IEC 61400-24:2019/AMD1:2024
(Amendment)Amendment 1 - Wind energy generation systems - Part 24: Lightning protection
Amendment 1 - Wind energy generation systems - Part 24: Lightning protection
Amendement 1 - Systèmes de génération d'énergie éolienne - Partie 24: Protection contre la foudre
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IEC 61400-24 ®
Edition 2.0 2024-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
AMENDMENT 1
AMENDEMENT 1
Wind energy generation systems –
Part 24: Lightning protection
Systèmes de génération d'énergie éolienne –
Partie 24: Protection contre la foudre
IEC 61400-24:2019-07/AMD1:2024-11(en-fr)
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IEC 61400-24 ®
Edition 2.0 2024-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
AMENDMENT 1
AMENDEMENT 1
Wind energy generation systems –
Part 24: Lightning protection
Systèmes de génération d'énergie éolienne –
Partie 24: Protection contre la foudre
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 27.180 ISBN 978-2-8322-9911-1
– 2 – IEC 61400-24:2019/AMD1:2024
© IEC 2024
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
WIND ENERGY GENERATION SYSTEMS –
Part 24: Lightning protection
AMENDMENT 1
FOREWORD
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Amendment 1 to IEC 61400-24:2019 has been prepared by IEC technical committee 88: Wind
energy generation systems.
The text of this Amendment is based on the following documents:
Draft Report on voting
88/1040/FDIS 88/1054/RVD
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 Amendment is English.
© IEC 2024
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• withdrawn, or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.
___________
INTRODUCTION to Amendment 1
This amendment to IEC 61400-24:2019 addresses an update of the content in Annex L
regarding monitoring systems for detecting lightning strikes on wind turbines.
___________
2 Normative references
Add the following document to the existing list, after IEC 62305-4:2010:
IECRE OD-501, Type and Component Certification Scheme (wind turbines)
– 4 – IEC 61400-24:2019/AMD1:2024
© IEC 2024
Replace the existing Annex L with the following new Annex L:
Annex L
(informative)
Lightning detection and measurement systems
L.1 General
L.1.1 Purpose
It is recommended that wind turbines are equipped with systems capable of detecting lightning,
measuring its current components, and processing the parameters of the lightning strikes. The
purpose of such systems is to:
• provide information to the operator on the occurrence of lightning strikes to the wind turbine
and to give input to operation and maintenance regimes;
• provide valuable data on lightning strikes to wind turbines thus allowing post-assessment of
the lightning magnitude/characteristics and contribution to the operator's risk assessment
processes;
• enable the operator to compare the measured current parameters of lightning strikes to the
lightning protection level, LPL, used for designing the wind turbine lightning protection
system (e.g. for assessing if the lightning current intercepted by the LPS is below or above
the values defined in Table 1);
• avoid hazardous activities such as maintenance when there is a risk of lightning strike.
L.1.2 Nomenclature
The following nomenclature applies to this annex.
a) Thunderstorm warning systems (TWS), composed of thunderstorm detector(s) able to
monitor the lightning or upcoming lightning activity and tools for processing the acquired
data to provide a valid alarm (warning). They are based on local sensors (either based on
electrostatic or electromagnetic fields), a group of local sensors or lightning location
systems (LLS).
b) Lightning measurement systems (LMS) measuring lightning events and their features with
devices installed on the turbine. These systems range from a combination of simple
electromechanical event counters to complex systems measuring and analyzing lightning
parameters.
L.2 Benefits of lightning detection and measurement systems
There are many benefits of measuring actual lightning exposure. Depending on the specific
stakeholder, a non-exhaustive list is included in Table L.1, Table L.2 and Table L.3. The
industry is encouraged to share lightning data across all stakeholders (OEM/Owner/Insurance),
to ensure benefits across the entire value chain.
© IEC 2024
Table L.1 – Considerations and benefits for the OEM (original equipment manufacturer)
Statement Value aspect
For turbines delivered with long service contracts, the OEM (Original This enables condition-based
Equipment Manufacturer) with a service contract would like to know when maintenance or repair, lowering
the receptor/LPS has reached the design lifetime and needs to be downtime and unexpected damage
replaced. This can be achieved by monitoring the accumulated charge costs significantly. Maintenance is
and specific energy for each blade and correlating with test performance cheaper than repair.
of the receptor/LPS.
