SIST EN 50343:2014
(Main)Railway applications - Rolling stock - Rules for installation of cabling
Railway applications - Rolling stock - Rules for installation of cabling
This European Standard specifies requirements for the installation of cabling on railway vehicles and within electrical enclosures on railway vehicles, including magnetic levitation trains and trolley buses. NOTE With respect to trolley buses, this European Standard applies to the whole electric traction system, including current collecting circuits, power converters and the respective control circuits. The installation of other circuits is covered by street vehicle standards for example those for combustion driven buses. This European Standard covers cabling for making electrical connections between items of electrical equipment, including cables, busbars, terminals and plug/socket devices. It does not cover special effect conductors like fibre optic cables or hollow conductors (waveguides). The material selection criteria given here are applicable to cables with copper conductors. This European Standard is not applicable to the following: – special purpose vehicles, such as track-laying machines, ballast cleaners and personnel carriers; – vehicles used for entertainment on fairgrounds; – vehicles used in mining; – electric cars; – funicular railways. As the field of cabling in rolling stock is also dealt with in the cable makers’ standard, references are made to EN 50264 series, EN 50306 series, EN 50382 series and EN 50355. This European Standard applies in conjunction with the relevant product and installation standards. Stricter requirements than those given in this European Standard may be necessary.
Bahnanwendungen - Fahrzeuge - Regeln für die Installation von elektrischen Leitungen
Applications ferroviaires - Matériel roulant - Règles d'installation du câblage
Železniške naprave - Vozna sredstva - Pravila za inštaliranje kablov
EN 50343 določa zahteve za inštaliranje kablov na železniških vozilih in v električnih ohišjih na železniških vozilih, vključno z vlaki na magnetni blazini in trolejbusi. Ta evropski standard zajema kable za ustvarjanje električnih vezav med predmeti električne opreme, vključno s kabli, zbiralčnimi vodili, terminali in napravami z vtičem/vtičnico. Ne vključuje vodnikov za posebne učinke, kot so kabli optičnih vlaken ali votli vodniki (valovodi). Kriteriji za izbiro materiala v tem standardu veljajo za kable z bakrenimi vodniki. Ta evropski standard se ne uporablja za: - vozila za posebne namene, kot so stroji za polaganje tirnic, odstranjevalci balasta in vozila za prevoz osebja; - vozila za zabavo na sejmih; - vozila za uporabo v rudnikih; električna vozila; - vzpenjače. Ker kable v voznih sredstvih obravnava tudi standard za proizvajalce kablov, standard navaja serije EN 50264, EN 50306, EN 50382 in EN 50355. Ta evropski standard se uporablja v povezavi z ustreznim izdelkom in standardi namestitve. Morda so potrebne strožje zahteve od zahtev iz tega evropskega standarda.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-julij-2014
Železniške naprave - Vozna sredstva - Pravila za inštaliranje kablov
Railway applications - Rolling stock - Rules for installation of cabling
Bahnanwendungen - Fahrzeuge - Regeln für die Installation von elektrischen Leitungen
Applications ferroviaires - Matériel roulant - Règles d'installation du câblage
Ta slovenski standard je istoveten z: EN 50343:2014
ICS:
45.060.01 Železniška vozila na splošno Railway rolling stock in
general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD EN 50343
NORME EUROPÉENNE
EUROPÄISCHE NORM
May 2014
ICS 45.060.01 Supersedes EN 50343:2003
English Version
Railway applications - Rolling stock - Rules for installation of
cabling
Applications ferroviaires - Matériel roulant - Règles Bahnanwendungen - Fahrzeuge - Regeln für die Installation
d'installation du câblage von elektrischen Leitungen
This European Standard was approved by CENELEC on 2014-01-27. 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, 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
© 2014 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 50343:2014 E
Contents
1 Scope . 6
2 Normative references . 6
3 Terms, definitions and abbreviations . 8
3.1 Terms and definitions . 8
3.2 Abbreviations . 10
4 Technical requirements . 10
4.1 General requirements . 10
4.2 Selection of type and size of cables . 11
4.2.1 General . 11
4.2.2 Selection of cable size for control cables . 12
4.2.3 Selection of cable size for cables for power distribution, on the basis of continuous load current . 12
4.2.4 Selection of cable size for cables for power distribution, on the basis of rating of protection device 18
4.2.5 Motor cables . 18
4.2.6 Cables for protective bonding . 18
4.2.7 Cables used under short time current (below 5 s) . 18
4.3 Bundling of cables . 19
4.4 Flexibility of cables. 19
4.5 Minimum cross-sectional area of conductors . 20
4.6 Use of green and yellow colour . 20
