IEC TS 61400-28:2025

Wind energy generation systems - Part 28: Through-life management and life extension of wind power assets

IEC TS 61400-28:2025 sets out minimum requirements for actions, investigations and assessments to ensure the continued structural integrity of wind farm assets, particularly wind turbines, aimed at verifying that they remain safe for personnel to operate. The document describes how to maintain those assets and collect suitable evidence to demonstrate to third parties that risks are minimised, particularly where risks are related to collateral damage or injury, such as could be suffered by personnel or structures neighbouring the wind farm. Covered in this document are assessments of current condition and remaining useful life, resulting in the technical basis for justifying extended operation beyond the design life (defined in 3.1.3) and also beyond the site-specific assessed lifetime, whichever is shorter, for structural or major components and systems contributing to primary layer of the safety system.

General Information

• Status: Published
• Publication Date: 19-Mar-2025
• ICS: 27.180 - Wind turbine energy systems
• Technical Committee: TC 88 - Wind energy generation systems
• Drafting Committee: PT 61400-28 - TC 88/PT 61400-28
• Current Stage: PPUB - Publication issued
• Start Date: 20-Mar-2025
• Completion Date: 15-Nov-2024

Overview

IEC TS 61400-28:2025 - "Wind energy generation systems - Part 28: Through-life management and life extension of wind power assets" - provides minimum requirements for investigations, assessments and records to ensure the continued structural integrity and safe operation of wind farm assets (particularly wind turbines). The Technical Specification explains how to collect and manage evidence that risks are minimised for personnel and neighbouring structures, and defines the technical basis for justifying extended operation beyond the original design life and site‑specific assessed lifetime for structural and major safety‑critical components.

Key topics and technical requirements

• Through‑life management framework: Guidance on phased management (early life, mid‑life, life‑extension preparation) and iterative assessment of component safety and remaining useful life (RUL).
• Data management and uncertainty: Requirements for design data, meteorological and site data, SCADA, instrumentation, maintenance and inspection history, plus classification and treatment of data uncertainty.
• Risk management: Scope and processes for life‑extension risk assessments, including failure mode analysis and detectability evaluation.
• Operation, maintenance and inspection: Best practice schedules, inspection scopes for tower, blades, bearings, foundations, nacelle and safety systems; reporting and documentation requirements.
• Condition & structural health monitoring (SHM): Minimum condition monitoring devices (CMD) and system expectations (vibration, temperature, oil/grease analysis, load and site monitoring) and how monitoring integrates into asset management.
• Analytical assessment methods: Relative and absolute approaches to determine loads and probabilistic techniques to estimate RUL, with model and input uncertainty treatment.
• Annex guidance: Informative annexes covering data requirements for primary load paths, inspection documentation best practice, bearing and hydraulic CMDs, example methodologies for risk assessment, and life‑extension procedures.

Practical applications - who should use it

• Wind farm owners and operators assessing life‑extension opportunities and seeking to justify continued operation.
• Asset managers and O&M providers implementing inspection, monitoring and data strategies.
• Structural and condition monitoring engineers performing RUL assessments and load modelling.
• Technical consultants, certification bodies, insurers and regulators requiring documented evidence that safety risks are minimised.
• Investment and due‑diligence teams evaluating asset health and long‑term value.

Benefits and SEO keywords

Applying IEC TS 61400-28:2025 helps extend asset life safely, improve confidence in remaining useful life estimates, reduce unplanned failures and provide third‑party evidence for life‑extension decisions. Relevant keywords: through-life management, life extension, wind power assets, wind turbines, remaining useful life (RUL), condition monitoring, SCADA data, structural health monitoring, risk assessment, IEC TS 61400-28:2025.

Related standards

This TS complements other parts of the IEC 61400 series addressing design, testing, load assessment and electrical performance; it should be used alongside relevant national regulations and industry best practices.