The OEM would like to know all information of strikes, to determine the This information is used to market
efficiency of the receptors/LPS (the observed number of strikes the OEM products, "with a field
intercepted correctly divided by the total number of strikes to the efficiency of XX%, our turbines
turbine/blade observed – see 3.12). comply fully with YY".
Every strike will be different, and cross correlating strike information with Get more information on the
other sensor signals can provide valuable information to the OEM to fully lightning susceptibility of the
understand the turbine operation and design performance. turbines, to enable stronger and
cheaper designs for future turbines.
Turbine LPS have developed intensively during the past 10 years to By measuring all strikes in field,
20 years, and OEMs are still following different paradigms for the design evaluating the strike parameters,
and verification air terminations, down conductors and lightning and comparing them to design
coordination with additional conductive components like CFRP. performance from laboratory tests
and/or modelling verification, the
If a blade design, known from verification tests or modelling, is
consequence of specific strikes can
challenged by certain features of the lightning current, an active
be assessed.
monitoring of the lightning exposure will allow targeted maintenance.
By evaluating the consequence of
Not all lightning strikes exhibit the same strike parameters, hence the
each lightning event, maintenance
consequence of strikes will differ.
and inspections can be tailored and
optimized.
In case lightning damages occur, the detailed measurements of the Enable the discussion on splitting
lightning parameters can be used to assign and split the cost of repair costs of blade damages based on
between OEM and owner/operator. lightning impact.
Table L.2 – Considerations and benefits for owner and/or operator
Statement Value aspect
The operator would like to know if a lightning flash exceeded Lightning damage is paid by the responsible
IEC LPL current parameters to which the turbine has been party.
certified as this is useful information in relation to warranty and
insurance.
The owner and/or operator would like to know if a lightning In case the measurement can be used to
flash was potentially dangerous to the turbine. identify a strike as representing a risk, the
turbine could be checked (online or on site)
before it is restarted. This could prevent
further damage on the turbine.
The owner and/or operator would like to know when the This enables condition-based
receptor and/or LPS has reached the design lifetime and maintenance/repair, lower downtime and
needs to be replaced. This is performed by monitoring the unexpected damage cost significantly.
accumulated charge and/or specific energy in each blade and Maintenance is cheaper than repair.
correlating it with the receptor and/or LPS performance as
proven by testing according to Annex D.
Additionally, the collection of lightning exposure will enable a
determination of potential LPS performance degradation.
A correlation of lightning performance across large fleets with Enable the owner to select turbines with
LMS will provide knowledge on the performance of a specific documented good experience on the lightning
design and enable customisation of the LPS design to specific performance, as required by the specific site.
site conditions (altitude, lightning regime, number of WTs in
the WF, etc.).
Every strike will be different, and cross correlating strike Get more information to support condition-
information with other sensor signals can provide valuable based maintenance strategies.
information to the owner and/or operator to fully understand
the turbine operation and design performance.
In case lightning damages occur, the detailed measurements Enable the discussion on splitting costs of
of the lightning parameters can be used to assign and split the blade damages based on lightning impact.
cost of repair between OEM and owner/operator.
– 6 – IEC 61400-24:2019/AMD1:2024
© IEC 2024
Table L.3 – Considerations and benefits for the Insurance company
Statement Value aspect
Sites with severe lightning exposure will potentially have more downtime Utilizing a dynamic insurance
to allow for extra service and maintenance, and the damage rate in terms premium, where that insurance
of failures per year could also be larger. The insurance company could premiums scale with documented
customize the insurance tariff according to site conditions in terms of lightning activity, would allow the
challenging lightning activity, such that sites experiencing significant insurance company to target the
lightning activity could be priced higher than sites with limited lightning premiums more correctly to the
activity. risk.
A correlation of lightning performance across large fleets will provide Optimize insurance premiums and
knowledge of which designs work well and which designs don't for similar exclude designs with poor
lightning environments. Since the lightning environment is documented by performance, to eventually optimise
LMS, a correlation between insurance claims and LMS data will provide the insurance business.
the needed information (e.g. protection efficiency of the LPS).
