IEC 61643-41:2025

Low-voltage surge protective devices - Part 41: Surge protective devices connected to DC low-voltage power systems – Requirements and test methods

IEC 61643-41:2025 is applicable to devices for surge protection against indirect and direct effects of lightning or other transient overvoltages.
These devices are intended to be connected to DC power circuits and equipment rated up to 1 500 V DC. Performance and safety requirements, tests and ratings are specified in this document. These devices contain at least one nonlinear component and are intended to limit surge voltages and divert surge currents.
The test requirements provided by this document are based on the assumption that the SPD is connected to a DC power circuit fed by a power source providing a linear voltage-current characteristic. When the SPD is to be connected to a different kind of source, careful consideration is required. This mainly applies with regard to system and fault conditions to be expected in such a system (e.g. expected short circuit current, TOV-stresses).
This document can apply for railway applications, when related product standards do not exist for that area or for certain applications.
Based on a risk assessment it might not be necessary to apply all requirements of this document to SPDs designed for specific power applications only, e.g. circuits with a low power capability, circuits supplied by nonlinear sources, circuits with protective separation from the utility supply.
NOTE 1 More information on risk assessment is provided in IEC Guide 116.
SPDs for PV applications are not covered by this document.
NOTE 2 Such SPDs for PV applications are covered by IEC 61643-31.
NOTE 3 Other exclusions based on national regulations are possible.
This International Standard is to be used in conjunction with IEC 61643-01.

Parafoudres basse tension - Partie 41: Parafoudres connectés aux réseaux basse tension en courant continu - Exigences et méthodes d’essai

IEC 61643-41: 2025 s’applique aux dispositifs de protection contre les effets indirects et directs de la foudre ou contre les surtensions transitoires.
Ces dispositifs sont destinés à être connectés à des circuits d’alimentation ou à des équipements en courant continu de tension assignée allant jusqu’à 1 500 V en courant continu. Les exigences de performance et de sécurité, les essais et les valeurs assignées sont spécifiés dans le présent document. Ces dispositifs comportent au moins un composant non linéaire et sont utilisés pour limiter les surtensions et écouler les courants de foudre.
Les exigences d’essai prévues par le présent document reposent sur l’hypothèse que le parafoudre est connecté à un circuit d’alimentation en courant continu alimenté par une source d’alimentation présentant une caractéristique tension-courant linéaire. Lorsque le parafoudre doit être connecté à un autre type de source, une attention particulière est exigée, notamment s’agissant des conditions de réseau et des conditions de défaut qui peuvent être attendues dans un tel réseau (par exemple le courant de court-circuit prévu, les contraintes TOV).
Le présent document peut s’appliquer aux applications ferroviaires, lorsqu’il n’existe pas de normes de produits connexes pour ce domaine ou pour certaines applications.
Sur la base d’une évaluation des risques, il peut ne pas être nécessaire d’appliquer toutes les exigences du présent document aux parafoudres conçus uniquement pour des applications électriques spécifiques, par exemple les circuits ayant une faible capacité électrique, les circuits alimentés par des sources non linéaires, les circuits avec une séparation de protection de l’alimentation électrique.
NOTE 1 Des informations supplémentaires sur l’évaluation des risques sont données dans le Guide 116 de l’IEC.
Les parafoudres pour les applications photovoltaïques ne sont pas couverts par le présent document.
NOTE 2 Les parafoudres pour les applications photovoltaïques sont couverts par l’IEC 61643-31.
NOTE 3 D’autres exclusions fondées sur des réglementations nationales sont possibles.
La présente Norme internationale doit être utilisée conjointement avec l’IEC 61643-01.

General Information

• Status: Published
• Publication Date: 22-May-2025
• 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: 23-May-2025
• Completion Date: 23-May-2025

Standards Content (Sample)

IEC 61643-41 ®
Edition 1.0 2025-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Low-voltage surge protective devices –
Part 41: Surge protective devices connected to DC low-voltage power systems –
Requirements and test methods
Parafoudres basse tension –
Partie 41: Parafoudres connectés aux réseaux basse tension en courant continu –
Exigences et méthodes d’essai
ICS 29.240.10  ISBN 978-2-8327-0447-9

