SIST-TP IEC/TR2 61000-5-4:2004
(Main)Electromagnetic compatibility (EMC) - Part 5: Installation and mitigation guidelines - Section 4: Immunity to HEMP - Specifications for protective devices against HEMP radiated disturbance. Basic EMC Publication
Electromagnetic compatibility (EMC) - Part 5: Installation and mitigation guidelines - Section 4: Immunity to HEMP - Specifications for protective devices against HEMP radiated disturbance. Basic EMC Publication
This technical report defines how protective devices for High Altitude Nuclear Electromagnetic Pulse (HEMP) protection of civilian systems are specified. Performance requirements will be given in future IEC standards. This technical report is intended to be used for the harmonization of existing or future specifications issued by protective devices manufacturers, electronic equipment manufacturers, administrative bodies and other buyers.[
]This technical report covers protective devices currently used for protection against HEMP radiated EM fields. In general, parameters relevant to HEMP, that is parameters related to very fast changes of EM fields, as a function of time, are dealt with.
Compatibilité électromagnétique (CEM) - Partie 5: Guide d'installation et d'atténuation - Section 4: Immunité à l'IEM-HA - Spécifications des dispositifs de protection contre les perturbations rayonnées IEM-HA. Publication fondamentale en CEM
Le présent rapport technique définit comment les dispositifs de protection utilisés pour la protection des systèmes civils, vis-à-vis de l'impulsion électromagnétique nucléaire à haute altitude (IEM-HA) sont spécifiés. Les performances requises seront données dans d'autres documents de la CEI. Son utilisation est prévue pour l'harmonisation des spécifications existantes et futures fournies par les fabricants de dispositifs de protection, d'équipements électroniques, les administrations et les acheteurs finaux.[
]Ce rapport technique couvre les dispositifs de protection couramment utilisés pour la protection contre les champs électromagnétiques rayonnés au cours d'une IEM-HA. En général, les paramètres IEM-HA appropriés, c'est-à-dire ceux qui sont relatifs à des changements très rapides de champs EM dans le domaine du temps, sont traités.
Electromagnetic compatibility (EMC) - Part 5: Installation and mitigation guidelines - Section 4: Immunity to HEMP - Specifications of protective devices against HEMP radiated disturbance - Basic EMC publication
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IEC 60794-4-10
®
Edition 2.0 2014-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Optical fibre cables –
Part 4-10: Family specification – Optical ground wires (OPGW) along electrical
power lines
Câbles à fibres optiques –
Partie 4-10: Spécification de famille – Câbles de garde à fibres optiques le long
des lignes électriques de puissance
IEC 60794-4-10:2014-10(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 60794-4-10
®
Edition 2.0 2014-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Optical fibre cables –
Part 4-10: Family specification – Optical ground wires (OPGW) along electrical
power lines
Câbles à fibres optiques –
Partie 4-10: Spécification de famille – Câbles de garde à fibres optiques le long
des lignes électriques de puissance
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.180.10 ISBN 978-2-8322-6970-1
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 – IEC 60794-4-10:2014 © IEC 2014
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
3.1 Cables . 7
3.2 Other definitions . 7
4 Optical fibre . 8
4.1 General . 8
4.2 Attenuation . 9
Attenuation coefficient . 9
Attenuation uniformity and attenuation discontinuities . 9
4.3 Cut-off wavelength of cabled fibre . 9
4.4 Fibre colouring . 9
4.5 Polarization mode dispersion (PMD) . 9
5 Cable element . 9
6 Cable construction . 10
7 Cable design characteristics . 10
8 Cable tests . 11
8.1 General . 11
8.2 Classification of tests . 11
Type tests . 11
Factory acceptance tests . 11
Routine tests . 12
8.3 Type tests . 12
General . 12
Tensile performance . 12
Stress-strain test . 13
Breaking strength test . 13
Sheave test . 13
Aeolian vibration test . 14
Creep . 14
Low frequency vibration test (Galloping test) . 14
Temperature cycling . 15
Water penetration (applicable to optical unit(s) only). 15
Short-circuit . 16
Lightning test . 16
8.4 Factory acceptance tests . 17
General . 17
Typical tests . 17
8.5 Routine tests. 17
General . 17
Typical tests . 18
9 Quality assurance . 18
Annex A (informative) Packaging and marking . 19
Bibliography . 20
---------------------- Page: 4 ----------------------
IEC 60794-4-10:2014 © IEC 2014 – 3 –
Table 1 – Cable design characteristics . 10
Table 2 – Lightning test conditions and parameters to be informed in the test report . 17
---------------------- Page: 5 ----------------------
– 4 – IEC 60794-4-10:2014 © IEC 2014
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
OPTICAL FIBRE CABLES –
Part 4-10: Family specification –
Optical ground wires (OPGW) along electrical power lines
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.
