IEC 60939-3:2024

IEC 60939-3 ®
Edition 2.0 2024-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Passive filter units for electromagnetic interference suppression –
Part 3: Passive filter units for which safety tests are appropriate

Filtres passifs d'antiparasitage –
Partie 3: Filtres passifs pour lesquels des essais de sécurité sont appropriés
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IEC 60939-3 ®
Edition 2.0 2024-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Passive filter units for electromagnetic interference suppression –

Part 3: Passive filter units for which safety tests are appropriate

Filtres passifs d'antiparasitage –

Partie 3: Filtres passifs pour lesquels des essais de sécurité sont appropriés

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 31.160  ISBN 978-2-8322-8175-8

– 2 – IEC 60939-3:2024 © IEC 2024
CONTENTS
FOREWORD . 8
1 Scope . 10
2 Normative references . 10
3 Terms and definitions . 12
4 General requirements . 16
4.1 Classification and usage of class X and Y capacitors . 16
4.1.1 General . 16
4.1.2 Class X capacitors . 16
4.1.3 Class Y capacitors . 16
4.2 Information to be given in a detail specification . 17
4.2.1 General . 17
4.2.2 Outline drawing and dimensions . 18
4.2.3 Mounting . 18
4.2.4 Ratings and characteristics . 18
4.3 Marking . 19
4.3.1 General . 19
4.3.2 Coding . 19
4.3.3 Marking details . 19
4.3.4 Marking of filters . 19
4.3.5 Marking of packaging . 19
4.3.6 Additional marking . 19
4.4 Components . 20
4.5 Overcurrent protective devices . 20
4.6 Wiring and Insulation . 20
4.6.1 General . 20
4.6.2 Sleeving, tubing and wire insulation . 20
4.6.3 Properties of insulation material. 20
4.7 Protective Bonding Conductors . 21
4.8 Corrosion . 21
5 Preferred ratings and characteristics . 21
5.1 Preferred characteristics . 21
5.1.1 General . 21
5.1.2 Preferred climatic categories . 21
5.2 Preferred values of ratings . 22
5.2.1 Rated voltage (U ) . 22
R
5.2.2 Rated temperature . 22
5.2.3 Passive flammability . 22
6 Test plan for safety tests . 22
6.1 Structurally similar filters . 22
6.2 Safety approval procedure . 23
6.2.1 General . 23
6.2.2 Sampling . 23
6.2.3 Tests . 23
6.3 Requalification tests. 24
7 Test and measurement procedures . 24
7.1 Measurement conditions . 24

7.1.1 General . 24
7.1.2 Standard atmospheric conditions for testing . 24
7.1.3 Recovery conditions . 25
7.1.4 Referee conditions . 25
7.1.5 Reference conditions . 25
7.1.6 Drying . 25
7.2 Visual examination and check of dimensions . 26
7.2.1 Visual examination . 26
7.2.2 Dimensions (gauging) . 26
7.2.3 Dimensions (detail) . 26
7.2.4 Creepage distances and clearances . 26
7.3 Inductance measurement . 29
7.3.1 General . 29
7.3.2 Measuring conditions . 29
7.4 Earth inductors incorporated in filters . 29
7.5 Capacitance . 29
7.5.1 General . 29
7.5.2 Measuring conditions . 29
7.6 Insertion loss . 30
7.7 Insulation resistance . 30
7.7.1 General . 30
7.7.2 Measuring voltage . 30
7.7.3 Application of measuring voltage . 31
7.7.4 Mean time to measuring . 32
7.7.5 Temperature correction factor . 32
7.7.6 Information to be given in a detail specification . 32
7.7.7 Requirements . 34
7.8 Voltage proof . 35
7.8.1 General . 35
7.8.2 Test procedure . 35
7.8.3 Applied voltage . 35
7.8.4 Tests . 36
7.8.5 Requirements . 37
7.8.6 Repetition of the voltage proof test . 37
7.8.7 Information to be given in a detail specification . 37
7.8.8 Requirements . 37
7.9 DC line resistance or voltage drop at rated current . 37
7.9.1 General . 37
7.9.2 DC line resistance . 38
7.9.3 Voltage drop at rated current . 38
7.10 Discharge resistance . 38
7.10.1 General . 38
7.10.2 Resistor Test . 38
7.11 Capacitor discharge . 39
7.11.1 General . 39
7.11.2 Discharge measurement . 39
7.12 Robustness of terminations . 39
7.12.1 General . 39
7.12.2 Test Ua1 – Tensile . 39