A blade certified according to IEC/RE OD-501 (referencing to Qualify discussion of insurance
IEC 61400-24 for lightning matters) eventually means that the turbine coverage by providing actual
should be able to continue operation without the need of repair until next lightning strike data.
scheduled maintenance; see 8.2.2. An additional perception is that
strikes outside the range of the LPL are disregarded. In both cases,
knowledge on the actual strike data is useful for deciding the insurance
coverage.
In the event that blades suffer damages due to lightning, a discussion on Discussions on lightning exposure
insurance coverage can be assisted by accurate measurements. The can be eliminated once suitable
insurance companies could require the installation of proper LMS to LMS complying to industry
quantify the lightning exposure (current magnitude, specific energy, flash standards are used efficiently.
charge, accumulated charge, di/dt, etc.).
L.3 Lightning detection and measurement systems
L.3.1 General
Lightning detection and measurement systems are devices that provide information about
lightning affecting wind turbines. By detecting the presence of lightning strikes on and/or around
the wind turbine, different strategies for optimized operation or maintenance of the turbines can
be implemented.
Brief descriptions of the different options are given below.
L.3.2 Lightning detection systems
IEC 62793 describes sensors and networks of sensors (including LLS) able to provide real-time
information on the risk of lightning strikes. Sensors measuring electrostatic field detect lightning
related conditions and are usually employed as local detectors since they measure the
formation, approach or dissipation of the thunderstorm in the area where they are installed.
Sensors measuring electromagnetic field produced by lightning strokes can be used as
standalone detectors or used in networks. LLS use multiple antennae to locate lightning strokes
based on direction-finding, time of arrival, or interferometric techniques. Data from these
systems are generally available in real-time according to IEC 62793 requirements.
It is important for the user of data from TWS to know several parameters that affect the
performance of the system. Considerations relevant to lightning detection systems should be
compliant in full with IEC 62793.
© IEC 2024
L.3.3 Lightning measurement systems (LMS)
L.3.3.1 General
Lightning measurement systems are devices that provide information about lightning strikes on
a wind turbine by measuring various parameters caused by that lightning strike (e.g., current
magnitude, specific energy, flash charge, accumulated charge, di/dt, transient magnetic fields
generated by lightning currents flowing through down conductors including the tower).
L.3.3.2 Lightning event counters and peak current sensors
Lightning counters and peak current sensor cards (PCS) provide minimal information about
lightning events to a wind turbine. The simplest lightning counters (e.g. electromechanical) just
provide the number of strikes. Electronic lightning counters can also provide time stamp and
estimation of lightning parameters. Peak current sensor cards provide an estimation of the
maximum peak current for the time period since the sensor was installed. Considerations
relevant for lightning event counters and peak current sensors are listed in Table L.4.
Table L.4 – Considerations relevant for lightning event counters
and peak current sensors
Types Considerations
Lightning Lightning counters designed in accordance with IEC 62561-6 could not be suitable for wind
strike turbines exposed to large fractions of upward lightning.
counters
Some lightning counters also estimate one or several current parameters: peak current,
charge, specific energy. Devices designed for the standard lightning currents (e.g. in
IEC 62561-6) will not provide realistic data for all the strikes. The manufacturer should define
test waveforms including continuing currents. The manufacturer should provide the reference
waveforms and the uncertainties. The manufacturer should provide information about the
frequency response of the sensitivity and uncertainty of the estimated parameters.
The measurement capability of lightning counters used in wind turbines should demonstrate
sensitivity to upward lightning.
Manufacturer should provide the sensitivity versus frequency curve.
Peak This type of sensors designed and calibrated only with the standard lightning current
current waveforms is not suitable for the registration of real lightning currents. The manufacturer
sensors should provide information about the performance of the sensor at typical lightning currents of
wind turbines.
The manufacturer should provide information about the minimum detectable current and the
tested waveforms.
This type of sensors is not suitable for detecting continuing currents.
The manufacturer should provide the frequency response of the sensitivity and its uncertainty.
Users should be careful interpreting the information provided by the manufacturers of these
types of devices.
L.3.3.3 Local lightning current measurement systems
Special systems, e.g. with sensors mounted on the tower and/or in the blades of a wind turbine
to trigger a lightning alarm based on electromagnetic or optical criteria are called local lightning
current measurement systems. The sensor measures what actually strikes the turbines and
prevents remote lightning flashes from triggering a false alarm. Such systems can be connected
to a SCADA system giving a useful indication of lightning strikes in real-time. The systems could
give an indication of current waveform and strike severity and can hence be used by operators
to evaluate the degree of wear and damage, and to prepare maintenance for the relevant
turbines after a lightning storm.
