EN 61400-2:2014

Wind turbines - Part 2: Small wind turbines

IEC 61400-2:2013 deals with safety philosophy, quality assurance, and engineering integrity and specifies requirements for the safety of small wind turbines (SWTs) including design, installation, maintenance and operation under specified external conditions. It provides the appropriate level of protection against damage from hazards from these systems during their planned lifetime. This standard is concerned with all subsystems of SWTs such as protection mechanisms, internal electrical systems, mechanical systems, support structures, foundations and the electrical interconnection with the load. While this standard is similar to IEC 61400-1, it does simplify and make significant changes in order to be applicable to small wind turbines. The main changes with respect to the previous edition are as follows: - the title has been modified to better reflect the scope; - restructured into a part Design evaluation and a part Type testing to harmonise use with IEC 61400-22 conformity testing and certification; - caution provided regarding the use of simplified equations; - added various annexes (wind conditions, tropical storms, extreme environmental conditions, EMC testing, dynamic behavior, etc.).

Windenergieanlagen - Teil 2: Anforderungen für kleine Windenergieanlagen

Eoliennes-- Partie 2: Petits aérogénérateurs

La CEI 61400-2:2013 traite de la philosophie relative à la sécurité, l'assurance de la qualité et l'intégrité de l'ingénierie, et elle spécifie les exigences relatives à la sécurité des petits aérogénérateurs (PAG), comprenant leur conception, leur installation et leur maintenance, ainsi que leur exploitation dans des conditions externes spécifiées. Elle fixe un niveau approprié de protection contre les dommages dus aux dangers que ces systèmes pourraient causer pendant leur durée de vie. La présente norme se préoccupe de tous les sous-systèmes des PAG tels que les mécanismes de protection, les systèmes électriques internes, les systèmes mécaniques, les structures de support, les fondations et l'interconnexion électrique avec la charge. Bien que la présente norme soit similaire à la CEI 61400-1, elle la simplifie et y apporte des changements significatifs afin d'être applicable aux petits aérogénérateurs. Cette nouvelle édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente: - le titre a été modifié pour mieux refléter le domaine d'application; - restructuration en une partie Evaluation de la conception et une partie Essais de type pour harmoniser l'utilisation avec les essais de conformité et la certification de la CEI 61400-22; - des précautions ont été ajoutées concernant l'utilisation des équations simplifiées; - diverses annexes ont été ajoutées (conditions de vent, tempêtes tropicales, conditions d'environnement extrêmes, essais CEM, comportement dynamique).

Vetrne turbine - 2. del: Male vetrne turbine (IEC 61400-2:2013)

Ta del standarda IEC 61400 obravnava varnostna načela, zagotavljanje kakovosti in celovitost zasnove ter določa zahteve za zaščito malih vetrnih turbin (SWT), vključno z načrtovanjem, namestitvijo, vzdrževanjem in delovanjem pri določenih zunanjih pogojih. Njegov namen je zagotoviti ustrezno raven zaščite pred poškodbami zaradi nevarnih lastnosti teh sistemov v njihovi predvideni življenjski dobi.
Ta standard obravnava vse podsisteme enot SWT, kot so varnostni mehanizmi, notranji električni sistemi, mehanski sistemi, podporne konstrukcije, temelji in električne povezave z obremenitvijo. Sistem male vetrne turbine vključuje vetrno turbino, vključno s podporno konstrukcijo, regulator turbine, regulator napajanja/inverter (če je potrebno), napeljavo in odklopnike, navodila za namestitev in uporabo ter drugo dokumentacijo.
Čeprav je ta standard podoben standardu IEC 61400-1, vključuje poenostavitve in bistvene spremembe za namen uporabe za male vetrne turbine. Katere koli zahteve tega standarda se lahko spremenijo v primeru, če je mogoče ustrezno prikazati, da varnostne lastnosti sistema turbine niso ogrožene. Vendar se ta določba ne uporablja za klasifikacijo in povezane definicije zunanjih pogojev iz točke 6. Skladnost s tem standardom ne odvezuje nobene osebe, organizacije ali družbe odgovornosti za zagotavljanje skladnosti z drugimi veljavnimi predpisi.
Ta standard se uporablja za vetrne turbine z območjem delovanja rotorja, manjšim ali enakim 200 m2, ki proizvajajo električno energijo pri napetosti manj kot 1000 V (izmenični tok) ali 1500 V (enosmerni tok) pri načinih uporabe znotraj in zunaj omrežja. Ta standard naj bi se uporabljal skupaj z ustreznimi standardi IEC in ISO (glej točko 2).