– 4 – IEC 60939-3:2024 © IEC 2024
7.12.3 Test Ub – Bending . 40
7.12.4 Test Uc – Torsion . 40
7.12.5 Test Ud – Torque . 40
7.12.6 Visual examination . 41
7.13 Resistance to soldering heat . 41
7.13.1 Applicability of the test. 41
7.13.2 Pre-measurement . 41
7.13.3 Test conditions . 41
7.13.4 Test severity . 42
7.13.5 Intermediate inspection, measurements and requirements . 42
7.14 Climatic sequence. 42
7.14.1 General . 42
7.14.2 Initial measurements . 42
7.14.3 Dry heat . 42
7.14.4 Damp heat, cyclic . 42
7.14.5 Cold. 43
7.14.6 Low air pressure . 43
7.14.7 Damp heat, cyclic, remaining cycles . 43
7.14.8 Final inspection, measurements and requirements. 43
7.15 Damp heat, steady state . 44
7.15.1 Pre-measurements . 44
7.15.2 Test method . 44
7.15.3 Test conditions . 44
7.15.4 Final inspection, measurements and requirements. 44
7.16 Temperature rise . 44
7.16.1 General . 44
7.16.2 Test method . 45
7.16.3 Test description . 45
7.16.4 Requirements . 46
7.17 Current overload . 47
7.17.1 Pre-measurements . 47
7.17.2 Test method . 47
7.17.3 Final inspection, measurements and requirements. 48
7.18 Leakage current . 48
7.19 Protective conductor resistance . 48
7.20 Impulse voltage. 48
7.20.1 General . 48
7.20.2 Initial measurements . 48
7.20.3 Test conditions . 48
7.20.4 Requirements . 49
7.21 Endurance . 49
7.21.1 General . 49
7.21.2 General test conditions . 49
7.21.3 Test conditions – current test . 50
7.21.4 Test conditions – voltage test, terminations/case . 50
7.21.5 Test conditions – voltage test between terminations . 51
7.21.6 Test conditions – combined voltage/current tests . 51
7.21.7 Final inspection, measurements and requirements. 51
7.22 Passive flammability . 52

7.22.1 General . 52
7.22.2 Test method . 52
7.23 Active flammability . 53
7.24 Solvent resistance of the marking . 53
7.24.1 General . 53
7.24.2 Test description . 53
7.24.3 Requirements after test . 53
8 Optional tests (for performance only) . 53
8.1 Solderability . 53
8.1.1 General . 53
8.1.2 Test method . 53
8.1.3 Test conditions . 53
8.1.4 Requirements . 54
8.1.5 Final measurements and requirements . 54
8.2 Rapid change of temperature . 54
8.2.1 Pre-measurements . 54
8.2.2 Test method . 54
8.2.3 Final inspection . 55
8.3 Vibration . 55
8.3.1 Pre-measurements . 55
8.3.2 Test method . 55
8.3.3 Test conditions . 55
8.3.4 Intermediate inspection . 55
8.3.5 Final Inspection . 55
8.4 Shock . 55
8.4.1 Pre-measurements . 55
8.4.2 Test method . 55
8.4.3 Test conditions . 55
8.4.4 Final Inspection . 56
8.5 Container sealing . 56
8.5.1 General . 56
8.5.2 Test conditions . 56
8.5.3 Requirements . 56
8.6 Charge and discharge . 56
8.6.1 General . 56
8.6.2 Test circuits and wave forms . 56
8.6.3 Information given in detail specification . 58
8.6.4 Initial measurements . 58
8.6.5 Test conditions . 59
8.6.6 Final measurements and requirements . 59
8.7 Component solvent resistance . 59
8.7.1 General . 59
8.7.2 Initial measurements . 59
8.7.3 Test description . 60
8.7.4 Final measurements . 60
Annex A (informative) Calculation of leakage current . 61
A.1 General . 61
A.2 Calculation of leakage current for 1-line filters . 61
A.3 Calculation of leakage current for 2-line filters . 62

– 6 – IEC 60939-3:2024 © IEC 2024
A.4 Calculation of leakage current for 3-line filters . 62
A.5 Calculation of leakage current for 4-line filters . 64
Annex B (normative) Sampling plan for safety requirements only . 65
Annex C (normative) Test schedule for safety requirements only . 67
Annex D (normative) Circuit for the impulse voltage test . 70
Annex E (normative) Circuit for the endurance test . 72
Annex F (normative) Declaration of design. 73
Annex G (informative) Safety and performance tests qualification approval –
Assessment level DZ . 74
Annex X (informative) Cross reference for references to the previous edition of this
document . 76
Bibliography . 79