4.7 Bending radii and other mechanical requirements . 20
4.8 Re-termination . 22
4.9 Busbars . 22
4.10 Connections to busbars . 23
4.11 Separation of cables with different voltage levels and for safety reasons . 23
4.12 Provisions for refurbishment and maintenance, including inspection and repair . 24
4.13 Fire prevention, cable laying and cabling behaviour in case of fire . 25
4.14 Provision of spares . 26
4.14.1 Provision of spares for control cabling . 26
4.14.2 Provision of spares for auxiliary power distribution cabling. 26
4.15 Requirements for fixing . 26
4.16 Clearances and creepage distances . 27
4.17 Requirements for electrical terminations . 27
4.17.1 General . 27
4.17.2 Electrical terminations at the cable ends . 28
4.17.3 Electrical terminations at the terminal or device side . 28
4.18 Use of heat-shrinkable sleeves . 30
4.19 Connections for return current . 30
4.20 Storage of cables . 30
4.21 Cable conduits . 31
4.22 Electrical bolted connections . 31
5 EMC requirements . 33
5.1 General . 33
5.2 Cable categories . 34
5.3 Separation of cables . 34
5.4 Return conductor . 35
5.5 Use of conductive structure . 35
5.6 Shielding and earthing . 35
5.7 Supply connection from battery . 35
5.8 Databus lines . 36
6 Marking for identification . 36
6.1 General . 36
6.2 Marking for identification of cables and busbars . 36
6.3 Marking for identification of terminal blocks, individual terminals, plugs and sockets . 37
6.4 Marking of insulators . 37
6.5 Marking for warning against electrical shock . 37
– 3 – EN 50343:2014
6.6 Marking using heat-shrinkable sleeves . 37
7 Testing . 37
7.1 General concerning testing . 37
7.2 Electrical insulation tests . 38
7.2.1 General . 38
7.2.2 Voltage withstand test . 38
7.2.3 Insulation impedance test . 40
Annex A (normative) Cable sizing – Calculation under short time current conditions . 42
Annex B (informative) Cable sizing – Examples of current ratings . 43
Annex C (normative) Cable sizing – Calculating current ratings for temperature classes other
than 90 °C . 45
Annex D (normative) Cable sizing – Correction factor k for expected ambient temperature . 46
Annex E (normative) Cable sizing – Prediction of cable lifetime . 47
E.1 General cable lifetime considerations . 47
E.2 Reducing cable lifetime . 48
E.3 Increasing cable lifetime . 49
Annex F (informative) Cable sizing – Calculation examples . 50
Annex G (informative) Terminations . 54
G.1 Methods of terminating cables . 54
G.2 Tensile strength test values . 60
Annex H (normative) Tests on marking when using heat-shrinkable sleeves . 62
H.1 General . 62
H.2 Preparation of specimens . 62
H.3 Testing of specimens . 63
H.4 Result of test . 63
Annex I (informative) Effects of the number of earth connections to a cable screen. 64
Annex J (informative) Differences of electrochemical potentials between some conductive
materials . 65
Electrolyte: water with 2 % NaCl salt. . 65
Source: EN 3197:2010. . 65
Annex K (informative) Locations on board rolling stock to be distinguished . 66
Bibliography . 68
Tables
Table 1 – Modification factor k for individual cores within a multi core cable . 15
Table 2 – Modification factor k for installation type (grouping and installation conditions) . 16
Table 3 – Selection of cable conductor size on the basis of rating of protection device . 18
Table 4 – Minimum internal bending radii R for static applications . 21
Table 5 – Cable categories with respect to EMC . 34
Table 6 – Minimum distances between cables of different EMC categories . 34
Table 7 – Test voltages according to on-board voltages . 40
Table 8 – Test voltages according to supply line voltages . 40
Table A.1 – Modification factor k . 42
Table B.1 – Examples of current ratings for standard wall cables, with 90 °C maximum conductor
operating temperature . 44
Table C.1 – Factor k*, used when comparing current ratings for 90 °C maximum conductor operating
temperature with other temperature classes . 45
Table D.1 – Modification factor k . 46
Table E.1 – Examples of values of correction factor k to allow for decrease in predicted cable
lifetime for a 90 °C cable . 46
Table G.1 – Methods of terminating cables – Conductor side . 54
Table G.2 – Methods of terminating cables – Terminal side – Crimp connections (1/2) . 55
Table G.3 – Methods of terminating cables – Terminal side – Screwed and bolted connection . 57
Table G.4 – Methods of terminating cables – Terminal side – Connection by clamping . 58
Table G.5 – Methods of terminating cables – Terminal side – Connection by insulation displacement
or penetration . 59
Table G.6 – National standards for termination methods . 60
Table G.7 – Pull out force for crimp connections . 61
Table H.1 – Preparation of heat-shrinkable sleeve for test of marking quality . 62
Table I.1 – Effects of shielding . 64
Table J.1 – Differences of electrochemical potentials between some conductive materials (in mV). 65
– 5 – EN 50343:2014
Foreword
This document (EN 50343:2014) has been prepared by CLC/SC 9XB "Electromechanical material on
board rolling stock".
