IEC 61400-1:2005/AMD1:2010

Amendment 1 - Wind turbines - Part 1: Design requirements

Amendement 1 - Eoliennes - Partie 1: Exigences de conception

General Information

• Status: Published
• Publication Date: 12-Oct-2010
• ICS: 27.180 - Wind turbine energy systems
• Technical Committee: TC 88 - Wind energy generation systems
• Drafting Committee: MT 1 - TC 88/MT 1
• Current Stage: DELPUB - Deleted Publication
• Completion Date: 08-Feb-2019

Relations

• Amends: IEC 61400-1:2005 - Wind turbines - Part 1: Design requirements
• Effective Date: 05-Sep-2023
• Revised: IEC 61400-1:2019 - Wind energy generation systems - Part 1: Design requirements
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 61400-1 ®
Edition 3.0 2010-10
INTERNATIONAL
STANDARD
AMENDMENT 1
Wind turbines –
Part 1: Design requirements
IEC 61400-1:2005/A1:2010(E)
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form

or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester.
If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,

please contact the address below or your local IEC member National Committee for further information.

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CH-1211 Geneva 20
Switzerland
Email: [e-mail]
Web: www.iec.ch
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

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IEC 61400-1 ®
Edition 3.0 2010-10
INTERNATIONAL
STANDARD
AMENDMENT 1
Wind turbines –
Part 1: Design requirements
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
U
ICS 27.180 ISBN 978-2-88912-201-1
– 2 – 61400-1 Amend.1 © IEC:2010(E)

FOREWORD
This amendment has been prepared by IEC technical committee 88: Wind turbines.

The text of this amendment is based on the following documents:

FDIS Report on voting
88/374/FDIS 88/378/RVD
Full information on the voting for the approval of this amendment can be found in the report
on voting indicated in the above table.
The committee has decided that the contents of this amendment and the base publication will
remain unchanged until the stability date indicated on the IEC web site 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 may be issued at a later date.
_____________
61400-1 Amend.1 © IEC:2010(E) – 3 –

2 Normative references
Replace the existing list of normative references by the following new list:

IEC 60204-1, Safety of machinery – Electrical equipment of machines – Part 1: General

requirements
IEC 60204-11, Safety of machinery – Electrical equipment of machines – Part 11:

Requirements for HV equipment for voltages above 1 000 V a.c. or 1 500 V d.c. and not

exceeding 36 kV
IEC 60364 (all parts), Low-voltage electrical installations
IEC 60364-5-54, Electrical installations of buildings – Part 5-54: Selection and erection of
electrical equipment – Earthing arrangements, protective conductors and protective bonding
conductors
IEC 60721-2-1, Classification of environmental conditions – Part 2: Environmental conditions
appearing in nature – Temperature and humidity
IEC 61000-6-1, Electromagnetic compatibility (EMC) – Part 6-1: Generic standards –
Immunity for residential, commercial and light-industrial environments
IEC 61000-6-2, Electromagnetic compatibility (EMC) – Part 6-2: Generic standards –
Immunity for industrial environments
IEC 61000-6-4, Electromagnetic compatibility (EMC) – Part 6-4: Generic standards –
Emission standard for industrial environments
IEC 61400-2, Wind turbines – Part 2: Design requirements for small wind turbines
IEC 61400-21, Wind turbines – Part 21: Measurement and assessment of power quality
characteristics of grid connected wind turbines
IEC 61400-24, Wind turbines – Part 24: Lightning protection
IEC 62305-3, Protection against lightning – Part 3: Physical damage to structures and life
hazard
IEC 62305-4, Protection against lightning – Part 4: Electrical and electronic systems within
structures
ISO 76:2006, Rolling bearings – Static load ratings
ISO 281, Rolling bearings – Dynamic load ratings and rating life
ISO 2394:1998, General principles on reliability for structures
ISO 2533:1975, Standard atmosphere
ISO 4354, Wind actions on structures
ISO 6336-2, Calculation of load capacity of spur and helical gears – Part 2: Calculation of
surface durability (pitting)
– 4 – 61400-1 Amend.1 © IEC:2010(E)

