SIST-TS CLC/TS 61643-22:2007

SLOVENSKI STANDARD
SIST-TS CLC/TS 61643-22:2007
01-januar-2007
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Low-voltage surge protective devices -- Part 22: Surge protective devices connected to
telecommunications and signalling networks - Selection and application principles
berspannungsschutzgerte fr Niederspannung -- Teil 22: berspannungsschutzgerte fr den
Einsatz in Telekommunikations- und signalverarbeitenden Netzwerken - Auswahl- und
Anwendungsprinzipien
Parafoudres basse tension -- Partie 22: Parafoudres connects aux rseaux de signaux et
de tlcommunications - Principes de choix et d'application
Ta slovenski standard je istoveten z: CLC/TS 61643-22:2006
ICS:
29.120.50 9DURYDONHLQGUXJD Fuses and other overcurrent
PHGWRNRYQD]DãþLWD protection devices
29.240.10 Transformatorske postaje. Substations. Surge arresters
Prenapetostni odvodniki
SIST-TS CLC/TS 61643-22:2007 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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TECHNICAL SPECIFICATION
CLC/TS 61643-22

SPÉCIFICATION TECHNIQUE
April 2006
TECHNISCHE SPEZIFIKATION

ICS 29.240; 29.240.10


English version


Low-voltage surge protective devices
Part 22: Surge protective devices connected to telecommunications
and signalling networks -
Selection and application principles
(IEC 61643-22:2004, modified)


Parafoudres basse tension Überspannungsschutzgeräte
Partie 22: Parafoudres connectés für Niederspannung
aux réseaux de signaux Teil 22: Überspannungsschutzgeräte
et de télécommunications - für den Einsatz in Telekommunikations-
Principes de choix et d'application und signalverarbeitenden Netzwerken -
(CEI 61643-22:2004, modifiée) Auswahl- und Anwendungsprinzipien
(IEC 61643-22:2004, modifiziert)





This Technical Specification was approved by CENELEC on 2005-09-10.

CENELEC members are required to announce the existence of this TS in the same way as for an EN and to
make the TS available promptly at national level in an appropriate form. It is permissible to keep conflicting
national standards in force.

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



CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels


© 2006 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. CLC/TS 61643-22:2006 E

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CLC/TS 61643-22:2006 - 2 -
Foreword
The text of the International Standard IEC 61643-22:2004, prepared by SC 37A, Low-voltage surge
protective devices, of IEC TC 37, Surge arresters, together with common modifications prepared by the
Technical Committee CENELEC TC 37A, Low voltage surge protective devices, was submitted to the formal
vote and was approved by CENELEC as CLC/TS 61643-22 on 2005-09-10.
The following date was fixed:
– latest date by which the existence of the CLC/TS
has to be announced at national level (doa) 2006-07-01
__________

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Contents
Introduction.6
1 Scope.7
2 Normative references.7
3 Terms and definitions.7
4 Description of technologies.8
4.1 Voltage-limiting devices .8
4.1.1 Clamping-type .8
4.1.2 Switching-type.8
4.2 Current-limiting devices .8
4.2.1 Current-interrupting type.8
4.2.2 Current-reducing type.9
4.2.3 Current-diverting type.9
5 Parameters for selection of SPDs and appropriate tests from EN 61643-21 .9
5.1 Controlled and uncontrolled environments .9
5.1.1 Controlled environments.9
5.1.2 Uncontrolled environments.9
5.2 SPD parameters that may affect normal system operation .10
6 Risk management.10
6.1 Risk analysis .11
6.2 Risk identification .11
6.3 Risk treatment.11
7 Application of SPDs.13
7.1 General.13
7.2 Coupling mechanisms.13
7.3 Application, selection and installation of surge protective devices (SPDs) .15
7.3.1 Application requirements for SPDs .15
7.3.2 SPD installation cabling considerations.20
8 Multiservice surge protective devices .23
9 Coordination of SPDs/ITE .23
Annex A (informative) Voltage-limiting devices.25
A.1 Voltage-clamping devices .25
A.1.1 Metal oxide varistor (MOV) .25
A.1.2 Silicon semiconductors .25
A.2 Voltage-switching devices.27
A.2.1 Gas discharge tube (GDT).27
A.2.2 Air gaps.27
A.2.3 Thyristor surge suppressor (TSS) – Fixed voltage types (self-gating) .28
A.2.4 Thyristor surge suppressor (TSS) – Gated types .28