International Standard IEC 60794-4-10 has been prepared by subcommittee 86A: Fibres and
Cables, of IEC technical committee 86. Fibre optics
This bilingual version (2019-05) corresponds to the monolingual English version, published in
2014-10.
This second edition cancels and replaces the first edition published in 2006 and constitutes a
technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) galloping test (9.7) has been added to the type tests list;
b) update of definitions clause; maximum installation tension (MIT) defined and used in the
sheave test description;
---------------------- Page: 6 ----------------------
IEC 60794-4-10:2014 © IEC 2014 – 5 –
c) definition of characterization of OPGW’s mechanical behaviour in order to provide
information useful for electrical power transmission lines designers;
d) improved definition of lightning test parameters and conditions to improve reproducibility
among different laboratories.
The text of this standard is based on the following documents:
CDV Report on voting
86A/1594/CDV 86A/1627/RVC
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
The French version of this standard has not been voted upon.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all 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.
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.
---------------------- Page: 7 ----------------------
– 6 – IEC 60794-4-10:2014 © IEC 2014
OPTICAL FIBRE CABLES –
Part 4-10: Family specification –
Optical ground wires (OPGW) along electrical power lines
1 Scope
This part of IEC 60794-4, which is a family specification, covers cable construction, test
methods and optical, mechanical, environmental and electrical performance requirements for
OPGW (optical ground wire) which is used for the protection of electrical power lines against
atmospheric discharges or short-circuits and, at the same time, as a high bandwidth transport
media for communications-and-control optical signals. The corresponding environmental
declaration may be built according to IEC TR 62839-1.
The OPGW is a substitute for a conventional ground-/shield-wire containing optical fibres for
control and/or telecommunication purposes. Usually the fibres are embedded loosely in
protective buffer tubes. To fulfil mechanical and electrical requirements; an armouring of one
or more layers with aluminium, aluminium alloy, and aluminium clad steel, galvanized steel or
a mixture of them is helically stranded. If the construction contains an aluminium tube or an
aluminium slotted core, this cross section is considered as a conductive part.
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 60104, Aluminium-magnesium-silicon alloy wire for overhead line conductors
IEC 60304, Standard colours for insulation for low-frequency cables and wires
IEC 60793 (all parts), Optical fibres
IEC 60793-1-40, Optical fibres – Part 1-40: Measurement methods and test procedures –
Attenuation
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 –
Polarizationn mode dispersion
IEC 60793-2-50, Optical fibres – Part 2-50: Product specifications – Sectional specifications for
class B single-mode fibres
IEC 60794-1-1, Optical fibre cables – Part 1-1: Generic specification – General
---------------------- Page: 8 ----------------------
IEC 60794-4-10:2014 © IEC 2014 – 7 –
IEC 60794-1-21, Optical fibre cables – Part 1-21: Generic specification – Basic optical cable
1
test procedures –Mechanical test methods
IEC 60794-1-22:2012, Optical fibre cables – Part 1-22: Generic specification – Basic optical
cable test procedures –Environmental test methods
IEC 60794-1-24:2014, Optical fibre cables – Part 1-24: Generic specification – Basic optical
cable test procedures – Electrical testmethods
IEC 60794-4:2003, Optical fibre cables – Part 4: Sectional specification – Aerial optical cables
along electrical power lines
IEC 60888, Zin-coated steel wires for stranded conductors
IEC 60889, Hard-drawn aluminium wire for overherad line conductors
IEC 61089:1991, Round wire concentric lay overhead electrical stranded conductors
IEC 61232, Aluminium-clad steel wires for electrical purposes
IEC 61394, Overhead lines – Characteristics of greases for aluminium, aluminium alloy and
steel bare conductors
IEC 61395, Overhead electrical conductors – Creep test procedures for stranded conductors
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 Cables
optical ground wire
OPGW
metallic optical cable that has the dual performance functions of a conventional ground wire
with telecommunication capabilities
3.2 Other definitions
rated tensile strength
RTS
summation of the product of nominal cross-sectional area, nominal tensile strength and
stranding factor (minimum 0,9) for each load bearing material in the cable construction
Note 1 to entry: See Annex A of IEC 60794-4:2003 for details of the recommended method to calculate rated tensile
strength of OPGW.