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– 2 – IEC 61643-41:2025 © IEC 2025
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms, definitions and abbreviated terms . 7
4 Classification . 7
5 Void . 7
6 Marking and other product information . 7
7 Service conditions . 8
8 Requirements . 8
9 Tests . 9
Annex AA (normative) Application of annexes from IEC 61643-01 . 20
Annex BB (normative) Test voltages for SPDs – U . 21
test
Annex CC (normative) TOV test values for DC power systems . 23
Annex DD (informative) DC power systems . 25
Bibliography . 31

Figure 100 – Procedure for sample preparation for dedicated overstress test . 16
Figure 101 – Example of a test circuit for the TOV tests . 18
Figure 102 – Timing diagram for the TOV tests . 18
Figure DD.1 – TT DC distribution system . 25
Figure DD.2 – TT DC distribution system with a mid-point. 26
Figure DD.3 – TN-S DC distribution system . 26
Figure DD.4 – TN-S DC distribution system with a mid-point . 27
Figure DD.5 – TN-C DC distribution system with a mid-point . 27
Figure DD.6 – TN-C DC distribution system. 28
Figure DD.7 – TN-C-S DC distribution system . 28
Figure DD.8 – TN-C-S DC distribution system with a mid-point . 29
Figure DD.9 – IT DC distribution system . 29
Figure DD.10 – IT DC distribution system with a mid-point . 30

Table 100 – Type test requirements for SPDs . 10
Table 101 – Prospective short circuit current and time constant . 14
Table AA.1 – Application of annexes from IEC 61643-01 . 20
Table BB.1 – Test voltage values . 22
Table CC.1 – TOV test values for DC power systems . 23
Table CC.2 – Prospective short-circuit currents for TOV tests . 24

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE SURGE PROTECTIVE DEVICES –

Part 41: Surge protective devices connected to DC low-voltage power
systems – Requirements and test methods

FOREWORD
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
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IEC 61643-41 has been prepared by subcommittee 37A: Low-voltage surge protective devices,
of IEC technical committee 37: Surge arresters. It is an International Standard.
This first edition only contains the specific requirements for SPDs for DC applications.
This International Standard is to be used in conjunction with IEC 61643-01.
The requirements of this document supplement, modify or replace certain of the general
requirements contained in IEC 61643-01 and shall be read and applied together with the latest
edition of IEC 61643-01, as indicated by the undated normative reference in Clause 2 of this
document.
Numbering of clauses follows the numbering of IEC 61643-01, but, dependent on the application
of clauses from IEC 61643-01, does not necessarily follow sequentially.

– 4 – IEC 61643-41:2025 © IEC 2025
If a clause in IEC 61643-01 is not explicitly called up or referred to in this document, then this
clause does not apply to SPDs covered by this document. Any instructions in this document
calling up clauses from IEC 61643-01 are written in Italic type.
NOTE In other words, if e.g. Clause 4 is called up in this document all subclauses of Clause 4 of IEC 61643-01 are
applied without modification. But, if e.g. some modifications are required on subclauses of Clause 9 of IEC 61643-01,
then the relevant second level subclauses of IEC 61643-01 (e.g. 9.3, 9.5 etc.) are called up separately and it is
indicated how they are applied.
The numbering of additional subclauses to IEC 61643-01 in this document starts with the
number 100 in the last section of the subclause added (see e.g. 4.100). The numbering of
additional tables and figures to IEC 60643-01 in this document starts with the number 100.
The text of this International Standard is based on the following documents:
Draft Report on voting
37A/426/FDIS 37A/430/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts 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 document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
INTRODUCTION
It has been assumed in the drafting of this International Standard that the execution of its
provisions is entrusted to appropriately qualified and experienced persons.
This document recognizes the internationally accepted level of protection against hazards such
as electrical, mechanical, thermal, fire and radiation of SPDs when operated as in normal use
taking into account the manufacturer's instructions. It also covers abnormal situations that can
be expected in practice.
This document takes into account the requirements of IEC 60364 as far as possible so that
there is compatibility with the wiring rules when the SPD is connected to the supply mains.
However, national wiring rules may differ.
If the intended applications of an SPD are covered by different parts of the IEC 61643-x1 series,
all relevant parts shall be applied, as far as is reasonable.
This part of the IEC 61643 series addresses safety and performance tests for surge protective
devices (SPDs) for DC applications in conjunction with IEC 61643-01.
This document addresses T1 SPD, T2 SPD and T3 SPD according to IEC 61643-01.
IEC 61643-12 addresses the general selection and application principles of SPDs, but focusing
on SPDs for AC low-voltage power systems. A separate standard IEC 61643-42 is planned,
which is intended to specifically address selection and application principles for SPDs for DC
low-voltage power systems.
– 6 – IEC 61643-41:2025 © IEC 2025
LOW-VOLTAGE SURGE PROTECTIVE DEVICES –

