IEC 61439-6:2012

Low-voltage switchgear and controlgear assemblies - Part 6: Busbar trunking systems (busways)

IEC 61439-6:2012 lays down the definitions and states the service conditions, construction requirements, technical characteristics and verification requirements for low voltage BTS (see 3.101) as follows:
- BTS for which the rated voltage does not exceed 1 000 V in case of a.c. or 1 500 V in case of d.c.;
- BTS intended for use in connection with the generation, transmission, distribution and conversion of electric energy, and for the control of electric energy consuming equipment;
- BTS designed for use under special service conditions, for example in ships, in rail vehicles, and for domestic applications (operated by unskilled persons), provided that the relevant specific requirements are complied with;
- BTS designed for electrical equipment of machines. Supplementary requirements for BTS forming part of a machine are covered by the IEC 60204 series. This first edition of IEC 61439-6 cancels and replaces the third edition of IEC 60439-2 (2000) and its Amendment 1 (2005), and constitutes a technical revision. This edition of IEC 61439-6 includes the following significant technical changes with respect to the latest edition of IEC 60439-2:
- alignment on the second edition of IEC 61439-1 (2011) regarding the structure and technical content, as applicable;
- introduction of new verifications, accordingly;
- correction of inconsistencies in resistance, reactance and impedance measurements and calculations;
- numerous editorial improvements.
This publication is to be read in conjunction with IEC 61439-1:2011.

Ensembles d'appareillage à basse tension - Partie 6: Systèmes de canalisation préfabriquée

La CEI 61439-6:2012 formule les définitions et indique les conditions d'emploi, les exigences de construction, les caractéristiques techniques et les exigences de vérification pour les SCP à basse tension (voir 3.101), comme suit:
- SCP dont la tension assignée ne dépasse pas 1 000 V en courant alternatif ou 1 500 V en courant continu;
- SCP destinés à être utilisés avec des équipements conçus pour la production, le transport, la distribution et la conversion de l'énergie électrique et la commande des matériels consommant de l'énergie électrique;
- SCP conçus pour être utilisés dans des conditions spéciales d'emploi, par exemple, à bord de navires et de véhicules ferroviaires, et pour des applications domestiques (utilisation par des personnes non qualifiées), sous réserve que les autres exigences spécifiques correspondantes soient respectées;
- SCP conçus pour l'équipement électrique des machines. Les exigences supplémentaires relatives aux SCP faisant partie intégrante d'une machine sont couvertes par la série CEI 60204. Cette première édition de la CEI 61439-6 annule et remplace la troisième édition de la CEI 60439-2 (2000) et son Amendement 1 (2005), dont elle constitue une révision technique. Cette édition de la CEI 61439-6 inclut les modifications techniques majeures suivantes par rapport à la dernière édition de la CEI 60439-2:
- alignement sur la deuxième édition de CEI 61439-1 (2011) concernant la structure et le contenu technique, selon le cas;
- introduction de nouvelles vérifications, en conséquence;
- correction des incohérences en termes de mesures et de calculs des valeurs de résistance, de réactance et d'impédance;
- nombreuses améliorations rédactionnelles.
Cette publication doit être lue conjointement avec la CEI 61439-1:2011.

General Information

• Status: Published
• Publication Date: 22-May-2012
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 29.130.20 - Low voltage switchgear and controlgear
• ICS: 33.200 - Telecontrol. Telemetering
• Technical Committee: SC 121B - Low-voltage switchgear and controlgear assemblies
• Current Stage: PPUB - Publication issued
• Start Date: 23-May-2012
• Completion Date: 23-May-2012

Standards Content (sample)

IEC 61439-6
Edition 1.0 2012-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Low-voltage switchgear and controlgear assemblies –
Part 6: Busbar trunking systems (busways)
Ensembles d'appareillage à basse tension –
Partie 6: Systèmes de canalisation préfabriquée
IEC 61439-6:2012
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 61439-6
Edition 1.0 2012-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Low-voltage switchgear and controlgear assemblies –
Part 6: Busbar trunking systems (busways)
Ensembles d'appareillage à basse tension –
Partie 6: Systèmes de canalisation préfabriquée
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX X
ICS 29.130.20 ISBN 978-2-83220-084-1