General Information

• Status: Published
• Publication Date: 09-Oct-2014
• Withdrawal Date: 15-Jan-2017
• ICS: 27.180 - Wind turbine energy systems
• Technical Committee: CLC/TC 88 - Wind turbines
• Drafting Committee: IEC/TC 88 - IEC_TC_88
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 10-Oct-2014
• Completion Date: 10-Oct-2014
• Ref Project: SIST EN 61400-2:2015 - Wind turbines - Part 2: Small wind turbines (IEC 61400-2:2013)

Relations

• Replaces: EN 61400-2:2006 - Wind turbines - Part 2: Design requirements for small wind turbines
• Effective Date: 29-Jan-2023
• Corrected By: EN 61400-2:2014/AC:2019-11 - Wind turbines - Part 2: Small wind turbines
• Effective Date: 05-Nov-2019

Overview

EN 61400-2:2014 (identical to IEC 61400-2:2013) is the European/International standard for small wind turbines (SWTs). It defines a safety philosophy, quality assurance and engineering integrity requirements for the full lifecycle of SWTs - covering design, installation, operation, maintenance and testing under specified external conditions. The standard aims to provide an appropriate level of protection against hazards throughout the planned lifetime of an SWT and addresses all subsystems: protection and shutdown, electrical and mechanical systems, support structures, foundations and electrical interconnection with loads.

Key editorial updates in this edition include:

• Title clarified to better reflect scope;
• Restructuring into Design evaluation and Type testing to harmonise with IEC 61400-22 conformity testing and certification;
• Warnings about the use of simplified equations;
• New annexes (wind conditions, tropical storms, extreme environmental conditions, EMC testing, dynamic behaviour, etc.).

Key Topics and Requirements

• Design evaluation and type testing: structured approach to assess SWT designs and carry out type tests for certification.
• External conditions and SWT classes: classification of wind and environmental loads including normal and extreme conditions.
• Structural design: load cases, fatigue and ultimate strength assessment, simulation modelling and load measurement guidance.
• Protection and shutdown systems: functional requirements for safety systems, manual and maintenance shutdown.
• Electrical systems: protective devices, disconnects, earthing (grounding), lightning protection, and interfacing with grids or local loads.
• Support structures and foundations: dynamic and environmental design considerations and earthing.
• Quality assurance & documentation: manufacturer documentation, product manuals, installation, operation and maintenance instructions, and labelling.
• Annexes: guidance on EMC testing, dynamic behaviour, tropical storms and other extreme environmental factors.

Practical Applications

EN 61400-2:2014 is used to:

• Support designers and manufacturers in developing safe, certifiable SWTs.
• Guide testing laboratories and certification bodies performing type testing and conformity assessment.
• Inform installers and integrators on installation, earthing and electrical interconnection requirements.
• Help regulators, procurement teams and asset owners evaluate safety, performance and documentation.
• Provide a reference for maintenance planning, field inspections and end-of-life considerations.

Who should use this standard

• SWT manufacturers and R&D teams
• Certification bodies and testing labs
• Structural, electrical and control system engineers
• Installers, site assessors and O&M providers
• Regulators and procurement/specification authors

Related Standards (if applicable)

Relevant documents referenced include IEC/EN 61400‑1, IEC/EN 61400‑11, IEC/EN 61400‑12‑1, IEC/EN 61400‑21, IEC/EN 61400‑22, and laboratory/quality standards such as ISO/IEC 17025. These complement SIST EN 61400-2 for full conformity, testing and certification workflows.