Part 41: Surge protective devices connected to DC low-voltage power
systems – Requirements and test methods

1 Scope
This document, together with IEC 61643-01, is applicable to devices for surge protection
against indirect and direct effects of lightning or other transient overvoltages.
These devices are intended to be connected to DC power circuits and equipment rated up to
1 500 V DC. Performance and safety requirements, tests and ratings are specified in this
document. These devices contain at least one nonlinear component and are intended to limit
surge voltages and divert surge currents.
The test requirements provided by this document are based on the assumption that the SPD is
connected to a DC power circuit fed by a power source providing a linear voltage-current
characteristic. When the SPD is to be connected to a different kind of source, careful
consideration is required. This mainly applies with regard to system and fault conditions to be
expected in such a system (e.g. expected short circuit current, TOV-stresses).
This document can apply for railway applications, when related product standards do not exist
for that area or for certain applications.
Based on a risk assessment it might not be necessary to apply all requirements of this document
to SPDs designed for specific power applications only, e.g. circuits with a low power capability,
circuits supplied by nonlinear sources, circuits with protective separation from the utility supply.
NOTE 1 More information on risk assessment is provided in IEC Guide 116.
SPDs for PV applications are not covered by this document.
NOTE 2 Such SPDs for PV applications are covered by IEC 61643-31.
NOTE 3 Other exclusions based on national regulations are possible.
2 Normative references
For the purposes of this document the normative references given in IEC 61643-01 with the
following additions apply.
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 61643-01, Low-voltage surge protective devices – Part 01: General requirements and test
methods
3 Terms, definitions and abbreviated terms
Clause 3 of IEC 61643-01 applies.
4 Classification
Clause 4 of IEC 61643-01 applies with the following additions:
4.13 End-of-life mode of the SPDA
4.13 of IEC 61643-01 applies with the following additions:
For SPDAs for DC power circuits fed by a power source providing a linear voltage-current
characteristic, only the open circuit mode according to 4.13.1 of IEC 61643-01 is applicable.
NOTE A short circuiting SPD, when used with its required SPD disconnectors (SPDA), fulfils the conditions to be
classified open circuit mode (OCM).
5 Void
6 Marking and other product information
Clause 6 of IEC 61643-01 applies with the following additions.
6.2 List of items
6.2 of IEC 61643-01 applies with the following additions:
The following information from the list of items in 6.2 of IEC 61643-01 and any additional items
specified shall be provided as required below.
Item 20) from 6.2 of IEC 61643-01 applies with the following addition:
This includes information e.g. on the separation of the DC system from any upstream AC or DC
system and their interconnection as related to system earthing.
Item 25) from 6.2 of IEC 61643-01 applies with the following addition:
The AC and DC values or a curve shall be provided in accordance with 9.3.3.1.
6.2.100 Markings which are required on the body, or permanently attached to the body,
of the SPD:
6.2.100.1 Markings which shall be visible after installation:
Items 1) to 3) from 6.2 of IEC 61643-01 shall be visible after installation.
For portable SPDs and for pluggable SPDs it is sufficient that above markings are visible in the
unplugged condition. This does not apply to the minimum marking requirements according to
6.1 of IEC 61643-01.
6.2.100.2 Markings which are not required to be visible after installation:
Items 4) to 8) from 6.2 of IEC 61643-01 shall be visible on the SPD but are not required to be
visible after installation.
– 8 – IEC 61643-41:2025 © IEC 2025
6.2.101 Information to be provided by the manufacturer:
Items 1) to 40) from 6.2 of IEC 61643-01 shall be provided, if applicable, and as amended
according to 6.2 of this document.
6.2.102 Information which shall be provided by the manufacturer for type testing, as
applicable:
Items 41) to 43) from 6.2 of IEC 61643-01 shall be provided.
7 Service conditions
Clause 7 of IEC 61643-01 applies:
8 Requirements
Clause 8 of IEC 61643-01 applies with the following additions and exemption:
8.3 Electrical requirements
8.3 of IEC 61643-01 applies with the following additions and exemption:
8.3.6.4 Dedicated overstress behaviour
8.4.6.4 from IEC 61643-01 applies with the following exemption:
This test is not performed on SPD’s modes of protection classified according to 4.14.1.4 of IEC
61643-01.
8.3.9 Behaviour under temporary overvoltages
8.3.9 of IEC 61643-01 applies with the following additions:
SPD shall either withstand the overvoltages caused by faults or disturbances in the high or low
voltage system or fail in a manner not creating a hazard.
8.3.9.100 General requirements for TOV tests
Compliance is checked by the test in accordance with 9.3.9.100 and the following clauses,
depending on the kind of TOV.
For this test, Annex CC is to be considered.
8.3.9.101 TOVs caused by DC low voltage system faults (earth faults and short circuits)
Compliance is checked by the test in accordance with 9.3.9.100 and 9.3.9.101.
8.3.9.102 TOVs caused by DC low voltage system faults (loss of mid-point connection)
Compliance is checked by the test in accordance with 9.3.9.100 and 9.3.9.102.

