IEC 61820-3-4:2023
(Main)Electrical installations for lighting and beaconing of aerodromes - Part 3-4: Safety secondary circuits in series circuits - General safety requirements
Electrical installations for lighting and beaconing of aerodromes - Part 3-4: Safety secondary circuits in series circuits - General safety requirements
IEC 61820-3-4:2023 specifies protective provisions for the operation of lamp systems powered by series circuits in aeronautical ground lighting.
The protective provisions described here refer only to secondary supply systems for loads that are electrically separated from the series circuit.
This document specifies the level of SELV, and alternatively PELV, under consideration of additional personnel protection during work on live secondary circuits by electrically skilled persons. This document also covers the special operational features of aeronautical ground lighting and addresses the level of training and the requirements for maintenance procedures detailed in IEC 61821 and other national or regional regulation.
The requirements and tests are intended to set a specification framework for system designers, system installers, users, and maintenance personnel to ensure a safe and economic use of electrical systems in installations for the beaconing of aerodromes.
This document complements existing IEC aeronautical ground lighting (AGL) standards and can be used as a design specification.
Installations électriques pour l'éclairage et le balisage des aérodromes - Partie 3-4: Circuits secondaires de sécurité dans les circuits série - Exigences générales de sécurité
L'IEC 61820-3-4:2023 spécifie des dispositions de protection pour le fonctionnement de systèmes d'éclairage alimentés par des circuits série pour le balisage aéronautique au sol.
Les dispositions de protection décrites ici se rapportent uniquement à des systèmes d'alimentation secondaires pour des charges séparées électriquement du circuit série.
Le présent document spécifie le niveau de TBTS et, en variante, de TBTP envisagé pour une protection supplémentaire du personnel lors d'un travail effectué sur des circuits secondaires sous tension par des personnes qualifiées en électricité. Le présent document couvre également les caractéristiques opérationnelles spéciales du balisage aéronautique au sol et traite du niveau de formation et des exigences relatives aux procédures de maintenance décrites dans l'IEC 61821 et dans d'autres réglementations nationales ou régionales.
Les exigences et les essais sont destinés à définir un cadre de spécification pour les concepteurs de systèmes, les installateurs de systèmes, les utilisateurs et le personnel de maintenance afin d'assurer une utilisation économique et en toute sécurité des systèmes électriques dans les installations destinées au balisage des aérodromes.
Le présent document complète les normes existantes de l'IEC relatives au balisage aéronautique au sol (AGL, Aeronautical Ground Lighting) et peut être utilisé comme spécification de conception.
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Standards Content (Sample)
IEC 61820-3-4 ®
Edition 1.0 2023-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electrical installations for lighting and beaconing of aerodromes –
Part 3-4: Safety secondary circuits in series circuits – General safety
requirements
Installations électriques pour l'éclairage et le balisage des aérodromes –
Partie 3-4: Circuits secondaires de sécurité dans les circuits série – Exigences
générales de sécurité
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IEC 61820-3-4 ®
Edition 1.0 2023-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electrical installations for lighting and beaconing of aerodromes –
Part 3-4: Safety secondary circuits in series circuits – General safety
requirements
Installations électriques pour l'éclairage et le balisage des aérodromes –
Partie 3-4: Circuits secondaires de sécurité dans les circuits série – Exigences
générales de sécurité
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.140.50; 93.120 ISBN 978-2-8322-7017-2
– 2 – IEC 61820-3-4:2023 © IEC 2023
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms, definitions, and abbreviated terms . 9
3.1 Terms and definitions . 9
3.2 Abbreviated terms . 12
4 Requirements for the SELV/PELV supply . 12
4.1 General . 12
4.2 SELV/PELV-safety demarcation line in an AGL series circuit . 12
4.3 Environmental conditions . 14
4.4 Degree of protection provided by enclosures . 14
4.5 Electromagnetic compatibility (EMC) . 14
4.5.1 Limits of electromagnetic emission . 14
4.5.2 Limits of immunity . 14
4.6 Marking . 14
4.6.1 Marking of the SELV/PELV power supply (single unit: safety transformer
combined with a limiter) . 14
4.6.2 Marking of the SELV/PELV power supply (multiple units: safety
transformer in series with a separate limiter) . 15