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CLC/TS 61643-22:2006 - 4 -
Annex B (informative) Current-limiting devices.29
B.1 Current-interrupting devices.29
B.1.1 Fusible resistor.29
B.1.2 Fuses.30
B.1.3 Thermal fuses .30
B.2 Current-reducing devices.30
B.2.1 Polymer PTC (positive temperature coefficient resistor) .31
B.2.2 Ceramic PTC.31
B.2.3 Electronic current limiters.31
B.3 Current-diverting devices.31
B.3.1 Heat coils.32
B.3.2 Gated thyristor, current operated .32
B.3.3 Thermal switch .33
Annex C (informative) Risk management.34
C.1 Risk due to lightning discharges .34
C.1.1 Risk assessment.34
C.1.2 Risk analysis.34
C.1.3 Risk evaluation.35
C.1.4 Risk treatment.36
C.2 Risk due to power line faults.36
C.2.1 AC power systems .36
C.2.2 DC power systems.37
C.3 Earth potential rise.37
Annex D (informative) Transmission characteristics related to IT systems.38
D.1 Telecommunications systems.38
D.2 Signalling, measurement and control systems .39
D.3 Cable TV systems.39
Annex E (informative) Coordination of SPDs/ITE .40
E.1 Determination of UIN and IIN.40
E.2 Determine the output protective voltage and current waveforms for SPD 1.40
E.3 Compare SPD 1 and SPD 2 values.41
E.4 Necessity of verification of the coordination by testing.42

Figure 1 – SPD installation in telecommunications and signalling networks. 12
Figure 2 – Coupling mechanisms . 14
Figure 3 – Example of a configuration of the lightning protection concept . 16
Figure 4 – Example of a configuration according to the zones(Figure 2). 18
Figure 5 – Example of protecting measures against common-mode voltages and
        differential mode voltages of the data (f) and supply voltage input (g) of an ITE . 19
Figure 6 – Influence of the voltages U and U on the protection level U
L1 L2 P
        caused by the inductance of the leads . 20

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Figure 7 – Removal of the voltages U and U from the protector unit
L1 L2
        by connecting leads to a common point. . 21
Figure 8 – Necessary installation conditions of a three, five or multi-terminal SPD
        with an ITE for minimizing the interference influences on the protection level . 22
Figure 9 – Coordination of two SPDs . 23
Figure A.1 – Circuit for voltage-clamping devices . 25
Figure A.2 – Circuit for voltage-switching devices . 27
Figure B.1 – Circuit for interrupting devices . 29
Figure B.2 – Circuit for current-reducing devices . 30
Figure B.3 – Circuit for current-diverting devices. 32
Figure C.1 – Risk evaluation procedure . 35
Figure E.1 – Coordination verification process . 41

Table 1 – Responsibility for managing the protective measures . 11
Table 2 – Coupling mechanisms . 15
Table 3 – Selection aid for rating SPDs for the use in (zone) interfaces
        according to IEC 61312-1 and EN 61000-4-5. 17
Table C.1 – AC overhead power systems. 36
Table C.2 – AC underground electric cables . 37
Table C.3 – DC overhead power systems . 37
Table C.4 – DC underground electric cables . 37
Table D.1 – Transmission characteristics for telecommunications systems in access networks. 38
Table D.2 – Transmission characteristics of IT systems in customer premises . 39
Table D.3 – Transmission characteristics of cable TV-systems . 39

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CLC/TS 61643-22:2006 - 6 -
Introduction
This TS is a guide for the application of SPDs to telecommunications and signalling lines and those SPDs
which have telecom or signalling SPDs in the same enclosure with power line SPDs. Definitions,
requirements and test methods are given in EN 61643-21. The decision to use SPDs is based on an
analysis of the risks that are seen by the network or system under consideration. Because
telecommunications and signalling systems may depend on long lengths of wire, either buried or aerial,
the exposure to overvoltages from lightning, power line faults and power line/load switching, can be
significant. If these lines are unprotected, the resultant risk to information technology equipment (ITE) can
also be significant. Other factors that may influence the decision to use SPDs are local regulators and
insurance stipulations. This TS provides indications for evaluating the need for SPDs, the selection,
installation and dimensioning of SPDs and for achieving coordination between SPDs and between SPDs
and ITE installed on telecommunication and signal lines.
Coordination of SPDs assures that the interaction between them, as well as between an SPD and the ITE
to be protected will be realized. Coordination requires that the voltage protection level, U , and let-through
p
current, I , of the initial SPD does not exceed the resistibility of subsequent SPDs or the ITE.
p
In general, the SPD closest to the source of the impinging surge diverts most of the surge: a downstream
SPD will divert the remaining or residual surge. The coordination of SPDs in a system is affected by the
operation of the SPDs and the equipment to be protected as well as the characteristics of the system to
which the SPDs are connected.
The following variables should be reviewed when attempting to attain proper coordination:
− waveshape of the impinging surge (impulse or AC);
− ability of the equipment to withstand an overvoltage/overcurrent without damage;
− installation, e.g. distance between SPDs and between SPDs and ITE;
− SPD voltage-limiting levels and response times.
The performance of an SPD and its coordination with other SPDs can be affected by exposure to
previous transients. This is especially true for transients which approach the limit of the capacity of the
SPD. If there is considerable doubt concerning the number and severity of the surges handled by the
SPDs under consideration, it is suggested that SPDs with higher capabilities be used.
One of the direct effects of poor coordination may be bypassing of the SPD closest to the surge source,
with the result that the following SPD will be forced to handle the entire surge. This can result in damage
to that SPD.
Lack of proper coordination can also lead to equipment damage and, in severe cases, may lead to a fire
hazard.
There are several technologies used in the design of the SPDs covered in this TS. These are explained in
the main text and also in informative Annexes A and B.

