prEN IEC 61621:2026

SLOVENSKI STANDARD
01-julij-2026
Suhi, trdni izolacijski materiali - Preskus odpornosti na visokonapetostne,
nizkotokovne obločne razelektritve
Dry, solid insulating materials - Resistance test to high-voltage, low-current arc
discharges
Trockene, feste Isolierstoffe - Prüfung der Lichtbogenbeständigkeit bei hoher Spannung
und niedrigem Strom
Matériaux isolants solides secs - Essai de résistance aux décharges à l'arc haute
tension, faible courant
Ta slovenski standard je istoveten z: prEN IEC 61621:2026
ICS:
17.220.99 Drugi standardi v zvezi z Other standards related to
elektriko in magnetizmom electricity and magnetism
29.035.01 Izolacijski materiali na Insulating materials in
splošno general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

112/722/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 61621 ED2
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2026-05-29 2026-08-21
SUPERSEDES DOCUMENTS:
112/693/CD, 112/713/CC
IEC TC 112 : EVALUATION AND QUALIFICATION OF ELECTRICAL INSULATING MATERIALS AND SYSTEMS
SECRETARIAT: SECRETARY:
Germany Mr Bernd Komanschek
OF INTEREST TO THE FOLLOWING COMMITTEES: HORIZONTAL FUNCTION(S):

TC 15
ASPECTS CONCERNED:
Electricity transmission and distribution
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
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TITLE:
Dry, solid insulating materials – Resistance test to high-voltage, low-current arc discharges

PROPOSED STABILITY DATE: 2030
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IEC CDV 61621 © IEC 2026
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 6
4 Apparatus . 6
4.1 Test circuit . 6
4.1.1 Transformer, T . 7
v
4.1.2 Variable autotransformer, T . 7
c
4.1.3 Voltmeter, V . 7
L
4.1.4 Milliammeter, A . 8
4.1.5 Current control resistors, R , R , R and R and switches S , S ,
10 20 30 40 2 3
S , S . 8
4 5
4.1.6 Suppressing resistor, R . 8
4.1.7 Air core inductors, Xs . 8
4.1.8 Breaker, B . 8
4.1.9 Timer, TT . 8
4.2 Electrodes and electrode assembly . 8
4.2.1 Electrode geometry . 8
4.2.2 Electrode assembly . 9
4.2.3 Cleaning and sharpening electrodes . 10
4.2.4 Specimen support . 10
4.3 Test chamber . 11
4.4 Calibration . 11
4.4.1 Open circuit operating voltage . 11
4.4.2 Adjustment of secondary current . 11
5 Specimens. 11
5.1 Specimen geometry . 11
5.2 Cleaning and conditioning . 11
6 Procedure and failure recognition . 11
6.1 Test procedure. 11
6.2 Failure and failure recognition . 12
7 Results . 14
8 Report . 14
Annex A (informative) Failure recognition by measurement . 15
Bibliography . 17

Figure 1 – Example for electrical circuit . 7
Figure 2 – Electrode mounted in a shank (example) . 9
Figure 3 – Electrode assembly (example) . 10
Figure 4 – Example of arc appearance on silicone elastomere . 13
Figure 5 – Example of arc appearance on resin material . 14
Figure A.1 – Schematic of characteristic temperature changes in the event of specimen
failure . 15
Figure A.2 – . 16
IEC CDV 61621 © IEC 2026
Table 1 – Sequence of 1 min steps . 12

IEC CDV 61621 © IEC 2026
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Dry, solid insulating materials –
Resistance test to high-voltage, low-current arc discharges