– 8 – IEC 61400-24:2019/AMD1:2024
© IEC 2024
The lightning parameters which individually or in combination are closely related to the wear of
the lightning protection system and/or damages of the wind turbine are the current magnitude,
total charge transfer, specific energy and front time of the lightning current, etc. Whether these
parameters can be measured accurately depends largely on the frequency response and
resolution of the system.
The subclauses below highlight important features of local lightning current measurement
system to effectively capture the desired outcome of the lightning strikes.
L.3.3.4 Classifications
The characteristics of lightning current such as the current magnitude, charge, specific energy
and front time, etc. vary and could depend on the installation areas. Therefore, it is
recommended to investigate available information about characteristics of lightning currents for
the installation area when selecting the lightning measurement system to actually meet the
expected performance. To aid the selection, local lightning current measurement systems are
classified into four types according to the measurement performance, and hence the adequacy
of measuring the different lightning characteristics. The classification is shown in Table L.5.
Table L.5 – Requirement for each class of lightning measurement systems
Class II- Class II-
Class III
Range Class I
Category
PC EC
0,1 Hz to 1 MHz or wider ×
1 Hz to 1 MHz or wider ×
a
Frequency bandwidth
0,1 Hz to 100 kHz or wider ×
1 Hz to 100 kHz or wider ×
200 kA or higher × ×
Maximum measurable current
b
value
100 kA or higher × ×
1 000 C or higher × ×
Maximum measurable electric
c
charge value
600 C or higher × ×
1 kA or lower × ×
Minimum detectable current
d
value
2 kA or lower × ×
16 bit or higher x
e
12 bit or better x x
Digital resolution
8 bit or higher x
0,5 s or longer × ×
f
Observation period
1 s or longer × ×
a
A high upper cut off frequency allows measurement of short stroke pulses, a low lower cut off frequency
ensures measurement of long strokes.
b
Upper boundary for current detection, only Class I and Class II-PC ensures measurement of LPL1 current
magnitude.
c
Sites exposed to winter lightning should consider the risk of large charge transfer.
d
ICC strokes could transfer significant amount of charge at current magnitudes less than 1 kA. This charge
transfer will add to the erosion of air terminations, which is why a minimum measurable current should consider
this.
e
Digital resolution is important when measuring small current signals with a system having a large dynamic
range.
f
Especially UW lightning and/or bipolar events are known to persist for up to 1 s and above.
© IEC 2024
A guidance on the suitable classes of measurement systems is provided below:
Class I: Suitable for measuring all quantities of a lightning strike
Class II-PC: Focus on measuring the peak current (PC) of the lightning strike
Class II-EC: Focus on measuring the electric charge (EC) of the lightning strike
Class III: Limited measurement performance
Class IV: Any lightning measurement systems not complying with Class I-III
The classification of a lightning measurement system follows the lowest classification in any of
the categories, i.e. a LMS complying with class I in five out of six categories, but only to Class
II-PC in one category, is classified as Class II-PC.
L.3.3.5 Properties of lightning measurement systems
L.3.3.5.1 General
Several properties of a lightning measurement system for a wind turbine are important for
ensuring that expectations are met, including the electrical properties of the front-end
measuring system, the quantities which are recorded and stored by the system, and the ability
to interface to the turbine or operator SCADA system. The following is a non-exhaustive
informative list of topics to consider. The following subclauses of L.3.3.5 are a non-exhaustive
informative list of topics to consider.
L.3.3.5.2 Electrical performances
L.3.3.5.2.1 Detection method
The front end of the lightning measurement system defines the detection method. Several
principles exist ranging from full current measurements in individual blades, full current in the
tower, or partial current measurement in earthing systems. When measuring lightning current
in wind turbines, it is important to consider that the structure itself could affect the current
measurement. This appears due to impedance mismatch at interfaces between blade and
nacelle, and/or tower and ground. The result can be reflections in the measured lightning current,
which are still part of the actual current component affecting the turbine but would not be present
if the lightning current could be measured without the turbine.
