IEC 62783-1:2023
(Main)Twinax cables for digital communications - Part 1: Generic specification
Twinax cables for digital communications - Part 1: Generic specification
IEC 62783-1:2023 specifies definitions, requirements and test methods of twinax cables used in digital communication systems: computer rooms, data centres, servers, etc. These cables are intended to be used indoors.
This document details the requirements and transmission characteristics for single twinax elements as well as multiple twinax elements within the same sheath, i.e. “twinax cable”. IEC 62783-1 ED2 is applicable to twinax cables and also twinax cable assemblies. This document is supplemented with family specifications that give additional requirements based on the specific application, for example, the minimum and maximum specified frequency of the cables.
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Standards Content (Sample)
IEC 62783-1
®
Edition 2.0 2023-05
INTERNATIONAL
STANDARD
Twinax cables for digital communications –
Part 1: Generic specification
IEC 62783-1:2023-05(en)
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IEC 62783-1
®
Edition 2.0 2023-05
INTERNATIONAL
STANDARD
Twinax cables for digital communications –
Part 1: Generic specification
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 33.120.20 ISBN 978-2-8322-7002-8
Warning! Make sure that you obtained this publication from an authorized distributor.
® Registered trademark of the International Electrotechnical Commission
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– 2 – IEC 62783-1:2023 © IEC 2023
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 9
4 Materials and cable construction . 9
4.1 General remarks . 9
4.2 Cable construction . 10
4.2.1 General . 10
4.2.2 Conductor . 10
4.2.3 Insulation . 10
4.2.4 Cable element . 10
4.2.5 Cable make-up . 11
4.2.6 Screening of the cable core . 11
4.2.7 Sheath . 12
4.2.8 Identification . 12
4.2.9 Finished cable . 12
5 Requirements and test methods . 13
5.1 General requirements . 13
5.2 Electrical characteristics and tests . 13
5.2.1 General . 13
5.2.2 Conductor resistance . 13
5.2.3 Resistance unbalance. 13
5.2.4 Dielectric strength . 13
5.2.5 Insulation resistance . 13
5.2.6 Surface transfer impedance . 14
5.2.7 Coupling attenuation . 14
5.3 Transmission characteristics and tests . 14
5.3.1 General . 14
5.3.2 Length . 14
5.3.3 Characteristic impedance . 15
5.3.4 Return loss . 15
5.3.5 Attenuation . 15
5.3.6 Propagation delay, inter-pair skew, and intra-pair skew . 16
5.3.7 Near-end crosstalk (NEXT) . 16
5.3.8 Differential mode to common mode conversion (Scd21) . 17
5.3.9 Equal level transverse conversion transfer loss (Scd21-Sdd21) . 17
5.4 Mechanical and dimensional requirements and test methods . 17
5.4.1 General . 17
5.4.2 Measurement of dimensions . 17
5.4.3 Elongation at break of the conductor. 17
5.4.4 Tensile strength of the insulation . 17
5.4.5 Elongation at break of the sheath . 18
5.4.6 Tensile strength of the sheath . 18
5.4.7 Crush test of the cable . 18
5.4.8 Cold impact test of the cable . 18
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IEC 62783-1:2023 © IEC 2023 – 3 –
5.4.9 Repeated bending of the cable . 18
5.4.10 Tensile performance of the cable . 18
5.4.11 Vibration test of the cable . 18
5.5 Environmental tests . 18
5.5.1 Shrinkage of the insulation . 18
5.5.2 Wrapping test of the insulation after thermal ageing . 18
5.5.3 Bending test of the insulation at low temperature . 18
5.5.4 Tensile strength and elongation of the sheath after ageing . 18
5.5.5 Sheath pressure test at high temperature . 18
5.5.6 Cold bend test of the cable . 19
5.5.7 Heat shock test . 19
5.5.8 Damp heat steady state . 19
5.5.9 Salt mist . 19
5.5.10 Flame propagation characteristics of a single cable . 19
5.5.11 Flame propagation characteristics of bunched cables . 19
5.5.12 Halogen-free compounds test . 19
5.5.13 Smoke generation . 19
5.5.14 Combined flame and smoke test for cables in environmental air
handling spaces . 19
Bibliography . 20
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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
TWINAX CABLES FOR DIGITAL COMMUNICATIONS –
Part 1: Generic specification
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 this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
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.