The following dates are fixed:
• latest date by which this document has
(dop) 2015-01-27
to be implemented at national level by
publication of an identical national
standard or by endorsement
• latest date by which the national
(dow) 2017-01-27
standards conflicting with this
document have to be withdrawn
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.
This document supersedes EN 50343:2003.
– references to other standards updated and harmonized;
– factor k concerning sizing of multi core cables introduced;
– factor k detailed, see Table 2;
– short time current detailed;
– mechanical aspects detailed;
– separation of cables due to safety reasons and EMC reasons harmonized;
– details added and changed concerning electrical and mechanical requirements for electrical terminations;
– cable lifetime considerations updated.
This document has been prepared under a mandate given to CENELEC by the European Commission
and the European Free Trade Association.
1 Scope
This European Standard specifies requirements for the installation of cabling on railway vehicles and
within electrical enclosures on railway vehicles, including magnetic levitation trains and trolley buses.
NOTE With respect to trolley buses, this European Standard applies to the whole electric traction system, including current
collecting circuits, power converters and the respective control circuits. The installation of other circuits is covered by street vehicle
standards for example those for combustion driven buses.
This European Standard covers cabling for making electrical connections between items of electrical
equipment, including cables, busbars, terminals and plug/socket devices. It does not cover special effect
conductors like fibre optic cables or hollow conductors (waveguides).
The material selection criteria given here are applicable to cables with copper conductors.
This European Standard is not applicable to the following:
– special purpose vehicles, such as track-laying machines, ballast cleaners and personnel carriers;
– vehicles used for entertainment on fairgrounds;
– vehicles used in mining;
– electric cars;
– funicular railways.
As the field of cabling in rolling stock is also dealt with in the cable makers’ standard, references are made
to EN 50264 series, EN 50306 series, EN 50382 series and EN 50355.
This European Standard applies in conjunction with the relevant product and installation standards.
Stricter requirements than those given in this European Standard may be necessary.
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.
EN 45545 (all parts), Railway applications – Fire protection on railway vehicles
EN 45545-1, Railway applications – Fire protection on railway vehicles – Part 1: General
EN 45545-2, Railway applications – Fire protection on railway vehicles – Part 2: Requirements for fire
behaviour of materials and components
EN 45545-3 Railway applications - Fire protection on railway vehicles - Part 3: Fire resistance
requirements for fire barriers
EN 45545-5, Railway applications – Fire protection on railway vehicles – Part 5: Fire safety requirements
for electrical equipment including that of trolley buses, track guided buses and magnetic levitation vehicles
EN 50121-3-1, Railway applications – Electromagnetic compatibility – Part 3-1: Rolling stock – Train and
complete vehicle
EN 50121-3-2, Railway applications – Electromagnetic compatibility – Part 3-2: Rolling stock – Apparatus
EN 50124-1, Railway applications – Insulation coordination – Part 1: Basic requirements – Clearances
and creepage distances for all electrical and electronic equipment
– 7 – EN 50343:2014
EN 50125-1, Railway applications – Environmental conditions for equipment – Part 1: Equipment on board
rolling stock
EN 50153, Railway applications – Rolling stock – Protective provisions relating to electrical hazards
EN 50200, Method of test for resistance to fire of unprotected small cables for use in emergency circuits