Most of the systems that measure the lightning current flowing through the LPS (air termination,
down conductor, tower and earthing system, etc.) and hence detect lightning strikes on wind
turbines use various current sensors (Rogowski coil, CT, solenoid coil, resistive shunt, etc.) to
measure the above-mentioned lightning parameters.
The manufacturer should specify the detection method used, the applicability of the chosen
detection method for the frequency range considered, and for systems measuring partial current
in the earthing system, the manufacturer should ensure that the current share is well defined
across the frequency range stated.
L.3.3.5.2.2 Current detection frequency bandwidth
The current detection frequency bandwidth (the frequency bandwidth with a gain characteristic
between –3 dB and +3 dB) should be defined by the manufacturer. Since lightning current is
known to exhibit a wide range of frequencies from short strokes at downward lightning to long
strokes experienced as ICC or winter lightning, the frequency range should be chosen for the
application.
L.3.3.5.2.3 Observation period
The observation period, or total time of recording and processing, should ensure that the entire
duration of the expected lightning flashes is covered.
– 10 – IEC 61400-24:2019/AMD1:2024
© IEC 2024
L.3.3.5.2.4 Minimum detectable current value
The minimum detectable current magnitude is the magnitude that the LMS can measure reliably
relative to noise floor, DC offset, dynamic range, etc. ICC strokes are known to transfer
significant amount of charge at low current magnitude; hence a small minimum detectable
current is desirable at sites experiencing upward lightning and lightning during cold seasons,
and in particular when the turbine design is prone to damages resulting from excessive charge
transfer.
L.3.3.5.2.5 Maximum measurable current value
The maximum measurable current magnitude should reflect the risk of observing such strikes
in field. For areas exposed to mainly low magnitude strikes (cold season winter lightning),
100 kA for the full lightning current could be sufficient [2], whereas the general ability of
justifying exposure within the LPL I range as specified in Clause 8 requires a LMS capable of
measuring the full lightning current of at least 200 kA.
L.3.3.5.2.6 Resolution
The resolution of the current measurement within the dynamic range is a measure of how well
the current waveform is digitized in discrete steps. A high resolution means that the current
magnitude is discretized in small steps, such that even small magnitude events like ICC can be
measured and the associate charge transfer can be accurately calculated.
L.3.3.5.2.7 Measurement of electric charge
The charge transfer of the entire lightning flash is associated with the erosion of metal surfaces
at the arc root, and damages of sliding rail interfaces, bearings and other moving parts along
the lightning path. The charge is calculated by the time integral of the current, and its accuracy
and minimum/maximum parameters will therefore depend on both the dynamic range (maximum
and minimum detectable current magnitude), the resolution, the observation time and the
sampling rate. For areas exposed to long strokes transferring significant amounts of charge
(winter lightning during cold seasons), the LMS should be capable of measuring the extensive
charge levels.
L.3.3.5.2.8 Trigger process
The trigger process is the mechanism in a lightning detection system at which the recording of
the lightning current is triggered. The trigger process can be defined by the current magnitude,
certain waveform features, magnetic fields, or a combination thereof. The overall goal of the
trigger process is to ensure a reliable discrimination of lightning events over false positives.
Some LMS have a fixed and high trigger level chosen to ensure a reliable triggering in the event
of what is perceived as real lightning strikes and to avoid too many false alarms, which could
result in low current amplitude lightning events being neglected, whereas other systems provide
a customizable trigger level enabling the user to also measure small magnitude lightning events.
Small trigger levels will provide a high number of events, since also induced current and aborted
leaders are measured, whereas higher trigger levels could miss the recordings of ICC
potentially transferring significant amount of charge.
The manufacturer should specify the fixed trigger levels or the options of customized trigger
levels.
L.3.3.5.2.9 Measurement accuracy and tolerances
The manufacturer should specify the measurement accuracy for the current measurement
system, and the measurement tolerances with regards to the different key parameters as peak
current, specific energy, charge, and current gradient. The accuracy should be specified and
verified within the relevant range of the different parameters, potentially by executing lightning
current tests using principles from Annex D.
© IEC 2024
Information on calibration intervals and procedure should be provided.
L.3.3.5.2.10 Electromagnetic compliance
The LMS should be compliant with the lightning environment and remain operational during the
event. The performance should be documented by demonstrating compliance with relevant
EMC standards and tests, as described in the IEC 61000 series.
