IEC 61643-11:2011

Low-voltage surge protective devices - Part 11: Surge protective devices connected to low-voltage power systems - Requirements and test methods

IEC 61643-11:2011 is applicable to devices for surge protection against indirect and direct effects of lightning or other transient overvoltages. These devices are packaged to be connected to 50/60 Hz a.c. power circuits, and equipment rated up to 1 000 V r.m.s. Performance characteristics, standard methods for testing and ratings are established. These devices contain at least one nonlinear component and are intended to limit surge voltages and divert surge currents. This first edition of IEC 61643-11 cancels and replaces the second edition of IEC 61643-1 published in 2005. The main changes with respect of the second edition of IEC 61643-1 are the complete restructuring and improvement of the test procedures and test sequences. NOTE: The attention of National Committees is drawn to the fact that equipment manufacturers and testing organizations may need a transitional period following publication of a new, amended or revised IEC publication in which to make products in accordance with the new requirements and to equip themselves for conducting new or revised tests. It is the recommendation of the committee that the content of this publication be adopted for national implementation not earlier than 12 months from the date of publication. In the meantime, the previous edition can still be ordered by contacting your local IEC member National Committee or the IEC Central Office.

Parafoudres basse tension - Partie 11: Parafoudres connectés aux systèmes basse tension - Exigences et méthodes d'essai

La CEI 61643-11:2011 est applicable aux dispositifs de protection contre les effets indirects et directs de la foudre ou contre les surtensions transitoires. Ces dispositifs sont conçus pour être connectés à des circuits sous tension alternative 50/60 Hz et à des équipements de tension assignée efficace allant jusqu'à 1 000 V efficace. Sont définies les caractéristiques de fonctionnement, les méthodes normalisées d'essai ainsi que les valeurs assignées applicables. Ces dispositifs comportent au moins un composant non linéaire et sont utilisés pour limiter les surtensions et écouler les courants de foudre. Cette première édition de la CEI 61643-11 annule et remplace la deuxième édition de la CEI 61643-1 parue en 2005. Les modifications principales par rapport à la deuxième édition de la CEI 61643-1 sont une restructuration complète et l'adaptation des procédures et séquences d'essai. NOTE: L'attention des Comités Nationaux est attirée sur le fait que les fabricants d'appareils et les organismes d'essai peuvent avoir besoin d'une période transitoire après la publication d'une nouvelle publication CEI, ou d'une publication amendée ou révisée, pour fabriquer des produits conformes aux nouvelles exigences et pour adapter leurs équipements aux nouveaux essais ou aux essais révisés. Le comité recommande que le contenu de cette publication soit entériné au niveau national au plus tôt 12 mois après la date de publication. Dans l'intervalle, l'édition précédente peut encore être commandée en communiquant avec le membre de votre local CEI Comité National ou le Bureau Central de la CEI.

General Information

• Status: Published
• Publication Date: 08-Mar-2011
• ICS: 29.240.10 - Substations. Surge arresters
• Technical Committee: SC 37A - Low-voltage surge protective devices
• Drafting Committee: WG 5 - TC 37/SC 37A/WG 5
• Current Stage: PPUB - Publication issued
• Start Date: 09-Mar-2011
• Completion Date: 15-Feb-2011

Relations

• Replaces: IEC 61643-1:2005 - Low-voltage surge protective devices - Part 1: Surge protective devices connected to low-voltage power distribution systems - Requirements and tests
• Effective Date: 05-Sep-2023
• Replaced By: IEC 61643-01:2024 - Low-voltage surge protective devices - Part 01: General Requirements and test methods
• Effective Date: 05-Sep-2023
• Revised: IEC 61643-11:2025 - Low-voltage surge protective devices - Part 11: Surge protective devices connected to AC low-voltage power systems - Requirements and test methods
• Effective Date: 05-Sep-2023

Overview

IEC 61643-11:2011 is an international standard published by the International Electrotechnical Commission (IEC) that defines the requirements and test methods for low-voltage surge protective devices (SPDs) connected to low-voltage power systems. Applicable to devices designed for 50/60 Hz AC power circuits with equipment rated up to 1,000 V rms, this standard addresses surge protection against both indirect and direct effects of lightning and other transient overvoltages.