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 – 61439-6 © IEC:2012
CONTENTS

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

1 Scope ............................................................................................................................... 5

2 Normative references ....................................................................................................... 5

3 Terms and definitions ....................................................................................................... 6

4 Symbols and abbreviations ............................................................................................... 8

5 Interface characteristics ................................................................................................... 8

6 Information ..................................................................................................................... 12

7 Service conditions .......................................................................................................... 12

8 Constructional requirements ........................................................................................... 13

9 Performance requirements ............................................................................................. 14

10 Design verifications ........................................................................................................ 15

11 Routine verifications ....................................................................................................... 27

Annexes ............................................................................................................................... 28

Annex C (informative) Specification schedule ...................................................................... 29

Annex D (informative) Design verification ............................................................................ 33

Annex AA (informative) Voltage drop of the system.............................................................. 34

Annex BB (informative) Phase conductor characteristics ...................................................... 35

Annex CC (informative) Fault-loop zero-sequence impedances ............................................ 37

Annex DD (informative) Fault-loop resistances and reactances ............................................ 39

Annex EE (informative) Determination of the magnetic field in the vicinity of the BTS .......... 41

Bibliography .......................................................................................................................... 42

Figure 101 – Mechanical load test of a straight unit .............................................................. 16

Figure 102 – Mechanical load test of a joint .......................................................................... 16

Figure 103 – Test arrangement for verification of a fire-barrier BTU ...................................... 27

Figure BB.1 – Phase conductors characteristics determination ............................................. 35

Figure CC.1 – Fault loop zero-sequence impedances determination ..................................... 37

Figure DD.1 – Fault loop resistances and reactances determination ..................................... 39

Figure EE.1 – Magnetic field measurement arrangement ...................................................... 41

Table 101 – Rated diversity factor for a tap-off unit ............................................................... 10

Table 102 – Phase conductor characteristics ........................................................................ 11

Table 103 – Fault-loop characteristics .................................................................................. 11

Table 104 – Characteristics to be used for fault currents calculations ................................... 12

Table 105 – Conditioning for the thermal cycling test ............................................................ 18

Table C.1 – User specification schedule ............................................................................... 29

Table D.1 – Design verifications ........................................................................................... 33

---------------------- Page: 4 ----------------------
61439-6 © IEC:2012 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR ASSEMBLIES –
Part 6: Busbar trunking systems (busways)
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote

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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 61439-6 has been prepared by subcommittee 17D: Low-voltage

switchgear and controlgear assemblies, of IEC technical committee 17: Switchgear and

controlgear.

This first edition of IEC 61439-6 cancels and replaces the third edition of IEC 60439-2 (2000)

and its Amendment 1 (2005), and constitutes a technical revision.

This edition of IEC 61439-6 includes the following significant technical changes with respect

to the latest edition of IEC 60439-2:

• alignment on the second edition of IEC 61439-1 (2011) regarding the structure and

technical content, as applicable;
• introduction of new verifications, accordingly;

• correction of inconsistencies in resistance, reactance and impedance measurements and

calculations;
• numerous editorial improvements.
---------------------- Page: 5 ----------------------
– 4 – 61439-6 © IEC:2012
The text of this standard is based on the following documents:
FDIS Report on voting
17D/452/FDIS 17D/454/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.

This standard is to be read in conjunction with the second edition of IEC 61439-1. The

provisions of the general rules dealt with in IEC 61439-1 (hereinafter referred to as Part 1) are

only applicable to this standard insofar as they are specifically cited. When this standard

states “addition”, “modification” or “replacement”, the relevant text in Part 1 is to be adapted

accordingly.

Subclauses that are numbered with a 101 (102, 103 etc.) suffix are additional to the same

subclause in Part 1.
Tables and figures in this Part 6 that are new are numbered starting with 101.
New annexes in this Part 6 are lettered AA, BB, etc.

The “in some countries” notes regarding differing national practices are contained in the

following subclauses:
5.4

A list of all parts of the IEC 61439 series, under the general title Low-voltage switchgear and

controlgear assemblies can be found on the IEC website.