Standards Content (Sample)

IEC TS 61400-28 ®
Edition 1.0 2025-03
TECHNICAL
SPECIFICATION
Wind energy generation systems –
Part 28: Through-life management and life extension of wind power assets

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IEC TS 61400-28 ®
Edition 1.0 2025-03
TECHNICAL
SPECIFICATION
Wind energy generation systems –

Part 28: Through-life management and life extension of wind power assets

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.180  ISBN 978-2-8327-0295-6

– 2 – IEC TS 61400-28:2025 © IEC 2025
CONTENTS
FOREWORD . 6
INTRODUCTION . 8
1 Scope . 10
2 Normative references . 10
3 Terms, definitions and abbreviated terms . 11
3.1 Terms and definitions . 11
3.2 Abbreviated terms . 16
4 User guidance: Concept of through-life management and lifetime extension . 18
4.1 Overview. 18
4.2 Data management . 24
4.3 Reading guideline . 24
5 Data management, requirements and uncertainty . 28
5.1 Preamble . 28
5.2 Data management . 28
5.3 Data and information definition . 29
5.4 Data / information sources . 30
5.4.1 Design information . 30
5.4.2 Meteorological data . 31
5.4.3 Wind data from nacelle . 31
5.4.4 Extreme site conditions . 32
5.4.5 SCADA data . 32
5.4.6 Instrumentation . 33
5.4.7 Operational experience . 33
5.4.8 Maintenance and field history . 33
5.4.9 Inspection history . 33
5.5 Data requirements for components in the primary load path . 34
5.6 Data uncertainty. 35
5.7 Classification of uncertainty . 36
5.8 Data requirements for new wind farms . 36
6 Risk management process . 36
6.1 General approach . 36
6.2 Scope of risk assessment . 38
6.3 Life extension risk assessment . 39
7 Wind farm operation, maintenance and inspections . 39
7.1 Name plate and design class requirements . 39
7.2 Replacement of structural or major components . 40
7.3 Operation and maintenance . 40
7.4 Physical inspections . 42
7.5 Scheduling of physical inspections . 42
7.5.1 General . 42
7.5.2 Early life inspections (15 % to 25 % through operational life) . 43
7.5.3 Mid-life inspections (45 % to 55 % through operational life) . 43
7.5.4 Life extension preparation inspections (70 % to 80 % through
operational life) . 43
8 Condition and structural health monitoring . 44
8.1 Purpose . 44

8.2 CMD minimum necessary requirement . 46
8.2.1 General . 46
8.2.2 Vibration monitoring system (VMS) . 46
8.2.3 Temperature monitoring . 46
8.2.4 Oil and grease wear particle analysis. 47
8.2.5 Site (wind) condition monitoring . 48
8.3 Structural health and load monitoring . 48
8.4 Data acquisition . 48
8.5 Integration to asset management . 49
8.5.1 General . 49
8.5.2 Documentation . 49
8.5.3 Business procedures . 49
9 Health and safety information . 50
10 Analytical assessment of turbine lifetime . 50
10.1 Overview. 50
10.2 Methods to determine loads . 50
10.2.1 General . 50
10.2.2 Relative assessment . 51
10.2.3 Absolute assessment . 51
10.3 Model data, input data and their uncertainties . 52
Annex A (informative) Health and safety – inspection and performance criteria . 54
A.1 General . 54
A.2 Content and format of any reports issued . 56
A.3 Operation and maintenance data . 57
Annex B (informative) Data requirements for primary load path . 58
B.1 Input data requirements . 58
B.2 Condition monitoring data requirements . 65
Annex C (informative) Physical inspections – best practice for documentation of
results, findings and insights . 72
C.1 Physical inspections . 72
C.2 Inspection scope . 74
C.3 Highly recommended inspections . 74
C.3.1 Tower . 74
C.3.2 Blades . 75
C.3.3 Pitch bearings. 75
C.3.4 Yaw ring and bearing . 75
C.3.5 Foundation . 76
C.3.6 Transition piece (offshore) . 76
C.3.7 Nacelle frame / bedplate . 77
C.3.8 Hub . 77
C.3.9 Bolted connections . 78
C.3.10 Safety systems . 78
C.3.11 Main bearing . 79
C.3.12 Main shaft . 79
C.4 Recommended inspections . 79
C.4.1 Gearbox inspections . 79
C.4.2 Generator inspection . 79
C.4.3 Yaw drives . 80