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for
standardization comprising all national electrotechnical committees (IEC National Committees).
The object of IEC is to promote international co-operation on all questions concerning
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of, or reliance upon, this IEC Publication or any other IEC Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced
publications is indispensable for the correct application of this publication.
9) IEC draws attention to the possibility that the implementation of this document may involve
the use of (a) patent(s). IEC takes no position concerning the evidence, validity or applicability
of any claimed patent rights in respect thereof. As of the date of publication of this document,
IEC had not notice of (a) patent(s), which may be required to implement this document.
However, implementers are cautioned that this may not represent the latest information, which
IEC CDV 61621 © IEC 2026
may be obtained from the patent database available at https://patents.iec.ch and
www.iso.org/patents . IEC shall not be held responsible for identifying any or all such patent
rights.
IEC 6XXXX has been prepared by subcommittee XX: [TITLE]:, of IEC technical committee XX:
[TITLE]. It is an International Standard.
In the case of a new edition replacing a previous edition, complete the following text. In the
case of a first edition, delete it, as it does not apply.
This second edition cancels and replaces the first edition published in XXXX, Amendment
1:[publication year of amd1] and Amendment 2:[publication year of amd2] . This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) [short description of the main changes]
b) .
The text of this International Standard is based on the following documents:
Draft Report on voting
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 [change
language if necessary].
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.
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.
IEC CDV 61621 © IEC 2026
1 Scope
This International Standard describes a test method which can provide preliminary
differentiation between similar insulating materials, with respect to their resistance to damage
when exposed to high-voltage, low-current arc discharges, occurring close to their surfaces.
The discharges cause localized thermal and chemical decomposition and erosion and
eventually a conductive path forms across the insulating material. The severity of the test
conditions is gradually increased: in the early stages a low-current arc discharge is repeatedly
interrupted, whereas in the later stages, the arc current is raised in successive steps.
Because of its convenience and because of the short time required for testing, the test method
is applicable for preliminary screening of materials, for detecting the effects of changes in
formulation and for quality control testing.
Previous experience with this test, showed acceptable reproducibility with thermoset materials.
Using thermoplastics, some testing laboratories report unacceptably large variation in test
results which lead to the recommendation not to use the test for thermoplastics.
NOTE Attempts are being made to reduce the variability of the results of tests on thermoplastics by controlling the
electrode pressure and depth of penetration into the material during the test. Without such electrode control, tests
on many thermoplastics may not be sufficiently meaningful to be performed.
This test method will not, in general, permit conclusions to be drawn concerning the relative arc
resistance rankings of materials which may be subjected to other types of arcs.
The ranking of materials may differ from what is found in wet tracking tests (e.g. IEC
60112:2025, IEC 60587:2022 and IEC 61302:1995) and from their performance in service,
where the intensity, recurrence frequency and time of exposure to arc discharges ar e very
different.Nevertheless, a certain correlation with the Inclined-Plane-Test according to IEC
60587:2022 was found within one material group (e.g. silicone elastomers). [1][2]
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.
IEC 60112:2025, Method for the determination of the proof and the comparative tracking indices
of solid insulating materials
IEC 60212:2010, Standard conditions for use prior to and during the testing of solid electrical
insulating materials
IEC 60587:2022, Electrical insulating materials used under severe ambient conditions - Test
methods for evaluating resistance to tracking and erosion
IEC 61302:1995, Electrical insulating materials - Method to evaluate the resistance to tracking
and erosion - Rotating wheel dip test
EN 50191:2000, Erection and operation of electrical test equipment
EN IEC 60112:2020, Method for the determination of the proof and the comparative tracking
indices of solid insulating materials
IEC CDV 61621 © IEC 2026
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
– IEC Electropedia: available at http://www.electropedia.org/
– ISO Online browsing platform: available at http://www.iso.org/obp
3.1
failure
failure is considered to have occurred when a conducting path is formed in the material; failure
is also considered to have occurred if the arc causes a material to burn and the burning
continues when the arc is interrupted
3.2
arc resistance
total elapsed time in seconds from the start of test until specimen failure
3.3
tracking
the progressive degradation of the surface of a solid insulating material by local discharges to
form conducting or partially conducting paths

[SOURCE: EV ref 442-01-41 [IEC 60050-442-01-4]]
4 Apparatus
4.1 Test circuit
The principal components of the electrical circuit for the apparatus are shown in Figure 1.
IEC CDV 61621 © IEC 2026
Figure 1 – Example for electrical circuit
NOTE 1 In the secondary circuit wiring the stray capacitance should be less than 40 pF. Large stray capacitance
may disturb the arc shape and influence the test results.
NOTE 2 Due to electrical hazards, the appliance should be equipped with state-of-the-art safety technology to
prevent contact with live parts (e.g. EN 50191:2000)
4.1.1 Transformer, T
v
A transformer with a rated secondary potential (on open circuit) of 15 kV, and a rated secondary
current (on short circuit) of 60 mA, line frequency (48 Hz to 62 Hz).
4.1.2 Variable autotransformer, T
c
Rated 1 kVA and suitable for the line voltage.
NOTE A constant primary voltage supply ±2 % is recommended.
4.1.3 Voltmeter, V
L
AC voltmeter with an accuracy of ±0,5 %, capable of reading line voltage +10−20%.
Voltage on the secondary side shall be regularly controlled by a reference measurement.
Alternatively, measurement of th
...