8.3.9.103 TOVs caused by faults in the high (medium) voltage AC system transferred to
a DC system, which is derived from a low-voltage AC TT- or IT-system without
separation
Compliance is checked by the test in accordance with 9.3.9.100 and 9.3.9.103 and according
to items 20) and 30) from 6.2 of IEC 61643-01 as amended according to 6.2 of this document.
This requirement does not apply to SPDs which shall only be used in a DC system with
separation from the AC system or when the AC system is a TN system.
8.3.9.104 TOVs caused by faults in the high (medium) voltage DC system transferred to
a DC TT- or IT-system with common earthing
Compliance is checked by the test in accordance with 9.3.9.100 and 9.3.9.104 and according
to items 20) and 30) from 6.2 of IEC 61643-01 as amended according to 6.2 of this document.
This requirement does not apply to SPDs which shall only be used in a DC system without
common high (medium) voltage DC system earthing.
9 Tests
Clause 9 of IEC 61643-01 applies with the following additions:
9.1 Type testing procedures
9.1 of IEC 61643-01 applies with the following additions:
9.1.1 General
9.1.1 of IEC 61643-01 applies with the following additions:
The test voltage U shall be selected from Annex BB based on the information given by the
test
manufacturer according to 6.2.101 and according to items 9), 10), 20) and 21) from 6.2 of
IEC 61643-01.
For SPDs with a designated mid-point connection, which may be applied in systems without
distributed mid-point according to the manufacturer's instructions, separate testing is required
for the L-PE mode of protection with the mid-point being unconnected.
Table 100 shows all tests and for which tests the tissue paper and/or the metallic screen are
required.
Annex AA provides information which Annexes from IEC 61643-01 apply to SPDs for DC low-
voltage power systems.
Annex DD provides general information about DC power system grounding and connection
naming.
– 10 – IEC 61643-41:2025 © IEC 2025

Table 100 – Type test requirements for SPDs
SPD assembly SPD
SPD Design
External
classified
Require- Tissue Metallic
outdoor
SPD
dis-
T1 T2 T3
Test Test clause ment paper screen
and
connec- e)
SPD SPD SPD
voltage combi- voltage
M-PE
clause used used
inacces-
a) OCM SCM
tors
limiting nation switching
f)
sible
Marking and product
9.2 6 / 8.2 - - - M M M M M M M M M M
information
Protection against direct
9.3.1 8.3.1 - - - M M M M M M M M M M
contact
Continuous current 9.3.2 8.3.2 - - - M M M M M M M M M M
Protective conductor current 9.3.3 8.3.3 - - - A A A A A A A A A A
Measured limiting voltage 9.3.4 8.3.4 - - - M M M M M M M M M M
Residual voltage 9.3.4.2 - - - M M - M M M M M M M
Front-of-wave sparkover
9.3.4.3 - - - A A - A A - A A A A
voltage
Limiting voltage with
9.3.4.4 - - - - - M M M M M M M M
combination wave
b), g) c)
Operating duty test 8.3.5 - - M M M M M M M M M M
9.3.5 A
T1 SPD and T2 SPD
c)
9.3.5.3 - - M M - M M M M M M M
A
operating duty tests
Additional duty test for T1
c)
9.3.5.4 - - M - - M M M M M M M
A
SPD
Additional test for T1 SPD
c)
and T2 SPD with follow 9.3.5.5 A - - M M - M M - M M M M
current
c)
T3 SPD operating duty tests 9.3.5.6 - - - - M M M M M M M M
A
Temperature withstand 9.3.6.1 8.5.2 - - - M M M M M M M M M M