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

the stability date indicated on the IEC web site 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.
---------------------- Page: 6 ----------------------
61439-6 © IEC:2012 – 5 –
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR ASSEMBLIES –
Part 6: Busbar trunking systems (busways)
1 Scope

NOTE 1 Throughout this part, the abbreviation BTS is used for a busbar trunking system. Where reference to

Part 1 is made, the term ASSEMBLY therefore reads as “BTS”.

This part of IEC 61439 lays down the definitions and states the service conditions,

construction requirements, technical characteristics and verification requirements for low

voltage BTS (see 3.101) as follows:

• BTS for which the rated voltage does not exceed 1 000 V in case of a.c. or 1 500 V in

case of d.c.;

• BTS intended for use in connection with the generation, transmission, distribution and

conversion of electric energy, and for the control of electric energy consuming equipment;

• BTS designed for use under special service conditions, for example in ships, in rail

vehicles, and for domestic applications (operated by unskilled persons), provided that the

relevant specific requirements are complied with;
NOTE 2 Supplementary requirements for BTS in ships are covered by IEC 60092-302.

• BTS designed for electrical equipment of machines. Supplementary requirements for BTS

forming part of a machine are covered by the IEC 60204 series.

This standard applies to all BTS whether they are designed, manufactured and verified on a

one-off basis or fully standardized and manufactured in quantity.

The manufacture and/or assembly may be carried out by a manufacturer other than the

original manufacturer (see 3.10.1 and 3.10.2 of Part 1).

This standard does not apply to individual devices and self-contained components, such as

motor starters, fuse switches, electronic equipment, etc. which will comply with the relevant

product standard.

This standard does not apply to the specific types of ASSEMBLIES covered by other parts of the

IEC 61439 series, to supply track systems in accordance with IEC 60570, to cable trunking

and ducting systems in accordance with the IEC 61084 series, nor to power track systems in

accordance with the IEC 61534 series.
2 Normative references
This clause of Part 1 is applicable except as follows.
Addition:

IEC 60332-3-10:2000, Tests on electric and optical fibre cables under fire conditions –

Part 3-10: Test for vertical flame spread of vertically-mounted bunched wires or cables –

Apparatus

IEC 60439-2:2000, Low-voltage switchgear and controlgear assemblies – Part 2: Particular

requirements for busbar trunking systems (busways)
---------------------- Page: 7 ----------------------
– 6 – 61439-6 © IEC:2012

IEC 61439-1:2011, Low-voltage switchgear and controlgear assemblies – Part 1: General

rules

IEC 61786:1998, Measurement of low-frequency magnetic and electric fields with regard to

exposure of human beings – Special requirements for instruments and guidance for
measurements

ISO 834-1:1999, Fire-resistance tests – Elements of building construction – Part 1: General

requirements
3 Terms and definitions
This clause of Part 1 is applicable except as follows.
Additional definitions:
3.101
busbar trunking system
BTS
busway

enclosed ASSEMBLY used to distribute and control electrical energy for all types of loads,

intended for industrial, commercial and similar applications, in the form of a conductor system

comprising busbars which are spaced and supported by insulating material in a duct, trough

or similar enclosure
[SOURCE: IEC 60050-441:1984, 441-12-07 modified]
Note 1 to entry: See 3.1.1 of Part 1 for the definition of ASSEMBLY.

Note 2 to entry: The BTS may consist of a full range of mechanical and electrical components such as:

– busbar trunking units with or without tap-off facilities;
– phase transposition, expansion, flexible, feeder and adapter units;
– tap-off units;
– additional conductors for communication and/or control.

Note 3 to entry: The term "busbar'' does not presuppose the geometrical shape, size and dimensions of the

conductor.
3.102
busbar trunking unit
BTU

unit of a BTS complete with busbars, their supports and insulation, external enclosure and

any fixing and connecting means to other units, with or without tap-off facilities

Note 1 to entry: BTUs may have different geometrical shapes such as straight length, elbow, tee or cross.