Keywords: EN 61400-2:2014, IEC 61400-2, small wind turbines, SWT, design evaluation, type testing, structural design, protection systems, electrical system, certification.

Standards Content (Sample)

SLOVENSKI STANDARD
01-maj-2015
1DGRPHãþD
SIST EN 61400-2:2006
Vetrne turbine - 2. del: Male vetrne turbine (IEC 61400-2:2013)
Wind turbines - Part 2: Small wind turbines (IEC 61400-2:2013)
Windenergieanlagen - Teil 2: Anforderungen für kleine Windenergieanlagen (IEC 61400-
2:2013)
Aérogénérateurs - Partie 2: Petits aérogénérateurs (IEC 61400-2:2013)
Ta slovenski standard je istoveten z: EN 61400-2:2014
ICS:
27.180 Sistemi turbin na veter in Wind turbine systems and
drugi alternativni viri energije other alternative sources of
energy
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 61400-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2014
ICS 27.180 Supersedes EN 61400-2:2006
English Version
Wind turbines - Part 2: Small wind turbines
(IEC 61400-2:2013)
Eoliennes-- Partie 2: Petits aérogénérateurs Windenergieanlagen - Teil 2: Anforderungen für kleine
(CEI 61400-2:2013) Windenergieanlagen
(IEC 61400-2:2013)
This European Standard was approved by CENELEC on 2014-01-16. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, 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: Avenue Marnix 17, B-1000 Brussels
© 2014 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 61400-2:2014 E
Foreword
The text of document 88/465/FDIS, future edition 3 of IEC 61400-2, prepared by IEC/TC 88 "Wind
turbines" and ISO/TC 60 "Gears" was submitted to the IEC-CENELEC parallel vote and approved by
CENELEC as EN 61400-2:2014.
The following dates are fixed:
(dop) 2015-04-10
• latest date by which the document has
to be implemented at national level by
publication of an identical national
standard or by endorsement
• latest date by which the national (dow) 2017-01-16
standards conflicting with the
document have to be withdrawn
This document supersedes EN 61400-2:2006
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such patent
rights.
Endorsement notice
The text of the International Standard IEC 61400-2:2013 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 60034 (Series) NOTE  Harmonized as EN 60034 (Series).
IEC 60364 (Series) NOTE  Harmonized as HD 60364 (Series).
IEC 60529:1989 NOTE  Harmonized as EN 60529:1991.
IEC 61400-1:2005 NOTE  Harmonized as EN 61400-1:2005.
IEC 61400-4 NOTE  Harmonized as EN 61400-4.
IEC 61400-21:2008 NOTE  Harmonized as EN 61400-21:2008.
IEC 61400-22:2010 NOTE  Harmonized as EN 61400-22:2011.
IEC 61400-24 NOTE  Harmonized as EN 61400-24.
ISO/IEC 17020:2012 NOTE  Harmonized as EN ISO/IEC 17020:2012.
ISO 9000 (Series) NOTE  Harmonized as EN ISO 9000 (Series).
ISO 9001:2008 NOTE  Harmonized as EN ISO 9001:2008.

- 3 - EN 61400-2:2014
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.