d)
Thermal protection test 9.3.6.2 8.3.6.2 A - - M M M M M M M - A M
d)
Short-circuit current behaviour 8.3.6.3 A - M M M M M - M M M - -
9.3.6.3
d)
Dedicated overstress test 8.3.6.4 A - M M M M M - M M M - -
9.3.6.4
Insulation resistance 9.3.7 8.3.7 - - - M M M M M M M M M M
Dielectric withstand 9.3.8 8.3.8 - - - M M M M M M M M M M

SPD assembly SPD
SPD Design
External
classified
Require- Tissue Metallic
outdoor
SPD
dis- T1 T2 T3
Test Test clause ment paper screen
and
connec- e)
SPD SPD SPD
voltage combi- voltage M-PE
clause used used
a) inacces-
OCM SCM
tors
limiting nation switching
f)
sible
Behavior under temporary
9.3.9 8.3.9 A M - A A A A - A A A - A
overvoltages (TOVs)
b)
5 s LVDC-TOV test 8.3.9 A M - A A A A - A A A - A
9.3.9.101
b)
120 min LVDC-TOV test 8.3.9 A M - A A A A - A A A - A
9.3.9.102
b)
HVAC-TOV test 8.3.9 A M - A A A A - A A A - A
9.3.9.103
b)
HVDC-TOV test 8.3.9 A M - A A A A - A A A - A
9.3.9.104
Mounting / screws, current- 8.4.1 /
9.4.2 - - - M M M M M M M M M M
carrying parts and connections 8.4.2
External connections 9.4.3 8.4.3 - - - M M M M M M M M M M
Air clearances and creepage
9.4.4 8.4.4 - - - M M M M M M M M M M
distances
Mechanical strength 9.4.5 8.4.5 - - - M M M M M M M M M M
IP code 9.5.1 8.5.1 - - - M M M M M M M M M M
Heat test 9.5.2.1 8.5.2 - - - M M M M M M M M M M
Ball pressure test 9.5.2.2 8.5.2 - - - A A A A A A A A A A
Resistance to abnormal heat
9.5.3 8.5.3 - - - A A A A A A A A A A
and fire
Tracking resistance 9.5.4 8.5.4 - - - A A A A A A A A A A
Life test under damp heat 9.5.5 8.5.5 - - - A A A A A A A A A A
Additional tests for SPDs with active electronic circuits
EMC tests 8.5.6 - - - A A A A A A A A A A
Additional tests for two-port SPDs and one port-SPDs with separate input / output connections
Rated load current 9.6.1.1 8.6.1.1 A - - A A A A A A A A A A
b) d)
Overload behaviour 8.6.1.2 - - - A A A A - A A A A A
9.6.1.2
Load side short-circuit current
b)
9.6.1.3 8.6.1.3 A - M A A A A A A A A A A
behaviour
Additional tests for SPDs for outdoor use
9.6.2 /
Environmental tests for outdoor Annex D of
8.6.2 - - - A A A A A A A A A A
SPDs IEC 61643-
– 12 – IEC 61643-41:2025 © IEC 2025