– 4 – IEC TS 61400-28:2025 © IEC 2025
C.4.4 Nacelle condition . 80
C.5 Scheduled service (change or prolong existing schedule service) . 80
C.6 Additional inspections and testing . 80
C.7 Inspection reporting . 80
Annex D (informative) Analytical assessment of turbine lifetime – relative approach

with accuracy assessment . 83
D.1 General . 83
D.2 Sources of uncertainties . 83
D.3 Input data uncertainty . 83
D.4 Model sensitivity to input data . 84
D.5 Model uncertainties . 84
D.6 Uncertainty assessment by accuracy assessment numbers (AAN) . 84
D.6.1 General . 84
D.6.2 Example for the determination of AAN . 87
D.7 Probabilistic assessment of remaining lifetime . 89
Annex E (informative) Minimal CMDs for rolling element bearings and hydraulic
systems . 90
E.1 Preamble . 90
E.2 Bearing failure modes . 91
E.3 The pragmatic approach . 91
E.4 VMS . 92
E.5 Temperatures . 93
E.6 Grease cleanliness . 93
E.7 Oil lubricant cleanliness (acceptable values over whole lifetime) . 95
Annex F (informative) Example of a methodology for assessment of risk . 97
F.1 Overview. 97
F.2 Application of failure modes and effects analysis . 97
F.3 Using the potential failure (P-F) interval to assess detectability . 99
F.4 Summary . 100
Annex G (informative) Through-life management and remaining useful life . 101
G.1 Through-life management . 101
G.2 Life extension . 102
G.3 Remaining useful life . 104
Bibliography . 107

Figure 1 – Updated assessments and estimates of component safety and remaining life . 19
Figure 2 – Illustration of how the level of confidence can be improved by applying
IEC TS 61400-28 (for example, relating to the estimated RUL) . 20
Figure 3 – The 3 typical phases of operation of a wind turbine . 21
Figure 4 – Effect on asset life due to improved strategies and increased levels of
confidence . 22
Figure 5 – Process of through-life management and lifetime extension − Data
management is the backbone of the process. 25
Figure 6 – Increase level of confidence, gradually by applying the methods . 27
Figure 7 – Iterative sequence in general risk assessment procedures . 37
Figure 8 – Condition and structural health monitoring management process . 45
Figure D.1 – AAN levels . 85

Figure D.2 – Load increase factors γ depending weighted model uncertainty and
weighted data uncertainty . 86
Figure E.1 – Example of reduction in life with filter rating (note L50 is shown here for

illustrative purposes, whereas L10 life is used for wind turbine applications) . 96
Figure F.1 – Illustrative example showing the increase of RPN in later life due to
increasing occurrence . 98
Figure F.2 – Illustrative example of the management RPN by improving detectability in
later life . 99
Figure G.1 – Through-life management of a wind turbine . 101
Figure G.2 – Through-life management of a wind farm . 101
Figure G.3 – Life extension scenarios . 103
Figure G.4 – Single component with no failures . 104
Figure G.5 – Single component with symptom . 105
Figure G.6 – Multiple components with symptoms . 106

Table 1 – Comparison between definitions of remaining life used in this document . 17
Table 2 – Classification of uncertainty . 36
Table 3 – Key properties of failure mode and components of a risk priority number . 38
Table 4 – Example of distinctions between data, information, advice and decision . 46
Table B.1 – Input data requirements . 59
Table B.2 – Condition monitoring data requirements . 66
Table B.3 – Condition monitoring requirements for main bearings . 67
Table B.4 – Condition monitoring requirements for gearbox . 68
Table B.5 – Data requirements for yaw mechanism . 69
Table B.6 – Data requirements for tower . 70
Table B.7 – Data requirements for foundation . 70
Table B.8 – Data requirements from measurements and characterisation of site

conditions . 71
Table C.1 – Required physical inspections . 72
Table C.2 – Reporting inspection findings . 81
Table D.1 – Relationship between COV of data and uncertainty category . 83
Table D.2 – Weighted uncertainty . 85
Table D.3 – Assessment of weighted data uncertainty . 87
Table D.4 – Assessment of weighted data model uncertainty . 88

– 6 – IEC TS 61400-28:2025 © IEC 2025
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
WIND ENERGY GENERATION SYSTEMS –

Part 28: Through-life management and
life extension of wind power assets

FOREWORD
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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) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
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shall not be held responsible for identifying any or all such patent rights.
IEC TS 61400-28 has been prepared by IEC technical committee 88: Wind energy generation
systems. It is a Technical Specification.
The text of this Technical Specification is based on the following documents:
Draft Report on voting
88/955/DTS 88/1053/RVDTS
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Technical Specification is English.