IEC 62783-1 has been prepared by subcommittee 46C: Wires and symmetric cables, of IEC
technical committee 46: Cables, wires, waveguides, RF connectors, RF and microwave passive
components and accessories. It is an International Standard.
This second edition cancels and replaces the first edition published in 2019. This edition
constitutes a technical revision.
This edition includes the following significant technical changes compared with the previous
edition:
– 4.1: single pair twinax cable is permitted;
– 5.2.1: addition of length requirement for electrical tests;
– 5.3.1, 5.3.2: addition of test equipment, fixtures and length requirements of cable under test
for transmission tests;
– 5.3.3.2: introduction of characteristic impedance in time domain;
– 5.4.11: addition of vibration test of the cable;
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IEC 62783-1:2023 © IEC 2023 – 5 –
– 5.5.8, 5.5.9 and 5.5.12: addition of environmental tests: damp heat steady state, salt mist,
halogen-free compounds;
– 5.5.11: updating the test method of flame propagation characteristics of bunched cables.
The text of this International Standard is based on the following documents:
Draft Report on voting
46C/1257/FDIS 46C/1261/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts in the IEC 62783 series, published under the general title Twinax cables for
digital communications, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
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INTRODUCTION
This document specifies the generic characteristics of twinax cables for the transmission of
digital signals, which use single or multiple twinax cable element(s).
Twinax cables are intended for use in high-performance information technology systems and
data interface interconnection systems. These cables are generally used in short-reach data
communication links, which reach about 0,3 m to 10 m. Information technology interconnection
standards that use twinax cables include Ethernet, Fibre channel, SAS, SATA, SFP, PCIE and
others.
IEC 62783 (all parts) includes separate family specifications, which provide the requirements
for each specific twinax cable used in information technology interconnection systems.
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IEC 62783-1:2023 © IEC 2023 – 7 –
TWINAX CABLES FOR DIGITAL COMMUNICATIONS –
Part 1: Generic specification
1 Scope
This part of IEC 62783 specifies definitions, requirements and test methods of twinax cables
used in digital communication systems: computer rooms, data centres, servers, etc. These
cables are intended to be used indoors.
This document details the requirements and transmission characteristics for single twinax
elements as well as multiple twinax elements within the same sheath, i.e. “twinax cable”.
This document is applicable to twinax cables and also twinax cable assemblies.
This document is supplemented with family specifications that give additional requirements
based on the specific application, for example, the minimum and maximum specified frequency
of the cables.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60028, International standard of resistance for copper
IEC 60050-726, International Electrotechnical Vocabulary (IEV) − Part 726: Transmission lines
and waveguides
IEC 60068 (all parts), Environmental testing
IEC 60068-2-78, Environmental testing – Part 2-78: Tests – Test Cab: Damp heat, steady state
IEC 60189-1, Low-frequency cables and wires with PVC insulation and PVC sheath – Part 1:
General test and measuring methods
IEC 60304, Standard colours for insulation for low-frequency cables and wires
IEC 60332-1-2, Tests on electric and optical fibre cables under fire conditions – Part 1-2: Test
for vertical flame propagation for a single insulated wire or cable – Procedure for 1 kW
pre-mixed flame
IEC 60332-2-2, Tests on electric and optical fibre cables under fire conditions – Part 2-2: Test
for vertical flame propagation for a single small insulated wire or cable – Procedure for diffusion
flame
IEC 60332-3-24, Tests on electric and optical fibre cables under fire conditions – Part 3-24:
Test for vertical flame spread of vertically-mounted bunched wires or cables – Category C
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IEC 60332-3-25, Tests on electric and optical fibre cables under fire conditions – Part 3-25:
Test for vertical flame spread of vertically-mounted bunched wires or cables – Category D
IEC 60684-2, Flexible insulating sleeving – Part 2: Methods of test
