EN 61400-25-6:2017

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Wind turbines - Part 25-6: Communications for monitoring and control of wind power
plants - Logical node classes and data classes for condition monitoring (IEC 61400-25-
6:2016)
Windenergieanlagen - Teil 25-6: Kommunikation für die Überwachung und Steuerung
von Windenergieanlagen - Klassen logischer Knoten und Datenklassen für die
Zustandsüberwachung (IEC 61400-25-6:2016)
Eoliennes - Partie 25-6: Communications pour la surveillance et la commande des
centrales éoliennes - Classes de noeuds logiques et classes de données pour la
surveillance d'état (IEC 61400-25-6:2016)
Ta slovenski standard je istoveten z: EN 61400-25-6:2017
ICS:
27.180 Vetrne elektrarne Wind turbine energy systems
35.240.50 Uporabniške rešitve IT v IT applications in industry
industriji
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 61400-25-6

NORME EUROPÉENNE
EUROPÄISCHE NORM
April 2017
ICS 27.180 Supersedes EN 61400-25-6:2011
English Version
Wind energy generation systems -
Part 25-6: Communications for monitoring and
control of wind power plants - Logical node classes and data
classes for condition monitoring
(IEC 61400-25-6:2016)
Systèmes de production d'énergie éolienne -  Windenergieanlagen -
Partie 25-6: Communications pour la surveillance et la Teil 25-6: Kommunikation für die Überwachung und
commande des centrales éoliennes - Classes de nœuds Steuerung von Windenergieanlagen - Klassen logischer
logiques et classes de données pour la surveillance d'état Knoten und Datenklassen für die Zustandsüberwachung
(IEC 61400-25-6:2016) (IEC 61400-25-6:2016)
This European Standard was approved by CENELEC on 2017-01-20. 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, 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: Avenue Marnix 17, B-1000 Brussels
© 2017 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 61400-25-6:2017 E
European foreword
The text of document 88/606/FDIS, future edition 2 of IEC 61400-25-6, prepared by IEC/TC 88 "Wind
energy generation systems" was submitted to the IEC-CENELEC parallel vote and approved by
CENELEC as EN 61400-25-6:2017.
The following dates are fixed:
(dop) 2017-10-20
• latest date by which the document has to be implemented at
national level by publication of an identical national
standard or by endorsement
(dow) 2020-01-20
• latest date by which the national standards conflicting with
the document have to be withdrawn

This document supersedes EN 61400-25-6:2011.
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 61400-25-6:2016 was approved by CENELEC as a
European Standard without any modification.
In the official version, for Bibliography, the following note has to be added for the standard indicated :
IEC 61400-25 NOTE Harmonized in EN 61400-25 series.
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 61400-25-1 2006 Wind turbines - Part 25-1: EN 61400-25-1 2007
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: EN 61400-25-2 2015
Communications for monitoring and
control of wind power plants -
Information models
IEC 61400-25-3 2015 Wind turbines - Part 25-3: EN 61400-25-3 2015
Communications for monitoring and
control of wind power plants -
Information exchange models
IEC 61400-25-4 2016 Wind energy generation systems - EN 61400-25-4 2017
Part 25-4: Communications for
monitoring and control of wind power
plants - Mapping to communication
profile
1)
1) EN 61400-25-5 —
IEC 61400-25-5 — Wind energy generation systems -
Part 25-5: Communications for
monitoring and control of wind power
plants - Conformance testing
IEC 61850-7-1 2011 Communication networks and systems EN 61850-7-1 2011
for power utility automation - Part 7-1:
Basic communication structure -
Principles and models
IEC 61850-7-2 2010 Communication networks and systems EN 61850-7-2 2010
for power utility automation - Part 7-2:
Basic information and communication
structure - Abstract communication
service interface (ACSI)
1) To be published.
Publication Year Title EN/HD Year
IEC 61850-7-3 2010 Communication networks and systems EN 61850-7-3 2011
for power utility automation - Part 7-3:
Basic communication structure -
Common data classes
ISO 13373-1 2002 Condition monitoring and diagnostics of - -
machines - Vibration condition
monitoring - Part 1: General procedures

IEC 61400-25-6 ®
Edition 2.0 2016-12
INTERNATIONAL
STANDARD
colour
inside
Wind energy generation systems –

