CLC/TR 50174-99-2:2020

SLOVENSKI STANDARD
01-maj-2020
Informacijska tehnologija - Polaganje kablov - 99-2. del: Zmanjševanje električnih
motenj iin zaščita pred njimi
Information technology - Cabling installation - Part 99-2: Mitigation and protection from
electrical interference
Informationstechnik - Installation von Kommunikationsverkabelung - Teil 99-2:
Abschwächung von und Schutz vor elektrischer Störung
Technologies de l'information - Installation de câblages - Partie 99-2:
Ta slovenski standard je istoveten z: CLC/TR 50174-99-2:2020
ICS:
33.040.50 Vodi, zveze in tokokrogi Lines, connections and
circuits
35.110 Omreževanje Networking
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

TECHNICAL REPORT CLC/TR 50174-99-2

RAPPORT TECHNIQUE
TECHNISCHER BERICHT
March 2020
ICS 35.110
English Version
Information technology - Cabling installation - Part 99-2:
Mitigation and protection from electrical interference
Technologies de l'information - Installation de câblages - Informationstechnik - Installation von
Partie 99-2: Kommunikationsverkabelung - Teil 99-2: Abschwächung
von und Schutz vor elektrischer Störung

This Technical Report was approved by CENELEC on 2020-02-10.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2020 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. CLC/TR 50174-99-2:2020 E

Contents Page
European foreword .3
Introduction .4
1 Scope .5
2 Normative references .5
3 Definitions, abbreviations and symbology .5
3.1 Definitions .5
3.2 Abbreviations .6
4 Coupling mechanisms and countermeasures .6
4.1 General .6
4.2 Countermeasures against galvanic or common mode impedance coupling .6
4.3 Countermeasures against capacitive coupling .6
4.4 Countermeasures against inductive coupling .7
4.5 Countermeasures against radiative coupling.8
4.6 Protection against very low frequency fields.9
5 Assessment of the electromagnetic environment .9
6 Filtering and electrical isolation components and surge protective devices . 14
6.1 Filtering . 14
6.1.1 General . 14
6.1.2 Design . 15
6.1.3 Installation . 15
6.2 Electrical isolation components . 16
6.2.1 General . 16
6.2.2 Design . 16
6.2.3 Installation . 17
6.3 Surge protective devices. 19
6.3.1 General . 19
6.3.2 Design . 19
6.3.3 Installation . 19
Bibliography . 21