creep test
test designed to determine the long-term tensile creep characteristics of metallic aerial installed
cables
_______________
1
To be published.
---------------------- Page: 9 ----------------------
– 8 – IEC 60794-4-10:2014 © IEC 2014
Note 1 to entry: The information derived from this test is used in the sag-tension calculations during the design
layout of the OPGW in the electrical system.
fittings
hardware used for stringing and clipping of OPGW to the structures at the end of the installation
procedure
Note 1 to entry: Suspension, dead end, vibration damper and bonding clamps hardware are designed for a specific
size and/or type of OPGW cable.
optical fibre unit
cable element designed to house and to protect the optical fibres from damage due to
mechanical, thermal and electrical influences and moisture penetration
Note 1 to entry: Further details are given in Clause 6.
maximum allowable ovality
MAOC
unit or its component that does not exceed the specified value when calculated as (d – d )/(d
1 2 1
+ d ) in %
2
where
d is the maximum measured diameter of the cable or the component;
1
d is the minimum diameter of the cable or the component at the same cross-section as d .
2 1
maximum allowable tension
MAT
maximum tensile load that may be applied to the cable without detriment to the tensile
performance requirement
Note 1 to entry: Such performances requirements may be optical, fibre strain and mechanical.
maximum installation tension
MIT
maximum recommended stringing tension during installation
strain margin
commonly referred to as 30 % of proof test level and the basis for defining the MIT and MAT of
the optical cable
Note 1 to entry: The strain margin (%) is directly related to the amount of mechanical tension, in N, a specific cable
design can sustain without strain on the optical fibres due to cable elongation.
4 Optical fibre
4.1 General
Single-mode optical fibres shall be used which meet the requirements of the relevant part of
IEC 60793. Fibres other than those specified above can be used, if mutually agreed between
the customer and supplier.
---------------------- Page: 10 ----------------------
IEC 60794-4-10:2014 © IEC 2014 – 9 –
4.2 Attenuation
Attenuation coefficient
The typical maximum attenuation coefficient of the cabled fibres shall meet the requirements of
the relevant part of IEC 60793.
Particular values shall be agreed between customer and supplier.
The attenuation coefficient shall be measured in accordance with IEC 60793-1-40.
Attenuation uniformity and attenuation discontinuities
The local attenuation shall not have point discontinuities in excess of 0,10 dB.
Any reflective discontinuity shall be specified with the optical return loss measurement which
shall be ≥55 dB.
The test method best suited to provide the functional requirements is 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
If the primary coated fibres are coloured for identification, the coloured coating shall be readily
identifiable throughout the lifetime of the cable and shall be at a reasonable match to
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 Polarization mode dispersion (PMD)
When mutually agreed between customer and supplier, PMD shall be measured in accordance
with IEC 60793-1-48. The individual PMD and link PMD value of optical fibres shall meet the
limit values indicated in the IEC 60793-2-50 specific table corresponding to the type of fibre
used in the OPGW.
5 Cable element
The material(s) used for a cable element shall be selected so that they are compatible with the
other elements that are in contact with it. Refer to the relevant parts of the sectional
specification IEC 60794-4. The following requirements apply specifically to OPGW:
a) Optical elements (buffer tubes containing optical fibres, bundles, etc) and each fibre within
a cable optical element shall be uniquely identified, for example, by colours, by a positional
scheme, by markings or as agreed between customer and supplier.
b) The optical fibre unit(s) shall house the optical fibres and protect them from damage due to
environmental or mechanical forces such as longitudinal compression, crushing, bending,
twisting, tensile stress, long- and short-term heat effects caused by environmental variations
or by atmospheric discharges.
c) 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. Polymeric
tubes may be reinforced with a composite wall as long as the cable complies with this
specification.
