IEC 61156-1:2007/AMD1:2009

IEC 61156-1 ®
Edition 3.0 2009-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
AMENDMENT 1
AMENDEMENT 1
Multicore and symmetrical pair/quad cables for digital communications –
Part 1: Generic specification
Câbles multiconducteurs à paires symétriques et quartes pour transmissions
numériques –
Partie 1: Spécification générique

IEC 61156-1:2007/A1:2009
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IEC 61156-1 ®
Edition 3.0 2009-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
AMENDMENT 1
AMENDEMENT 1
Multicore and symmetrical pair/quad cables for digital communications –
Part 1: Generic specification
Câbles multiconducteurs à paires symétriques et quartes pour transmissions
numériques –
Partie 1: Spécification générique

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
J
CODE PRIX
ICS 33.120.20 ISBN 978-2-88910-416-1
– 2 – 61156-1 Amend.1 © IEC:2009
FOREWORD
This amendment has been prepared by subcommittee 46C: Wires and symmetric cables, of
IEC technical committee 46: Cables, wires, waveguides, R.F. connectors, R.F. and microwave
passive components and accessories.
The text of this amendment is based on the following documents:
FDIS Report on voting
46C/897/FDIS 46C/899/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 maintenance result 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• withdrawn,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.
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 publication using a colour printer.
_____________
3 Terms and definitions
Replace definitions 3.17, 3.18, 3.19, 3.20 and 3.24 by the following:
3.17
characteristic impedance
Z
C
impedance at the input of a homogeneous line of infinite length
The impedance value is expressed in Ω, calculated, at relevant frequencies, as the square
root of the product of the impedances measured at the near end (input) of a cable pair when
the far end is terminated by a short-circuit load and then an open-circuit load.
NOTE 1 The asymptotic value at high frequencies is denoted as Z .
∞
NOTE 2 The characteristic impedance of a homogeneous cable pair is given by the quotient of a voltage wave
and current wave which are propagating in the same direction, either forwards or backwards.
NOTE 3 For homogeneous ideal cables, this method yields a flat smooth curve over the whole frequency range.
Real cables with distortions give curves with some roughness.

61156-1 Amend.1 © IEC:2009 – 3 –
3.18
terminated input impedance
Z
in
impedance value, expressed in Ω, at relevant frequencies, measured at the near end (input)
when the far end is terminated with the system nominal impedance, Z
R
(See IEC/TR 62152.)
3.19
fitted characteristic impedance
Z
m
impedance value, expressed in Ω, calculated by applying a least squares function fitting
algorithm to the measured characteristic impedance values
3.20
mean characteristic impedance
Z
∞
asymptotic value at which the characteristic impedance approaches at sufficiently high
frequencies (≈100 MHz) such that the imaginary part (phase angle) is insignificant
NOTE 1 Normally measured from the capacitance and time delay.
NOTE 2 Applicable for cables with frequency independence of mutual capacitance.
3.24
current carrying capacity
maximum current a cable circuit (one or several conductors) can support resulting in a
specified increase of the surface temperature of the conductor beyond the ambient
temperature, not exceeding the maximum allowed operating temperature of the cable
Add, after definition 3.27, the following new definitions 3.28 and 3.29:
3.28
ambient temperature
the temperature of the room or space surrounding the cable
3.29
operating temperature
the surface temperature of the conductors of a cable
The operating temperature is the sum of ambient temperature and of the temperature
increase due to the carried power.
6 Characteristics and requirements
6.1 General remarks – Test configurations
Add, at the beginning of 6.1, the following new paragraph:
Unless otherwise specified, all the tests shall be performed assuming that the operating
temperature is 20 °C. The temperature of the cable shall be stabilized at 20 °C and the test
signal shall be low enough to avoid any temperature increase.
6.2.6 Capacitance unbalance to earth
Delete “to earth” in the heading of 6.2.6 as follows:

– 4 – 61156-1 Amend.1 © IEC:2009
6.2.6 Capacitance unbalance
6.2.9 Current-carrying capacity

The correction concerns the French text only.