EN 50215:2009, Railway applications – Rolling stock – Testing of rolling stock on completion of
construction and before entry into service
EN 50264 (all parts), Railway applications – Railway rolling stock power and control cables having special
fire performance
EN 50306 (all parts), Railway applications – Railway rolling stock cables having special fire performance –
Thin wall
EN 50306-2, Railway applications – Railway rolling stock cables having special fire performance – Thin
wall – Part 2: Single core cables
EN 50355:2013, Railway applications - Railway rolling stock cables having special fire performance -
Guide to use
EN 50362, Method of test for resistance to fire of larger unprotected power and control cables for use in
emergency circuits
EN 50382 (all parts), Railway applications – Railway rolling stock high temperature power cables having
special fire performance
EN 50467, Railway applications – Rolling stock – Electrical connectors, requirements and test methods
EN 50553, Railway applications – Requirements for running capability in case of fire on board of rolling
stock
EN 60228, Conductors of insulated cables (IEC 60228)
EN 60423, Conduit systems for cable management - Outside diameters of conduits for electrical
installations and threads for conduits and fittings (IEC 60423)
EN 60684-3-212, Flexible insulating sleeving – Part 3: Specifications for individual types of sleeving –
Sheet 212: Heat-shrinkable polyolefin sleevings (IEC 60684-3-212)
EN 60684-3-216 , Flexible insulating sleeving – Part 3: Specifications for individual types of sleeving –
Sheet 216: Heat-shrinkable, flame-retarded, limited-fire hazard sleeving (IEC 60684-3-216)
EN 60684-3-271, Flexible insulating sleeving – Part 3: Specifications for individual types of sleeving –
Sheet 271: Heat-shrinkable elastomer sleevings, flame retarded, fluid resistant, shrink ratio 2:1
(IEC 60684-3-271)
EN 61180-1, High-voltage test techniques for low-voltage equipment – Part 1: Definitions, test and
procedure requirements (IEC 61180-1)
EN 61386-1, Conduit systems for cable management - Part 1: General requirements (IEC 61386-1)
EN 61310-2, Safety of machinery – Indication, marking and actuation – Part 2: Requirements for marking
(IEC 61310-2)
HD 60364-5-54:2011, Low-voltage electrical installations – Part 5-54: Selection and erection of electrical
equipment – Earthing arrangements and protective conductors (IEC 60364-5-54:2011)
3 Terms, definitions and abbreviations
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1.1
cable
assembly consisting of
- one or more cores (screened or unscreened),
- their individual covering(s) (if any),
- assembly protection (if any),
- screen(s) (if any),
- sheath (if any)
[SOURCE: IEC 60050-461, 461-06-01, mod.]
3.1.2
conductor (of a cable)
part of a cable which has the specific function of carrying current
[SOURCE: IEC 60050-461, 461-01-01]
3.1.3
core
assembly comprising a conductor with its own insulation (and screens if any)
[SOURCE: IEC 60050-461, 461-04-04]
3.1.4
solid conductor
conductor consisting of a single wire
[SOURCE: IEC 60050-461, 461-01-06, mod.]
3.1.5
stranded conductor
conductor consisting of a number of individual wires or strands all or some of which generally have a
helical form
[SOURCE: IEC 60050-461, 461-01-07, mod.]
3.1.6
busbar
conductor consisting of a rigid metal profile
3.1.7
screen (of a cable)
conducting layer(s) having the function of control of the electro magnetic field within the cable and/or to
protect the cable from external electro magnetic influences
[SOURCE: IEC 60050-461, 461-03-01, mod.]
3.1.8
bundle
group of cables tied together
– 9 – EN 50343:2014
3.1.9
bolted connection
connection in which the pressure to the conductor is applied by bolting
[SOURCE: IEC 60050-461, 461-19-05]
3.1.10
crimp
cable termination in which a permanent connection is made by applying pressure, inducing the
deformation or reshaping of a barrel part of the termination around the conductor
[SOURCE: IEC 60050-461, 461-19-01, mod.]