4.6.3 Marking at the installation locations . 15
4.7 Protection against electric shock . 15
4.7.1 Basic requirements . 15
4.7.2 Protective measure to be applied . 15
4.7.3 Voltage limit for the SELV/PELV circuit . 15
4.7.4 Protective separation from the primary series circuit . 17
4.7.5 Assemblies in the SELV/PELV supply . 18
4.8 Interfaces . 18
4.8.1 Supply unit . 18
4.8.2 Connectors . 18
5 Useful methodic for a SELV/PELV series circuit configuration . 18
5.1 General . 18
5.2 Method: systemic approach . 19
5.3 Method: extended systemic approach (with limiter) . 19
5.4 Verification of the chosen method . 19
6 Testing . 19
6.1 General . 19
6.2 System design test. 20
6.2.1 General . 20
6.2.2 Test for the "systemic approach" method . 20
6.2.3 Test for "extended systemic approach" method (device type test) . 21
6.3 Production routine tests . 23
6.3.1 Transformer test . 23
6.3.2 Limiter test . 23
6.4 Field test . 23
6.4.1 Field test without additional limiter . 23
6.4.2 Field test with additional limiter . 24
Annex A (informative) System design selection . 26
Annex B (informative) Marking and hazard risk information . 27
B.1 Examples for marking . 27
B.2 Hazard risk information . 29
B.3 Measurement information . 30
B.3.1 Open running safety transformer. 30
B.3.2 65 VA safety transformer unloaded in a real series circuit . 31
B.3.3 100 VA safety transformer unloaded with a quasi-sinewave primary
current . 32
Annex C (informative) Additional information . 33
C.1 Determination of the peak voltage for SELV/PELV applications . 33
C.1.1 Standards used . 33
C.1.2 Reason for using . 33
C.2 Case I sinusoidal voltage (SELV, PELV) . 33
C.3 Case II current pulses . 37
Bibliography . 45
Figure 1 – Safety demarcation line in a safety extra low voltage system (SELV system) . 13
Figure 2 – Safety demarcation line in a protective extra-low voltage system
(PELV system) . 13
Figure 3 – Short-term non-recurring AC touch voltage limit . 16
Figure 4 – Short-term recurring peak touch voltage limit . 17
Figure 5 – Test setup for type tests without limiter . 21
Figure 6 – Test setup for type tests with limiter . 22
Figure 7 – Test setup for field tests without limiter . 24
Figure 8 – Test setup for field tests with limiter . 25
Figure B.1 – Example for marking (luminaire, bolt, cable) . 27
Figure B.2 – Example for marking tags . 27
Figure B.3 – Example for field marking (elevated luminaires) . 28
Figure B.4 – Example for field marking (inset luminaires) . 28
Figure B.5 – Example for field marking (cables) . 29
Figure B.6 – Example for field marking (CCRs) . 29
Figure B.7 – Current time effect diagram for alternating current 15 Hz to 100 Hz (for
ventricular fibrillation current pathway left hand to both feet) . 30
Figure B.8 – Principle voltage shape of an open running safety transformer (output
voltage) . 31
Figure B.9 – Voltage shape measured in a real circuit at an open running 65 W-
transformer with a series circuit voltage of 384 V AC RMS and series current of 4,1 A . 31
Figure B.10 – Voltage shape on the output of an unloaded safety transformer;
measured secondary voltage of 47,49 V AC RMS and a peak-to-peak voltage of 265 V . 32
Figure C.1 – Conventional time/current zones of effects of AC currents (15 Hz to
100 Hz) on persons for a current path corresponding to left hand to feet (see
Table C.2) . 35
Figure C.2 – Probability of fibrillation risks for current flowing in the path left hand to feet . 38
Figure C.3 – Extracted data from IEC 60479-2:2019, Figure 23 . 39
Figure C.4 – Modified IEC 60479-2:2019, Figure 23 . 40
Figure C.5 – Peak voltage vs peak impulse duration . 41
– 4 – IEC 61820-3-4:2023 © IEC 2023
Figure C.6 – Peak voltage vs peak impulse duration with permissible (rectangular)
pulses . 42
Figure C.7 – Open secondary voltage peak . 42
Figure C.8 – Example – t vs t comparison . 44
erp max
Table A.1 – Comparison of characteristics of PELV and SELV . 26
Table C.1 – Total body impedances Z for a current path hand to hand for small
T
surface areas of contact in dry conditions at touch voltages U = 25 V to 200 V AC
T
50/60 Hz (values rounded to 25 Ω). 34
Table C.2 – Time/current zones for AC 15 Hz to 100 Hz for hand to feet pathway –
Summary of zones of Figure C.1 . 35
Table C.3 – Heart-current factor F for different current paths . 36
Table C.4 – Estimate for ventricular fibrillation threshold after each pulse of current in
a series of pulses each of which excited the heart tissue in such a manner as to
trigger ventricular responses . 39
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL INSTALLATIONS FOR
LIGHTING AND BEACONING OF AERODROMES –
Part 3-4: Safety secondary circuits in series circuits –
General safety requirements
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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indispensable for the correct application of this publication.
