Electrical installations for lighting and beaconing of aerodromes - Safety secondary circuits in series circuits - General safety requirements

IEC 62870:2015 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.

Installations électriques pour l'éclairage et le balisage des aérodromes - Circuits secondaires de sécurité dans des circuits série - Exigences générales de sécurité

L'IEC 62870:2015 spécifie des dispositions de protection pour le fonctionnement de systèmes de feux alimentés par des circuits série pour le balisage lumineux 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.

General Information

Status
Published
Publication Date
15-Sep-2015
Current Stage
PPUB - Publication issued
Start Date
16-Sep-2015
Completion Date
16-Sep-2015
Ref Project

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IEC 62870
Edition 1.0 2015-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electrical installations for lighting and beaconing of aerodromes –Safety
secondary circuits in series circuits – General safety requirements
Installations électriques pour l’éclairage et le balisage des aérodromes –
Circuits secondaires de sécurité dans des circuits série – Exigences générales
de sécurité
IEC 62870:2015-09(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 62870
Edition 1.0 2015-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electrical installations for lighting and beaconing of aerodromes –Safety
secondary circuits in series circuits – General safety requirements
Installations électriques pour l’éclairage et le balisage des aérodromes –
Circuits secondaires de sécurité dans des circuits série – Exigences générales
de sécurité
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.140.50; 93.120 ISBN 978-2-8322-2896-8

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – IEC 62870:2015 © IEC 2015
CONTENTS

FOREWORD ........................................................................................................................... 3

INTRODUCTION ..................................................................................................................... 5

1 Scope .............................................................................................................................. 6

2 Normative references ...................................................................................................... 6

3 Terms and definitions ...................................................................................................... 7

4 Requirements for the SELV/PELV supply ......................................................................... 9

4.1 General ................................................................................................................... 9

4.2 SELV/PELV-safety demarcation line in an AGL series circuit ................................ 10

4.3 Environmental conditions ...................................................................................... 11

4.4 Degree of protection provided by enclosures ........................................................ 11

4.5 Electromagnetic compatibility (EMC) ..................................................................... 11

4.5.1 Limits of electromagnetic emission ................................................................ 11

4.5.2 Limits of immunity .......................................................................................... 12

4.6 Marking ................................................................................................................. 12

4.6.1 Marking of the SELV/PELV power supply ....................................................... 12

4.6.2 Marking at the installation locations ............................................................... 12

4.7 Protection against electric shock ........................................................................... 12

4.7.1 Basic requirements ........................................................................................ 12

4.7.2 Protective measure to be applied ................................................................... 12

4.7.3 Protective separation from the primary series circuit ...................................... 13

4.7.4 Assemblies in the SELV/PELV supply ............................................................ 13

4.7.5 Load of the SELV/PELV supply ...................................................................... 13

4.8 Interfaces .............................................................................................................. 14

4.8.1 Supply unit .................................................................................................... 14

4.8.2 Connectors .................................................................................................... 14

5 Testing .......................................................................................................................... 14

5.1 Type tests ............................................................................................................. 14

5.2 Routine tests......................................................................................................... 14

Annex A (informative) System design selection .................................................................... 15

Bibliography .......................................................................................................................... 16

Figure 1 – Safety demarcation line in a SELV system ........................................................... 10

Figure 2 – Safety demarcation line in a PELV system ........................................................... 11

Table A.1 – Comparison of characteristics of PELV and SELV .............................................. 15

---------------------- Page: 4 ----------------------
IEC 62870:2015 © IEC 2015 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL INSTALLATIONS FOR
LIGHTING AND BEACONING OF AERODROMES –
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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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 62870 has been prepared by IEC technical committee 97:

Electrical installations for lighting and beaconing of aerodromes.
The text of this standard is based on the following documents:
FDIS Report on voting
97/167/FDIS 97/169/RVD

Full information on the voting for the approval of this standard can be found in the report on

voting indicated in the above table.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

---------------------- Page: 5 ----------------------
– 4 – IEC 62870:2015 © IEC 2015

The committee has decided that the contents of this publication will remain unchanged until

the stability date indicated on the IEC website under "http://webstore.iec.ch" in the data

related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

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.
---------------------- Page: 6 ----------------------
IEC 62870:2015 © IEC 2015 – 5 –
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 a.c. 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 circuits, 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, maybe 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

taken into account in the requirements for lamp systems in this standard.

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 standard 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 illuminant technology that has lower power requirements

and hence requires a lower voltage supply.

NOTE This standard is based on SELV specification according to IEC 60364-4-41 and IEC 61558-1.

---------------------- Page: 7 ----------------------
– 6 – IEC 62870:2015 © IEC 2015
ELECTRICAL INSTALLATIONS FOR
LIGHTING AND BEACONING OF AERODROMES –
SAFETY SECONDARY CIRCUITS IN SERIES CIRCUITS –
GENERAL SAFETY REQUIREMENTS
1 Scope

This International Standard 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 standard 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 standard 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.

The requirements and tests are intended to set a specification framework for system

designers, users, and maintenance personnel to ensure a safe and economic use of electrical

systems in installations for the beaconing of aerodromes.

This standard complements existing IEC Airfield-Ground- Lighting (AGL) standards and can

be used as a design specification.
2 Normative references

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.