Part 25-6: Communications for monitoring and control of wind power plants –

Logical node classes and data classes for condition monitoring

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.180 ISBN 978-2-8322-3723-6

– 2 – IEC 61400-25-6:2016  IEC 2016
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 9
2 Normative references . 10
3 Terms and definitions . 10
4 Abbreviated terms . 12
5 General . 14
5.1 Overview . 14
5.2 Condition monitoring information modelling . 14
5.3 Coordinate system applied for identifying direction and angles . 15
5.4 Operational state bin concept . 16
5.4.1 General . 16
5.4.2 Example of how to use active power as an operational state. 16
6 Logical nodes for wind turbine condition monitoring . 16
6.1 General . 16
6.2 Logical nodes inherited from IEC 61400-25-2 . 17
6.3 Wind turbine condition monitoring logical node WCON . 17
6.3.1 General . 17
6.3.2 CDCs applicable for the logical node WCON . 18
7 Common data classes for wind turbine condition monitoring . 18
7.1 General . 18
7.2 Common data classes defined in IEC 61400-25-2 . 18
7.3 Conditions for data attribute inclusion . 18
7.4 Common data class attribute name semantic . 19
7.5 Condition monitoring bin (CMB) . 20
7.6 Condition monitoring measurement (CMM) . 21
7.7 Scalar value array (SVA). 22
7.8 Complex measurement value array (CMVA) . 23
8 Common data class CMM attribute definitions . 24
8.1 General . 24
8.2 Attributes for condition monitoring measurement description . 25
8.2.1 General . 25
8.2.2 Condition monitoring sensor (trd) . 25
8.2.3 Shaft identification (shfId) and bearing position (brgPos) . 30
8.2.4 Measurement type (mxType) . 31
Annex A (informative) Recommended mxType values . 33
A.1 General about tag names and datanames of the WCON Class . 33
A.2 Mapping of measurement tags to mxTypes . 33
A.2.1 General . 33
A.2.2 Scalar values (MV)(Descriptors) . 33
A.2.3 Array measurements (SVA) – Frequency domain . 33
A.2.4 Array measurements (SVA) – Time domain . 33
A.3 mxType values . 33
Annex B (informative) Application of data attributes for condition monitoring
measurement description for measurement tag naming. 37

IEC 61400-25-6:2016  IEC 2016 – 3 –
B.1 General . 37
B.2 Naming principle using the data attributes in CMM CDC . 37
B.3 Examples . 38
Annex C (informative) Condition monitoring bins examples . 39
C.1 Example 1: One dimensional bins . 39
C.2 Example 2: Two dimensional bins . 40
C.3 Example 3: Two dimensional bins with overlap . 42
Annex D (informative) Application example . 45
D.1 Overview of CDCs essential to IEC 61400-25-6 . 45
D.2 How to apply data to CDCs . 45
D.3 How to apply an alarm . 47
Bibliography . 49

Figure 1 – Condition monitoring with separated TCD/CMD functions . 8
Figure 2 – Schematic flow of condition monitoring information . 9
Figure 3 – Reference coordinates system for the drive train . 15
Figure 4 – Active power bin concept . 16
Figure 5 – Sensor angular orientation as seen from the rotor end . 29
Figure 6 – Sensor motion identification . 29
Figure 7 – Sensor normal and reverse motion . 30
Figure 8 – Principle of shaft and bearing identification along a drive train . 31
Figure B.1 – Naming principles for trd data attribute . 37
Figure C.1 – Bin configuration example 1 . 40
Figure C.2 – Bin configuration example 2 . 42
Figure C.3 – Bin configuration example 3 . 44
Figure D.1 – Linkage of the CDCs . 45

Table 1 – Abbreviated terms applied . 13
Table 2 – Coordinate system and wind turbine related characteristics . 15
Table 3 – LN: Wind turbine condition monitoring information (WCON) . 18
Table 4 – Conditions for the presence of a data attribute . 19
Table 5 – Common data class attribute name semantic . 20
Table 6 – CDC: Condition monitoring bin (CMB) . 21
Table 7 – CDC: Condition monitoring measurement (CMM) . 22
Table 8 – CDC: Scalar value array (SVA) . 23
Table 9 – CDC: Complex measurement value array (CMVA) . 24
Table 10 – Data attributes used for measurement description . 25
Table 11 – Sensor identification convention for “trd” attribute . 25
Table 12 – Abbreviated terms for “trd” – “location” description . 26
Table 13 – Sensor type code . 28
Table 14 – Reference code for sensor sensitive axis orientation . 29
Table 15 – Gearbox shaft and bearing identification . 31
Table A.1 – Examples of applicable mappings from tag to MxType . 34
Table B.1 – Examples of Tag names and corresponding short datanames . 38