---------------------- Page: 11 ----------------------
– 10 – IEC 60794-4-10:2014 © IEC 2014
6 Cable construction
Refer to the relevant parts in Clause 6 of IEC 60794-4 2003. The following requirements apply
specifically to OPGW cables:
a) The optical fibre unit shall house the optical fibres and protect them from damage due to
environmental or mechanical forces such as longitudinal compression, crushing, bending,
twisting, tensile stress, long- and short-term heat effects caused by environmental
variations or by atmospheric discharges.
b) The stranded wires used for cable armouring may be round according to IEC 61089 or other
cross-sectional shapes, i.e. trapezoidal or z-form.
c) The wire types composing the external armour can be from one or more of the following
standards and their mechanical properties shall comply, before stranding, with the
requirements of the specification indicated.
– aluminum alloy IEC 60104
– zinc coated steel IEC 60888
– aluminum IEC 60889
– aluminum-clad steel IEC 61232.
Unless other requirements are mutually agreed between the customer and the supplier, after
stranding, the wires shall meet the requirements of IEC 61089.
7 Cable design characteristics
Table 1 is a summary of important cable characteristics which may be of relevance to both the
customer and the supplier. Other characteristics may be mutually agreed by both customer and
supplier.
Table 1 – Cable design characteristics
Ref Design characteristics Units
1 Number and type of fibres
2 Detailed description of the cable design
3 Overall diameter mm
2
4 Calculated cross-sectional area of wires concerning
mm
calculation of RTS
5 Calculated mass kg/km
6 RTS kN
7 Modulus of elasticity MPa
-6 -1
8 Coefficient of linear expansion
10 K
9 DC resistance at 20°C
Ω/km
2
10 Fault current capacity
(kA) s
11 Lightning resistance Coulomb
12 MAT – Maximum allowable tension kN
13 MIT – Maximum Installation tension kN
14 Allowable temperature range for storage, installation °C
and operation
15 Strain margin of OPGW % length
16 Maximum tension for strain margin of OPGW N
17 Lay direction of outer layer
18 Minimum bending radius during installation mm
19 Minimum bending radius installed mm
---------------------- Page: 12 ----------------------
IEC 60794-4-10:2014 © IEC 2014 – 11 –
In order to reduce the risk of corrosion the external side of wires or the whole wires themselves
on the strands and the tube protecting the fibre optic element(s) of cables should be composed
of the same metal or be coated with grease. If used, the necessary type and the amount of
grease to be applied shall be in accordance with IEC 61394 or shall be defined between the
supplier and the customer.
The type of fittings shall be approved between the customer and the supplier and their
compatibility shall be checked according to the customer or the supplier fitting specification.
8 Cable tests
8.1 General
The parameters specified in this standard may be affected by measureme
...