ISO 6336-3:2006, Calculation of load capacity of spur and helical gears – Part 3: Calculation

of tooth bending strength
ISO 81400-4, Wind turbines – Part 4: Design and specification of gearboxes

3 Terms and definitions
3.26 – limit state
Replace ISO 2394 by 2.2.9 of ISO 2394.

3.55 – ultimate limit state
Replace ISO 2394 by 2.2.10 of ISO 2394.
4 Symbols and abbreviated terms
4.1 Symbols and units
Switch the definitions of σ and σ . The vertical wind velocity standard deviation should be σ ,
2 3 3
not σ .
6 External conditions
6.3.1.3 Normal turbulence model (NTM)
Replace the existing Figures 1a and 1b by the following new figures:

Category A
4,5
Category B
Category C
3,5
2,5
1,5
0,5
0 5 10 15 20 25 30
V  (m/s)
IEC  2236/10
hub
Figure 1a –Turbulence standard deviation for the normal turbulence model (NTM)

σ  (m/s)
61400-1 Amend.1 © IEC:2010(E) – 5 –

0,5
Category A
Category B
0,4
Category C
0,3
0,2
0,1
0 5 10 15 20 25 30
V  (m/s)
hub
IEC  2237/10
Figure 1b – Turbulence intensity for the normal turbulence model (NTM)
6.3.2.6 Extreme wind shear (EWS)
Replace the number 2,5 in equations (26) and (27) to 2,5 [m/s]. (The number 2,5 in equations
(26) and (27) is not dimensionless.)
7 Structural design
7.4.2 Power production plus occurrence of fault or loss of electrical network
connection (DLC 2.1 – 2.4)
nd
paragraph, the following new text:
Add, as 2
As an alternative to the specification of DLC 2.3 above and in Table 2, DLC 2.3 may instead
be considered as a normal event (i.e. a partial safety factor for load of 1,35) to be analyzed
using stochastic wind simulations (NTM - V in hub out
electrical system fault (including loss of electrical network connection). In this case, 12
response simulations shall be carried out for each considered mean wind speed. For each
response simulation, the extreme response after the electrical fault has occurred is sampled.
The fault must be introduced after the effect of initial conditions has become negligible. For
each mean wind speed, a nominal extreme response is evaluated as the mean of the 12
sampled extreme responses plus three times the standard deviation of the 12 samples. The
characteristic response value for DLC 2.3 is determined as the extreme value among the
nominal extreme responses.
7.5 Load calculations
Add, after second paragraph, the following new text:
When turbulent winds are used for dynamic simulations, attention should be given to the grid
resolution regarding the spatial and time resolution.
—————————
Concerning the spatial resolution, the maximum distance between adjacent points should be smaller than 25 %
of Λ1 (Equation (5)) and no larger than 15 % of the rotor diameter. This distance is meant to be the diagonal
distance between points in each grid cell defined by four points. In the case of a non-uniform grid, an average
value over the rotor surface of the distance between grid points can be considered as the representative spatial
resolution, but this distance should always decrease towards the blade tip.
Turbulence intensity
– 6 – 61400-1 Amend.1 © IEC:2010(E)

Replace the last paragraph by the following new text:

Ultimate load components may also be combined in a conservative manner assuming the
extreme component values occur simultaneously. In case this option is pursued, both
minimum and maximum extreme component values shall be applied in all possible

combinations to avoid introducing non-conservatism.

Guidance for the derivation of extreme design loads from contemporaneous loads taken from

a number of stochastic realisations is given in Annex H.