– 4 – IEC 61400-25-6:2016  IEC 2016
Table C.1 – CMB example 1 . 39
Table C.2 – CMB data object example 1 . 39
Table C.3 – CMB example 2 . 41
Table C.4 – CMB data object example 2 . 41
Table C.5 – CMB example 3 . 43
Table C.6 – CMB data object example 3 . 43
Table D.1 – Object overview . 46
Table D.2 – Name plate (LPL) . 46
Table D.3 – CDC example: Condition monitoring measurement (CMM) . 47
Table D.4 – CDC example: Condition monitoring bin (CMB) . 47
Table D.5 – CDC example: Alarm definition (ALM) . 48
Table D.6 – LN example: Alarm container definition . 48

IEC 61400-25-6:2016  IEC 2016 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
WIND ENERGY GENERATION SYSTEMS –

Part 25-6: Communications for monitoring and control of wind power
plants – Logical node classes and data classes for condition monitoring

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
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
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
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
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 61400-25-6 has been prepared by IEC technical committee 88:
Wind energy generation systems.
This second edition cancels and replaces the first edition published in 2010. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Major restructuring of the datamodel to accommodate needed flexibility.
b) UFF58 format is no longer used.
c) Access to data is now using the standard reporting and logging functions.
d) Recommendations for creating datanames to accommodate needed flexibility have been
defined.
– 6 – IEC 61400-25-6:2016  IEC 2016
The text of this standard is based on the following documents:
FDIS Report on voting
88/606/FDIS 88/611/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
As the title of technical committee 88 was changed in 2015 from Wind turbines to Wind
energy generation systems a list of all parts of the IEC 61400 series, under the general title
Wind turbines and 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 "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
IEC 61400-25-6:2016  IEC 2016 – 7 –
INTRODUCTION
The IEC 61400-25 series defines information models and information exchange models for
monitoring and control of wind power plants. The modelling approach (for information models
and information exchange models) of IEC 61400-25-2 and IEC 61400-25-3 uses abstract
definitions of classes and services such that the specifications are independent of specific
communication protocol stacks, implementations, and operating systems. The mapping of
these abstract definitions to specific communication profiles is defined in IEC 61400-25-4 .
This document defines an information model for condition monitoring information and explains
how to use the existing definitions of IEC 61400-25-2 as well as the required extensions in
order to describe and exchange information related to condition monitoring of wind turbines.
The models of condition monitoring information defined in this document may represent
information provided by sensors or by calculation.
In the context of this document, condition monitoring means a process with the purpose of
observing components or structures of a wind turbine or wind power plant for a period of time
in order to evaluate the state of the components or structures and any changes to it, in order
to detect early indications of impending failures. With the objective to be able to monitor
components and structures recorded under approximately the same conditions, this document
introduces the operational state bin concept. The operational state bin concept is
multidimensional in order to fit the purpose of sorting complex operational conditions into
comparable circumstances.
Condition monitoring is most frequently used as a predictive or condition-based maintenance
technique (CBM). However, there are other predictive maintenance techniques that can also
be used, including the use of the human senses (look, listen, feel, smell) or machine
performance monitoring techniques. These could be considered to be part of the condition
monitoring.
Condition monitoring techniques
Condition monitoring techniques that generate information to be modelled include, but are not
limited to, measured or processed values such as:
a) vibration measurements and analysis;
b) oil debris measurement and analysis;
c) temperature measurement and analysis;
d) strain gauge measurement and analysis;
e) acoustic measurement and analysis.
Components and structures can be monitored by using automatic measurement retrieval or
via a manual process.
Condition monitoring devices
The condition monitoring functions may be located in different physical devices. Some
information may be exposed by a turbine controller device (TCD) while other information may
be exposed by an additional condition monitoring device (CMD). Various actors may request
to exchange data values located in the TCD and/or CMD. A SCADA device may request data
values from a TCD and/or CMD; a CMD may request data values from a TCD. The information
exchange between an actor and a device in a wind power plant requires the use of
information exchange services as defined in IEC 61400-25-3. A summary of the above is
shown in Figure 1.
—————————
To be published.
...
– 8 – IEC 61400-25-6:2016  IEC 2016
Actors like operators, control centre,
maintenance teams, owners, .
IEC 61400-25-3, IEC 61400-25-4
and IEC 61400-25-6
Information exchange
IEC 61400-25-3, IEC 61400-25-4
Condition monitoring device or function
and IEC 61400-25-6
with logical nodes and data objects
Information exchange
Gearbox
Generator
Brake
Tower
TC/CM
...
Scope of
document
Information
exchange
…
Logical nodes and data objects