L.3.3.5.3 Recording of lightning information
L.3.3.5.3.1 General
The important information of the lightning strike should be recorded and stored for tailoring
maintenance and inspection intervals or aiding the discussion of liability in the event of damages.
L.3.3.5.3.2 Time of lightning strike
The time of the lightning strike is recorded, and if a correlation with other sensor systems is
desired, the accuracy should in general be within 0,1 s. The method of reading the time should
be specified by the manufacturer, and could range between ground positioning system (GPS)
synchronized time stamps, network time protocol (NTP) synchronized time stamps, internal
clock with manual synchronization, etc.
The manufacturer should specify the time zone used.
L.3.3.5.3.3 Lightning key parameters
The important lightning key parameters for the intended application should be recorded and
stored, potentially including maximum current value, electric charge transfer, specific energy,
strike polarity, strike direction of initiation, di/dt, etc.
For sites exposed to a lightning environment with charge transfer during long strokes, the
accumulated charge transfer could also be very important to evaluate lifetime of air terminations,
etc.
L.3.3.5.3.4 Current waveform
For additional analysis of the lightning impact to the blade, or for validation of the calculated
key parameters, the current waveform itself can be valuable to record. The manufacturer should
specify whether the current waveform is recorded as well as the resolution and the sampling
rate of the recording.
L.3.3.5.4 Interface properties
L.3.3.5.4.1 General
Besides the measurement properties of the active lightning detection systems, another
important feature is how it interfaces to the turbine, to turbine SCADA systems, operator SCADA
systems, customer cloud solutions, etc.
L.3.3.5.4.2 Alarm output
Many systems feature the option of an alarm output to notify the operator when a lightning event
has occurred. For some systems, the alarm output is set to trigger at a lightning event whereas
other systems enable a trigger output when one or more of the key parameters exceed a
predefined threshold level.
The manufacturer should specify the alarm output options, whether it triggers on the lightning
event or a key data trigger threshold, or a combination of trigger thresholds (current magnitude,
charge, accumulated charge, specific energy, etc.) has been exceeded.
– 12 – IEC 61400-24:2019/AMD1:2024
© IEC 2024
The alarm output may be electrical, optical, wireless, etc.
L.3.3.5.4.3 Communication interface
Several options for communicating the measurements exist:
– online system where data is transferred to an external cloud solution;
– online system where data is transferred to the operator SCADA system;
– online system where the data is transferred to the local turbine SCADA system;
– offline system, where lightning recordings are only accessible at the turbine;
– other systems not covered by the above.
The manufacturer should specify the options for communication with the lightning measurement
system.
L.3.3.6 Installation and commissioning
The method of installation and commissioning should be provided by the manufacturer, to
ensure a durable installation with respect to the location within the turbine and specific site
conditions. If the LMS utilizes conductive elements in the blade, the designer/installer should
ensure that it doesn't compromise the lightning protection coordination.
Working instructions and maintenance manuals should be part of the manufacturer's
documentation.
L.3.3.7 Operation flow chart
The operation flowchart should be developed by the user in collaboration with the blade
designer, to ensure that actionable information is provided by the LMS. A simple example is
shown in Figure L.1, where the evaluation of current magnitude and secondly charge transfer
decides if an alarm is raised.
Depending on the LMS capabilities and measurement accuracy provided, other combinations
of insight providing actionable information can be defined: measurement of accumulated charge
correlated with results from verification tests of the present LPS will identify the expected wear
of air terminations, current magnitude and di/dt provide insight on induced voltages and
differential voltage distribution, specific energy provides insight on electrical loading of
connection components and equipotential bonding, the number of lightning events attaching to
one turbine relative to others could affect inspection plans, etc.
© IEC 2024
Key
i maximum value of detected lightning current
p
Q electric charge value of detected lightning
i trigger current value
t
i alarm current value
a
Q alarm electric charge value
a
Figure L.1 – Example of flow chart for lightning detection and alarm output
for LPS designs sensitive to charge transfer
___________
– 14 – IEC 61400-24:2019/AMD1:2024
© IEC 2024
COMMISSION ÉLECTROTECHNIQUE INTERNATIONALE
____________
SYSTĖMES DE GÉNÉRATION D’ÉNERGIE ÉOLIENNE –
Partie 24: Protection contre la foudre
AMENDEMENT 1
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