3.1.11
spring-clamp connection
terminal connection in which the pressure between the conductor and terminal is applied by a spring
3.1.12
penetration (connection)
terminal connection in which the contact with the conductor is achieved by jaws which penetrate the
insulation
3.1.13
plug
connector intended to be coupled at the free end of an insulated conductor or cable, to be inserted into a
matching socket, or readily removed when required
3.1.14
socket
connector intended to be mounted on a rigid surface and to hold a matching plug, such that the
conductors contained within the socket make electrical contact individually with those in the plug
3.1.15
heat-shrinkable sleeve
tube that on exposure to heat during installation, will at a critical temperature, permanently reduce in
diameter, while increasing in wall thickness
3.1.16
manufacturer
organisation that has the responsibility for the supply of vehicle(s), equipment or groups of equipment to
the purchaser
3.1.17
purchaser
organisation that orders the vehicle or equipment or groups of equipment and has the responsibility for
direct negotiations with the manufacturer
3.1.18
cable tie
mechanical construction needed for either keeping cables or assemblies of cables together, or for
attaching them in a defined place.
3.1.19
Short time current
Certain operation case where an electrical circuit carries a current that will introduce an amount of heat
into the electrical circuit, which in general will increase its temperature. “Short time” means that the heat
exchange against the surrounding material is not significant.
3.2 Abbreviations
For the purposes of this document, the following abbreviations apply.
EMC Electromagnetic compatibility
CSA Cross sectional area
IP Ingress protection
UV Ultraviolet
rms root mean square
DC Direct current
AC Alternating current
4 Technical requirements
4.1 General requirements
Cables and installation materials shall be type tested, selected for size and installed so as to be suitable
for their function under their operating conditions. Size and installation of cables (including busbars and
bare conductors) shall take into account the particular stresses to be expected in rolling stock. The
materials used and methods of cabling shall be such as to prevent strain or chafing and excessive lengths
of unsupported cable shall be avoided.
Cables on rolling stock shall not be used for any purpose other than for transmission, distribution and
collection of electrical energy, electrical controls or monitoring systems. All components of cabling shall be
selected, installed, protected, used and maintained so as to prevent danger (e.g. electrical or fire hazard,
EMC problems).
The electrical connections shall be made in such a way that they can not be unintentionally disconnected
or interrupted during service.
Effects that have impact on electrical connections and should be considered are at least:
– thermal effects
– dynamic loads as shock, vibration, car-body motions.
– material creepage
For consideration of environmental conditions, EN 50125-1 shall apply.
When considering operating conditions and environmental conditions, the locations as presented in
Annex K (informative) should be taken into account.
For correct use of connectors, EN 50467 shall apply.
– 11 – EN 50343:2014
For protection against electrical hazard, the cabling installed shall be in accordance with EN 50153.
4.2 Selection of type and size of cables
4.2.1 General
When selecting cables or busbars the expected operating conditions should be taken into account. These
should include but are not limited to the following parameters:
– voltage;
– current;
– overload current;
– short time current;
– voltage drop;
– short-circuit current;
– shape and frequency of current;
– fusing characteristic of the protection device;
– grouping of cables;
– ambient temperature and temperature due to load current;
– methods of installation;
– predicted cable lifetime;
– presence of rain or steam or snow or accumulation of condensing water;
– presence of corrosive, polluting or damaging substances;
– mechanical stresses;
– radiation such as sunlight.
Consideration should be given to the expected lifetime of the cabling compared with the expected lifetime
of the vehicle.
The cable type (i.e. cable family) shall be selected in accordance with EN 50264 series, EN 50382 series
or EN 50306 series, as applicable.
Once the cable type has been selected, the selection of conductor size if the cable is intended for power
distribution shall be based on either load current and current carrying capacity calculated in accordance
with 4.2.3 or based on protection device size in accordance with 4.2.4.
Short-circuit conditions and overload conditions should be checked with respect to the fusing
characteristic of the protection device and the resistance of the chosen cable. See example in Figure 1.
Short-circuit conditions should be checked according to 4.2.7.
This short-circuit or overload case should be checked according to:
Normal load < nominal current rating of protection device ≤ current carrying capacity of the cable
( I , see definition in 4.2.3 b) ).
corr
+
Power supply
Protection device
Short circuit Impedance of complete current path
Load
0V
Figure 1 – Example of short-circuit condition
where cable size will have influence on protection device behaviour
The cross-sectional area of any conductor shall be not less than the value specified in 4.5.
Cables and cabling shall be conform to the fire safety requirements specified in EN 45545-2, EN 45545-3
and EN 45545-5.
The number of different types of cables installed on any one type of vehicle should be minimized for
practical reasons.
4.2.2 Selection of cable size for control cables
Control cables, which are intended to carry control signals only, shall have a minimum conductor cross-
sectional area as specified in 4.5. This is also valid if the load current would make a smaller cross-
sectional area possible.