This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts in the IEC 61400 series, published under the general title Wind energy
generation systems, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
– 8 – IEC TS 61400-28:2025 © IEC 2025
INTRODUCTION
The purpose of this Technical Specification (TS) is to define a common basis for the
management of physical and digital assets associated with wind farms throughout the operating
life. The objective is to ensure the integrity of the structure whilst operating, both within the
design life and beyond. The focus of the guidance in this document is safety, defined as
ensuring the structural integrity of the components in the primary load path of a given turbine
or site and the continued function of critical systems. It is anticipated the reader will make an
assessment of risks and uncertainties, aligned with safety, technical and commercial
requirements of the particular project, in order to determine the level of detail justified for any
assessments undertaken.
This document has been published to enable wind farm operators to manage the production of
electricity from wind turbines for the longest possible safe time, delaying the unnecessary social
and environmental costs of premature decommissioning. Defined here are the procedures for
amassing the minimum body of evidence to justify continued operation.
It is highlighted that the cumulative uncertainty, as defined in ISO/IEC guide 98-3 and estimated
using methods defined in this document, including uncertainties in calculations, are used to
estimate the variability of the results. It is described how this variability is to be stated alongside
any estimates of remaining life of components.
Regarding risks to personnel or third parties, no attempt is made to incorporate the many
individual interpretations by regulatory authorities in different regions or jurisdictions.
The earlier in the wind farm operational life the guidance in this document is implemented the
better, but suitable procedures can be developed and followed, by any stakeholder, at any point
in the life of a wind farm. The guidance should be applied to each mode of failure for each
component in the primary load path and associated critical systems. Estimates of life can be
made, relating to the most significant mode of failure and taking full account of specific
conditions at the site and operational practices. Phases of operation, at which this guidance
can be applied, include amongst others the following:
• reviews of site-specific assessed life prior to construction,
• site specific expected life at end-of-warranty,
• points of re-financing and sale,
• proposed extended operation beyond the site-specific assessed life.
The guidance can be used by designers, manufacturers, developers, operators or third parties
and can be used as part of due diligence. Application by stakeholders of practices and
techniques specified in this document can be used to minimise costs of operation and maximise
safe, useful, productive life. In particular, recommendations are given and approaches
described for the assessment of the following examples of situations:
• historical duty, usage and working life consumed,
• current component health, and
• expected future remaining life.
These could be used to assess the condition and productivity of individual turbines, safety
systems and the primary structure at specific turbine locations within a wind farm or
comprehensively for all locations of a site. The principles defined, practical guidance and
theoretical techniques described could be used to update the expected useful life of the assets.
Additionally, assessments of expected technical availability, reliability and safe operation
beyond the end of the design life could also be made.