6.3.3.1 Attenuation at ambient temperature
Change the heading of 6.3.3.1 as follows:
6.3.3.1 Attenuation at 20 °C operating temperature

6.3.3.2 Attenuation at elevated temperatures
Change the heading of 6.3.3.2 as follows:
6.3.3.2 Attenuation at elevated ambient temperatures

6.3.3.2.3 Test procedure
Add the following text to the second paragraph of 6.3.3.2.3:
The test signal shall be low enough to avoid any temperature increase.
6.3.7 Alien (exogenous) near-end crosstalk
Replace, at the end of the subclause, the following text:
Two test cable configurations are specified as follows:
a) an assembly of six cables around one cable;
b) a helical wrap of four parallel cables onto a drum.
by
The test methods configuration involves six cables around one cable.
The cable arrangement shall be either
a) a bundle
or
b) three layers of cables on a drum.
6.3.7.2 Four parallel cables
Replace the existing title and text of 6.3.7.2, including Figures 11 and 12, by the following:

61156-1 Amend.1 © IEC:2009 – 5 –
6.3.7.2 Six cables around one cable on a drum (three layers on a drum)
The principle is to reproduce a "6 around 1" on the drum. The sample is a set of 3 specimens
of cable of 100 m length. They are wound all together and side by side on a wooden drum in
order to form a first layer (cables 8, 5 and 4 in Figure 18). The wooden drum shall have a
minimum diameter of 1,20 m. Next, a new set of 3 cables of 100 m is wound above the first
layer in order to build a second layer; the cables are put as shown in Figure 18 and described
as cables 6, V and 3. Finally, a third set of 3 cables is wound to obtain a third layer described
as cables 1, 2 and 7. All of the (9×100) m cables shall come from the same production batch.

1 2 7 1 2 7
6 V 3 6 V 3
8 5 4 8 5 4
IEC  1502/09
Figure 18 – Schematic diagram representing the position
of the 9 cables on a wooden drum
According to the "6 around 1" principle, the disturbed cable V is surrounded by 6 cables called
cable 1 to cable 6 (see Figure 18).
The regularity of this construction is maintained for example by a wrapping tape around the
assembly as shown in the Figure 19. At both ends, a bundle is set-up by using adhesive tapes
spaced on the assembly every 10 cm.

– 6 – 61156-1 Amend.1 © IEC:2009

IEC  1503/09
Figure 19 – Arrangement of the cables on the drum
Figure 20 shows the "6 around 1" construction at both ends and 2 extra cables (cable 7 and
cable 8) which are here only for insuring a perfect assembly, but also for further investigation,
if needed.
IEC  1504/09
Figure 20 – Preparation of one end
6.3.10 Mean characteristic impedance and input impedance
Replace the existing title and text of 6.3.10 by the following:
6.3.10 Impedance
6.3.10.1 Preparation of cable under test
The cable under test (CUT) shall be prepared so that end effects are minimized. Unscreened
cables shall be suspended or laid on a non-conducting surface so that multiple traversals are
separated by a minimum of 25 mm.

61156-1 Amend.1 © IEC:2009 – 7 –
6.3.10.1.1 Test equipment for characteristic impedance, terminated input impedance
and fitted impedance
The measurement is in a balanced configuration with a network analyser (together with an S-
parameter unit) or an impedance meter. The balun shall have the relevant characteristics
given in Table 1 corresponding to the measurement frequency range. The measurement
schematic is given in Figure 13.
The measurement shall be done at the frequency, or in the whole frequency range, indicated
in the relevant sectional specification.

Network analyser/
S-parameter unit
Port 1
Port 2
BALUN
Short
CUT
Z
R
Open
IEC  1505/09
Figure 13 – Test set-up for characteristic impedance
and return loss
– 8 – 61156-1 Amend.1 © IEC:2009
6.3.10.1.2 Procedure
A three-step calibration procedure (using open, short and reference-load terminations) is
performed at the secondary of the balun with the cable pair disconnected.
The S parameter is measured with the cable pair connected to the balun and terminated
with open circuit, short circuit and reference load, Z . The impedance is calculated from the
R
measured S parameters.
1+ S
Z = Z ⋅ (37)
meas R
1− S
where
Z is the impedance for open circuit, short circuit terminations (Ω);
meas
Z is the reference load (Ω);
R
S is the measured wave scattering parameter for open- and short-circuit terminations.
The characteristic impedance is calculated as the square root of the product of the open and
short circuit measured values and is given by
Z = Z ⋅ Z (38)
C OC SC
where
Z is the characteristic impedance (Ω);
C
Z is the measured open circuit impedance (Ω);
OC
Z is the measured short circuit impedance (Ω).
SC
6.3.10.2 Fitted charac
...