This first edition replaces the previous IEC 61643-1:2005 standard, introducing a complete restructuring and enhancement of test procedures and sequences. The publication ensures uniform performance characteristics, testing methods, and rating definitions to enhance the reliability, safety, and efficiency of surge protective devices used worldwide.

Key Topics

• Scope of Application: Covers SPDs designed to limit surge voltages and divert surge currents in low-voltage power systems.
• Classification Criteria: Based on number of ports (one or two), SPD design (voltage switching, voltage limiting, or combination), classification by test classes (Class I, II, III), mounting location (indoor or outdoor), and accessibility.
• Technical Requirements:
  • Electrical aspects such as protection against direct contact, residual current limits, voltage protection level, operating duty, and insulation resistance.
  • Mechanical requirements including mounting, termination, air clearance, creepage distances, and mechanical strength.
  • Environmental and material standards for heat and fire resistance, electro-magnetic compatibility, and protection against moisture ingress.
• Testing Procedures:
  • Defined type tests covering electrical, mechanical, environmental, and additional tests for specific designs.
  • Detailed test sequences for impulse discharge current, voltage impulse, and combination waves.
• Marking and Identification: Specifications for clear product identification and marking to ensure traceability and compliance.
• Failure Behavior: Defines expected SPD failure modes such as open-circuit or short-circuit behavior to ensure safe end-of-life performance.

Applications

IEC 61643-11:2011 applies to surge protective devices used in:

• Residential, commercial, and industrial low-voltage electrical installations.
• Protection of sensitive electronic and electrical equipment from transient overvoltages caused by lightning or switching operations.
• Electrical panels, distribution boards, and power supply units operating at voltages up to 1,000 V rms.
• Equipment requiring compliance with international surge protection safety and performance guidelines.
• Design and manufacture of SPDs with reliable test methodologies for quality assurance and compliance with national and international electrical safety standards.

Related Standards

• IEC 61643 Series: Other parts of IEC 61643 cover surge protective devices for different applications and system types.
• IEC 60364: Electrical installations of buildings, including aspects related to protection against overvoltages.
• IEC 61000 Series: Electromagnetic compatibility (EMC) standards relevant to testing and measurement of SPDs.
• National Standards: Various countries adopt IEC 61643-11 for national implementation, sometimes with additional local requirements.

---

Keywords: IEC 61643-11, low-voltage surge protective devices, surge protection, transient overvoltage, lightning protection, SPD testing methods, surge protection standard, electrical safety standards, IEC surge protective devices, low-voltage power systems, SPD classification, surge arrester requirements.

Standards Content (Sample)

IEC 61643-11 ®
Edition 1.0 2011-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Low-voltage surge protective devices –
Part 11: Surge protective devices connected to low-voltage power systems –
Requirements and test methods
Parafoudres basse tension –
Partie 11: Parafoudres connectés aux systèmes basse tension – Exigences et
méthodes d'essai
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IEC 61643-11 ®
Edition 1.0 2011-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Low-voltage surge protective devices –
Part 11: Surge protective devices connected to low-voltage power systems –
Requirements and test methods
Parafoudres basse tension –
Partie 11: Parafoudres connectés aux systèmes basse tension – Exigences et
méthodes d'essai
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XD
ICS 29.240; 29.240.10 ISBN 978-2-88912-350-6

