IEC 60287-1-1:2006/AMD1:2014

IEC 60287-1-1 ®
Edition 2.0 2014-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
A MENDMENT 1
AM ENDEMENT 1
Electric cables – Calculation of the current rating –
Part 1-1: Current rating equations (100 % load factor) and calculation of losses –
General
Câbles électriques – Calcul du courant admissible –
Partie 1-1: Equations de l’intensité du courant admissible (facteur de charge
100 %) et calcul des pertes – Généralités

IEC 60287-1-1:2006-12/AMD1:2014-11(en-fr)

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IEC 60287-1-1 ®
Edition 2.0 2014-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
A MENDMENT 1
AM ENDEMENT 1
Electric cables – Calculation of the current rating –

Part 1-1: Current rating equations (100 % load factor) and calculation of losses –

General
Câbles électriques – Calcul du courant admissible – Partie 1-1: Equations de

l’intensité du courant admissible (facteur de charge 100 %) et calcul des pertes –

Généralités
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX E
ICS 29.060.20 ISBN 978-2-8322-1920-1

– 2 – IEC 60287-1-1:2006/AMD1:2014
© IEC 2014
FOREWORD
This amendment has been prepared by IEC technical committee 20: Electric cables.
The text of this amendment is based on the following documents:
FDIS Report on voting
20/1499/FDIS 20/1547/RVD
Full information on the voting for the approval of this amendment can be found in the report
on voting indicated in the above table.
The committee has decided that the contents of this amendment and the base 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• withdrawn,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.
_____________
1.4.3.1 AC cables
Replace the existing equation by the following:
0,5
 
∆θ − nW T
x d 4
I=
 
nRT (1+λ +λ )
 4 1 2 
2.1.2 Skin effect factor y
s
Replace the existing subclause by the following:
The skin effect factor y is given by the following equations:
s
x
s
For 0 < x ≤2,8 y =
s s
192+ 0,8 x
s
For 2,8 < x ≤3,8
y =−0,136− 0,017 7x + 0,056 3x
s s s s
For x >3,8 y = 0,354x − 0,733
s s s
where
© IEC 2014
8πf
2 −7
x = 10 k
s s
′
R
f is the supply frequency in hertz.
Values for k are given in Table 2.
s
In the absence of alternative formulae, it is recommended that the above formula should be
used for sector and oval-shaped conductors.
2.3 Loss factor for sheath and screen
In paragraph 5 replace "large segmental" by "Milliken".
Replace the equation for the maximum operating temperature of the sheath or screen by the
following:
θ =θ−(I R+ 0,5W )T (°C)
sc d 1
2.3.1 Two single-core cables, and three single-core cables (in trefoil formation),
sheaths bonded at both ends of an electrical section
In the final line replace "having large conductors of segmental construction" by "having
Milliken conductors".
2.3.2 Three single-core cables in flat formation, with regular transposition, sheaths
bonded at both ends of an electrical section
In the penultimate line, replace "having large conductors of segmental construction" by
"having Milliken conductors".
2.3.3 Three single-core cables in flat formation, without transposition, sheaths bonded
at both ends of an electrical section
In the explanation for λ ", replace "having large conductors of segmental construction" by
"having Milliken conductors".
2.3.5 Effect of large segmental type conductors
Replace the existing title by the following new title:
2.3.5 Effect of Milliken conductors
Replace the first paragraph by the following new paragraph:
Where the conductors are subject to a reduced proximity effect, as with Milliken conductors,
′′
the sheath loss factor λ of 2.3.1, 2.3.2 and 2.3.3 cannot be ignored, but shall be obtained by
′′
multiplying the value of λ , obtained from 2.3.6 for the same cable configuration, by the
factor F given by the formula:

2.4 Loss factor for armour, reinforcement and steel pipes (applicable to power frequency
a.c. cables only)
– 4 – IEC 60287-1-1:2006/AMD1:2014
© IEC 2014
Replace the existing equation for the maximum operating temperature of the armour by the
following new equation:
2 2
θ =θ−{ (I R+ 0,5 W ) T +[I R(1+λ)+ W ] n T } (°C)
ar d 1 1 d 2
2.4.2.1 Single-core lead-sheathed cables – steel wire armour, bonded to sheath at
both ends
Delete, in item b,) the unit "(Ω/m)" from the equation for H .
s
2.4.2.3.1 Round conductor cable
Add, at the end of this subclause, the following sentence to the end of the last paragraph:
This equation is under consideration because it may overestimate the armour loss factor for
some cable designs.
2.4.3 Losses in steel pipes
In the
...