3.103
busbar trunking run
BT run
number of BTUs connected together to form the BTS, excluding the tap-off units
3.104
busbar trunking unit with tap-off facilities
BTU with tap-off facilities

BTU designed to enable tap-off units to be installed at one or more points as predetermined

by the original manufacturer
---------------------- Page: 8 ----------------------
61439-6 © IEC:2012 – 7 –
3.105
busbar trunking unit with trolley-type tap-off facilities
BTU with trolley-type tap-off facilities
BTU designed to permit the use of roller- or brush-type tap-off units
3.106
busbar trunking adapter unit
adapter BTU

BTU intended to connect two units of the same system but of different type or of different

rated current
3.107
busbar trunking thermal expansion unit
thermal expansion BTU

BTU intended to permit a certain movement in the axial direction of the BT run due to thermal

expansion of the system

Note 1 to entry: This term does not presuppose which elements permit movement, e.g. the conductors within the

enclosure or both conductors and enclosure
3.108
busbar trunking phase transposition unit
phase transposition BTU

BTU intended to change the relative positions of the phase conductors in order to balance the

inductive reactances or to transpose the phases (such as L1-L2-L3-N to N-L3-L2-L1)

3.109
flexible busbar trunking unit
flexible BTU

BTU having conductors and enclosures designed to allow a specified change of direction

during installation
3.110
busbar trunking feeder unit
feeder BTU
BTU serving as an incoming unit
Note 1 to entry: See 3.1.9 of Part 1 for the definition of incoming unit.
3.111
tap-off unit
outgoing unit, either fixed or removable, for tapping-off power from the BTU

Note 1 to entry: See 3.1.10, 3.2.1 and 3.2.2 of Part 1 for the definition of outgoing unit, fixed part and removable

part.

Note 2 to entry: A plug-in tap-off unit is a removable tap-off unit (see 8.5.2) which can be connected or

disconnected by manual operation
3.112
busbar trunking unit for building movements
BTU for building movements

BTU intended to allow for building movements due to thermal expansion, contraction and/or

flexing of the building
3.113
busbar trunking fire barrier unit
fire barrier BTU

BTU or a part of, intended to prevent the propagation of fire through building divisions for a

specified time under fire conditions
---------------------- Page: 9 ----------------------
– 8 – 61439-6 © IEC:2012
4 Symbols and abbreviations
This clause of Part 1 is applicable except as follows.
Addition:
Symbol / Term Subclause
Abbreviation
k temperature factor of the BTS 5.3.1
temperature factor of a circuit 5.3.2
k mounting factor of a circuit 5.3.2
R, X, Z phase conductor and fault-loop characteristics 5.101
5 Interface characteristics
This clause of Part 1 is applicable except as follows.
5.1 General
Replacement:

The characteristics of the BTS shall ensure compatibility with the ratings of the circuits to

which it is connected and the installation conditions and shall be declared by the BTS

manufacturer using the criteria identified in 5.2 to 5.6 and 5.101 to 5.102.

The specification schedule according to informative Annex C is intended to help the user and

the BTS manufacturer to meet this objective, whether the user:

• select catalogue products the characteristics of which meet their needs, and the

requirements of this standard,
• and/or make a specific agreement with the manufacturer.
NOTE Annex C also relates to the topics dealt with in Clauses 6 and 7.

In some cases information provided by the BTS manufacturer may take the place of an

agreement.
5.2.4 Rated impulse withstand voltage (U ) (of the ASSEMBLY)
imp
Replacement of the NOTE:

NOTE Unless otherwise specified, the rated impulse withstand voltage is selected according to overvoltage

category IV (origin of installation level) or III (distribution circuit level) as given in Table G.1 of Part 1.

5.3.1 Rated current of the ASSEMBLY (I )
Addition:

NOTE 4 Where the BTS is not equipped with a single incoming unit at one end of the BT run, (e.g. incoming unit

not installed at one end of the BTS, or more than one incoming unit), the rated currents will be subject to

agreement between the user and the manufacturer.

The rated current shall apply for a specified mounting orientation (see 5.3.2). However the

influence of the mounting orientation may be ignored for short (e.g. less than 3 m long)

vertical sections in a horizontal BTS.
---------------------- Page: 10 ----------------------
61439-6 © IEC:2012 – 9 –

The BTS manufacturer may state the rated currents of the BTS for different ambient

temperatures for example by means of the following formula:
I’ = k I
nA 1A nA

where k is a temperature factor, equal to 1 at an ambient air temperature of 35 °C.