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rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC 61820-3-4 has been prepared by IEC technical committee 97: Electrical installations for
lighting and beaconing of aerodromes. It is an International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
97/253/FDIS 97/256/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 International Standard is English.
– 6 – IEC 61820-3-4:2023 © IEC 2023
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 61820 series, published under the general title Electrical installations
for lighting and beaconing of aerodromes, can be found on the IEC website.
Future documents in this series will carry the new general title as cited above. Titles of existing
documents in this series will be updated at the time of the next edition.
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,
• replaced by a revised edition, or
• amended.
IMPORTANT – The "colour inside" logo on the cover page of this document 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.
INTRODUCTION
With a few exceptions, aeronautical ground lighting is designed for series circuit technology
operating with a constant current and a maximum input voltage of 5 000 V AC RMS, including
tolerances. The input voltage to the series circuit is constantly adjusted by the constant current
regulator to maintain the series circuit current irrespective of the variations in the load. The
properties and characteristics of the constant current regulators are provided in IEC 61822.
Due to the structure of the series circuit, i.e., a series connection of all loads, the usual
protective devices for personnel protection of an IT, TT or TN network cannot be applied.
Aeronautical ground lighting is defined as any light provided as an aid to air navigation and as
such is subject to specific requirements with respect to its resilience, availability, and
serviceability levels. Therefore, insulation faults in the series circuit are often tolerated, and do
not lead to the automatic disconnection of the electrical supply to the series circuit.
In view of the above, IEC 61821 states that no work of any kind is normally permitted on live
series circuits without first conducting a suitable and sufficient risk assessment and using
appropriate protective equipment according to IEC 61821.
The electrical characteristics of the constant current series circuits are often confused with
those of IT, TT or TN networks, i.e., constant input voltage, equipment connected in parallel,
and a load-dependent current. In practice, it is not always easy to assign rated voltages
correctly to individual components of the series circuit or to determine possible touch voltages.
In a constant current series circuit, the rated voltage of the equipment in the series circuit and
the maximum touch voltage frequently exceed the normal mains input voltage.
In a series circuit installation, the series circuit input voltage is divided in proportion to the
internal resistances of the various loads. The rated voltage, i.e., the voltage between the input
lines of the equipment, is defined by the series circuit current that flows through the equipment
and its input impedance. Since input impedance depends on the equipment design and the
series circuit current is constant, the input voltage remains the same for each item of equipment.
As a result of the provision of current control in the series circuit, the series circuit input voltage
is load-dependent and corresponds to the sum of all partial voltages in the series circuit.
This is different to determining the maximum possible touch voltage to earth in a series circuit.
Since one or more earth faults of varying resistance to earth may be present, the touch voltage
to earth may assume any value up to the maximum series circuit input voltage depending on
the location of the earth fault and the equipment installed in the series circuit. Therefore, when
determining the dielectric strength against earth potential, it is usual to take the maximum series
circuit input voltage. Such peculiarities of the series circuit have been considered in the
requirements for lamp systems in this document.
Since there are only a few effective safety features available for personnel protection in series
circuit technology, the protective measure "safety extra low voltage (SELV)" and "protective
extra low voltage (PELV)" is applied in this document for the supply of lamp systems. This
measure is common practice and can resort to the application of well-known and accepted
methodology. The introduction of SELV/PELV in this type of application has been made possible
by the introduction of new illumination technology that has lower power requirements and hence
requires a lower voltage supply.
NOTE This document is based on SELV specification according to IEC 60364-4-41 and IEC 61558-1.
– 8 – IEC 61820-3-4:2023 © IEC 2023
ELECTRICAL INSTALLATIONS FOR
LIGHTING AND BEACONING OF AERODROMES –
Part 3-4: Safety secondary circuits in series circuits –
General safety requirements
1 Scope
This part of IEC 61820 specifies protective provisions for the operation of lamp systems
powered by series circuits in aeronautical ground lighting.