SLOVENSKI SIST-TP IEC/TR2 61000-5-
4:2004
STANDARD
april 2004
Electromagnetic compatibility (EMC) - Part 5: Installation and mitigation guidelines -
Section 4: Immunity to HEMP - Specifications of protective devices against HEMP
radiated disturbance - Basic EMC publication
ICS 33.100.01 Referenčna številka
SIST-TP IEC/TR2 61000-5-4:2004(en)
© Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno
---------------------- Page: 1 ----------------------
RAPPORT
CEI
TECHNIQUE - TYPE 2
I EC
1000-5-4
TECHNICAL
Première édition
First edition
REPORT-TYPE 2
1996-08
Compatibilité électromagnétique (CEM) -
Partie 5:
Guide d'installation et d'atténuation -
Section 4: Immunité à I'IEM-HA -
Spécifications des dispositifs de protection
contre les perturbations rayonnées IEM-HA -
Publication fondamentale en CEM
Electromagnetic compatibility (EMC)
-
Part 5:
Installation and mitigation guidelines
-
Section
4: Immunity to HEMP -
Specifications for protective devices against
HEMP radiated disturbance -
Basic EMC publication
© CEI 1996 Droits de reproduction réservés
— Copyright - all rights reserved
Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized
utilisée sous quelque forme que ce soit et par aucun procédé, in any form or by any means, electronic or mechanical,
électronique ou mécanique, y compris la photocopie et les including photocopying and microfilm, without permission
microfilms, sans l'accord écrit de l'éditeur. in writing from the publisher
Bureau central de la Commission Electrotechnique Inte rn
ationale 3, rue de Varembé Genève Suisse
Commission Electrotechnique Internationale CODE PRIX
International Electrotechnical Commission PRICE CODE
IEC
MehtgyHapo was 3neKTpoTexHH4ecKa q HoMHccuç
• Pour prix,
• voir catalogue en vigueur
For price, see current catalogue
---------------------- Page: 2 ----------------------
1000-5-4 © IEC: 1996 – 3 –
CONTENTS
Page
FOREWORD 5
Clause
1 Scope 9
2 Normative reference 9
3 Definitions 9
4 Specifications for protective devices against radiated disturbances 11
4.1 General classification for shielding devices 13
4.2 General requirements 13
4.3 Specifications 15
4.3.1 General 15
4.3.2 Barrier materials 15
4.3.3 Shielded cables and conduits 29
4.3.4 Gasketing materials 37
4.3.5 Shielding components 39
Annexes
A General theory 41
B Bibliography 54
---------------------- Page: 3 ----------------------
1000-5-4 © IEC: 1996 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
ELECTROMAGNETIC COMPATIBILITY (EMC) —
Part 5: Installation and mitigation guidelines
Section 4: Immunity to HEMP -- Specifications for protective devices
against HEMP radiated disturbance —
Basic EMC publication
FOREWORD
1)
The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the IEC is to promote
international cooperation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, the IEC publishes International Standards. 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. The 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 the IEC on technical matters, prepared by technical committees on which
all the National Committees having a special interest therein are represented, express, as nearly as possible, an
international consensus of opinion on the subjects dealt with.
3) They have the form of recommendations for international use published in the form of standards, technical
reports or guides and they are accepted by the National Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
6)
The IEC has not laid down any procedure concerning marking as an indication of approval and has no
responsibility when an item of equipment is declared to comply with one of its standards.
The main task of IEC technical committees is to prepare International Standards. In
exceptional circumstances, a technical committee may propose the publication of a technical
report of one of the following types:
• type 1, when the required support cannot be obtained for the publication of an
International Standard, despite repeated efforts;
• type 2, when the subject is still under technical development or where for any other
reason there is the future but not immediate possibility of an agreement on an International
Standard;
• type 3, when a technical committee has collected data of a different kind from that which
is normally published as an International Standard, for example "state of the art".
Technical reports of types 1 and 2 are subject to review within three years of publication to
decide whether they can be transformed into International Standards. Technical reports of
type 3 do not necessarily have to be reviewed until the data they provide are considered to be
no longer valid or useful.
IEC 1000-5-4, which is a technical report of type 2, has been prepared by subcommittee 77C:
Immunity to high altitude nuclear electromagnetic pulse (HEMP), of IEC technical committee 77:
Electromagnetic compatibility.
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1000-5-4 © IEC: 1996 –7–
The text of this this technical report is based on the following documents:
FDIS Repo rt on voting
77C/26/CDV 77C/36/RVC
Full information on the voting for the approval of this technical report can be found in the report
on voting indicated in the above table.
This document is issued in the type 2 Technical Report
series of publications (according to G.4.2.2 of pa
rt 1 of the
IEC/ISO Directives as a "prospective standard for
provisional application" in the field of electromagnetic
compatibility because there is an urgent requirement for
guidance on how standards in this field should be used to
meet an identified need.
This document is not to be regarded as an "International
Standard*. It is proposed for provisional application so that
information and experience of its use in practice may be
gathered. Comments on the content of this document should
be sent to the IEC Central Office.
A review of this type 2 Technical Report will be carried out
not later than three years after its publication, with the
options of either extension for a further three years or
conversion to an International Standard or withdrawal.
Annexes A and
B are for information only.