NOTE 1 When 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 60038 (mod) 2009 IEC standard voltages EN 60038 2011
IEC 60204-1 (mod) 2005 Safety of machinery - Electrical equipment EN 60204-1 2006
of machines -- Part 1: General requirements
+prA11
+EN 60204- 2010
1:2006/corrigendum
Feb. 2010
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
+FprAA 2011
IEC 60721-2-1 -  Classification of environmental conditions -- EN 60721-2-1 -
Part 2-1: Environmental conditions
appearing in nature - Temperature and
humidity
IEC 61400-1 2005 Wind turbines -- Part 1: Design requirements EN 61400-1 2005
+prA
IEC 61400-11 -  Wind turbines -- Part 11: Acoustic noise EN 61400-11 -
measurement techniques
IEC 61400-12-1 2005 Wind turbines -- Part 12-1: Power EN 61400-12-1 2006
performance measurements of electricity
producing wind turbines
IEC 61643-11 (mod) 2011 Low-voltage surge protective devices -- Part EN 61643-11 2012
11: Surge protective devices connected to
low-voltage power systems - Requirements
and test methods
ISO 2394 1998 General principles on reliability for structures - -
IEC/TS 61400-13 -  Wind turbine generator systems - Part 13: - -
Measurement of mechanical loads
IEC/TS 61400-23 2001 Wind turbine generator systems -- Part 23: - -
Full-scale structural testing of rotor blades
ISO/IEC 17025 -  General requirements for the competence of EN ISO/IEC 17025 -
testing and calibration laboratories

IEC 61400-2 ®
Edition 3.0 2013-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Wind turbines –
Part 2: Small wind turbines
Eoliennes –
Partie 2: Petits aérogénérateurs

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XF
ICS 27.180 ISBN 978-2-8322-1284-4

– 2 – 61400-2  IEC:2013
CONTENTS
FOREWORD . 9
1 Scope . 11
2 Normative references . 11
3 Terms and definitions . 12
4 Symbols and abbreviated terms . 21
4.1 General . 21
4.2 Symbols . 21
4.3 Coordinate system . 25
5 Principal elements . 26
5.1 General . 26
5.2 Design methods . 27
5.3 Quality assurance . 27
I Design evaluation . 29
6 External conditions . 29
6.1 General . 29
6.2 SWT classes . 29
6.3 Wind conditions . 30
6.3.1 General . 30
6.3.2 Normal wind conditions . 30
6.3.3 Extreme wind conditions . 32
6.4 Other environmental conditions . 36
6.4.1 General . 36
6.4.2 Other normal environmental conditions . 37
6.4.3 Other extreme environmental conditions . 37
6.5 Controlled test conditions . 38
6.6 Electrical load conditions . 38
6.6.1 General . 38
6.6.2 For turbines connected to the electrical power network . 38
6.6.3 For turbines not connected to the electrical power network . 38
7 Structural design . 39
7.1 General . 39
7.2 Design methodology . 39
7.3 Loads and load cases . 39
7.3.1 General . 39
7.3.2 Vibration, inertial and gravitational loads . 39
7.3.3 Aerodynamic loads . 39
7.3.4 Operational loads . 40
7.3.5 Other loads . 40
7.3.6 Load cases . 40
7.4 Simplified loads methodology . 40
7.4.1 General . 40
7.4.2 Load case A: normal operation . 42
7.4.3 Load case B: yawing . 43
7.4.4 Load case C: yaw error . 44
7.4.5 Load case D: maximum thrust . 44
7.4.6 Load case E: maximum rotational speed . 44