SPD assembly SPD
SPD Design
External
classified
Require- Tissue Metallic
outdoor
SPD
dis- T1 T2 T3
Test Test clause ment paper screen
and
connec- e)
SPD SPD SPD
voltage combi- voltage M-PE
clause used used
a) inacces-
OCM SCM
tors
limiting nation switching
f)
sible
Additional tests for SPDs with separate isolated circuits
SPDs with separated circuits 9.6.3 8.6.3 - - - A A A A A A A A A A
Additional tests for short-circuiting SPDs
Annex E of
Transition surge current rating IEC 61643- - - - O O - O O O O O O O
Additional tests for specific SPD designs
b)
Total discharge current 8.6.4 - - - O O - O O O O O O O
9.6.4
Voltage drop 9.6.5.1 8.6.5.1 - - - O O O O O O O O O O
b) d) c)
Load side surge withstand 8.6.5.2 A - - O O O O O O O O O O
9.6.5.2
Voltage rate of rise du/dt 9.6.5.3 8.6.5.3 - - - O O O O O O O O O O
M = Mandatory test
A = Mandatory test, if applicable
- = not applicable
O = Additional test, if a value is declared by the manufacturer
a)
External disconnectors means that all disconnectors as specified by the manufacturer shall be tested with the SPD during the type test.
b)
For these tests initial measurements of leakage current according to Table 3 of IEC 61643-01 are required, when criterion E is required after the test.
c)
When RCDs are specified as external disconnectors by the manufacturer and the surge current withstand for these RCDs, as specified by the relevant RCD standard, is lower
than the surge current applied during that type test, then they are not tested with the SPD during this type test.
d)
For this test more than one set of samples may be needed.
e)
SPDs for connection M-PE in TN and/or TT systems only.
f)
SPDs classified outdoor and inaccessible.
g)
For this test more than one set of samples may be needed, if the SPD is classified according to more than one type (see 4.4 of IEC 61643-01).

Pass criterion E from table 3 of IEC 61643-01 applies with the following addition:
In case of resettable or rearmable disconnectors the dielectric withstand shall be checked by
application of two times U or 1 500 V DC, whichever is greater.
C
9.3 Electrical tests
9.3 of IEC 61643-01 applies with the following additions:
9.3.3 Protective conductor current I
PE
9.3.3 of IEC 61643-01 applies with the following additions:
9.3.3.1 Test procedure
9.3.3.1 of IEC 61643-01 applies with the following additions:
A first measurement shall be performed with the SPD assembly being connected to a DC power
source as for normal use at the test voltage U .
test
In addition, a set of measurements shall be performed with the SPD assembly being connected
to an AC power source at any convenient voltage, providing a frequency between 47 Hz and
63 Hz. If higher frequencies are to be expected the measurement frequency range shall be
extended accordingly.
The measured AC current values shall then be extrapolated for the test voltage U .
test
For this measurement all terminals/connections except the PE terminal/connection are
connected together to one pole of the power source and the PE terminal/connection is
connected to the other pole of the power source.
9.3.5 Operating duty test
9.3.5 of IEC 61643-01 applies with the following additions:
9.3.5.2 Power source characteristics for the operating duty test
9.3.5.2 of IEC 61643-01 applies with the following additions:
9.3.5.2.1 General
9.3.5.2.1 of IEC 61643-01 applies with the following addition:
The mode of protection under test shall be connected to a DC power source.
9.3.5.2.2 SPDs modes of protection without follow current according to Annex B of
IEC 61643-01
9.3.5.2.2 of IEC 61643-01 applies with the following addition:
+10
The power source shall have a time constant L/R = 0,5 ms / %.
-10
– 14 – IEC 61643-41:2025 © IEC 2025
9.3.5.2.3 SPDs modes of protection with follow current according to Annex B of
IEC 61643-01
9.3.5.2.3 of IEC 61643-01 applies with the following addition:
The power source shall have a time constant according to 9.3.6.3.3.
9.3.6 Safety performance of overstressed SPDs
9.3.6 of IEC 61643-01 applies with the following additions:
9.3.6.2 Thermal protection test
9.3.6.2 of IEC 61643-01 applies with the following additions:
9.3.6.2.2 Test settings
9.3.6.2.2 of IEC 61643-01 applies with the following addition:
Test(s) according to procedures a) and b) shall be performed using a DC power source.
9.3.6.3 Short-circuit current behaviour test
9.3.6.3 of IEC 61643-01 applies with the following additions:
9.3.6.3.3 Test at the declared short-circuit current rating
9.3.6.3.3 of IEC 61643-01 applies with the following additions:
This test shall be made with dedicated DC power source according to 9.1.1 on an inductive
circuit with series resistance for the adjustment of the prospective current. The inductance can
be made up by series and parallel connection of suitable inductance coils. Inductance coils
using iron cores can be used provided they do not saturate during the test. The time constant
of the prospective short circuit current shall comply:
– with Table 101 if the short circuit protection function complies with 4.14.1.3 or 4.14.1.4 of
IEC 61643-01 or,
– with the required value from the relevant product standard for all other short circuit
protection functions according to 4.14 of IEC 61643-01.
Table 101 – Prospective short circuit current and time constant
+5 +10
I (kA) / % Time constant L/R (ms) / %
P 0 -10
≤ 0,5 0,5
0,5 < I ≤ 1,0 kA
P
1,0 < I ≤ 3,0 kA
P
3,0 < I ≤ 5,0 kA
P
5,0 < I ≤ 10 kA
P
10 < I ≤ 25 kA
P
25 < I
P
The mean value of linear DC power source recovery voltage during 100 ms after final arc
extinction shall be not less than U .
C
9.3.6.3.4 Test at low short-circuit current
9.3.6.3.4 of IEC 61643-01 applies with the following additions:
The test is carried out with U . The test sample shall be connected to a DC power source at
test
U according to 9.1.1.
test
The time constant of the prospective short circuit current shall comply with 9.3.6.3.3.
9.3.6.4 Dedicated overstress test
9.3.6.4 of IEC 61643-01 applies with the following additions:
9.3.6.4.100 Sample preparation
The manufacturer shall provide prepared samples, for each mode of protection declared by the
manufacturer according to item 37) from 6.2 of IEC 61643-01, as follows.
Step 1:
Voltage-limiting components in the mode of protection shall be replaced by components of
the same type, but with a lower U value, in such a way that the mode of protection
1mA
becomes equal to, or lower than, 0,9 U . If the U value of the mode of protection is
C 1mA
already lower or equal to 90% of U , the component(s) remain(s) unchanged. The
C
calculation assumes a condition of the mode of protection where any series connected
voltage switching components are short circuited. All other characteristics of the replaced
components, e.g. surge ratings, dimensions, etc. except those related to the U voltage
1mA
rating shall remain unchanged. Other parts of the SPD, e.g. disconnectors, connections,
interconnections etc. shall remain unchanged.
For modes of protection containing any series connected to switching components, the following
procedure shall be followed to reach a conductive state during testing.
Step 2:
Trigger the mode of protection modified as described above with an 1,2/50 voltage impulse
to start the current flow.
If it is not possible to reach a conductive state and current flow while connected to power source
as specified in 9.3.6.4.101 then continue as follows.
Step 3:
Replace the/any switching component within the mode of protection by a lower rated
switching component of the same type (e.g. DC sparkover voltage rating ≤ U ), if applicable.
C
NOTE 1 This might not be feasible for e.g. air gaps.
If it is still not possible to reach a conductive state and current flow or step 3) is not applicable
then continue as follows.
Step 4:
Short circuit the/any switching component within the mode of protection.
Figure 100 provides an overview of the above preparation process.
For modes of protection containing switching component(s) only, the modification according to
step 3) applies. If this is not feasible, this test is not applied to such mode of protection.
NOTE 2 In the case step 4) is applied to modes of protection containing switching component(s) only, the test is
covered by short circuit test 9.3.6.3.