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1000-5-4 © IEC: 1996 – g –
ELECTROMAGNETIC COMPATIBILITY (EMC) -
Part 5: Installation and mitigation guidelines
Section 4: Immunity to HEMP - Specifications for protective devices
against HEMP radiated disturbance -
Basic EMC publication
1 Scope
This technical report defines how protective devices for High Altitude Nuclear Electromagnetic
Pulse (HEMP) protection of civilian systems are specified. Performance requirements will be
given in future IEC standards. This technical report is intended to be used for the
harmonization of existing or future specifications issued by protective devices manufacturers,
electronic equipment manufacturers, administrative bodies and other buyers.
This technical report covers protective devices currently used for protection against HEMP
radiated EM fields. In general, parameters relevant to HEMP, that is parameters related to very
fast changes of EM fields, as a function of time, are dealt with.
2 Normative reference
The following normative document contains provisions which, through reference in this text,
constitute provisions of this technical report. At the time of publication, the edition indicated
was valid. All normative documents are subject to revision, and parties to agreements based
on this technical report are encouraged to investigate the possibility of applying the most recent
edition of the normative document indicated below. Members of IEC and ISO maintain registers
of currently valid International Standards.
IEC 50(161): 1990,
International Electrotechnical Vocabulary (IEV) – Chapter 161: Electro-
magnetic compatibility
3 Definitions
For the purpose of this technical report, the following definitions apply.
HEMP/HA-NEMP:
The two acronyms are equivalent and accepted for High Altitude Nuclear
Electromagnetic Pulse. HEMP is preferable to HA-NEMP.
barrier:
Separation used to insulate electrical circuits from electromagnetic disturbances.
(A shield is a special type of barrier.)
contact resistance:
Resistance measured in ohms between two objects in contact with each
other.
compression set:
The per cent of permanent height reduction in a material caused by
compression under specific conditions of heat, pressure and time.
corrosion resistance: Resistance to a chemical action which causes gradual destruction of
the surface of a metal by oxidation, electrolysis or chemical contamination.
cut-off frequency:
The frequency at which the magnitude of a measured characteristic
quantity has decreased to a specified fraction of its low-frequency value.
NOTE — For a waveguide it is the frequency below which electromagnetic energy is not efficiently propagated in
the guide. This frequency depends on the cross-section geometry and dimensions of the guide.
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1000-5-4 © IEC: 1996 – 11 –
elongation:
The increase in length of a material stressed under tension.
point of entry:
The physical place at the surface of a closed enclosure through which the
energy penetrates.
protective device:
An electrical component such as a filter, gas discharge tube, metal oxide
varistor, etc., for protection against conducted disturbances, or a shield, gasket, waveguide
trap, etc., for protection against radiated disturbances. Such an element, or a combination of
several of them, thus forms part of the conceptual electromagnetic barrier of the system.
shield:
Electrically conductive material placed around a system circuit, component, or cable to
suppress the effect of an electromagnetic field within or beyond definite regions.
shielding effectiveness:
The measure, generally in dB, of the reduction or attenuation of the
amplitude of an electromagnetic field at a point in space before and after the placement of a
shield, between a source and this point.
skin depth:
The depth of a conductive material beyond which the current density has
decreased by one Neper (1/e or 36,8 %) in comparison with its value at the surface of the
material.
surface resistivity: The resistance of a material between two opposite sides of a unit square
of its surface, commonly expressed in ohms per square.
surface transfer impedance
(of a coaxial line): The quotient of the voltage induced in the
centre conductor of a coaxial line per unit length by the current on the external surface of the
coaxial line. [I EV 161-04-15]
tensile strength:
The maximum tensile stress applied, during stretching, to a specimen to
rupture.
transfer admittance: A mathematical relationship between the induced current on a conductor
located on the protected side of a shielded region and the voltage on the unprotected side of
the enclosure. This is the dual quantity of the transfer impedance.
transfer impedance (of a screened circuit): The quotient of the voltage appearing between two
specified points in the screened circuit by the current in a defined cross-section of the screen.
[IEV 161-04-14]
volume resistivity:
The electrical resistance between opposite faces of 1 cm 3 of material,
commonly expressed in ohms.centimetres.
waveguide below cut-off: A protective element consisting of a length of waveguide which
limits the passage of electromagnetic energy below a fixed frequency.
waveguide trap:
A waveguide below cut-off serving as an electromagnetic protection device in
a barrier.