– 2 – 61643-11  IEC:2011
CONTENTS
FOREWORD . 7
INTRODUCTION . 9
1 Scope . 10
2 Normative references . 10
3 Terms, definitions and abbreviations . 10
3.1 Terms and definitions . 11
3.2 Abbreviations . 16
4 Service conditions . 18
4.1 Frequency . 18
4.2 Voltage . 18
4.3 Air pressure and altitude . 18
4.4 Temperatures . 18
4.5 Humidity . 18
5 Classification . 18
5.1 Number of ports . 18
5.1.1 One . 18
5.1.2 Two . 18
5.2 SPD design . 18
5.2.1 Voltage switching . 18
5.2.2 Voltage limiting . 18
5.2.3 Combination . 18
5.3 Class I, II and III tests . 18
5.4 Location . 19
5.4.1 Indoor . 19
5.4.2 Outdoor . 19
5.5 Accessibility . 19
5.5.1 Accessible . 19
5.5.2 Inaccessible . 19
5.6 Mounting method . 19
5.6.1 Fixed . 19
5.6.2 Portable . 19
5.7 Disconnectors (including overcurrent protection) . 19
5.7.1 Location . 19
5.7.2 Protection functions . 19
5.8 Degree of protection provided by enclosures . 19
5.9 Temperature and humidity range . 20
5.9.1 Normal . 20
5.9.2 Extended . 20
5.10 Power system . 20
5.10.1 AC between 47 Hz and 63 Hz . 20
5.10.2 AC other than the range of 47 Hz to 63 Hz . 20
5.11 Multipole SPD . 20
5.12 SPD failure behaviour . 20
5.12.1 open circuit (standard type SPD) . 20
5.12.2 short-circuit (short-circuiting type SPD) . 20

61643-11  IEC:2011 – 3 –
6 Preferred values for SPD . 20
6.1 Preferred values of impulse discharge current I for class I tests . 20
imp
6.2 Preferred values of nominal discharge current for class II tests I . 20
n
6.3 Preferred values of open-circuit voltage for class III tests U . 20
oc
6.4 Preferred values of voltage protection level U . 20
p
6.5 Preferred values of r.m.s. maximum continuous operating voltage U . 20
c
7 Requirements . 21
7.1 General requirements . 21
7.1.1 Identification . 21
7.1.2 Marking . 22
7.2 Electrical requirements . 22
7.2.1 Protection against direct contact . 22
7.2.2 Residual current I . 23
PE
7.2.3 Voltage protection level U . 23
p
7.2.4 Operating duty . 23
7.2.5 Disconnectors and status indicators . 23
7.2.6 Insulation resistance . 24
7.2.7 Dielectric withstand . 24
7.2.8 Behaviour under Temporary Overvoltages . 24
7.3 Mechanical requirements . 25
7.3.1 Mounting . 25
7.3.2 Screws, current carrying parts and connections . 25
7.3.3 External connections . 25
7.3.4 Air clearances and creepage distances. 27
7.3.5 Mechanical strength . 27
7.4 Environmental and material requirements . 27
7.4.1 Protection provided by enclosure (IP code) . 27
7.4.2 Heat resistance . 27
7.4.3 Fire resistance . 27
7.4.4 Tracking resistance . 27
7.4.5 Electromagnetic compatibility . 28
7.5 Additional requirements for specific SPD designs . 28
7.5.1 Two port SPDs and one port SPDs with separate input/output
terminals . 28
7.5.2 Environmental tests for outdoor SPDs . 28
7.5.3 SPDs with separate isolated circuits . 28
7.5.4 Short-circuiting type SPDs . 29
7.6 Additional requirements as may be declared by the manufacturer . 29
7.6.1 One-port and two-port SPDs . 29
7.6.2 Two port SPDs only . 29
8 Type tests . 29
8.1 General testing procedures . 30
8.1.1 Impulse discharge current used for class I additional duty test . 36
8.1.2 Current impulse used for class I and class II residual voltage and
operating duty tests . 36
8.1.3 Voltage impulse used for class I and II sparkover tests . 37
8.1.4 Combination wave used for class III tests . 37
8.2 Indelibility of markings . 40
8.3 Electrical tests . 40