– 16 – IEC 61643-41:2025 © IEC 2025

Figure 100 – Procedure for sample preparation for dedicated overstress test
Alternatively, this test may be performed on unmodified samples, but with a higher test voltage
than U , as this represents more stringent test conditions. In case the test result is negative,
C
the dedicated overstress test shall be performed on samples prepared as described above.
9.3.6.4.101 Test procedure
The SPD itself and its DC disconnectors, if specified by the manufacturer, shall be mounted
according to manufacturer's instructions and be connected with conductors of the highest
cross-sectional area according to the manufacturer's instructions.
The mode of protection under test shall be connected to a DC power source at U and a
C
time constant in accordance with 9.3.6.3.3. The test shall be performed for each of the
following prospective short-circuit currents.
– I ;
SCCR
– Low short circuit current as defined in 9.3.6.3.4.
For SPDs not satisfying the time criteria of acceptance the test is repeated for each of the steps
of sample preparation 1) to 4) according to 9.3.6.4.100, applying an increased test voltage
agreed between the test laboratory and the SPD manufacturer.

9.3.6.4.102 Pass criteria
The current of the source shall be interrupted by an internal or external SPD disconnector:
– in less than 60 s when I is applied.
SCCR
– in less than 20 min when Low short circuit current is applied.
The pass criteria C, H, I, J, M and N according to Table 3 of IEC 61643-01 shall apply.
9.3.9 Behaviour under temporary overvoltages (TOVs)
9.3.9 of IEC 61643-01 applies with the following additions:
Annex CC, Table CC.1 and Table CC.2 shall be applied to all SPDs depending on the
information given by the manufacturer according to item 30) from 6.2 of IEC 61643-01.
9.3.9.100 General test procedure for TOV
New samples shall be used and fitted as in normal use, according to the manufacturer's
instructions.
The mode of protection under test shall be connected to a power source voltage of U for a
T
+5
duration t / %.
T 0
This voltage source shall be capable of delivering a prospective short-circuit current given in
Table CC.2.
Immediately following the application of U , a voltage equal to U with a current capability as
T test
given in Table CC.2, shall be applied to the mode of protection under test for a period of 15 min
+5
/ %.
The time interval between the test periods shall be as short as possible and shall in any case
not exceed 100 ms. An example of a test circuit and a corresponding timing diagram to perform
this test is given in Figure 101 and Figure 102.
If the mode of protection under test gets disconnected by any internal or external SPD
disconnector during U application according to 8.3.9.102 already, the remaining test procedure
T
and consecutive application of U can be omitted after 15 min without detecting any current
test
flow.
– 18 – IEC 61643-41:2025 © IEC 2025

Key
Z : Impedance to adjust the prospective short-circuit current of U
1 T
Z : Impedance to adjust the prospective short-circuit current of U
2 test
Sw : Mechanical or static switch to apply the TOV to the DUT
Sw : Mechanical or static switch to apply the reference test voltage U to the DUT
2 test
DUT: Mode of protection under test including the SPD disconnectors as specified by the manufacturer
Figure 101 – Example of a test circuit for the TOV tests

Key
t = 0
+5
t = t  / %
2 T 0
+5
t ≤ t <(t +100 ms) / %
2 3 2 0
+5
t = t + 15 min / %
4 T 0
Figure 102 – Timing diagram for the TOV tests
Some examples for appropriate test setups are provided in Clause 7 of IEC TR 61643-03:2024.
9.3.9.101 Pass criteria for TOVs caused by DC low-voltage system faults (earth faults
and short circuits)
TOV withstand mode is required.
The pass criteria A, B, C, D, E, F, G, I, L and M according to Table 3 of IEC 61643-01 shall
apply.
9.3.9.102 Pass Criteria for TOV caused by DC low-voltage system faults (loss of mid-
point connection)
a) Safe end of life mode:
The pass criteria C, H, I, J, L and M according to Table 3 of IEC 61643-01 shall apply.
If disconnection occurs during the application of U , pass criterion K shall apply in
test
addition.
b) TOV withstand mode:
The pass criteria A, B, C, D, E, F, G, I, L and M according to Table 3 of IEC 61643-01 shall
apply.
9.3.9.103 Pass Criteria for TOVs caused by faults in the high (medium) voltage AC
system transferred to a DC system which is derived from a low voltage AC TT-
or IT-system without separation
a) Safe end of life mode:
The pass criteria C, H, I, J, L and M according to Table 3 of IEC 61643-01 shall apply.
, pass criterion K shall apply in
If disconnection occurs during the application of U
test
addition.
b) TOV withstand mode:
The pass criteria A, B, C, D, E, F, G, I, L and M according to Table 3 of IEC 61643-01 shall
apply.
9.3.9.104 Pass Criteria for TOVs caused by faults in the high (medium) voltage DC
system transferred to a DC TT- or IT-system with common earthing
a) Safe end-of-life mode:
The pass criteria C, H, I, J, L and M according to Table 3 of IEC 61643-01 shall apply.
If disconnection occurs during the application of U , pass criterion K shall apply in
test
addition.
b) TOV withstand mode:
The pass criteria A, B, C, D, E, F, G, I, L and M according to Table 3 of IEC 61643-01 shall
apply.
– 20 – IEC 61643-41:2025 © IEC 2025
Annex AA
(normative)
Application of annexes from IEC 61643-01
Table AA.1 provides information on which Annexes of IEC 61643-01 apply to SPDs for DC
low-voltage power systems.
Table AA.1 – Application of annexes from IEC 61643-01
Annex from Application to SPDs according to
Title
IEC 61643-0
...