IEC 61400-1, IEC 61400-2, IEC 61400-3-1 and IEC 61400-3-2, contain minimal requirements
for design, ensuring structural integrity of wind turbines, under standardized classes of
meteorological conditions and operational practices. Also included are many other contextual
conditions affecting loading and expected life. IECRE OD-502 describes the certification of a
wind farm project. If the wind farm is certified, loads analysis will be used to estimate site
specific life prior to construction. IEC TS 61400-28 is the only document amongst the IEC 61400
series which describes the following:
• method for updating the lifetime (estimated prior to construction) for a specific site,
• which is being operated under specific site conditions and management procedures,
• which shows symptoms of degradation, having experienced specific modifications, faults or
failures, taking into account evidence of turbine reliability, changes of operational status,
including starts, stops, errors, warnings, curtailment, sector management and grid outages.
It is recommended to re-assess the lifetime on this basis at regular periods during the life of the
wind farm. In particular, it should be assessed whether or not it would be safe to continue
operation of the wind farm, beyond the expected lifetime or beyond that stated in the type
certificate, if available for the wind turbine. Turbines could prove to be safe and suitable to
produce additional electricity, either during or beyond the site-specific lifetime. It is important
to note that these are estimates of remaining lifetime, whether based on observations,
measurements, statistical methods or simulations. The actual lifetime, with respect to the most
significant mode of failure, can be longer or shorter.
It could be appropriate to adjust the values of factors of safety or uncertainties, which were
applied prior to construction at the design stage, associated with key parameters required to
estimate integrity and life. Evidence to support any such adjusted values is provided, whether
through applying best practices of wind farm operation, collecting information about the
conditions at each turbine, the production, the maintenance tasks undertaken, the condition of
critical components, the modes of failure and their consequences.
This document may be used to define the technical inputs to any economic assessments,
developed by stakeholders to value assets throughout their lifetime, but does not describe any
particular economic models.
The focus of this document is on components in the primary load path and the safety system.
For loading and structural integrity, accumulation of fatigue damage is described. Regarding
ultimate limit states, however, comprehensive guidance is not given about methods to reassess
and update the statistics of extreme conditions, faults and failures which contribute to the
ultimate limit state. Detailed analyses of the reliability of components outside the primary load
path are not described here, even though these aspects could contribute to the objectives of
this document. It is left to the reader to extend the methods described in this document if
relevant to topics relating to component reliability, with reference to IEC TS 61400-26-4.

– 10 – IEC TS 61400-28:2025 © IEC 2025
WIND ENERGY GENERATION SYSTEMS –

Part 28: Through-life management and
life extension of wind power assets

1 Scope
This part of IEC 61400, which is a Technical Specification, sets out minimum requirements for
actions, investigations and assessments to ensure the continued structural integrity of wind
farm assets, particularly wind turbines, aimed at verifying that they remain safe for personnel
to operate. The document describes how to maintain those assets and collect suitable evidence
to demonstrate to third parties that risks are minimised, particularly where risks are related to
collateral damage or injury, such as could be suffered by personnel or structures neighbouring
the wind farm.
Covered in this document are assessments of current condition and remaining useful life,
resulting in the technical basis for justifying extended operation beyond the design life (defined
in 3.1.3) and also beyond the site specific assessed lifetime, whichever is shorter, for structural
or major components and systems contributing to primary layer of the safety system. Guidance
is also given on how best to manage a wind farm throughout the operational life.
2 Normative references
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.
IEC 60300-3-11:2009, Dependability management – Application guide – Reliability centred
maintenance
IEC 60812:2018, Failure modes and effects analysis (FMEA and FMECA)
IEC 61400‑1:2019, Wind energy generation systems − Part 1: Design requirements
IEC 61400‑2, Wind turbines − Part 2: Small wind turbines
IEC 61400-3-1:2019, Wind energy generation systems – Part 3-1: Design requirements for fixed
offshore wind turbines
IEC 61400-3-2, Wind energy generation systems − Part 3-2: Design requirements for floating
offshore wind turbines
IEC 61400-6, Wind energy generation systems – Part 6: Tower and foundation design
requirements
IEC 61400-12-1, Wind energy generation systems – Part 12-1: Power performance
measurements of electricity producing wind turbines
IEC 61400-12-2, Wind energy generation systems – Part 12-2: Power performance
measurements of electricity producing wind turbines based on nacelle anemometry

IEC 61400-13, Wind turbines – Part 13: Measurement of mechanical loads
IEC 61400-25-1:2017, Wind energy generation systems – Part 25-1: Communications for
monitoring and control of wind power plants – Overall description of principles and models
IEC 61400-25-2:2015, Wind turbines − Part 25-2: Communications for monitoring and control
of wind power plants − Information models
IEC 61400-26-1, Wind energy generation systems − Part 26-1: Availability for wind energy
generation systems
IEC TS 61400-26‑4, Wind energy generation systems − Part 26-4: Reliability of wind energy
generation systems
IEC 61511 (all parts), Functional safety − Safety instrumented systems for the process industry
sector
ISO/IEC Guide 98-3 Uncertainty of measurement − Part 3: Guide to the expression of
uncertainty in measurement (GUM:1995)
ISO 13381-1:2015, Condition monitoring and diagnostics of machines – Prognostics – Part 1:
General guidelines
ISO 13822, Bases of design for structures – Assessment of existing structures
ISO 2394:2015, General principles on reliability for structures
EN 1990, Basis of structural design
WMO-TD No 1186, Guidelines on Climate Data and Homogenization
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1.1
boroscope inspection
visual inspection (generally of inaccessible internal parts of components) facilitated by the use
of a fibre-optic or camera mounted on the end of a flexible conduit