– 4 – 61643-11  IEC:2011
8.3.1 Protection against direct contact . 40
8.3.2 Residual current I . 40
PE
8.3.3 Measured limiting voltage . 41
8.3.4 Operating duty test . 44
8.3.5 Disconnectors and safety performance of overstressed SPDs . 48
8.3.6 Insulation resistance . 54
8.3.7 Dielectric withstand . 55
8.3.8 Behaviour under Temporary Overvoltages (TOVs) . 56
8.4 Mechanical tests . 60
8.4.1 Reliability of screws, current-carrying parts and connections . 60
8.4.2 Terminals for external conductors . 61
8.4.3 Verification of air clearances and creepage distances. 65
8.4.4 Mechanical strength . 68
8.5 Environmental and material tests. 72
8.5.1 Resistance to ingress of solid objects and to harmful ingress of water . 72
8.5.2 Heat resistance . 72
8.5.3 Ball pressure test . 73
8.5.4 Resistance to abnormal heat and fire. 74
8.5.5 Tracking resistance . 75
8.6 Additional tests for specific SPD designs . 75
8.6.1 Test for two-port SPDs and one-port SPDs with separate input/output
terminals . 75
8.6.2 Environmental tests for outdoor SPDs . 78
8.6.3 SPDs with separate isolated circuits . 78
8.6.4 Short-circuiting type SPDs . 78
8.7 Additional tests for specific performance if declared by the manufacturer . 78
8.7.1 Total discharge current test for multipole SPDs . 78
8.7.2 Test to determine the voltage drop . 79
8.7.3 Load-side surge withstand capability . 79
8.7.4 Measurement of voltage rate of rise du/dt . 80
9 Routine and acceptance tests . 80
9.1 Routine tests . 80
9.2 Acceptance tests . 80
Annex A (normative) Reference test voltages for SPDs U . 81
REF
Annex B (normative) TOV Ratings . 86
Annex C (normative) Tests to determine the presence of a switching component and
the magnitude of the follow current . 89
Annex D (normative) Reduced test procedures . 91
Annex E (informative) Alternative circuits for testing SPDs under TOVs caused by
faults in the high (medium) voltage system . 93
Annex F (informative) Environmental tests for outdoor SPDs . 94
Annex G (normative) Temperature rise limits . 96
Bibliography . 97

Figure 1 – Metallic screen test set-up . 31
Figure 2 – Example of a decoupling network for single-phase power . 39
Figure 3 – Example of a decoupling network for three-phase power . 39
Figure 4 – Alternate test for the measured limiting voltage . 39

61643-11  IEC:2011 – 5 –
Figure 5 – Flow chart of testing to check the voltage protection level U . 42
p
Figure 6 – Flow chart of the operating duty test . 45
Figure 7 – Test set-up for operating duty test . 46
Figure 8 – Operating duty test timing diagram for test classes I and II . 47
Figure 9 – Additional duty test timing diagram for test class I . 48
Figure 10 – Operating duty test timing diagram for test class III . 48
Figure 11 – Test circuit for SPD with I lower than the declared short-circuit rating. 52
fi
Figure 12 – Test circuit for SPD’s failure mode simulation . 53
Figure 13 – Timing diagram for SPD’s failure mode simulation . 53
Figure 14 – Example of a test circuit to perform the test under TOVs caused by faults
in the low voltage system . 57
Figure 15 – Timing diagram for the test under TOVs caused by faults in the low voltage
system . 57
Figure 16 – Example of circuit for testing SPDs for use in TT systems under TOVs
caused by faults in high (medium) voltage system . 59
Figure 17 – Timing diagram for use in testing SPDs under TOVs caused by faults in
the high (medium) voltage system using circuit of Figure 16 . 60
Figure 18 – Test apparatus for impact test . 69
Figure 19 – Striking element of the pendulum hammer . 70
Figure 20 – Ball thrust tester . 73
Figure 21 – Loading rod for ball thrust tester. 73
Figure 22 – Examples for appropriate test circuits of the load side short-circuit test(s) . 77
Figure E.1 – Examples of a three-phase and single-phase circuit for use in testing
SPDs under TOVs caused by faults in the high (medium) voltage system . 93