61400-2  IEC:2013 – 3 –
7.4.7 Load case F: short at load connection . 44
7.4.8 Load case G: shutdown (braking) . 44
7.4.9 Load case H: extreme wind loading . 45
7.4.10 Load case I: parked wind loading, maximum exposure . 46
7.4.11 Load case J: transportation, assembly, maintenance and
repair . 47
7.5 Simulation modelling . 47
7.5.1 General . 47
7.5.2 Power production (DLC 1.1 to 1.5) . 48
7.5.3 Power production plus occurrence of fault (DLC 2.1 to 2.3). 49
7.5.4 Normal shutdown (DLC 3.1 and 3.2) . 49
7.5.5 Emergency or manual shutdown (DLC 4.1) . 49
7.5.6 Extreme wind loading (stand-still or idling or spinning) (DLC
5.1 to 5.2) . 49
7.5.7 Parked plus fault conditions (DLC 6.1) . 50
7.5.8 Transportation, assembly, maintenance and repair (DLC 7.1) . 50
7.5.9 Load calculations . 50
7.6 Load measurements. 50
7.7 Stress calculation . 50
7.8 Safety factors. 51
7.8.1 Material factors and requirements . 51
7.8.2 Partial safety factor for loads . 52
7.9 Limit state analysis . 52
7.9.1 Ultimate strength analysis . 52
7.9.2 Fatigue failure . 53
7.9.3 Critical deflection analysis . 53
8 Protection and shutdown system . 54
8.1 General . 54
8.2 Functional requirements of the protection system . 54
8.3 Manual shutdown . 54
8.4 Shutdown for maintenance . 55
9 Electrical system . 55
9.1 General . 55
9.2 Protective devices . 55
9.3 Disconnect device . 56
9.4 Earthing (grounding) systems . 56
9.5 Lightning protection . 56
9.6 Electrical conductors and cables . 56
9.7 Electrical loads . 56
9.7.1 General . 56
9.7.2 Battery charging . 56
9.7.3 Electrical power network (grid connected systems) . 57
9.7.4 Direct connect to electric motors (e.g. water pumping) . 57
9.7.5 Direct resistive load (e.g. heating) . 57
9.8 Local requirements . 57
10 Support structure . 58
10.1 General . 58
10.2 Dynamic requirements . 58
10.3 Environmental factors . 58

– 4 – 61400-2  IEC:2013
10.4 Earthing . 58
10.5 Foundation . 58
10.6 Turbine access design loads . 58
11 Documentation requirements . 58
11.1 General . 58
11.2 Product manuals . 59
11.2.1 General . 59
11.2.2 Specification . 59
11.2.3 Installation . 60
11.2.4 Operation . 60
11.2.5 Maintenance and routine inspection . 61
11.3 Consumer label . 62
12 Wind turbine markings . 62
II Type testing. 63
13 Testing . 63
13.1 General . 63
13.2 Tests to verify design data . 63
13.2.1 General . 63
13.2.2 P , n , V and Q . 63
design design design design
13.2.3 Maximum yaw rate . 64
13.2.4 Maximum rotational speed . 64
13.3 Mechanical loads testing . 64
13.4 Duration testing . 65
13.4.1 General . 65
13.4.2 Reliable operation . 66
13.4.3 Dynamic behaviour . 68
13.4.4 Reporting of duration test . 69
13.5 Mechanical component testing . 70
13.5.1 General . 70
13.5.2 Blade test . 70
13.5.3 Hub test . 71
13.5.4 Nacelle frame test . 71
13.5.5 Yaw mechanism test . 71
13.5.6 Gearbox test . 71
13.6 Safety and function . 71
13.7 Environmental testing . 72
13.8 Electrical . 72
Annex A (informative) Variants of small wind turbine systems . 73
A.1 General . 73
A.2 Example 1: power forms. 73
A.3 Example 2: blades . 73
A.4 Example 3: support structures . 73
Annex B (normative) Design parameters for describing SWT class S . 75
Annex C (informative) Stochastic turbulence models . 76
C.1 General . 76
C.2 Exponential coherency model . 77
C.3 Von Karman isotropic turbulence model . 77
Annex D (informative) Deterministic turbulence description . 79

