IEC 60794-4-20:2012

IEC 60794-4-20


®


Edition 1.0 2012-10



INTERNATIONAL



STANDARD




colour
inside


Optical fibre cables –
Part 4-20: Aerial optical cables along electrical power lines – Family
specification for ADSS (All Dielectric Self Supported) optical cables

IEC 60794-4-20:2012(E)

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IEC 60794-4-20



®



Edition 1.0 2012-10







INTERNATIONAL





STANDARD











colour

inside










Optical fibre cables –

Part 4-20: Aerial optical cables along electrical power lines – Family

specification for ADSS (All Dielectric Self Supported) optical cables



























INTERNATIONAL

ELECTROTECHNICAL

COMMISSION

PRICE CODE
V


ICS 33.180.10 ISBN 978-2-83220-434-4



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


® Registered trademark of the International Electrotechnical Commission

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CONTENTS




FOREWORD . 4


1 Scope . 6

2 Normative references . 6

3 Terms, definitions and abbreviations . 7

4 Optical fibres . 9
4.1 General . 9
4.2 Attenuation . 9
4.2.1 Attenuation coefficient . 9
4.2.2 Attenuation discontinuities . 9
4.3 Cut-off wavelength of cabled fibre . 9
4.4 Fibre colouring . 9
4.5 Polarisation mode dispersion (PMD) . 9
5 Cable elements . 9
6 Optical fibre cable constructions . 10
6.1 General . 10
6.2 Optical unit . 10
6.3 Cable protection elements . 10
7 Main requirements for installation and operating conditions . 11
8 Cable design considerations . 11
9 Cable tests . 12
9.1 General . 12
9.2 Classification of tests . 12
9.2.1 Type tests . 12
9.2.2 Factory acceptance tests . 13
9.2.3 Routine tests . 13
9.3 Tensile performance . 13
9.3.1 General . 13
9.3.2 Maximum allowed tension (MAT) . 13

9.4 Installation capability . 13
9.4.1 General . 13
9.4.2 Sheave test . 13
9.4.3 Repeated bending . 14
9.4.4 Impact . 14
9.4.5 Crush . 15
9.4.6 Kink . 15
9.4.7 Torsion . 15
9.5 Vibration testing . 16
9.5.1 Aeolian vibration test . 16
9.5.2 Low frequency vibration test (galloping test) . 16
9.6 Temperature cycling . 17
9.7 Water penetration . 18
9.8 Weathering resistance . 18

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9.9 Tracking and erosion resistance test . 18

9.10 Creep behaviour . 19

9.11 Fitting compatibility . 19

10 Factory acceptance tests . 19

11 Routine tests . 19

12 Quality assurance . 20

Annex A (informative) Packaging and marking . 21

Annex B (informative) Installation considerations for ADSS cables. 22

Annex C (informative) Electrical test (TRACKING) . 23

Annex D (informative) All Dielectric Self-Supported (ADSS) cables to be used in
overhead power lines (Blank detail specification) . 31
Bibliography . 33

Figure C.1 – Draft of test equipment . 25
Figure C.2 – Test chamber . 25
Figure C.3 – Electric scheme for the test . 27
Figure C.4 – Details of the sample . 27
Figure C.5 – Nozzle . 28
Figure C.6 – Details for the spraying . 29
Figure C.7 – Pollution model . 30
Figure C.8 – Basic circuit for arcing test. 30

Table 1 – Cable design characteristics . 11
Table 2 – Optional parameters (if required by customer) . 12
Table C.1 – R and C values for different pollution index values . 29
eq eq
Table D.1 – Blank detail specification . 31

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INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________



OPTICAL FIBRE CABLES –



Part 4-20: Aerial optical cables along electrical power lines –

Family specification for ADSS (All Dielectric Self Supported)

optical cables





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
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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agreement between the two organizations.
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 60794-4-20 has been prepared by subcommittee 86A: Fibres and
cables, of IEC technical committee 86: Fibre optics.
The text of this standard is based on the following documents:
FDIS Report on voting
86A/1467/FDIS 86A/1482/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.

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60794-4-20 © IEC:2012(E) – 5 –


A list of all the parts in the IEC 60794 series, published under the general title Optical fibre

cables, 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.

A bilingual version of this standard may be published at a later date.
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.