Table 1 – List of Abbreviations . 17
Table 2 – Class I, II and III tests . 19
Table 3 – Type test requirements for SPDs . 32
Table 4 – Common pass criteria for type tests . 34
Table 5 – Cross reference for pass criteria versus type tests . 35
Table 6 – Preferred parameters for class I test . 36
Table 7 – Tests to be performed to determine the measured limiting voltage . 43
Table 8 – Prospective short-circuit current and power factor . 50
Table 9 – Dielectric withstand . 55
Table 10 – Screw thread diameters and applied torques . 61
Table 11 – Cross-sections of copper conductors for screw-type or screwless terminals . 62
Table 12 – Pulling forces (screw terminals) . 63
Table 13 – Conductor dimensions . 63
Table 14 – Pulling forces (screwless terminals) . 64
Table 15 – Air clearances for SPDs . 66
Table 16 – Creepage distances for SPDs . 67
Table 17 – Relationship between material groups and classifications . 68
Table 18 – Fall distances for impact requirements . 71
Table 19 – Test conductors for rated load current test . 75

– 6 – 61643-11  IEC:2011
Table 20 – Current factor k for overload behaviour . 76
Table 21 – Tolerances for proportional surge currents . 79
Table A.1 – Reference test voltage values . 82
Table B.1 – TOV test values for systems complying with IEC 60364 series . 86
Table B.2 – TOV test parameters for North American systems . 87
Table B.3 – TOV test parameters for Japanese systems . 88
Table D.1 – Reduced test procedure for SPDs complying with IEC 61643-1:2005 . 92
Table G.1 – Temperature-rise limits . 96

61643-11  IEC:2011 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE SURGE PROTECTIVE DEVICES –

Part 11: Surge protective devices connected
to low-voltage power systems –
Requirements and test methods
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61643-11 has been prepared by subcommittee 37A: Low-voltage
surge protective devices, of IEC technical committee 37: Surge arresters.
This first edition of IEC 61643-11 cancels and replaces the second edition of IEC 61643-1
published in 2005. This edition constitutes a technical revision.
The main changes with respect of the second edition of IEC 61643-1 are the complete
restructuring and improvement of the test procedures and test sequences.

– 8 – 61643-11  IEC:2011
The text of this standard is based on the following documents:
FDIS Report on voting
37A/229/FDIS 37A/232/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the IEC 61643 series can be found, under the general title Low-voltage
surge protective devices, 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.
NOTE The attention of National Committees is drawn to the fact that equipment manufacturers and testing
organizations may need a transitional period following publication of a new, amended or revised IEC publication in
which to make products in accordance with the new requirements and to equip themselves for conducting new or
revised tests.
It is the recommendation of the committee that the content of this publication be adopted for national
implementation not earlier than 12 months from the date of publication.

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 publication using a colour printer.

61643-11  IEC:2011 – 9 –
INTRODUCTION
This part of IEC 61643 addresses safety and performance tests for surge protective devices
(SPDs).
There are three classes of tests:
The Class I test is intended to simulate partial conducted lightning current impulses. SPDs
subjected to Class I test methods are generally recommended for locations at points of high
exposure, e.g., line entrances to buildings protected by lightning protection systems.
SPDs tested to Class II or III test methods are subjected to impulses of shorter duration.
SPDs are tested on a “black box” basis as far as possible.
IEC 61643-12 addresses the selection and application principles of SPDs in practical
situations.
– 10 – 61643-11  IEC:2011
LOW-VOLTAGE SURGE PROTECTIVE DEVICES –