61400-2  IEC:2013 – 5 –
Annex E (informative) Partial safety factors for materials . 81
E.1 General . 81
E.2 Symbols . 81
E.3 Characteristic value versus design values . 81
E.4 Material factors and requirements . 82
E.4.1 General . 82
E.4.2 Composites . 83
E.4.3 Metals . 85
E.4.4 Wood . 85
E.5 Geometry effects . 88
E.6 Reference documents . 89
Annex F (informative) Development of the simplified loads methodology . 90
F.1 Symbols used in this annex . 90
F.2 General . 91
F.3 Caution regarding use of simplified equations . 91
F.4 General relationships . 92
F.5 Reference documents . 100
Annex G (informative) Example of test reporting formats . 101
G.1 Overview. 101
G.2 Duration test . 101
G.2.1 General . 101
G.2.2 Table summarizing the duration test results . 101
G.2.3 Plot showing any potential power degradation . 102
G.3 Power/energy performance . 102
G.3.1 General . 102
G.4 Acoustic noise test . 105
Annex H (informative) EMC measurements . 106
H.1 Overview. 106
H.2 Measurement for radiated emissions . 106
H.3 Measurements of conducted emissions . 108
H.4 Reference documents . 108
Annex I (normative) Natural frequency analysis . 110
Annex J (informative) Extreme environmental conditions . 112
J.1 Overview. 112
J.2 Extreme conditions . 112
J.3 Low temperature . 112
J.4 Ice . 112
J.5 High temperature . 113
J.6 Marine . 113
Annex K (informative) Extreme wind conditions of tropical cyclones . 114
K.1 General . 114
K.2 Using SWT classes in tropical cyclone areas . 114
K.3 Extreme wind conditions . 114
K.3.1 Definition of tropical cyclones . 114
K.3.2 General features of tropical cyclones . 114
K.3.3 Extreme wind conditions . 115
K.4 Stochastic simulation (Monte Carlo simulation) . 116
K.5 Reference documents . 117

– 6 – 61400-2  IEC:2013
Annex L (informative) Other wind conditions . 120
L.1 General . 120
L.2 Typical situations . 120
L.3 Directionally dependent flow . 120
L.4 Inclined flow . 120
L.5 Turbulence . 122
L.6 Extreme wind direction changes . 125
L.7 Gust factors . 126
L.8 Reference documents . 127
Annex M (informative) Consumer label . 128
M.1 General . 128
M.2 Administration . 128
M.2.1 General . 128
M.2.2 Test summary report . 128
M.2.3 Publication of labels . 129
M.2.4 Wind turbine variants . 129
M.3 Tests for labelling . 129
M.3.1 General . 129
M.3.2 Duration test . 129
M.3.3 Power curve and reference annual energy . 130
M.3.4 Acoustic noise test . 130
M.4 Label layout . 130
M.5 Reference documents . 130
Bibliography . 133

Figure 1 – Definition of the system of axes for HAWT . 25
Figure 2 – Definition of the system of axes for VAWT . 26
Figure 3 – IEC 61400-2 decision path . 28
Figure 4 – Characteristic wind turbulence . 32
Figure 5 – Example of extreme operating gust (N=1, V = 25 m/s) . 33
hub
Figure 6 – Example of extreme direction change magnitude (N = 50, D = 5 m, z =
hub
20 m) . 35
Figure 7 – Example of extreme direction change transient (N = 50, V = 25 m/s) . 35
hub
Figure 8 – Extreme coherent gust (V = 25 m/s) (ECG) . 35
hub
Figure 9 – The direction change for ECD . 36
Figure 10 – Time development of direction change for V = 25 m/s . 36
hub
Figure E.1 – Normal and Weibull distribution . 82
Figure E.2 – Typical S-N diagram for fatigue of glass fibre composites (Figure 41 from
reference [E.2]) . 84
Figure E.3 – Typical environmental effects on glass fibre composites (Figure 25 from
reference [E.2]) . 84
Figure E.4 – Fatigue strain diagram for large tow unidirectional 0° carbon fibre/vinyl
ester composites, R = 0,1 and 10 (Figure 107 from reference [E.2]) . 84
Figure E.5 – S-N curves for fatigue of typical metals . 85
Figure E.6 – Fatigue life data for jointed softwood (from reference [E.5]) . 86
Figure E.7 – Typical S-N curve for wood (from reference [E.5]) . 86