– 12 – IEC TS 61400-28:2025 © IEC 2025
3.1.2
condition monitoring
CM
acquisition and processing of information and data that indicate the state of a machine over
time
Note 1 to entry: The machine state deteriorates if Faults or Failures occur.
[SOURCE: ISO 13372:2012, 1.3]
3.1.3
design life
period of wind farm / wind turbine / structural component operation at the end of which the
minimum required structural integrity according to the adopted design standard (the version of
IEC 61400-1, IEC 61400-2 or IEC 61400-3 series which was applicable at to time of the turbine
design) is still ensured
Note 1 to entry: For example, it is a minimum of 20 years for turbine classes I to III, with respect to operation in
accordance with IEC 61400-1:2019 and the IEC 61400-3-1:2019. For turbine class S, a different design life shall be
defined. Design life is also called type certified design life (TCDL) where it is defined by the OEM as part of a process
of type certification and recorded on the type certificate and related documentation.
Note 2 to entry: Several definitions of remaining life are used in this document and distinguished in Table 1.
3.1.4
detection
action or process of identifying the presence of something concealed
3.1.5
failure
termination of the ability of an item to perform a required function
[SOURCE: ISO 13372:2012, 1.7, modified – Notes have been deleted.]
3.1.6
fault
condition of a machine that occurs when one of its components or assemblies degrades or
exhibits abnormal behaviour, which can lead to the failure of the machine
Note 1 to entry: Identification of an existing fault is the result of CM process (from data issued from inspections,
SCADA and/or CMDs to information, from information to symptoms).
[SOURCE: ISO 133722012, 1.8, modified – Notes have been deleted, a Note to entry has been
added.]
3.1.7
information
interpretation of measurements, for example, to provide status or evaluation of health (for
example by comparison with tables, thresholds or standard values)
3.1.8
inspection
investigation of current condition or health, through physical attendance at the wind turbine, by
qualified personnel
3.1.9
lifetime extension
life extension
LTE
operation beyond the expected duration of safe operational life, specified for any major or
structural component of the wind turbine in the type certificate or according to estimates of site-
specific assessed life and/or site-specific expected life, if shorter
3.1.10
measurements
numerical information collected by sensors or by physical attendance at the wind turbine by
qualified personnel
Note 1 to entry: No interpretation of the resulting data is implied by the term.
3.1.11
measurement campaign
limited duration exercise to collect time series of measurements, either by sensors and data-
loggers, existing SCADA and condition monitoring equipment or repeated, direct, manual
measurements by qualified personnel
3.1.12
metallurgical examination
assessment of material properties via testing and/or microscopy
3.1.13
monitoring
observe and check the progress or quality of something over a period of time; keep under
systematic review
3.1.14
non-destructive testing
NDT
means for inspecting components for defects (either surface or subsurface defects) without
causing damage to them
3.1.15
remaining useful life
RUL
remaining time before system health falls below a defined failure threshold
Note 1 to entry: In this document, RUL is defined as the remaining time for which structural integrity and industrial
safety is ensured regarding hazards to the environment and personnel. The estimate of RUL should include all
relevant design safety factors, margins of safety due to uncertainties with site data, model parameters, methods and
assumptions, with regards to components in the primary load path. If structural components are exchanged, RUL of
the system may be recalculated after exchange.
Note 2 to entry: See Table 1.
[SOURCE: ISO 13381-1:2015, 3.9, modified – Note 1 to entry has been added.]
3.1.16
site specific evaluation
SSE
evaluation prior to wind farm construction of local site characteristics, the results of which to be
used for evaluation of turbines and structures
Note 1 to entry:
...