Part 11: Surge protective devices connected
to low-voltage power systems –
Requirements and test methods
1 Scope
This part of IEC 61643 is applicable to devices for surge protection against indirect and direct
effects of lightning or other transient overvoltages. These devices are packaged to be
connected to 50/60 Hz a.c. power circuits, and equipment rated up to 1 000 V r.m.s.
Performance characteristics, standard methods for testing and ratings are established. These
devices contain at least one nonlinear component and are intended to limit surge voltages
and divert surge currents.
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.
IEC 60060-1:1989, High-voltage test techniques – Part 1: General definitions and test
requirements
IEC 60112, Method for the determination of the proof and the comparative tracking indices of
solid insulating materials
IEC 60529, Degrees of protection provided by enclosures (IP Code)
IEC 60664-1:2007, Insulation coordination for equipment within low-voltage systems – Part 1:
Principles, requirements and tests
IEC 60695-2-11:2000, Fire hazard testing – Part 2-11: Glowing/hot-wire based test methods –
Glow-wire flammability test method for end-products
IEC 61000 (all parts), Electromagnetic compatibility (EMC)
IEC 61180-1, High-voltage test techniques for low voltage equipment – Part 1: Definitions, test
and procedure requirements
3 Terms, definitions and abbreviations
For the purposes of this document, the following terms, definitions and abbreviations apply.

61643-11  IEC:2011 – 11 –
3.1 Terms and definitions
3.1.1
surge protective device
SPD
device that contains at least one nonlinear component that is intended to limit surge voltages
and divert surge currents
NOTE An SPD is a complete assembly, having appropriate connecting means.
3.1.2
one-port SPD
SPD having no intended series impedance
NOTE A one port SPD may have separate input and output connections.
3.1.3
two-port SPD
SPD having a specific series impedance connected between separate input and output
connections
3.1.4
voltage switching type SPD
SPD that has a high impedance when no surge is present, but can have a sudden change in
impedance to a low value in response to a voltage surge
NOTE Common examples of components used in voltage switching type SPDs are spark gaps, gas tubes and
thyristors. These are sometimes called "crowbar type" components.
3.1.5
voltage limiting type SPD
SPD that has a high impedance when no surge is present, but will reduce it continuously with
increased surge current and voltage
NOTE Common examples of components used in voltage limiting type SPDs are varistors and avalanche
breakdown diodes. These are sometimes called "clamping type" components.
3.1.6
combination type SPD
SPD that incorporates both, voltage switching components and voltage limiting components.
The SPD may exhibit voltage switching, limiting or both
3.1.7
short-circuiting type SPD
SPD tested according to Class II tests which changes its characteristic to an intentional
internal short-circuit due to a surge current exceeding its nominal discharge current I
n
3.1.8
mode of protection of an SPD
an intended current path, between terminals that contains protective components, e.g. line-to-
line, line-to-earth, line-to-neutral, neutral-to-earth.
3.1.9
nominal discharge current for class II test

I
n
crest value of the current through the SPD having a current waveshape of 8/20