In case of significant harmonic currents, special agreement shall be made for a reduction

factor, if necessary.
5.3.2 Rated current of a circuit (I )
Addition:

The rated current (I ) of each circuit (i.e. incoming unit, BTU, tap-off unit, outgoing circuit)

shall be equal to or higher than its assumed loading. For tap-off units provided with more than

one main outgoing circuit, see also 5.4.

The rated current shall apply for specified mounting conditions. Mounting conditions may

include orientation and position, as follows:
a) orientation
Orientation may be horizontal or vertical.
Unless otherwise specified, the reference orientation is horizontal.
b) position

Position may be for example edgewise or flatwise for a BT run, and/or below or on top of

the BTU for a tap-off unit.

The BTS manufacturer may state different rated currents for different ambient temperatures

and/or mounting conditions, where applicable, for example by means of the following formula:

I’ = k k I
nc 1c 2c nc
where
k is a temperature factor, equal to 1 at an ambient air temperature of 35 °C;
k is a mounting factor, equal to 1 in the reference mounting conditions.

In case of significant harmonic currents, special agreement shall be made for a reduction

factor, if necessary.
5.4 Rated diversity factor (RDF)
Replacement:

For the whole BTS, unless otherwise specified, the RDF (see 3.8.11 of Part 1) shall be equal

to 1, i.e. all tap-off units can be continuously and simultaneously loaded with their full rated

current, within the limit of the rated current of the BT run(s) and feeder BTU(s)

NOTE 1 This is because thermal influence between tap-off units is considered negligible.

For tap-off units provided with more than one main outgoing circuit, these circuits shall be

able to be continuously and simultaneously loaded at their rated current multiplied by the

RDF, within the limit of the rated current of the tap-off unit. Unless otherwise specified, the

RDF of such tap-off units shall be equal to the values given in Table 101.
---------------------- Page: 11 ----------------------
– 10 – 61439-6 © IEC:2012
Table 101 – Rated diversity factor for a tap-off unit
Number of main outgoing circuits Rated diversity factor
2 and 3 0,9
4 and 5 0,8
6 to 9 inclusive 0,7
10 (and above) 0,6
The RDF is applicable with the BTS operating at rated current (I )

NOTE 2 The RDF recognizes that multiple functional units are in practice not fully loaded simultaneously or are

intermittently loaded.

NOTE 3 The assumed loading of the outgoing circuits can be a steady continuous current or the thermal

equivalent of a varying current.

NOTE 4 In Norway, the overload protection of conductors is not solely based on the use of diversity factors of the

downstream circuits.
5.6 Other characteristics
Modification of item e):
e) stationary BTS ;
Modification of item j):
j) enclosed BTS;
Addition:
aa) ability to withstand mechanical loads, either normal or heavy (see 8.1.101);
bb) resistance to flame propagation, if applicable (see 9.101);
cc) fire resistance in building penetration, if applicable (see 9.102).
Additional subclauses:
5.101 Phase conductor and fault-loop characteristics
NOTE 1 For BTS rated below 100 A, the reactances are deemed negligible.

R and X according to Table 102 are intended to be used to calculate voltage drops (see

informative Annex AA).
---------------------- Page: 12 ----------------------
61439-6 © IEC:2012 – 11 –
Table 102 – Phase conductor characteristics
Mean phase conductor characteristics
at rated current I , and rated frequency f
nc n
Ω per-metre length
Resistance,
- at an ambient air temperature of 35 °C
- at a conductor temperature of 20 °C
Reactance (independent from temperature) X
Positive-sequence and negative-sequence impedances
- at an ambient air temperature of 35 °C Z = Z = Z
(1) (2)
- at a conductor temperature of 20 °C Z = Z = Z
20 (1)20 (2)20
All phase conductor characteristics may be determined according to Annex BB.

R and X according to Table 102, and fault-loop resistances and reactances according to

Table 103, i.e. the total resistances and reactances of the phase conductor(s) and return

path, are intended to be used to calculate fault currents according to the method of

impedances (see Table 104).

Z and Z according to Table 102, and fault-loop zero-sequence impedances according to

Table 103, i.e. the total zero-sequence impedances of the phase conductor(s) and return

path, are intended to be used to calculate fault currents according to the method of

symmetrical components (see Table 104).

NOTE 2 Fault currents reach their lowest value for the highest impedance values; this is deemed to

...