IEC
Figure 1 – Condition monitoring with separated TCD/CMD functions
The state of the art in the wind power industry is a topology with separated devices for control
and condition monitoring applications. Based on this fact, the information and information
exchange modelling in the present document is based on a topology with a TCD and a CMD.
IEC 61400-25-6 represents an extension of the IEC 61400-25 series focussing on condition
monitoring.
Actors like operators,
control centre, maintenance
teams, owners, .
IEC 61400-25-3, IEC 61400-25-4
Information exchange
Wind turbine control device or function with
logical nodes and data objects

IEC 61400-25-6:2016  IEC 2016 – 9 –
WIND ENERGY GENERATION SYSTEMS –

Part 25-6: Communications for monitoring and control of wind power
plants – Logical node classes and data classes for condition monitoring

1 Scope
This part of IEC 61400-25 specifies the information models related to condition monitoring for
wind power plants and the information exchange of data values related to these models.
NOTE Conformance to IEC 61400-25-6 presupposes in principle conformance to IEC 61400-25-2, IEC 61400-25-3
and IEC 61400-25-4.
Figure 2 illustrates the information flow of a system using condition monitoring to perform
condition based maintenance. The figure illustrates how data values are refined and
concentrated through the information flow, ending up with the ultimate goal of condition based
maintenance; actions to be performed via issuing work orders to maintenance teams in order
to prevent the wind power plant device to stop providing its intended service.
Data acquisition
Local condition
Local alarming
monitoring
(Long term trending)
(Long term trending)
Central condition Alarming
Long term data storage
monitoring
Condition
Alarm management
monitoring
Diagnosis
supervision
reporting
Service Work
management orders
Service staff
IEC
Figure 2 – Schematic flow of condition monitoring information
Data Data
Data
Data reduction
Refinement of information
Scope of IEC 61400-25-6
– 10 – IEC 61400-25-6:2016  IEC 2016
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 61400-25-1:2006, Wind turbines – 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 61400-25-3:2015, Wind turbines – Part 25-3: Communications for monitoring and control
of wind power plants – Information exchange models
IEC 61400-25-4:2016, Wind energy generation systems – Part 25-4: Communications for
monitoring and control of wind power plants – Mapping to communication profile
, Wind energy generation systems – Part 25-5: Communications for
IEC 61400-25-5:—
monitoring and control of wind power plants – Conformance testing
IEC 61850-7-1:2011, Communication networks and systems for power utility automation –
Part 7-1: Basic communication structure – Principles and models
IEC 61850-7-2:2010, Communication networks and systems for power utility automation –
Part 7-2: Basic information and communication structure – Abstract communication service
interface (ACSI)
IEC 61850-7-3:2010 Communication networks and systems for power utility automation –
Part 7-3: Basic communication structure – Common data classes
ISO 13373-1:2002, Condition monitoring and diagnostics of machines – Vibration condition
monitoring – Part 1: General procedures
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61400-25-1,
IEC 61400-25-2, IEC 61400-25-3, IEC 61400-25-4 and IEC 61400-25-5 apply.
An exhaustive description of the term "bin" has been given in 5.4.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
actor
any entity that receives (sends) data values from (to) another device
Note 1 to entry: Examples of actors could be SCADA systems, maintenance systems, owner, etc.
—————————
To be published.
IEC 61400-25-6:2016  IEC 2016 – 11 –
3.2
mandatory
M
specific content provided to ensure compliance with this document
3.3
optional
O
specific content that can be provided to ensure compliance with this document
3.4
conditional
C
depending on stated conditions, specific content defined to ensure compliance with this
document
3.5
frequency analysis
raw time waveforms recorded by the sensor are post processed to measurement types in the
frequency domain
Note 1 to entry: The most common measurement type is the auto spectrum (AUS).
3.6
scalar value
data type representing a quantity which can be described by a single number, such as a
temperature
Note 1 to entry: A scalar value is a post processing of the raw vibration signal into one or more scalar values,
also called descriptors (see ISO 13379-1:2012). Each descriptor (scalar) value is used to indicate the presence of
a certain failure mode of a monitored machine part. E.g. one descriptor can indicate if a bearing fault is present by
measuring the vibration level at the outer ring of a certain bearing, another can indicate the vibration level of the
shaft running speed and can indicate misalignment, unbalance or other shaft related faults.
3.7
time waveform
sampled vibration signal recorded from the transducer
Note 1 to entry: Time waveform recordings have a certain length in time and represent the actual vibration level
at any instance during the recording of the waveform.
3.8
root mean square value
RMS
measure of the level of a signal calculated by squaring the instantaneous value of the signal,
averaging the squared values over time, and taking the square root of the average value
Note 1 to entry: The RMS value is the value which is used to calculate the energy or power in a signal.