4 Specifications for protective devices against radiated disturbances
The shielding effectiveness of a shielded enclosure (Faraday cage, cabinet or shielded
building) is violated by penetrations, openings and seams. All of these shall be treated in such
a way that the resulting degradation of the shielding effectiveness is as small as possible. This
goal is achieved by means of specific protection devices.
In the following, these protection devices are dealt with one by one, by explaining their
principles of operation, showing their limitations in some cases, and finally listing the
specifications that shall be given by the manufacturers.
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1000-5-4 © IEC: 1996 – 13 –
The figures help demonstrate the principle of operation and may also serve as examples of
how the frequency-dependent parameters might be presented.
4.1
General classification for shielding devices
Barrier materials:
–
shielding materials;
–
viewing windows;
– air vent panels;
– waveguide traps;
– conductive coatings;
–
conductive adhesives and sealants.
Shielded cables and conduits:
– solid shields;
– leaky shields;
– connectors.
Gasketing materials:
–
knitted wire mesh gaskets;
– metal fibers and screen gaskets;
– oriented wire gaskets;
– conductive elastomer gaskets.
Shielding components:
– toggle boots;
– shaft seals;
– connector gaskets;
– ring seals;
– foil tapes;
– etc.
4.2
General requirements
The shielding materials needed to reach the required shielding effectiveness shall meet several
electrical, mechanical and environmental criteria.
Electrical requirements
For barrier materials, attenuation values shall be supplied for E and H fields, and for plane
waves in the frequency range 10 kHz to 1000 MHz. For gasketing materials the same
information as above is required, and in addition, the d.c. resistance shall be provided. For
shielded cables the specification of transfer impedance and, if necessary, transfer admittance
in the frequency range 10 kHz to 100 MHz is required.
Mechanical requirements
All the mechanical characteristics necessary for the correct use of the materials should be
available to the user. These are listed in the following subclauses.
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1000-5-4 © IEC: 1996 –15 –
Environmental requirements
The total shielding effectiveness of
a shielded enclosure is limited by the failure of seams to
achieve adequate electrical contact. The shielding integrity of a seam can be increased by
improving this contact. This might be achieved by using conductive gasketing.
However, the use of certain gaskets does not maintain the shielding integrity for a long time
and environmental conditions, such as dust, moisture and vapors shall be taken into
consideration. For example, to seal against dust and moisture, flat or strip EMI gaskets joined
to a sponge or solid elastomer are adequate. Therefore, information concerning the appropriate
environmental use of specific gasketing materials is required.
4.3
Specifications
4.3.1 General
Both mechanical and electrical design aspects should be considered in order to specify
protection devices.
Specifications include:
– general description (presentation, purpose);
– application information (specific use);
–
material description (material, consistency, color, finish, etc.);
– performance characteristics (E, H and plane wave attenuation, d.c. resistance,
temperature range, mechanical properties, transfer impedance and if necessary transfer
admittance);
– dimensions;
– recommendations for use (su rf
ace preparation, pressure, safety and operational
cautions);
– methods of construction;
–
mounting techniques (way of assembly);
– storage recommendations.
4.3.2
Barrier materials
4.3.2.1 Shielding materials
Two types are generally available:
a)
Wire mesh
The shielding effectiveness depends on the size of the volume to be shielded, and
especially on the mesh size and the wire mesh manufacturing. The shielding effectiveness
increases when the mesh size decreases or when using a double shield, the two shields
being insulated from each other and presenting only one connection point to the earth.
For the cage sizes presented in figure 1, the cut-off frequency is about 80 MHz. At higher
frequencies, there is a resonant effect resulting in oscillations.
---------------------- Page: 9 ----------------------
-17 -
1000-5-4 © IEC: 1996
100
^'
50
I!
G
U
0
100 1000 MHz
0,1 1 10
Frequency
IEC 495/Y6
Curve 1: dimensions 3 m x 3,25 m x 3 m
Hexagonal mesh: 15 mm x 17 mm
Curve 2: dimensions 4m x 4 m x 3 m
Square mesh: 4 mm
Figure 1 - Typical plane wave attenuation for double-wall cages
---------------------- Page: 10 ----------------------
– 19 –
1000-5-4 © IEC: 1996
b) Metal sheet
The attenuation of cages with homogeneous metal sheets is higher. The shielding
effectiveness increases with frequency due to the skin depth, so that even very thin sheets
are efficient at high frequencies.