7.6.1.2 Partial safety factor for consequence of failure and component classes

Add, after the bullets defining the component classes, the following new text:
The consequences of failure factor shall be included in the test load when performing tests
as for example full scale blade testing.
7.6.2 Ultimate strength analysis
Replace equation (31) by the following new equation:
1 1
γ F ≤ ⋅ f (31)
f k k
γ γ
n m
Add the following new paragraph after equation (31):
Note that γ is a consequence of failure factor and shall not be treated as a safety factor on
n
materials.
th
Delete the last sentence in 5 paragraph (“For guidance see Annex F”) and insert, after the
th
5 paragraph, the following two paragraphs:
Data used in extrapolation methods shall be extracted from time series of turbine simulations
of at least 10 min in length over the operating range of the turbine for DLC 1.1. A minimum of
15 simulations is required for each wind speed from (V – 2 m/s) to cut-out and six
rated
simulations are required for each wind speed below (V – 2 m/s). When extracting data,
rated
the designer must consider the effect of independence between peaks on the extrapolation
and minimize dependence when possible. The designer shall aggregate data and probability
distributions to form a consistent long-term distribution. To ensure stable estimation of long-
term loads, a convergence criterion shall be applied to a probability fractile less than the

mode of the data for either the short-term or long-term exceedance distributions. For
guidance, see Annex F.
The characteristic value for blade root in-plane and out-of-plane moments and tip deflection
may be determined by a simplified procedure . The characteristic value may then be
determined by calculating the mean of the extremes for each 10-min bin and using the largest
value, multiplied by an extrapolation factor of 1,5, while maintaining the partial load factor for
statistical load extrapolation, see Table 3.
—————————
This approach is considered conservative for 3-bladed upwind wind turbines. Caution should be exercised for
other wind turbine concepts.
61400-1 Amend.1 © IEC:2010(E) – 7 –

7.6.2.1 Partial safety factor for loads

Replace the existing formula in the footnote of Table 3 by the following new formula:

⎧ F
gravity
1− ; F ≤ F
⎪
gravity k
⎪
F
ς = k
⎨
⎪
0; F > F
⎪ gravity k
⎩
Add the following new text after Table 3:

The approach in 7.6.1.1, where the partial safety factor for loads is applied to the load
response, assumes that a proper representation of the dynamic response is of prime concern.
For foundations or where a proper representation of non-linear material behaviour or
geometrical non-linearities or both are of primary concern, the design load response S shall
d
be obtained from a structural analysis for the combination of the design loads F , where the
d
design load is obtained by multiplication of the characteristic loads F by the specified partial

k
load factor γ for favourable and unfavourable loads,
f
F = γ F
d f k
The load responses in the tower at the interface (shear forces and bending moments) factored
with γ from Table 3 shall be applied as boundary conditions.
f
For gravity foundations, the limit states considering overall stability (rigid body motion with no
failure in soil) and bearing capacity of soil and foundation shall be regarded and calculated
according to a recognized standard. In general, a partial safety factor of γ = 1,1 for
f
unfavourable permanent loads and γ = 0,9 for favourable permanent loads shall be applied
f
for foundation load, backfilling and buoyancy. If it can be demonstrated by respective quality
management and surveillance that the foundation material densities specified in the design
documentation are met on site, a partial safety factor for permanent foundation load γ = 1,0
f
can be used for the limit states regarding bearing capacity of soil and foundation. If buoyancy
is calculated equal to a terrain water level, a partial safety factor for buoyancy γ = 1,0 can be
f
applied.
Alternatively, the check of capacity of soil and foundation can be based on a partial safety
factor γ = 1,0 for both favourable and unfavourable permanent loads and the check of overall
f
stability can be based on a partial safety factor of γ = 1,1 for unfavourable permanent loads
f
and γ = 0,9 for favourable permanent loads, using in all cases conservative estimates of
f
weights or densities defined as 5 % / 95 % fractiles. The lower fractile is to be used when the
load is favourable. Otherwise, the upper fractile is to be used.

7.6.5 Critical deflection analysis
Replace the existing text by the following new text:
7.6.5.1 General
It shall be verified that no deflections affecting structural integrity occur in the design
conditions detailed in Table 2.
The maximum elastic deflection in the unfavourable direction shall be determined for the load
...