The protective provisions described here refer only to secondary supply systems for loads that
are electrically separated from the series circuit.
This document specifies the level of SELV, and alternatively PELV, under consideration of
additional personnel protection during work on live secondary circuits by electrically skilled
persons. This document also covers the special operational features of aeronautical ground
lighting and addresses the level of training and the requirements for maintenance procedures
detailed in IEC 61821 and other national or regional regulation.
The requirements and tests are intended to set a specification framework for system designers,
system installers, users, and maintenance personnel to ensure a safe and economic use of
electrical systems in installations for the beaconing of aerodromes.
This document complements existing IEC aeronautical ground lighting (AGL) standards and can
be used as a design specification.
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 60364-4-41:2005, Low-voltage electrical installations – Part 4-41: Protection for safety –
Protection against electric shock
IEC 60417, Graphical symbols for use on equipment, available at
http://www.graphicalsymbols.info/equipment
IEC 60529:1989, Degrees of protection provided by enclosures (IP Code)
IEC 60529:1989/AMD1:1999
IEC 60529:1989/AMD2:2013
IEC 61000-6-2:2016, Electromagnetic compatibility (EMC) – Part 6-2: Generic standards –
Immunity for industrial environments
IEC 61000-6-4:2018, Electromagnetic compatibility (EMC) – Part 6-4: Generic standards –
Emission standard for industrial environments
IEC 61140:2016, Protection against electric shock – Common aspects for installation and
equipment
IEC 61558-2-6:2021, Safety of transformers, reactors, power supply units and combinations
thereof – Part 2-6: Particular requirements and tests for safety isolating transformers and power
supply units incorporating safety isolating transformers for general applications
IEC 61820-1:2019, Electrical installations for aeronautical ground lighting at aerodromes –
Part 1: Fundamental principles
IEC 61821:2011, Electrical installations for lighting and beaconing of aerodromes –
Maintenance of aeronautical ground lighting constant current series circuits
IEC 61822:2009, Electrical installations for lighting and beaconing of aerodromes – Constant
current regulators
IEC 61823:2002, Electrical installations for lighting and beaconing of aerodromes – AGL series
transformers
IEC 63067:2020, Electrical installations for lighting and beaconing of aerodromes – Connecting
devices – General requirements and tests
CISPR 11:2015, Industrial, scientific, and medical equipment – Radio-frequency disturbance
characteristics – Limits and methods of measurement
CISPR 11:2015/AMD1:2016
CISPR 11:2015/AMD2:2019
CISPR 32:2015, Electromagnetic compatibility of multimedia equipment – Emission
requirements
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
assembly
self-contained, closed functional unit forming a light system together with other assemblies
3.1.2
basic insulation
insulation of hazardous live parts providing basic protection
Note 1 to entry: This concept does not apply to insulation used exclusively for functional purposes.
[SOURCE: IEC 60050-581:2008, 581-21-24]
3.1.3
electrically skilled person
person with relevant education and experience to enable that person to perceive risks and to
avoid hazards which electricity can create
[SOURCE: IEC 60050-195:2021,195-04-01]
– 10 – IEC 61820-3-4:2023 © IEC 2023
3.1.4
extra-low voltage
ELV
voltage not exceeding the relevant voltage limit specified in 4.7.3
3.1.5
safety extra-low voltage
SELV
voltage values which do not exceed values in 4.7.3, between conductors, or between any
conductor and reference earth, in an electric circuit which has galvanic separation from the
supplying electric power system by such means as a separate-winding transformer
3.1.6
SELV system
electrical system in which the voltage cannot exceed the value of extra-low voltage:
– under normal conditions, and
– under single-fault conditions, including earth faults in other electric circuits
Note 1 to entry: SELV is the abbreviation for safety extra-low voltage.
[SOURCE: IEC 60050-195:2021, 195-06-28]
3.1.7
PELV system
electric system in which the voltage cannot exceed the value of extra-low voltage:
– under normal conditions, and
– under single fault conditions, including earth faults in other electric circuits
Note 1 to entry: PELV is the abbreviation for protective extra low voltage
[SOURCE: IEC 60050-195:2021, 195-06-29]
3.1.8
SELV/PELV power supply
single physical unit or assembly of physical units performing as the power supply according to
SELV/PELV definitions
3.1.9
protective separation
separation of one electric circuit from another by means of
– double insulation, or
– basic insulation and electrically protective screening, or
– reinforced insulation
3.1.10
power supply unit
components for the supply and transfer of energy used to operate a lighting unit in a series
circuit
3.1.11
electric shock
physiological effect resulting from an electric current passing through a human or animal body
[SOURCE: IEC 60050-195:2021, 195-01-04, modified – Words "human body or livestock"
replaced with "human or animal body".]