Simple formulas allow the computation of absorption losses, reflection losses and shielding
effectiveness of metal sheets for plane waves when their dimensions are large compared to
the wavelengths considered. These are presented in annex A.
An example of a specification for the shielding effectiveness of a Faraday cage is given in
figure 2.
110
2 3
... •
100
90
^
^
^
4 60
^
1
^
• 50
m
•
E• 40
•
-c
^
20
10
0
1 kHz 10 kHz' 100 kHz 1 MHz 0 MHz 100 MHz 1 GHz 10 GHz
20 MHz
1,6 GHz
14 kHz
Frequency
IEC 496156
1: magnetic field
2: electric field
3: plane wave
4: 10 cm diameter waveguide below cut-off
Figure 2 – Example of HEMP shielding effectiveness of a Faraday cage
Specifications required:
Shielded rooms:
– general description;
– dimensions of the different elements;
– weight;
– way of assembly;
– point and surface loads admitted;
– type of material;
– types of doors possible;
– different points of entry (POEs) with their mechanical characteristics;
– shielding effectiveness.
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1000-5-4 © IEC: 1996 – 21 –
Cabinets:
– general description;
– application information;
– overall dimensions;
–
weight;
– type of material and finish;
– shielding effectiveness (see example in figure 3).
NOTE – It is common practice to use a silicon base lubricant on the door seams. This can lead to an increase of
the contact resistance and consequently degrade the shielding effectiveness.
80
70
m 60
ur
CI
d
> 50
v
â 40
C
To 30
L
V!
20
10
0
1 kHz 10 kHz 100 kHz 1 MHz 10 MHz 100 MHz 1 GHz
Frequency
!EC 497/96
1: magnetic field
2: electric field
Galvanized steel thickness: 2 mm; dimensions: 2 m x 2 m x 1 m
Door: 1,8 m x 0,6 m; door contact: nickel - nickel
Figure 3 – Example of attenuation of a cabinet with gaskets
4.3.2.2 Viewing windows
Viewing windows are used in equipment requiring visual displays where the viewing panel shall
also serve to reduce radiated electromagnetic energy entering the protected area.
They can be manufactured in glass, plastic or combinations of both. EMI shielding is provided
by knitted or woven wire mesh, laminated between the glass or plastic substrates, or by
deposited conductive coatings.
The shielding effectiveness is determined by the size of the wire screen openings, electrical
contact between intersecting wires and the materials and techniques employed to terminate the
wires at the frame edge.
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1000-5-4 © IEC: 1996 – 23 –
By assuming a quasi-static approximation (dimensions « X), for viewing windows with
conductive coating, the electric field impedes only due to reflection effect. For the magnetic
field it is different. The magnetic field measured behind a viewing window (H2) is reduced as a
function of frequency relative to the field measured at the same location with an open aperture
(H1 ). The attenuation function is given by:
H2 1
H1 1+ fan
where
T = 8 L/(3 it (RS+2 7L Re));
RS
is the surface resistance of the conductive film;
Re is the contact resistance between the conductive film and the frame edge;
L is the window equivalent inductance.
In the case of viewing windows with meshes, the magnetic field attenuation function has the
same shape. However, R S is replaced by ZS = Rs + Jo) Ls, where Rs depends on the linear
resistance of the wire and mesh size, and Ls depends on the window and mesh sizes.
With magnetic fields, viewing windows behave like Iowpass filters (see example in figure 4).
For viewing windows with meshes, the attenuation function is not frequency-dependent, and
only depends on the nature and sizes of windows and mesh.
H
I2I
1
1 0 -1
-2
^
10
► f
100
1 10
21Lti 27ZZ
21Lti IBC 498/96
Figure 4 – Example of magnetic field attenuation function of a viewing window
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1000-5-4 © IEC: 1996 – 25 –
The electric field attenuation function is not frequency-dependent up to the cut-off frequency of
the window. It depends on the window dimensions and material.
Specifications requ
...
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