European foreword
This document (CLC/TR 50174-99-2:2020) was prepared by the Technical Committee CLC/TC 215,
“Electrotechnical aspects of telecommunication equipment”.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
A previous version of this document was published as informative Annex A in EN 50174-2:2009.
During the revision of EN 50174-2:2009, TC 215 decided to remove the Annex, revise and then
publish it as separate Technical Report.
Introduction
The EN 50174 series standards specify the specification, planning and practices applicable to
installation of telecommunications cabling.
This document supports the requirements and recommendations of the EN 50174 series in relation to
the mitigation and protection of telecommunications cabling from electromagnetic interference by
describing:
a) coupling mechanisms and possible countermeasures;
b) assessment of the electromagnetic environment;
c) filtering, isolation and surge protections measures.
1 Scope
This document addresses the mitigation and protection of telecommunications cabling from
electromagnetic interference by describing:
a) coupling mechanisms and possible countermeasures;
b) assessment of the electromagnetic environment;
c) filtering, isolation and surge protections measures.
Safety (electrical safety and protection, optical power, fire, etc.) and electromagnetic compatibility
(EMC) requirements are outside the scope of this document and are covered by standards and
regulations. However, information given in this document can be of assistance in meeting these
standards and regulations.
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.
EN 50173 (series), Information technology – Generic cabling systems
EN 50174 (series), Information technology - Cabling installation
EN 50174-2:2018, Information technology - Cabling installation - Part 2: Installation planning and
practices inside buildings
EN 50174-3, Information technology - Cabling installation - Part 3: Installation planning and practices
outside buildings
EN 50310:2016, Telecommunications bonding networks for buildings and other structures
3 Definitions, abbreviations and symbology
3.1 Definitions
For the purposes of this document, the terms and definitions given in the EN 50173 series and
EN 50174 series and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
3.1.1
common bonding network
set of interconnected conductive structures that combine the functions of a protective bonding network
and a telecommunications bonding network
[SOURCE: EN 50310:2016, 3.1.6]
3.1.2
isolated bonding network
bonding network that has a single point of connection to either the common bonding network or
another isolated bonding network
Note 1 to entry: All IBNs considered here will have a connection to earth through the single point of connection.
3.2 Abbreviations
For the purposes of this technical report the following abbreviations apply in addition to those of the
EN 50173 series and EN 50174 series of standards.
BN Bonding Network
CBN Common Bonding Network
CMS cable management system
IBN Isolated Bonding Network
SRPP System Reference Potential Plane
4 Coupling mechanisms and countermeasures
4.1 General
Electromagnetic interference is transferred to installed telecommunications cabling by the following
coupling phenomena which can have adverse effects at different frequencies including:
— galvanic or common mode impedance coupling (see 4.2);
— capacitive coupling (see 4.3);
— inductive coupling (see 4.4);
— radiative coupling (see 4.5);
— low frequency fields (se 4.6).
4.2 Countermeasures against galvanic or common mode impedance coupling
Impedances in common mode current paths, if they cannot be avoided, should be kept as low as
possible.
The main countermeasures to minimize the effects of common mode impedance coupling are the
reduction of the:
a) common mode impedance;
b) amplitude of the disturbing currents.
4.3 Countermeasures against capacitive coupling
The main countermeasures to minimize the effects of capacitive coupling are:
a) Symmetrical transmission on balanced cabling
Conductors are exposed to the same electric field. Induced interfering voltages in both conductors
have the same polarity and amplitude; the wanted differential mode signal remains unaffected up
to a frequency dependent on the balance of the cabling. The interference appears as an
unwanted common mode signal. Depending on its common mode rejection ratio, the correct
operation of connected equipment is influenced by the presence of common mode voltages.
b) Screened cabling specially designed to mitigate electromagnetic interference if the cable screen
is:
— of low impedance;
— of large surface area;
— continuous along the cabling channel;
— bonded as detailed in EN 50174-2 and EN 50310.
NOTE At high frequencies the method of bonding of the screen at the ends of the cable is important. Even a
few centimetres of unscreened lead (pigtail) can compromise the screen effectiveness.
c) A cable management system (CMS) specially designed to mitigate electromagnetic interference if
it is:
— of low impedance;
— of large surface area;
— continuous along the cabling channel;
— bonded as detailed in EN 50174-2 and EN 50310.
NOTE Since the cable management system is fixed at earth potential via the bonding network, unwanted
electric charges cannot cause voltage rises.
4.4 Countermeasures against inductive coupling
The main countermeasures to minimize the effects of inductive couplings are:
a) Symmetrical transmission on balanced cabling
Conductors are twisted together making the surfaces of possible induction loops very small. Only
a few magnetic field lines penetrate these loops. Adjacent twists create induced voltages in phase
opposition which as a consequence cancel each other. The induced difference between the two
conductors approaches zero. However, a common mode disturbance is induced in the loop
formed with the (twisted) conductors and the bonding network. The influence on the equipment is
reduced by the common mode rejection of the connected port.
b) Screened cabling
The degree of protection against magnetic fields over a given frequency range provided by
screened cabling depends:
— upon the materials used in the screen;
— the bonding of the screen to the bonding network (BN) at the ends of the cable (see
EN 50174-2:2018, 4.7).
NOTE In general, no effective protection against magnetic fields is given if the screen of the cable is not
bonded in accordance with EN 50310. Exceptions to this rule exist e.g. when the unconnected cable screen
is placed on the surface of or near to a system reference potential plane (SRPP).
c) Metallic or composite CMS specially designed for to mitigate electromagnetic interference
The degree of protection against magnetic fields over a given frequency range provided depends
upon:
— the material used in the CMS and its thickness;
— the bonding of the elements of the CMS;
— the bonding of the CMS to the BN.
The disturbing magnetic field also induces a current in the loop built up by CMS and the BN. This
current creates an opposite magnetic field which compensates the initial one.
A limited degree of protection can be obtained with a parallel earthing conductor (PEC). The PEC
principle is explained in IEC/TR 61000-5-3.
Both capacitive and inductive coupling exist simultaneously, the counterm
...