NOTE It is not necessary for the conductor size of these cables to be selected according to 4.2.3.
4.2.3 Selection of cable size for cables for power distribution, on the basis of continuous load
current
This subclause specifies a method for calculation of continuous maximum load current, of time duration
longer than 5 s, of different cable sizes dependent on their method of installation and ambient
temperature, to enable cables to be selected so as to ensure that the predicted lifetime is achieved.
For short time current, up to 5 s, see 4.2.7.
– 13 – EN 50343:2014
Correction factors from cable manufacturers should not be combined with correction factors given in this
standard, in order to avoid miscalculation or oversizing.
The continuous maximum conductor temperature for the cable types defined in the various parts of
EN 50264, EN 50306 and EN 50382 is either 90 °C, 105 °C and 120 °C or 150 °C. This is based either on
proven experience and reliability over many years or in the case of newer, less well defined, insulations
upon an acceptance test, using long-term thermal endurance ageing to demonstrate a lifetime of at least
20 000 h at 110 °C, 125 °C and 140 °C or 170 °C respectively (i.e. 20 °C above the continuous rating).
Data from this thermal testing can, with care, be extrapolated to the conductor temperature to provide a
predicted lifetime of the cable when continuously loaded. This predicted lifetime may be used in
conjunction with the known duty cycle of the vehicle, and its predicted time out of service, to estimate the
ability of the cable to function reliably for the predicted lifetime of the whole vehicle.
NOTE 1 Because the cable standards allow a variety of solutions for insulation type, it is important to confirm lifetime
extrapolations with the cable manufacturer.
NOTE 2 A predicted lifetime of cable of 100 000 h may be used as a theoretical basis value for cables according to EN 50264,
EN 50306 or EN 50382 series and their specific maximum conductor temperature at continuous operation.
This subclause only deals with thermal degradation of insulation material and it should be noted that
mechanical stresses (bending, wear, etc.) and other environmental factors (such as presence of fluids
such as cleaning detergents, aggressive atmosphere) may be the limiting factor determining predicted
cable lifetime.
For cables intended for power distribution, the cable size shall be selected on the basis of the load current
and the current carrying capacity in accordance with the following procedure (i.e. the three steps a), b)
and c)).
a) The load current
The load current I , in amperes (A) which a cable has to carry for sustained periods during normal
load
service shall be a basic value for cable sizing.
When the circuit(s) being supplied by the cable is in continuous or sustained cyclic operation, I
load
shall be calculated according to the following formula:
I = i dt
load
∫
t
where
t is the duration of a typical duty cycle during service, in minutes (min);
i is the instantaneous current – including overload, if any - in amperes (A).
NOTE 3 For continuous direct current operation, the above formula has the simple form I = i .
load
When operation is not continuous or sustained cyclic, I shall be calculated according to Annex A.
load
b) The current carrying capacity
The permissible continuous current carrying capacity I in amperes (A) of a single-core cable or a
cable
single core within a multi core cable being operated in free air shall be another basic value for cable
sizing. A particular value of I is valid for a particular reference ambient temperature T and for
cable ref
a particular maximum conductor temperature in service, T .
c(max)
I within the reference values T and T , shall be those provided by the cable manufacturer.
cable ref c(max)
Examples for I for single core cables are presented in Annex B.
cable
I for maximum conductor temperatures other than T = 90 °C, shall be calculated according
c(max)
cable
to Annex C.
The current carrying capacity of the cable in service, I , in amperes (A) shall be calculated from
corr
I using correction factors k , k , k , k , k , in accordance with the following formula.
1 2 3 4 5
cable
I = I × k× k × k × k × k
corr cable 1 2 3 4 5
where
k is a correction factor for the expected ambient temperature. It shall be calculated according
to the following formula:
T -T
c(max)
k =
T -T
c(max) ref
where
T is the maximum conductor temperature, in degrees Celsius (°C), in service, which
c(max)
will allow the predicted lifetime of the cable to be achieved;
T is the estimated value of the actual ambient temperature, in degrees Celsius (°C)
during operation, on the outside of the bundle or of the tube - if any. T is an
average value;
T is the reference ambient temperature, in degrees Celsius (°C), for which the
ref
I value is valid.
cable
Examples of values are given in Table D.1.
k
k is a correction factor for installation type (grouping and installation conditions).