– 12 – IEC 61400-25-6:2016  IEC 2016
4 Abbreviated terms
CDC Common data class
CM Condition monitoring (function)
CMD Condition monitoring device
DC Data class
ING Common data class for integer setting value (see IEC 61850-7-3)
LD Logical device
LN Logical node
LPHD Logical node physical device information
RCB Report control block
RMS Root mean square
SAV Common data class for sampled analogue values (see IEC 61850-7-3)
SHS Statistical and historical statistical data (as defined in IEC 61400-25-2:2015,
Annex A)
SMV Sampled measured values; sometimes short: SV = sampled values
TC Turbine controller (function)
TCD Turbine controller device
TMF Tooth meshing frequency
TOC Turbine operation conditions
WPP Wind power plant
WT Wind turbine
Abbreviated terms used to build names of data classes found in LNs shall be as listed in
Table 1 below and in the table of abbreviated terms in IEC 61400-25-2:2015, Clause 4.

IEC 61400-25-6:2016  IEC 2016 – 13 –
Table 1 – Abbreviated terms applied
Term Description Term Description
Acc Accuracy; Acceleration Pc Power class
An Analogue Per Period, periodic
Ane Anemometer PF Power factor
Ang Angle Ph Phase
Av Average Plu Pollution
Ax Axial Pos Position
Azi Azimuth Prcd Processed
Bec Beacon Pres Pressure
Bn Bin (e.g. Power Bin) Prod Production
Cab Cable Pwr Power
Ccw Counter clockwise Ra Radial
Cw Clockwise React Reactive
Dcl Dc-link RMS Root-mean-square
Deb Debris Roof Roof
Dec Decrease Sb Sideband
Dir Direction Sdv Standard deviation
Dsp Displacement Smok Smoke
Dtc Detection Snd Sound pressure
Emg Emergency Spd Speed
En Energy Stld Structural load
Ent Entrance Stn Strain
Ety Empty Stop Stop
Ext Excitation Str Start
Flsh Flash Sw Switch
Gri Grid Swf Swarf
Gs Grease Tmp Temperature
Harm Harmonic Torq Torque
Hi High Trd Transducer
Hor Horizontal Trg Trigger
Hum Humidity Trs Transient
Hz Frequency V Voltage
Ice Ice Vbr Vibration
Idl Idling Ver Vertical
Inl Inline Wdp Wind power
Lev Level Wup Windup
Lft Lift Xdir X-direction
Lo Low (state or value) Ydir Y-direction
Lum Luminosity
Max Maximum
Met Meteorological
Min Minimum
Mult Multiplier
– 14 – IEC 61400-25-6:2016  IEC 2016
5 General
5.1 Overview
The primary objective of condition monitoring is to detect symptoms of a potential failure of a
wind turbine component before it leads to functional failure resulting in serious damage or
destruction of the wind turbine.
In condition monitoring systems, predefined triggers are applied to initiate a sequence of
events, for example issuing an alarm to the local SCADA system or sending a message to a
monitoring centre in order to prevent further damage on components or structures. In general,
such messages can be used by a condition monitoring supervision function to generate
actionable information which can be used by a service organization to create work orders and
initiate actions. Figure 2 illustrates the information flow of a system using condition monitoring
to perform condition based maintenance.
Condition monitoring is mainly associated with the following kinds of information.
a) Time waveform records (samples) of a specific time interval to be exchanged either
directly or as processed values for analysis (e.g. acceleration, position detection, speed,
stress detection).
b) Status information and measurements (synchronized with the waveform records)
representing the turbine operation conditions.
c) Results of time waveform record analysis of vibration data (scalar values, array values,
statistical values, historical (statistical) values, counters and status information).
d) Results of, for example, oil debris analysis.
The condition monitoring information can be described by specified data attributes, trigger
options and data objects of the following common data classes:
• condition monitoring measurement (CMM);
• measurement value (MV);
• scalar value array (SVA);
• complex measurement value (CMV);
• complex measurement value array (CMVA);
• condition monitoring bin (CMB);
• alarm (ALM).
The purpose of this document is to model condition monitoring information by using the
information modelling approach as described in 6.2.2 of IEC 61400-25-1:2006 and by
extending the information model as specified in Clause 5 of IEC 61400-25-2:2015 with an
additional logical node WCON for modelling information specific to condition monitoring of
wind power plants.
As the WCON class is modelled using the approach of IEC 61400-25-1 and IEC 61400-25-2,
the information exchange models as specified in IEC 61400-25-3 and the mapping to
communication profiles as specified in IEC 61400-25-4 can be used for exchanging condition
monitoring information.
5.2 Condition monitoring information modelling
When applicable, the binding of a specific condition monitoring information to a specific
sensor and a specific location in a wind turbine shall be specified using:
a) a definition of the coordinate system applied for specifying direction and angles; see 5.3;