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1 Scope
This TS 61643-22 describes the principles for the selection, operation, location and coordination of SPDs
connected to telecommunication and signalling networks with nominal system voltages up to
1 000 V r.m.s. a.c. and 1 500 V d.c.
This TS also addresses SPDs that incorporate protection for signalling lines and power lines in the same
enclosure.
2 Normative references
The following referenced documents are indispensable for the application 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 61000-4-5:1995, Electromagnetic compatibility (EMC) – Part 4-5: Testing and measurement
techniques – Surge immunity test (IEC 61000-4-5:1995)
EN 61643-11:2002, Low-voltage surge protective devices – Part 11: Surge protective devices connected
to low-voltage power systems - Requirements and tests (IEC 61643-1:1998 + corr. Dec. 1998, mod.)
EN 61643-21:2001, Low-voltage surge protective devices – Part 21: Surge protective devices connected
to telecommunications and signalling networks – Performance requirements and testing methods
(IEC 61643-21:2000 + corr. Mar. 2001)
IEC 61312-1:1995, Protection against lightning electromagnetic impulse – Part 1: General principles
IEC 61312-2:1999, Protection against lightning electromagnetic impulse (LEMP) – Part 2: Shielding of
structures, bonding inside structures and earthing
ITU-T K.31:1993, Bonding configurations and earthing of telecommunication installations inside a
subscriber's building
3 Terms and definitions
For the purposes of this document, the following definitions apply.
3.1
resistibility
ability of an SPD or information technology equipment (ITE) to withstand an overvoltage or overcurrent
event without damage
1)
NOTE This definition is derived from EN 61663-2 [1] and is modified for this application. The equipment can lose some function
during the overvoltage/overcurrent, but works correctly after the application of the overvoltage/ overcurrent.
3.2
multiservice surge protective device
surge protective device providing protection for two or more services such as power, telecommunications
and signalling in a single enclosure in which a reference bond is provided between services during surge
conditions
———————
1)
Figures in square brackets refer to the bibliography.

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CLC/TS 61643-22:2006 - 8 -
4 Description of technologies
The following is a short description of various surge protection component technologies. More details are
available in Annexes A and B.
4.1 Voltage-limiting devices
These shunt-connected SPD components are non-linear elements that limit overvoltages that exceed a
given voltage by providing a low impedance path to divert currents. This voltage, U , is chosen to be
c1
greater than the maximum peak system voltage in normal operation. At the maximum system operating
voltage, the SPD’s leakage current should not interfere with normal system operation.
Multiple components may be used to form assemblies. Connecting voltage-limiting surge protective
components in series results in higher voltage protection levels. Parallel component connection will
increase the surge current capability of the assembly. However, care should be taken to assure current
sharing between the parallel components.
Some technologies, e.g. metal oxide varistors, have voltage-current characteristics that are inherently
symmetrical for positive and negative voltage polarities. Such devices are classified as symmetrical bi-
directional. Devices having positive and negative current-voltage characteristics with the same basic
shape, but with significantly different characteristic values are classified as asymmetrical bi-directional.
Other technologies, e.g. PN semiconductor junctions, have voltage-current characteristics that are
inherently different for positive and negative voltage polarities.
4.1.1 Clamping-type
These SPD components have continuous voltage-current characteristics. Generally, this will mean that
the protected equipment will be exposed to a voltage above the SPD’s threshold level for most of the
voltage impulse duration. As a result, these SPD components will absorb substantial energy during the
overvoltage.
4.1.2 Switching-type
These SPD components have a discontinuous current-voltage characteristic. At a designed voltage, they
switch to a low-voltage state. In this low-voltage state, the energy absorbed is low compared to that of
other SPDs that ”clamp” the voltage at a specific protection level. As a result of this switching action,
protected equipment will be subjected to a voltage above the normal system voltage for only a very short
time. If the system’s operating voltage and current exceed the reset characteristics of the switching-type
device, these devices remain in the conducting state. Appropriate SPD selection and circuit design will
allow the SPD to recover to a high resistance state under normal system voltage and currents.
4.2 Current-limiting devices
To limit an overcurrent, the protection device has to stop or reduce the current flowing to the protected
load. There are three possible methods: interruption, reduction or diversion. The majority of the
technologies used for overcurrent protection are thermally activated, resulting in relatively slow response
operating times. Until the overcurrent protection operates, the load, and possibly the SPDs, have to be
capable of withstanding the surge.
4.2.1 Current-interrupting type
These devices open the circuit path for the surge current to the SPD or ITE (see Figure B.1). Sudden
opening of a current-carrying circuit usually results in arcing, particularly if the current is at its peak. This
arcing has to be controlled to prevent a safety hazard. After interruption, maintenance is required to
restore service. One example of a current-interrupting device is a fuse.