Values for k given in Table 2 shall be used. Interpolation between the different numbers of cables in
Table 2 is allowed.
k is a correction factor to allow for a decrease in predicted cable lifetime, calculated according to
the formula in Annex E. In all cases where the standard predicted cable lifetime shall be used, the
value of k shall be 1,0.
is a correction factor to take into account short time current when operation is not continuous,
k
calculated according to the procedure in Annex A. When operation is continuous, the value of k
shall be 1,0.
k is a correction factor for multi core cables; the correction factor k is applicable for each individual
5 5
core within a multi core cable. Values for k are given in Table 1. Interpolation between the different
number of cores in Table 1 is allowed. When single core cables are used, the value of k shall be 1,0.
– 15 – EN 50343:2014
If single core cables and multi core cables are lying together on the same cable tray, open or close,
by the correction factor k , different values for are obtained for single core cables and multi core
I
corr
cables.
Table 1 – Modification factor k for individual cores within a multi core cable
Number of loaded cores
2 3 4 5 7 9 12 19
0,91 0,78 0,63 0,59 0,51 0,46 0,41 0,38
Correction factor k
c) Selection of cable size
The cable size shall be selected such that the current carrying capacity of the cable in service,
calculated in accordance with item b) is greater than or equal to the predicted load current, calculated
in accordance with item a) i.e.
I ≤ I
load corr
The minimum cross-sectional area of the conductor shall be as specified in 4.5.
NOTE 4 Combining the formulae from 4.2.3 a) and b) and c), would lead to the following formula:
I
load
I ≥
cable
k× k × k × k × k
1 2 3 4 5
This formula will in practice be more easy to use, because in cases with defined cable type and defined load conditions the
last term will be constant and so it is easy to find the right cable size via I in the current ratings table (see examples in
cable
Table B.1).
For a calculation example refer to Annex F.
Table 2 – Modification factor k for installation type (grouping and installation conditions)
Installation type
Cable in Cables Cables Cables Cables Cables in
Cables Cables
Number of cables
free air on trays, on trays, on a in a a closed
on trays, on the
being in one in two ceiling
closed tube or
in floor or
simultaneously layer layers or under tube, conduit,
several on a
loaded floor conduit thermally
layers wall
or tray insulated
Type e) Type f) Type g)
Type a) Type b) Type c) Type d)
1 single cable 1,0 1,0 1,0 1,0 1,0 0,95 0,95 0,76
2 cables together - 0,87 0,87 0,87 0,85 0,81 0,80 0,61
3 cables together - 0,83 0,83 0,78 0,79 0,72 0,70 0,53
4 cables together - 0,78 0,71 0,71 0,75 0,68 0,65 0,49
8 cables together - 0,74 0,59 0,52 0,75 0,62 0,52 0,40
12 cables together - 0,73 0,54 0,45 0,75 0,61 0,45 0,34
16 cables together - 0,72 0,51 0,41 0,75 0,61 0,41 0,31
20 cables and more - 0,71 0,47 0,38 0,75 0,61 0,38 0,29
together
Details of installation types are as follows:
Type a) One single cable in free air with heat dissipation into the surrounding air ensured by all the following
measures:
- distance between the cable and adjacent walls over, under or beside: At least equal to the cable diameter;
- distance between the cable and any other cable lying beside it in any direction: At least equal to the sum of
its own cable diameter and the adjacent cable diameters;
- cable lying in an open tray or ladder support with perforations, the total area “A” in Figure 2 of the
perforations being at least 15 % of the total supporting area in case of metallic tray or support with good
thermal contact to car-body (otherwise at least 30 %), and without any cover.
Type b) Cables lying in one layer, touching each other, on an open tray or ladder support, with perforations as
for type a).
Type c) As for type b) but cables in several layers over each other.
Type f) Cables lying in bundles in closed tubes, closed trays or boxes without significant air flow.
Type g) As for type f), but for thermally completely insulated closed tubes, closed trays or boxes.
Current flowing through the screen (e.g. motor cables and brake resistors) should be calculated as an
additional conductor.
NOTE Installation types a), b), c), d), e) and f) are illustrated in Figure 2.
– 17 – EN 50343:2014
a)
b)
≥ D
≥ (D+d)
D
d
A
A
c)
d)
A
e)
f)
g)
Figure 2 - Cable grouping and installation conditions
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