 Subsequent stroke attachment test . 123
D.3 High-current physical damage tests . 127
D.3.1 General . 127
D.3.2 Arc entry test . 127
D.3.3 Conducted current test . 132
Annex E (informative) Application of lightning environment and lightning protection
zones (LPZ) . 137
E.1 Lightning environment for blades . 137
E.1.1 Application . 137
E.1.2 Examples of simplified lightning environment areas . 137
E.1.3 Area transitions . 139
E.2 Definition of lightning protection zones for turbines (not blades). 139
E.2.1 General . 139
E.2.2 LPZ 0 . 140
E.2.3 Other zones . 141

– 6 – IEC 61400-24:2019 © IEC 2019
E.2.4 Zone boundaries . 142
E.2.5 Zone protection requirements . 143
Annex F (informative) Selection and installation of a coordinated SPD protection in
wind turbines . 146
F.1 Location of SPDs . 146
F.2 Selection of SPDs . 146
F.3 Installation of SPDs . 146
F.4 Environmental stresses of SPDs . 147
F.5 SPD status indication and SPD monitoring in case of an SPD failure . 148
F.6 Selection of SPDs with regard to protection level (U ) and system level
p
immunity . 148
F.7 Selection of SPDs with regard to overvoltages created within wind turbines . 148
F.8 Selection of SPDs with regard to discharge current (I ) and impulse current
n
(I ) . 148
imp
Annex G (informative) Information on bonding and shielding and installation technique . 150
G.1 Additional information on bonding . 150
G.2 Additional information on shielding and installation technique . 151
Annex H (informative) Testing methods for system level immunity tests . 154
Annex I (informative) Earth termination system . 159
I.1 General . 159
I.1.1 Types of earthing systems . 159
I.1.2 Construction . 159
I.2 Electrode shape dimensions . 161
I.2.1 Type of arrangement . 161
I.2.2 Frequency dependence on earthing impedance . 163
I.3 Earthing resistance expressions for different electrode configurations . 164
Annex J (informative) Example of defined measuring points . 167
Annex K (informative) Classification of lightning damage based on risk management . 169
K.1 General . 169
K.2 Lightning damage in blade . 169
K.2.1 Classification of blade damage due to lightning . 169
K.2.2 Possible cause of blade damage due to lightning . 170
K.2.3 Countermeasures against blade damage due to lightning . 171
K.3 Lightning damage to other components . 173
K.3.1 Classification of damage in other components due to lightning . 173
K.3.2 Countermeasures against lightning damage to other components . 173
K.4 Typical lightning damage questionnaire . 173
K.4.1 General . 173
K.4.2 Sample of questionnaire . 173
Annex L (informative) Monitoring systems . 177
Annex M (informative) Guidelines for small wind turbines . 179
Annex N (informative) Guidelines for verification of blade similarity . 180
N.1 General . 180
N.2 Similarity constraints . 180
Annex O (informative) Guidelines for validation of numerical analysis methods . 183
O.1 General . 183
O.2 Blade voltage and current distribution . 183
O.3 Indirect effects analysis . 184

IEC 61400-24:2019 © IEC 2019 – 7 –
Annex P (informative) Testing of rotating components . 185
P.1 General . 185
P.2 Test specimen . 185
P.2.1 Test specimen representing a stationary / quasi stationary bearing . 185
P.2.2 Test specimen representing a rotating bearing . 185
P.3 Test setup . 185
P.3.1 Test set-up representing a stationary/quasi-stationary bearing . 185
P.3.2 Test set-up representing a rotating bearing. 186
P.4 Test procedure . 187
P.5 Pass/fail criteria . 188
Annex Q (informative) Earthing systems for wind farms . 189
Bibliography . 190

Figure 1 – Collection area of the wind turbine . 30
Figure 2 – Example of collection area for a complete wind farm (A ) with 10 wind
DWF
turbines (black points) considering overlapping . 31
Figure 3 – Collection area of wind turbine of height H and another structure of height
a
H connected by underground cable of length L . 33
b c
Figure 4 – Examples of possible SPM (surge protection measures) . 49
Figure 5 – Interconnecting two LPZ 1 using SPDs . 50
Figure 6 – Interconnecting two LPZ 1 using shielded cables or shielded cable ducts. 50
Figure 7 –Magnetic field inside an enclosure due to a long connection cable from
enclosure entrance to the SPD . 53
Figure 8 –Additional protective measures . 54
Figure 9 – Examples of placement of HV arresters in two typical main electrical circuits
of wind turbines . 58
Figure A.1 – Processes involved in the formation of a downward initiated cloud-to-
ground flash . 74
Figure A.2 – Typical profile of a negative cloud-to-ground flash . 75
Figure A.3 – Definitions of short stroke parameters (typically T < 2 ms) . 75
Figure A.4 – Definitions of long stroke parameters (typically 2 ms < T < 1 s) . 76
long
Figure A.5 – Possible components of downward flashes (typical in flat territory and to
lower structures) . 78
Figure A.6 – Typical profile of a positive cloud-to-ground flash. 79
Figure A.7 – Processes involved in the formation of an upward initiated cloud-to-
ground flash during summer and winter conditions . 79
Figure A.8 – Typical profile of a negative upward initiated flash . 80
Figure A.9 – Possible components of upward flashes (typical to exposed and/or higher
structures) . 81
Figure B.1 – Winter lightning world map based on LLS data and weather conditions . 86
Figure B.2 – Detailed winter lightning maps based on LLS data and weather conditions . 87
Figure B.3 – Ratio h/d description . 87
Figure C.1 – Types of wind turbine blades . 101
Figure C.2 – Lightning protection concepts for large modern wind turbine blades. 104
Figure C.3 – Voltages between lightning current path and sensor wiring due to the
mutual coupling and the impedance of the current path . 107
Figure D.1 – Example of initial leader attachment test setup A . 115

– 8 – IEC 61400-24:2019 © IEC 2019
Figure D.2 – Possible orientations for the initial leader attachment test setup A . 116
Figure D.3 – Definition of the blade length axis during strike attachment tests . 117
Figure D.4 – Example of the application of angles during the HV test. 117
Figure D.5 – Example of leader connection point away from test specimen . 118
Figure D.6 – Initial leader attachment test setup B . 119
Figure D.7 – Typical switching impulse voltage rise to flashover (100 µs per division) . 121
Figure D.8 – Subsequent stroke attachment test arrangement . 124
Figure D.9 – Lightning impulse voltage waveform . 125
Figure D.10 – Lightning impulse voltage chopped on the front . 125
Figure D.11 – H
...