IEC 61400-1 ®
Edition 3.0 2010-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
A MENDMENT 1
AM ENDEMENT 1
Wind turbines –
Part 1: Design requirements
Eoliennes –
Partie 1: Exigences de conception

IEC 61400-1:2005-08/AMD1:2010-10(en-fr)

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form

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The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.

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IEC 61400-1 ®
Edition 3.0 2010-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
A MENDMENT 1
AM ENDEMENT 1
Wind turbines –
Part 1: Design requirements
Eoliennes –
Partie 1: Exigences de conception

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 27.180 ISBN 978-2-8322-1971-3

– 2 – IEC 61400-1:2005/AMD1:2010

© IEC 2010
FOREWORD
This amendment has been prepared by IEC technical committee 88: Wind turbines.

This bilingual version (2015-02) corresponds to the English version, published in 2010-10.

The text of this amendment is based on the following documents:

FDIS Report on voting
88/374/FDIS 88/378/RVD
Full information on the voting for the approval of this amendment can be found in the report
on voting indicated in the above table.
The French version of this amendment has not been voted upon.
The committee has decided that the contents of this amendment and the base publication will
remain unchanged until the stability date indicated on the IEC web site 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.
_____________
© IEC 2010
2 Normative references
Replace the existing list of normative references by the following new list:

IEC 60204-1, Safety of machinery – Electrical equipment of machines – Part 1: General

requirements
IEC 60204-11, Safety of machinery – Electrical equipment of machines – Part 11:

Requirements for HV equipment for voltages above 1 000 V a.c. or 1 500 V d.c. and not

exceeding 36 kV
IEC 60364 (all parts), Low-voltage electrical installations
IEC 60364-5-54, Electrical installations of buildings – Part 5-54: Selection and erection of
electrical equipment – Earthing arrangements, protective conductors and protective bonding
conductors
IEC 60721-2-1, Classification of environmental conditions – Part 2: Environmental conditions
appearing in nature – Temperature and humidity
IEC 61000-6-1, Electromagnetic compatibility (EMC) – Part 6-1: Generic standards –
Immunity for residential, commercial and light-industrial environments
IEC 61000-6-2, Electromagnetic compatibility (EMC) – Part 6-2: Generic standards –
Immunity for industrial environments
IEC 61000-6-4, Electromagnetic compatibility (EMC) – Part 6-4: Generic standards –
Emission standard for industrial environments
IEC 61400-2, Wind turbines – Part 2: Design requirements for small wind turbines
IEC 61400-21, Wind turbines – Part 21: Measurement and assessment of power quality
characteristics of grid connected wind turbines
IEC 61400-24, Wind turbines – Part 24: Lightning protection
IEC 62305-3, Protection against lightning – Part 3: Physical damage to structures and life
hazard
IEC 62305-4, Protection against lightning – Part 4: Electrical and electronic systems within
structures
ISO 76:2006, Rolling bearings – Static load ratings
ISO 281, Rolling bearings – Dynamic load ratings and rating life
ISO 2394:1998, General principles on reliability for structures
ISO 2533:1975, Standard atmosphere
ISO 4354, Wind actions on structures
ISO 6336-2, Calculation of load capacity of spur and helical gears – Part 2: Calculation of
surface durability (pitting)
– 4 – IEC 61400-1:2005/AMD1:2010

© IEC 2010
ISO 6336-3:2006, Calculation of load capacity of spur and helical gears – Part 3: Calculation

of tooth bending strength
ISO 81400-4, Wind turbines – Part 4: Design and specification of gearboxes

3 Terms and definitions
3.26 – limit state
Replace ISO 2394 by 2.2.9 of ISO 2394.

3.55 – ultimate limit state
Replace ISO 2394 by 2.2.10 of ISO 2394.
4 Symbols and abbreviated terms
4.1 Symbols and units
Switch the definitions of σ and σ . The vertical wind velocity standard deviation should be σ ,
2 3 3
not σ .
6 External conditions
6.3.1.3 Normal turbulence model (NTM)
Replace the existing Figures 1a and 1b by the following new figures:

Category A
4,5
Category B
Category C
3,5
2,5
1,5
0,5
0 5 10 15 20 25 30
V  (m/s)
hub IEC  2236/10
Figure 1a –Turbulence standard deviation for the normal turbulence model (NTM)

s  (m/s)
© IEC 2010
0,5
Category A
Category B
0,4
Category C
0,3
0,2
0,1
0 5 10 15 20 25 30
V  (m/s)
hub
IEC  2237/10
Figure 1b – Turbulence intensity for the normal turbulence model (NTM)
6.3.2.6 Extreme wind shear (EWS)
Replace the number 2,5 in equations (26) and (27) to 2,5 [m/s]. (The number 2,5 in equations
(26) and (27) is not dimensionless.)
7 Structural design
7.4.2 Power production plus occurrence of fault or loss of electrical network
connection (DLC 2.1 – 2.4)
nd
Add, as 2 paragraph, the following new text:
As an alternative to the specification of DLC 2.3 above and in Table 2, DLC 2.3 may instead
be considered as a normal event (i.e. a partial safety factor for load of 1,35) to be analyzed
using stochastic wind simulations (NTM - V in hub out
electrical system fault (including loss of electrical network connection). In this case, 12
response simulations shall be carried out for each considered mean wind speed. For each
response simulation, the extreme response after the electrical fault has occurred is sampled.
The fault must be introduced after the effect of initial conditions has become negligible. For
each mean wind speed, a nominal extreme response is evaluated as the mean of the 12
sampled extreme responses plus three times the standard deviation of the 12 samples. The
characteristic response value for DLC 2.3 is determined as the extreme value among the
nominal extreme responses.
7.5 Load calculations
Add, after second paragraph, the following new text:
When turbulent winds are used for dynamic simulations, attention should be given to the grid
resolution regarding the spatial and time resolution.
—————————
Concerning the spatial resolution, the maximum distance between adjacent points should be smaller than 25 %
of Λ1 (Equation (5)) and no larger than 15 % of the rotor diameter. This distance is meant to be the diagonal
distance between points in each grid cell defined by four points. In the case of a non-uniform grid, an average
value over the rotor surface of the distance between grid points can be considered as the representative spatial
resolution, but this distance should always decrease towards the blade tip.
Turbulence intensity
– 6 – IEC 61400-1:2005/AMD1:2010

© IEC 2010
Replace the last paragraph by the following new text:

Ultimate load components may also be combined in a conservative manner assuming the
extreme component values occur simultaneously. In case this option is pursued, both
minimum and maximum extreme component values shall be applied in all possible

combinations to avoid introducing non-conservatism.

Guidance for the derivation of extreme design loads from contemporaneous loads taken from

a number of stochastic realisations is given in Annex H.

7.6.1.2 Partial safety factor for consequence of failure and component classes

Add, after the bullets defining the component classes, the following new text:
The consequences of failure factor shall be included in the test load when performing tests
as for example full scale blade testing.
7.6.2 Ultimate strength analysis
Replace equation (31) by the following new equation:
1 1
γ F ≤ ⋅ f (31)
f k k
γ γ
n m
Add the following new paragraph after equation (31):
Note that γ is a consequence of failure factor and shall not be treated as a safety factor on
n
materials.
th
Delete the last sentence in 5 paragraph (“For guidance see Annex F”) and insert, after the
th
5 paragraph, the following two paragraphs:
Data used in extrapolation methods shall be extracted from time series of turbine simulations
of at least 10 min in length over the operating range of the turbine for DLC 1.1. A minimum of
15 simulations is required for each wind speed from (V – 2 m/s) to cut-out and six
rated
simulations are required for each wind speed below (V – 2 m/s). When extrac
...