61400-2  IEC:2013 – 7 –
Figure E.8 – Effect of moisture content on compressive strength of lumber parallel to
grain (Figure 4-13 from reference [E.6]) . 87
Figure E.9 – Effect of moisture content on wood strength properties (Figure 4-11 from
reference [E.6]) . 87
Figure E.10 – Effect of grain angle on mechanical property of clear wood according to
Hankinson-type formula (Figure 4-4 from reference [E.6]) . 88
Figure G.1 – Example power degradation plot . 102
Figure G.2 – Example binned sea level normalized power curve . 103
Figure G.3 – Example scatter plot of measured power and wind speed . 104
Figure G.4 – Example immission noise map . 105
Figure H.1 – Measurement setup of radiated emissions (set up type A) . 107
Figure H.2 – Measurement setup of radiated emissions (set up type B) . 107
Figure H.3 – Measurement setup of conducted emissions (setup type A) . 108
Figure H.4 – Measurement setup of conducted emissions (setup type B) . 108
Figure I.1 – Example of a Campbell diagram . 111
Figure K.1 – Comparison of predicted and observed extreme winds in a mixed climate
region (after Isihara, T. and Yamaguchi, A.) . 117
Figure K.2 – Tropical cyclone tracks between 1945 and 2006 . 119
Figure L.1 – Simulation showing inclined flow on a building (courtesy Sander Mertens) . 121
Figure L.2 – Example wind flow around a building . 122
Figure L.3 – Turbulence intensity and wind speed distribution, 5 m above treetops in a
forest north of Uppsala, Sweden, during Jan-Dec 2009 . 123
Figure L.4 – Turbulence intensity and wind speed distribution, 69 m above treetops in
a forest north of Uppsala, Sweden, during 2009 (limited data for high wind speeds) . 123
Figure L.5 – Turbulence intensity and wind distribution, 2 m above rooftop in Melville,
Western Australia, during Jan-Feb 2009, reference [L.4] . 124
Figure L.6 – Turbulence intensity and wind speed distribution, 5,7 m above a rooftop in
Port Kennedy, Western Australia, during Feb-Mar 2010, reference [L.4] . 124
Figure L.7 – Example extreme direction changes; 1,5 m above a rooftop in Tokyo,
Japan during three months February-May of 2007 (0,5 Hz data, reference [L.5]). 125
Figure L.8 – Example extreme direction changes; 1,5 m above a rooftop in Tokyo,
Japan during five months September 2010 to February 2011 (1,0 Hz data, reference
[L.5]) . 126
Figure L.9 – Gust factor measurements during storm in Port Kennedy, Western
Australia, during March 2010, measured 5 m above rooftop compared with 10-min
average wind speed . 126
Figure M.1 – Sample label in English . 131
Figure M.2 – Sample bilingual label (English/French) . 132

Table 1 – Basic parameters for SWT classes . 30
Table 2 – Design load cases for the simplified load calculation method . 42
Table 3 – Force coefficients (C ) . 47
f
Table 4 – Minimum set of design load cases (DLC) for simulation by aero-elastic
models . 48
Table 5 – Equivalent stresses . 51
Table 6 – Partial safety factors for materials . 52
Table 7 – Partial safety factors for loads . 52

– 8 – 61400-2  IEC:2013
Table C.1 – Turbulence spectral parameters for Kaimal model . 76
Table E.1 – Factors for different survival probabilities and variabilities. 82
Table E.2 – Geometric discontinuities . 89
Table G.1 – Example duration test result . 101
Table G.2 – Example calculated annual energy production (AEP) table . 104
Table K.1 – Top five average extreme wind speeds recorded at meteorological stations . 115
Table K.2 – Extreme wind speeds recorded at meteorological stations . 116

61400-2  IEC:2013 – 9 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
WIND TURBINES –
Part 2: Small wind turbines
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61400-2 has been prepared by IEC technical committee 88: Wind
turbines.
This third edition cancels and replaces the second edition published in 2006.
This edition constitutes a technical revision. This edition includes the following significant
technical changes with respect to the previous edition:
• the title has been modified to better reflect the scope;
• restructured into part I (design evaluation) and part II (type testing) to harmonise use with
IEC 61400-22 conformity testing and certification;
• caution provided regarding the use of simplified equations;
• added annex on other wind conditions;
• added annex on tropical storms;
• added annex on extreme environmental conditions;

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