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OPTICAL FIBRE CABLES –



Part 4-20: Aerial optical cables along electrical power lines –

Family specification for ADSS (All Dielectric Self Supported)

optical cables








1 Scope

This part of IEC 60794, which is a family specification, covers optical telecommunication
cables, commonly with single-mode fibres to be used primarily in overhead power lines
applications. The cable may also be used in other overhead utility networks, such as for
telephony or TV services. Requirements of the sectional specification IEC 60794-4 for aerial
optical cables along electrical power lines are applicable to cables covered by this standard.
NOTE In some particular situations in the electrical industry, short overhead links can be also designed with
multimode fibres.
The ADSS cable consists of single-mode optical fibres contained in one or more protective
dielectric fibre optic units surrounded by or attached to suitable dielectric strength members
and sheaths. The cable does not contain metallic components. An ADSS cable is designed to
meet the optical and mechanical requirements under different types of installation, operating
and environmental conditions and loading, as described in Annex B.
This standard covers the construction, mechanical, electrical, and optical performance,
installation guidelines, acceptance criteria, test requirements, environmental considerations,
and accessories compatibility for an all dielectric, self-supporting fibre optic (ADSS) cable.
The standard provides both construction and performance requirements that ensure, within
the guidelines of this standard, that the mechanical capabilities of the cable components and
maintenance of optical fibre integrity and optical transmissions are proper.
This standard excludes any “lashed” or “wrapped” OPAC cables.
Cables intended for installation in conformity with ISO/IEC 24702 and related standards may
require the specification of additional tests to ensure their suitability in the applicable
environments defined by the mechanical, ingress, climatic and chemical, and electromagnetic
(MICE) classification. These tests are outside of the scope of IEC 60794 cable specifications,
and MICE criteria are not part of the requirements for IEC 60794 specifications. The MICE
tests may be the same as, similar to, or substantially different from, the tests required by
IEC 60794 specifications. Cables manufactured per IEC 60794 specifications may or may not
meet the MICE criteria. For supplemental discussion, see IEC/TR 62362.
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 60304, Standard colours for insulation for low-frequency cables and wires
IEC 60793-1-40, Optical fibres – Part 1-40: Measurement methods and test procedures –
Attenuation

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60794-4-20 © IEC:2012(E) – 7 –


IEC 60793-1-44, Optical fibres – Part 1-44: Measurement methods and test procedures – Cut-

off wavelength


IEC 60793-1-48, Optical fibres – Part 1-48: Measurement methods and test procedures –

Polarization mode dispersion


IEC 60793-2-50, Optical fibres – Part 2-50: Product specifications – Sectional specification for

class B single-mode fibres


IEC 60794-1-1, Optical fibre cables – Part 1: Generic specification – General


IEC 60794-1-2, Optical fibre cables – Part 1-2: Generic specification – Basic optical cable test
1 2
procedures ,
IEC 60794-1-22, Optical fibre cables – Part 1-22: Generic specification – Basic optical cable
test procedures – Environmental test methods
IEC 60794-1-23, Optical fibre cables – Part 1-23: Generic specification – Basic optical cable
test procedures – Cable element test methods
IEC 60794-4, Optical fibre cables – Part 4: Sectional Specification – Aerial optical cables
along electrical power lines
IEC 61395, Overhead electrical conductors – Creep test procedures for stranded conductors
3 Terms, definitions and abbreviations
For the purposes of this document, the terms and definitions given in IEC 60794-1-1 and
IEC 60794-4, as well as the following, apply.
3.1
maximum allowable tension
MAT
maximum tensile load that may be applied to the cable without detriment to the performance
requirements (optical performance, fibre durability) due to fibre strain
Note 1 to entry: Due to installation codes the MAT value is sometimes restricted to be less than 60 % of the
breaking tension of the cable.
3.2

maximum operation tension
MOT
tensile load that can be applied to the cable either permanently or for a long term without
producing any strain to the fibres
Note 1 to entry: This condition should correspond to the tension with no ice and no gale wind at average mean
temperatures throughout the year, assumed to be between 16 ºC and 20 ºC.
3.3
zero strain margin
tensile load that the cable can sustain without strain on fibres due to cable elongation
___________
1
 This document has been withdrawn, but can still be purchased, if necessary. Until IEC 60794-1-21 will be
available, the tests stated in Clause 9 have to be taken from IEC 60794-1-2.
2
 This standard will be replaced by IEC 60794-1-21, Optical fibre cables – Part 1-21: Generic specification –
Basic optical cable test procedures – Mechanical test methods (see also Bibliography), as soon as it will be
available.

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3.4

breaking tension

tensile load that will produce physical rupture of the cable


Note 1 to entry: There is no optical consideration related to this parameter.

Note 2 to entry: The breaking tension should be calculated. The design model shall be validated; the cables do not

need to be tested.


3.5

maximum installation tension

MIT

maximum load that should be applied during the installation procedure
Note 1 to entry: The maximum installation tension refers mainly to the final adjust of sag (also called sagging
load), and the same tension limit can be used for the deployment of the cable (also called stringing load).
Note 2 to entry: This is a recommended value aimed at avoiding tension values higher than MAT during
operational life due to wind, ice or temperature changes.
3.6
ADSS
all dielectric self supported cable
dielectric cable that is capable of enduring aerial installation and providing long term service,
without any external tensile support
3.7
OPAC
optical attached cable
dielectric, not self-supported, optical attached cable
Note 1 to entry: OPACs can be used with one of the following attachment methods:
• wrapped, known as an all-dielectric (wrap): using special machinery, a lightweight flexible non-metallic cable is
wrapped helically around either the earth wire or the phase conductor;
• lashed: non-metallic cables are installed longitudinally alongside the earth wire, the phase conductor or on a
separate support cable (on a pole route) and are held in position with a binder or adhesive cord;
• spiral attached: similar to the lashed cables except that the method of attachment involves the use of special
preformed spiral attachment clips.
Note 2 to entry: OPAC cable designs are not covered by this specification.
3.8
cable fittings and dampers