3.1.12
hazardous live part
live part which, under certain conditions, can give a harmful electric shock
[SOURCE: IEC 60050-195:2021, 195-06-05, modified – Note to entry deleted.]
3.1.13
touch voltage
voltage between conductive parts when touched simultaneously by a person or an animal
Note 1 to entry: The value of the effective touch voltage may be appreciably influenced by the impedance of the
person or the animal in electric contact with these conductive parts.
[SOURCE: IEC 60050-195:2021, 195-05-11, modified – Words "a human being or livestock"
replaced with "person or animal"; "effective" and "appreciably" added in Note 1 to entry.]
3.1.14
single fault condition
condition in which there is a fault of a single protection (but not a reinforced protection) or of a
single component or a device
[SOURCE: IEC 60050-903:2013, 903-01-15, modified – Note 1 to entry deleted.]
3.1.15
light fixture (US)
light fitting (UK)
luminaire
electrical device used to create artificial light by use of an electric lamp/LED/light source above
ground or within the pavement
Note 1 to entry: The luminaire is an apparatus which distributes, filters or transforms the light transmitted from one
or more lamps and which includes all the parts necessary for supporting, aiming, fixing and protecting the lamps, but
not the lamps themselves and, where necessary, circuit auxiliaries together with the means for connecting them to
supply.
3.1.16
limiter
device which limits the safety transformer output voltage to a defined maximum value
Note 1 to entry: The probability of electric shock increases with voltage level, surface area of the accessible
conductive part or circuit in contact with the skin and the humidity condition of skin.
3.1.17
safety transformer
isolating transformer with protective separation between the input winding(s) and output
winding(s)
[SOURCE: IEC 61558-1:2017, 3.1.2, modified – Word "isolating" replaced with "safety" in the
term, and "isolating" added to the definition.]
3.1.18
dry condition
skin condition of a surface area of contact with regards to humidity of a living person being at
rest under normal indoor condition
– 12 – IEC 61820-3-4:2023 © IEC 2023
3.2 Abbreviated terms
AGL aeronautical ground lighting
IP code to define the degree of protection of an enclosure
ELV extra low voltage
EMC electromagnetic compatibility
CISPR International Special Committee on Radio Interference
AC alternating current
DC direct current
CCR constant current regulator
DUT device under test
ISO International Standard Organization
IEC International Electrotechnical Commission
ILCMS integrated lamp control and monitoring system
4 Requirements for the SELV/PELV supply
4.1 General
Light fittings for use in aeronautical ground lighting shall be designed for use in a series circuit.
The maximum power ratings of the series circuit supply are given by the constant current
regulators according to IEC 61822. If the light systems are designed for other current ranges,
such information shall be provided by the manufacturer.
The series circuit shall be designed for a nominal system voltage of class V2: nominal system
voltage up to and including 1 000 V AC according to IEC 61820-1:2019, 6.3.
The design of the safety secondary circuit shall support safe working conditions for electrically
skilled persons.
The maintenance practices shall follow IEC 61821. Applicable national or regional regulations
can exist. When considering live work on the secondary circuit, the risk assessment should
consider the nature of the work (fault finding, testing, and repair), the nature of the hazards
present, and the provision of SELV/PELV designs.
The recommendation is to implement a PELV design because it is considered the more practical
solution over complete lifetime of the installation but with the same safety level as a SELV
design. If this recommendation cannot be fulfilled, then it shall be considered that a
maintenance effort needs to be enforced to achieve a suitable insulation level to implement the
SELV design.
In Annex A, Table A.1 gives comparison information of characteristics of PELV and SELV
installations.
NOTE This document does not consider any specific requirements regarding the lightning over voltages. The
SELV/PELV voltage is no more guaranteed in case of lightning that can happen on or at proximity of any of the
component of the system.
4.2 SELV/PELV-safety demarcation line in an AGL series circuit
Figure 1 and Figure 2 show the extent of the safety secondary system. The safety secondary
system (limit defined in 4.7.3) is all circuitry below the dashed red safety demarcation line.