IEC 61400-25-6:2016  IEC 2016 – 15 –
b) data attributes for identifying the environment for a condition monitoring measurement –
operational state bin concept, see 5.4;
c) data attributes for identifying a condition monitoring measurement by sensor type, angular
orientation, direction of motion, and physical location in a wind turbine such as shaft
number, bearing position as well as identification of the primary measurement object for a
sensor. For further details, see Clause 8.
The sensor and location specifications in this document are in principle coordinated with the
specifications defined in ISO 13373-1, where coordination has been applicable.
5.3 Coordinate system applied for identifying direction and angles
In order to be able to unambiguously identify a sensor location, a coordination system is used
as a reference to specify all directions and angles. Figure 3 shows an X, Y, Z coordinate
system superimposed on the wind turbine drive train. The drive train is seen in the direction of
the wind. It is defined that the Z direction is always the same as the wind direction.
Main bearing Gearbox Generator
Y
Z
X
IEC
Figure 3 – Reference coordinates system for the drive train
Table 2 lists other commonly used designations as related to the reference coordinate system
defined in this document.
Table 2 – Coordinate system and wind turbine related characteristics
Used in this document Other designations
Z direction Downwind (as opposed to Upwind)
Axial (wind direction)
X direction Lateral
Transverse
Horizontal
Right (as opposed to Left)
Y direction Vertical
Up (as opposed to Down)
– 16 – IEC 61400-25-6:2016  IEC 2016
5.4 Operational state bin concept
5.4.1 General
In order to describe the environment for a set of condition monitoring measurements, the
operational state bin concept has been developed. A wind turbine operates in principle over a
wide range of wind speeds causing a large variety of loads on the mechanical structures. An
adaptive monitoring technique is often applied to secure a higher degree of reliability and
repeatability of measurements used to detect developing faults in the full operating range,
thus reducing the risk of triggering false alarms. In order to adapt to the varying operating
conditions, data can be stored according to several operational states in multiple dimensions.
The basic principle of condition monitoring is to observe the evolution of specific measured
variables by comparing new measurements with previous measurements. The effect of
changes in operational conditions can be limited by comparing information belonging only to
the same operational state bin.
5.4.2 Example of how to use active power as an operational state
Active power levels are used for the adaptive monitoring technique rather than the wind speed
as the vibration level measured and the stress on the turbine components are found to be
closely related to the active power production of the turbine. By using the active power level
as measurement trigger, it is also ensured that vibration measurements are recorded only
when a wind turbine is producing active power.
An example of vibration
...