IEC 60754-1, Test on gases evolved during combustion of materials from cables – Part 1:
Determination of the halogen acid gas content
IEC 60754-2, Test on gases evolved during combustion of materials from cables – Part 2:
Determination of acidity (by pH measurement) and conductivity
IEC 60794-1-21:2015, Optical fibre cables – Part 1-21: Generic specification – Basic optical
cable test procedures – Mechanical tests methods
IEC 60811-201, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 201: General tests – Measurement of insulation thickness
IEC 60811-202, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 202: General tests – Measurement of thickness of non-metallic sheath
IEC 60811-203, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 203: General tests – Measurement of overall dimensions
IEC 60811-401, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 401: Miscellaneous tests – Thermal ageing methods – Ageing in an air oven
IEC 60811-406, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 406: Miscellaneous tests – Resistance to stress cracking of polyethylene and
polypropylene compounds
IEC 60811-501, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 501: Mechanical tests – Tests for determining the mechanical properties of insulating and
sheathing compounds
IEC 60811-502, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 502: Mechanical tests – Shrinkage test for insulations
IEC 60811-504, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 504: Mechanical tests – Bending tests at low temperature for insulation and sheaths
IEC 60811-506, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 506: Mechanical tests – Impact test at low temperature for insulations and sheaths
IEC 60811-508, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 508: Mechanical tests – Pressure test at high temperature for insulation and sheaths
IEC 60811-509, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 509: Mechanical tests – Test for resistance of insulations and sheaths to cracking (heat
shock test)
IEC 60811-510, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 510: Mechanical tests – Methods specific to polyethylene and polypropylene compounds –
Wrapping test after thermal ageing in air
IEC 61034 (all parts), Measurement of smoke density of cables burning under defined
conditions
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IEC 62783-1:2023 © IEC 2023 – 9 –
IEC 61156-1, Multicore and symmetrical pair/quad cables for digital communications – Part 1:
Generic specification
IEC TR 61156-1-2, Multicore and symmetrical pair/quad cables for digital communications –
Part 1-2: Electrical transmission characteristics and test methods of symmetrical pair/quad
cables
IEC 61196-1-105, Coaxial communication cables – Part 1-105: Electrical test methods – Test
for withstand voltage of cable dielectric
IEC 62012-1:2002, Multicore and symmetrical pair/quad cables for digital communications to
be used in harsh environments – Part 1: Generic specification
IEC 62153-4-3, Metallic communication cable test methods – Part 4-3: Electromagnetic
compatibility (EMC) – Surface transfer impedance – Triaxial method
IEC 62153-4-5, Metallic communication cable test methods – Part 4-5: Electromagnetic
compatibility (EMC) – Screening or coupling attenuation – Absorbing clamp method
IEC 62153-4-9, Metallic communication cable test methods − Part 4-9: Electromagnetic
compatibility (EMC) – Coupling attenuation of screened balanced cables, triaxial method
IEC 62783-1-1, Twinax cables for digital communications - Part 1-1: Time domain test methods
for twinax cables for digital communications − General requirements
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61156-1,
IEC 62783-1-1, IEC 60050-726 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• ISO Online browsing platform: available at http://www.iso.org/obp
• IEC Electropedia: available at http://www.electropedia.org/
3.1
twinax element
pair consisting of two insulated conductors that are laid parallel, side-by-side and designated
wire "a" and wire "b", enclosed in a metal foil shield with or without drain wire(s) or enclosed in
a wire braid with or without a metal foil
3.2
twinax cable
cable composed of one or multiple twinax elements
3.3
twinax cable assembly
twinax cable terminated on both ends with one or more connectors
4 Materials and cable construction
4.1 General remarks
The choice of materials and cable construction shall be suitable for the intended application
and installation of the cable.