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4.2.2 Current-reducing type
These devices reduce the current flow by effectively inserting a large series resistance with the load (see
Figure B.2). An example of a current-reducing type used for this action is a self-heating positive
temperature coefficient (PTC) thermistor. Overcurrents cause resistive heating of the PTC thermistor,
which results in the thermistor’s temperature exceeding its threshold temperature (typically 120 °C).
Consequently, this causes a thermistor resistance change from ohms to hundreds of kilo-ohms, thereby
reducing the current. The lower current, after changing to a high resistance, maintains the PTC
thermistor's temperature, forcing the PTC thermistor to remain in the high resistance state. A thermistor
dissipation of typically about 1 W is needed to maintain the temperature, e.g. 5 mA from a 200 V a.c.
overvoltage. If the system’s operating voltage and current do not exceed the PTC reset characteristics,
the PTC thermistor will cool and return to a low resistance value after the surge.
4.2.3 Current-diverting type
These devices effectively place a short-circuit across the network at the point of installation (see
Figure B.3). Activation occurs due to temperature rise of the voltage-limiting type or load current sensing.
Although the load is protected, the surge current in the network feed is the same or greater. After
operation, maintenance may be required to restore service.
5 Parameters for selection of SPDs and appropriate tests from EN 61643-21
This clause discusses the parameters of SPDs and their relevance to the operation of the SPDs and the
normal operation of the networks to which they are connected. These parameter values can be used to
form the basis for comparison amongst SPDs and also to provide guidance in their selection for signalling
and power systems. Values for these parameters are available from SPD manufacturers and suppliers.
Verification of the values, or obtaining them when not provided by suppliers, should be performed using
the tests and methods described in EN 61643-21.
5.1 Controlled and uncontrolled environments
The SPD parameters should be suitable for the intended environment.
5.1.1 Controlled environments
− Temperature range: -5 °C to 40 °C
− Humidity range: 10 % RH to 80 % RH
− Air pressure range: 80 kPa to 106 kPa
The controlled environment is one within the managed environment of a building or other infrastructure.
This controlled environment will be at the very least naturally heated and cooled but will be protected
against the extremes of the natural environment.
5.1.2 Uncontrolled environments
− Temperature range: -40 °C to 70 °C
− Humidity range: 5 % RH to 96 % RH
− Air pressure range: 80 kPa to 106 kPa

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CLC/TS 61643-22:2006 - 10 -
5.2 SPD parameters that may affect normal system operation
The essential characteristics for the operation of SPDs having voltage-limiting or both voltage-limiting and
current-limiting functions used in protecting telecommunication and signalling systems are as follows:
− maximum continuous operating voltage U ;
c
− voltage protection level U ;
p
− impulse reset;
− insulation resistance (leakage current);
− rated current.
SPDs should conform to application-specific requirements. Some SPD parameters can influence the
transmission characteristics of the network. These are listed below, as follows:
− capacitance;
− series resistance;
− insertion loss;
− return loss;
− longitudinal balance;
− near end cross-talk (NEXT).
Therefore, SPDs may need to be tested using selected tests from EN 61643-21. Annex D provides
information about information technologies and some of their transmission characteristics that have to be
taken into account when applying SPDs to these systems.
6 Risk management
The need for protective measures (e.g. protection with SPDs) for Information Technology Systems should
be based on a risk assessm
...