IEC 60364-4-41, Low-voltage electrical installations – Part 4-41: Protection for safety –

Protection against electric shock

IEC 60417, Graphical symbols for use on equipment (available from: http://www.graphical-

symbols.info/equipment)
IEC 60529, Degrees of protection provided by enclosures (IP Code)

IEC 61000-6-2, Electromagnetic compatibility (EMC) – Part 6-2: Generic standards –

Immunity for industrial environments

IEC 61000-6-4, Electromagnetic compatibility (EMC) – Part 6-4: Generic standards –

Emission standard for industrial environments

IEC 61140, Protection against electric shock – Common aspects for installation and

equipment
---------------------- Page: 8 ----------------------
IEC 62870:2015 © IEC 2015 – 7 –

IEC 61558-2-4, Safety of transformers, reactors, power supply units and similar products for

supply voltages up to 1 100 V – Part 2-4: Particular requirements and tests for isolating

transformers and power supply units incorporating isolating transformers

IEC 61558-2-6, Safety of transformers, reactors, power supply units and similar products for

supply voltages up to 1 100 V – Part 2-6: Particular requirements and tests for safety isolating

transformers and power supply units incorporating safety isolating transformers

IEC 61821, Electrical installations for lighting and beaconing of aerodromes – Maintenance of

aeronautical ground lighting constant current series circuits

IEC 61822, Electrical installations for lighting and beaconing of aerodromes – Constant

current regulators

IEC 61823, Electrical installations for lighting and beaconing of aerodromes – AGL series

transformers

CISPR 11, Industrial, scientific and medical equipment – Radio-frequency disturbance

characteristics – Limits and methods of measurement

CISPR 22, Information technology equipment – Radio disturbance characteristics – Limits and

methods of measurement
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
assembly

self-contained, closed functional unit forming a lamp system together with other assemblies

3.2
electrical equipment
equipment

anything used, intended to be used or installed for use, to generate, provide, transmit,

transform, rectify, convert, conduct, distributes, control, store, measure or use electrical

energy
3.3
basic protection
protection against electric shock under fault-free conditions
3.4
basic insulation
insulation of hazardous live parts providing basic protection

Note 1 to entry: The term “basic insulation” does not include insulation used exclusively for functional purposes.

3.5
electrically skilled person

person with relevant education and experience to enable him or her to perceive risks and to

avoid hazards which electricity can create
[SOURCE: IEC 60050-195:1998,195-04-01]
---------------------- Page: 9 ----------------------
– 8 – IEC 62870:2015 © IEC 2015
3.6
SELV/PELV power supply

single physical unit or an assembly of physical units performing as the power supply

according to SELV/PELV definitions
3.7
extra-low voltage
ELV
voltage not exceeding the relevant voltage limit specified in 3.9
3.8
lighting system
the SELV/PELV power supply unit and all connected components supplied from the
SELV/PELV
3.9
safety extra-low voltage
SELV

voltage values of which does not exceed values in 4.7.2 , 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

3.10
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 60050-826:2004, 826-12-31]
3.11
SELV-circuit

ELV circuit with protective separation from other circuits, and which has neither provisions for

earthing of the circuit nor of the exposed conductive parts
Note 1 to entry: SELV circuit does not include the housing of the light fixture.
[SOURCE: IEC 61558-1:2005, 3.7.17, modified – addition of a note to entry]
3.12
electrically protective separation
protective separation
separation of one electric circuit from another by means of:
– double insulation or
– basic insulation and electrically protective screening or
– reinforced insulation
3.13
protective extra low voltage circuit
PELV-circuit

ELV circuit with protective separation from other circuits and which, for functional reasons,

may be earthed and/or the exposed conductive parts of which may be earthed

Note 1 to entry: PELV-circuits are used where the circuits are earthed and SELV is not required.

---------------------- Page: 10 ----------------------
IEC 62870:2015 © IEC 2015 – 9 –
[SOURCE: IEC 61558-1:2005, 3.7.18]
3.14
power supply unit

all components for the supply and transfer of energy used to operate a lighting unit in a series

circuit
3.15
electric shock

physiological effect resulting from an electric current passing through a human or animal body

[SOURCE: IEC 60050-195:1998, 195-01-04]
3.16
hazardous live part
live part which, under certain conditions, can give a harmful electric shock
[SOURCE: IEC 60050-195:1998, 195-06-05]
3.17
effective touch voltage
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 60050-195:1998, 195-05-11]
3.18
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]
3.19
light fixture(US)
light fitting (UK)
luminaire

electrical device used to create artificial light by use of an electric lamp above ground or

inside 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.
4 Requirements for the SELV/PELV supply
4.1 General

Lamp systems 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 lamp systems are designed for other current ranges, such information shall be provided

by the manufacturer.
---------------------- Page: 11 ----------------------
– 10 – IEC 62870:2015 © IEC 2015

The design of the safety secondary circuit shall support safe working conditions for electrically

skilled persons.

The maintenance practices shall follow IEC 61821. When considering life work on the

secondary circuit the risk assessment should take into account 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 live time of the installation but with the same safety level as a

SELV design. If this requirement could not be fulfilled then it has to be considered that you

need to enforce maintenance effort to achieve a suitable insulation level to implement the

SELV design.
4.2 SELV/PELV-safety demarcation line in an AGL series circuit

Figure 1 and Figure 2 below show the extent of the safety secondary system. The safety

secondary system (50 V a.c. or 120 V d.c. level) is all circuitry below the dashed safety

demarcation line.
circuit
circuit
mains
series circuit
CCR
Input
SELV/PELV
supply
supply input supply input supply input supply input
safety
demarcation
SELV/PELV SELV/PELV SELV/PELV SELV/PELV
line
output level output level output level output level
load load
load load
IEC
Figure 1 – Safety demarcation line in a SELV system
---------------------- Page: 12 ----------------------
IEC 62870:2015 © IEC 2015 – 11 –
circuit
circuit
mains
series circuit
CCR
Input
SELV/PELV
supply
supply input supply input supply input supply input
safety
demarcation
line
...

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