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Any special requirements of EMC (electromagnetic compatibility), or fire performance (burning
properties, smoke generation, evolution of acid gas, etc.), or both, should be considered.
If not specified otherwise, the nominal twinax cable characteristic impedance is 100 Ω. Normal
twinax cable configurations range from 1 to 16 elements, with a conductor size range from
0,1 mm to 0,5 mm (38 AWG to 24 AWG), or other sizes as specified in the family specification.
4.2 Cable construction
4.2.1 General
The cable construction shall be in accordance with the details and dimensions given in the
relevant family specification.
4.2.2 Conductor
The conductor shall consist of annealed copper, uniform in quality and free from defects. The
properties of the copper shall be in accordance with IEC 60028.
The conductor may be either solid or stranded and shall be circular in cross-section.
The conductor should be silver-coated, but tin-coated, bare copper, plated copper or copper
alloy are also permitted.
4.2.3 Insulation
4.2.3.1 General requirements
Conductor insulation is composed of one or more suitable dielectric materials. The suitable
materials are polyolefin or fluoropolymer. The insulation may be solid, cellular or composite
(e.g. foam skin).
The two conductors may be extruded in parallel within a single insulation.
An intermediate sheath or bedding may be extruded around the two insulated conductors.
Multi-layer insulation is permitted to achieve the performance requirements.
The insulation shall be continuous, having a uniform thickness. The minimum thickness of the
insulation shall be measured in accordance with the method specified in IEC 60189-1.
The insulation shall be applied to fit closely to the conductor.
When required, the insulated conductors shall be coloured for identification. Colours shall
reasonably correspond with the standard colours shown in IEC 60304.
4.2.3.2 Colour code
The colour code for insulation is given in the relevant cable specification.
4.2.4 Cable element
4.2.4.1 General remarks
The cable element is the twinax element specified in 3.1.
The two insulated conductors may be covered by one or multi-layer non-hygroscopic tapes.
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IEC 62783-1:2023 © IEC 2023 – 11 –
The cable element shall have screen(s) and shall correspond with the requirements in 4.2.4.2.
Intermediate sheath underneath the screen is permitted.
4.2.4.2 Screening of cable element
Screening material of cable element may be metallic tape, or metallic laminated to a plastic
tape, or braid. Other non-metallic appropriate material with screening performance is permitted.
Screening material(s) may be single-layer or multi-layer, and combination of different screening
materials is allowed.
Screening tape(s) may be wrapping or longitudinal lapping.
Non-hygroscopic tape without screening performance may be used.
Drain wire(s) if present shall be placed in continuous electrical contact with the metal foil.
Coatings or other methods of protection should be considered in order to prevent galvanic
interaction when putting dissimilar metals in contact with each other.
A protective wrapping may be applied over the screen.
Some typical screening of cable elements can be:
a) single-layer or multi-layer conductive screening tape, with or without drain wire;
b) single-layer or multi-layer conductive screening tape and non-hygroscopic tape without
screening performance, and drain wire(s) are allowed to be placed inside the screen;
c) single-layer or multi-layer conductive screening tape and one or multi-layer metallic braid,
with or without drain wire(s);
d) non-metallic conductive material applied as a tape or extruded optionally in combination
with other permitted screening elements.
4.2.5 Cable make-up
The cable assembly consisting of 1 to 16 element(s) may be laid up in concentric layers or in
sub-bundle construction. The cable core may be protected by wrappings of a non-hygroscopic
tape and fillers can be used to maintain a circular formation.
4.2.6 Screening of the cable core
When required, the cable core may be screened by a conductive metal foil laminated or not to
a plastic tape, or a copper braid (tin coated or plain), or both.
Coatings or other methods of protection should be considered in order to prevent galvanic
interaction when putting dissimilar metals in contact with each other.
A protective wrapping may be applied under or over the s
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