3.8.1
suspension cable fitting
device to hold up the cable in intermediate support points along an aerial line, where the
cable is under tension at both sides of the fitting
3.8.2
dead end cable fitting
device designed to terminate an installation run, isolate a splice location or maintenance coil,
provide slack span locations, or provide for extreme angle turns, where the cable is under
tensional load on one side of the fitting and tension free on the other
3.8.2
damper
device attached to a cable in order to suppress or minimize vibrations due to wind

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4 Optical fibres


4.1 General


Single mode optical fibres shall be used which meet the requirements of IEC 60793-2-50. In

this clause only the main characteristics are mentioned.


Fibres other than those specified above can be used, if mutually agreed between the

customer and supplier. In this case, fibre characteristics and attenuation criteria for

mechanical tests shall be specified in the detail specification.


4.2 Attenuation
4.2.1 Attenuation coefficient
The requirements for the uncabled fibres shall be according to IEC 60793-2-50.
Unless other values are agreed between supplier and customer, the maximum attenuation
coefficient of the cabled fibres shall be 0,35 dB/km when measured at 1 310 nm and/or
0,25 dB/km at 1 550 nm.
Different values from those stated above can be agreed between customer and supplier.
The attenuation coefficient shall be measured in accordance with IEC 60793-1-40.
4.2.2 Attenuation discontinuities
The local attenuation shall not have point discontinuities in excess of 0,10 dB.
The test method used to verify the functional requirements shall be in accordance with
IEC 60793-1-40.
4.3 Cut-off wavelength of cabled fibre
The cabled fibre cut-off wavelength λ shall be lower than the operational wavelength when
CC
measured in accordance with IEC 60793-1-44.
4.4 Fibre colouring
The primary coated fibres shall be coloured for identification. The coloured coating shall be
readily identifiable throughout the lifetime of the cable and shall be at a reasonable match to
the requirements stated on IEC 60304. If required, the colouring shall permit sufficient light to

be transmitted through the primary coating to allow local light injection and detection.
4.5 Polarisation mode dispersion (PMD)
PMD shall meet the values indicated in IEC 60793-2-50. The measurement procedure shall be
in accordance with IEC 60793-1-48.
5 Cable elements
Refer to the relevant parts of the sectional specification IEC 60794-4; the following
requirements apply specifically to ADSS cables:
The material(s) used for a cable element shall be selected to be compatible with the other
elements in contact with it.

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Optical elements (cable elements containing optical fibres) and each fibre within a cable

element shall be uniquely identified, for example, by colours, by a positional scheme, by

markings or as agreed between customer and manufacturer.


For loose tube construction, one or more primary coated fibres or optical elements are

packaged, loosely in a tube construction, with a suitable water-blocking system. The plastic

tube may be reinforced with a composite wall.


If required by the customer, the suitability of the tube shall be determined by an evaluation of

its kink resistance in accordance with IEC 60794-1-23, Method G7.


When used, optical fibre ribbons should comply with the requirements stated in IEC 60794-3.
6 Optical fibre cable constructions
6.1 General
The cable shall not contain any metallic material.
6.2 Optical unit
Optical unit elements as described in Clause 5 may be laid up as follows:
Single optical unit in the cable centre, which may contain one or more optical elements:
a) number of loose tubes using helical or SZ stranding configurations around a central
element of reinforced plastic, epoxy-glass, or other dielectric material. Ribbon elements
may be laid up by stacking two or more elements inside the loose tubes;
b) configuration based on a channelled dielectric rod, containing units such as ribbons or
plastic tubes, which may contain one or more optical elements.
6.3 Cable protection elements
In addition to optical unit, the cable construction may consist of the following.
a) The outer sheath shall be a weather-resistant type material. In certain conditions it shall
be necessary to consider the use of a tracking-resistant sheath.
b) ADSS cable shall contain self-supported systems that are integral to the cable. The
purpose of the support system is to ensure that the cable meets the optical requirements
under specified installation conditions, temperatures, and environmental loading for its
whole operating design life. This standard excludes any “lashed” or “wrapped” OPAC
cables.

c) The basic annular construction may have strength yarns (e.g. aramid yarns) or other
dielectric strands or a channelled dielectric rod as a support structure. In addition, other
cable elements, such as central members, may be load bearing.
d) Fibre strain allowance
e) The cable shall be designed such that fibre strain does not exceed the limit allowed by the
cable manufacturer under design tension limits of the cable (MAT). Maximum allowable
fibre strain under MAT condition will generally be a function of the proof test level and
strength and fatigue parameters of the optical fibre, 0,33 % is specified for fibre proof
tested to
...