U shall not exceed 1 kV AC RMS.
input
Figure 1 – Safety demarcation line in a safety
extra low voltage system (SELV system)
U shall not exceed 1kV AC RMS.
input
Figure 2 – Safety demarcation line in a protective
extra-low voltage system (PELV system)
NOTE The given earthing in Figure 2 is an example. The earthing connection can be performed anywhere in the
secondary circuit.
The PELV system can be used where local regulations require an earth (bonding of a live
conductor) to be provided.
It is strongly recommended that SELV and PELV systems are not mixed on a single circuit.
– 14 – IEC 61820-3-4:2023 © IEC 2023
4.3 Environmental conditions
Light fittings shall be designed for continuous outdoor operation without any derating factor,
under the following environmental conditions classes according to IEC 61820-1:2019, Table 1:
– class E10: outdoor installation at or above the surface;
– class E11: outdoor installation below the surface.
4.4 Degree of protection provided by enclosures
The degree of protection against contact with conducting parts or the ingress of solid objects
and liquids shall be indicated by the IP coding according to IEC 60529.
Where the supply is intended to be installed outdoors, the following component requirements
class according to IEC 61820-1:2019, Table 2, shall apply:
– class E11: outdoor installation below the surface.
4.5 Electromagnetic compatibility (EMC)
4.5.1 Limits of electromagnetic emission
The SELV/PELV supply (for example: safety transformer plus limiter) shall comply with the
requirements given in the EMC generic standard IEC 61000-6-4. The limits of electromagnetic
emission shall comply with CISPR 11:2015, class B.
4.5.2 Limits of immunity
The SELV/PELV supply (for example: safety transformer plus limiter) shall comply with the
requirements given in the generic standard for industrial environments IEC 61000-6-2. The
immunity limits and methods of measurement of CISPR 32 shall be complied with.
4.6 Marking
4.6.1 Marking of the SELV/PELV power supply (single unit: safety transformer
combined with a limiter)
Each SELV/PELV supply shall be permanently marked. The marking shall contain the following
information:
– unambiguous type designation of the manufacturer;
– name of the manufacturer of the assembly;
– nominal input current;
– nominal output current;
– maximum output power (W and VA);
– marking of the assembly as class III (SELV) with symbol IEC 60417-5180:2003-02 (Roman
III within a rhombus);
– number of the standard IEC 61820-3-4 and its date of publication.
The SELV/PELV marking shall be available to maintenance personnel and easily readable in
the normal installation position (see 4.7.4).
In SELV or PELV systems, only equipment marked as class III shall be used.
4.6.2 Marking of the SELV/PELV power supply (multiple units: safety transformer in
series with a separate limiter)
Each SELV/PELV connecting cable of each unit, starting on the secondary side of the series
circuit transformer, shall be permanently marked. The marking shall contain a SELV/PELV
information:
a) the output cable of the safety transformer and both connecting cables of the limiter unit shall
be marked with a label that indicates the system as a SELV/PELV circuit, but not with a
class III (SELV) symbol (see example in Figure B.1);
b) the label used in a) shall be used for all connecting cables between SELV/PELV power
supply and load (see examples in Figure B.1 to Figure B.6).
4.6.3 Marking at the installation locations
The location of a light fixture fed by a SELV/PELV power supply shall be marked as SELV/PELV.
The marking shall be clearly readable to allow maintenance people to confirm SELV/PELV
condition before starting any work on the installation. If the SELV/PELV supply will be replaced
by a non-SELV/PELV supply, the marking shall be removed or permanently covered
(see examples in Figure B.1 to Figure B.6).
4.7 Protection against electric shock
4.7.1 Basic requirements
Hazardous live parts shall not be accessible and accessible conductive parts shall not be
hazardous live
– neither in normal use without fault, nor
– under single fault conditions.
4.7.2 Protective measure to be applied
The protective mechanisms of the SELV/PELV supply shall not be lost if a single fault occurs.
For this purpose, the following shall be provided:
– limitation of voltage at the output of the SELV/PELV supply;
– protective separation of the SELV/PELV supply from all circuits other than SELV and PELV;
– simple separation of the SELV/PELV supply from other SELV/PELV supply.
For a SELV supply, operational earthing of active parts or the intentional connection of parts to
a protective conductor or to an earth conductor according to IEC 61140 shall not be performed.
Where the safety secondary system is explicitly defined as a PELV supply, the PELV circuits
and/or exposed conductive parts of equipment supplied by the PELV circuit may be earthed.
In locations where protective screening is used for the purp
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