– 12 – 61643-11  IEC:2011
3.1.10
impulse discharge current for class I test
I
imp
crest value of a discharge current through the SPD with specified charge transfer Q and
specified energy W/R in the specified time
3.1.11
maximum continuous operating voltage
U
C
maximum r.m.s. voltage, which may be continuously applied to the SPD's mode of protection
NOTE The U value covered by this standard may exceed 1 000 V.
C
3.1.12
follow current
I
f
peak current supplied by the electrical power system and flowing through the SPD after a
discharge current impulse
3.1.13
rated load current
I
L
maximum continuous rated r.m.s. current that can be supplied to a resistive load connected to
the protected output of an SPD
3.1.14
voltage protection level
U
p
maximum voltage to be expected at the SPD terminals due to an impulse stress with defined
voltage steepness and an impulse stress with a discharge current with given amplitude and
waveshape
NOTE The voltage protection level is given by the manufacturer and may not be exceeded by:
– the measured limiting voltage, determined for front-of-wave sparkover (if applicable) and the measured
limiting voltage, determined from the residual voltage measurements at amplitudes corresponding to I
n
and/or I respectively for test classes II and/or I;
imp
– the measured limiting voltage at U , determined for the combination wave for test class III.
OC
3.1.15
measured limiting voltage
highest value of voltage that is measured across the terminals of the SPD during the
application of impulses of specified waveshape and amplitude
3.1.16
residual voltage
U
res
crest value of voltage that appears between the terminals of an SPD due to the passage of
discharge current
3.1.17
temporary overvoltage test value
U
T
test voltage applied to the SPD for a specific duration t , to simulate the stress under TOV
T
conditions
3.1.18
load-side surge withstand capability for a two-port SPD
ability of a two-port SPD to withstand surges on the output terminals originating in circuitry
downstream of the SPD
61643-11  IEC:2011 – 13 –
3.1.19
voltage rate-of-rise of a two-port SPD
rate of change of voltage with time measured at the output terminals of a two port SPD under
specified test conditions
3.1.20
1,2/50 voltage impulse
voltage impulse with a nominal virtual front time of 1,2 µs and a nominal time to half-value of
50 µs
NOTE The Clause 6 of IEC 60060-1 (1989) defines the voltage impulse definitions of front time, time to half-
value and waveshape tolerance.
3.1.21
8/20 current impulse
current impulse with a nominal virtual front time of 8 µs and a nominal time to half-value of
20 µs
NOTE The Clause 8 of IEC 60060-1 (1989) defines the current impulse definitions of front time, time to half-value
and waveshape tolerance.
3.1.22
combination wave
a wave characterized by defined voltage amplitude (U ) and waveshape under open-circuit
OC
conditions and a defined current amplitude (I ) and waveshape under short-circuit
CW
conditions
NOTE The voltage amplitude, current amplitude and waveform that is delivered to the SPD are determined by the
combination wave generator (CWG) impedance Z and the impedance of the DUT.
f
3.1.23
open circuit voltage
U
OC
open circuit voltage of the combination wave generator at the point of connection of the
device under test
3.1.24
combination wave generator short-circuit current
I
CW
prospective short-circuit current of the combination wave generator, at the point of connection
of the device under test
NOTE When the SPD is connected to the combination wave generator, the current that flows through the device
is generally less than I .
cw
3.1.25
thermal stability
SPD is thermally stable if, after heating up during the operating duty test, its temperature
decreases with time while energized at specified maximum continuous operating voltage and
at specified ambient temperature conditions
3.1.26
degradation (of performance)
undesired permanent departure in the operational performance of equipment or a system from
its intended performance
3.1.27
short-circuit current rating
I
SCCR
maximum prospective short-circuit current from the power system for which the SPD, in
conjunction with the disconnector specified, is rated

– 14 – 61643-11  IEC:2011
3.1.28
SPD disconnector (disconnector)
device for disconnecting an SPD, or part of an SPD, from the power system
NOTE This disconnecting device is not required to have isolating capability for safety purposes. It is to prevent a
persistent fault on the system and is used to give an indication of an SPD’s failure. Disconnectors can be internal
(built in) or external (required by the manufacturer). There may be more than one disconnector function, for
example an over-current protection function and a thermal protection function. These functions may be in separate
units.
3.1.29
degree of protection of enclosure
IP
classification preceded by the symbol IP indicating the extent of protection provided by an
enclosure against access to hazardous parts, against ingress of solid foreign objects and
possibly harmful ingress of water
3.1.30
type test
conformity test made on one or more items representative of the production
[IEC 60050-151:2001, 151-16-16]
3.1.31
routine test
test made on each SPD or on parts and materials as required to ensure that the product
meets the design specifications
[IEC 60050-151:2001, 151-16-17, modified]
3.1.32
acceptance tests
contractual test to prove to the customer that the item meets certain conditions of its
specification
[IEC 60050-151:2001, 151-16-23]
3.1.33
decoupling network
an electrical circuit intended to prevent surge energy from being propagated to the power
network during energized testing of SPDs
NOTE This electrical circuit is sometimes called a "back filter".
3.1.34
Impulse test classification
3.1.34.1
class I tests
tests carried out with the impulse discharge current I , with an 8/20 current impulse with a
imp
crest value equal to the crest value of I , and with a 1,2/50 voltage impulse
imp
3.1.34.2
class II tests
tests carried out with the nominal discharge current I , and the 1,2/50 voltage impulse
n
3.1.34.3
class III tests
tests carried out with the 1,2/50 voltage - 8/20 current combination wave generator
...