Figure 1 – Asymmetrical and symmetrical test circuit . 15
Figure 2 – Examples for the application of Tests A and B of Table 7 . 33
Figure 3 – Examples for the application of Test C of Table 7. 34
Figure 4 – Impulse wave form . 49
Figure 5 – Relay circuit . 56
Figure 6 – Thyristor circuit . 57
Figure 7 – Voltage and current waveforms . 58
Figure A.1 – Leakage current for 1-line filters . 61
Figure A.2 – Leakage current for 2-line filters . 62
Figure A.3 – Leakage current for 3-line filters . 63
Figure A.4 – Leakage current for 4-line filters . 64
Figure D.1 – Impulse voltage test circuit . 70
Figure E.1 – Endurance test circuit . 72

Table 1 – Classification of Class X capacitors . 16
Table 2 – Classification of Class Y capacitors . 17
Table 3 – Standard atmospheric conditions . 25
Table 4 – Creepage distances . 28
Table 5 – Clearance. 28
Table 6 – DC voltage for insulation resistance . 31
Table 7 – Measuring points . 33
Table 8 – Insulation resistance – Safety tests only . 34
Table 9 – Insulation resistance – Safety and performance tests . 35
Table 10 – Voltage proof (filter connected to mains) . 36
Table 11 – Voltage proof (filter not connected to mains; e.g. DC filters) . 36
Table 12 – Force for wire terminations . 40
Table 13 – Torque . 40
Table 14 – Number of cycles . 43
Table 15 – Maximum temperatures . 47
Table 16 – Categories of flammability . 52
Table 17 – Preferred severity . 56

Table 18 – Measurements and requirements after charge and discharge . 59
Table B.1 – Tests concerning safety requirements only . 65
Table B.2 – Lot-by-lot test – Safety tests only approval . 66
Table C.1 – Test schedule for safety requirements only . 67
Table D.1 – Values of C , C , R , R , C . 70
X T P S P
Table D.2 – Values and tolerances of C , t , t . 71
x r d
Table G.1 – Sampling plan – Assessment level DZ . 74
Table X.1 – Reference to IEC 60939-3 for clause/subclause or annex . 76
Table X.2 – Reference to IEC 60939-3 for Figures/Tables. 78

– 8 – IEC 60939-3:2024 © IEC 2024
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PASSIVE FILTER UNITS FOR ELECTROMAGNETIC
INTERFERENCE SUPPRESSION –
Part 3: Passive filter units for which safety tests are appropriate

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 standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
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Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use 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 received 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 may be obtained from the patent database available at https://patents.iec.ch or
www.iso.org/patents. IEC shall not be held responsible for identifying any or all such patent rights.
IEC 60939-3 has been prepared by of IEC technical committee 40: Capacitors and resistors for
electronic equipment. It is an International Standard.
This second edition cancels and replaces the first edition published in 2015,
Corrigendum 1:2016 and Corrigendum 2:2018. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Separated clauses for safety and performance tests;
b) Added note for use of multiple X capacitors bridging basic insulation in 3 phase filters;
c) Characteristics and conditions to substitute X and Y capacitors are now described in a
separate Subclause 4.1;
d) Creepage and clearance tables updated and in line with the latest editions of IEC 60938-2
and IEC 60664-1;
e) Allowing voltage measurement for inductance measurements (7.3);
f) Added requirements for marking depending on remaining energy after disconnection;
g) Added content of CTL DSH 2044:2016 for temperature test of IEC filters;
h) Added note about temperature rise required specimens for safety testing;
i) Changed index of capacitors in Annex A to avoid confusion between index name and
capacitor class;
j) Moved tests from group 1A to 2. Now, samples in group 1A need to be submitted without
potting;
k) Revision of all parts of the document has taken place based on the ISO/IEC Directives, Part
2:2021, and harmonization with other similar kinds of documents. Annex X contains all
cross-references of changes in clause/subclause numbers.
The text of this International Standard is based on the following documents:
Draft Report on voting
40/3102/FDIS 40/3118/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 in the IEC 60939 series, published under the general title Passive filter units
for electromagnetic interference suppression, can be found 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.
– 10 – IEC 60939-3:2024 © IEC 2024
PASSIVE FILTER UNITS FOR ELECTROMAGNETIC
INTERFERENCE SUPPRESSION –
Part 3: Passive filter units for which safety tests are appropriate

1 Scope
This part of IEC 60939 covers passive filters used to attenuate unwanted radio-frequency
signals (such as noise or interference) generated from electromagnetic sources.
Both single and multi-channel filters within one enclosure or which are built on a printed circuit
board forming a compact entity are included within the scope of this document.
Filters constructed of capacitive elements where the inductance is inherent in the construction
of the filter are within the scope of this document. Similarly, filters constructed of inductive
elements where the capacitance is inherent in the construction of the filter are also within the
scope of this document. It is up to the manufacturer to state whether a given component is to
be designed as a capacitor, an inductor or a filter. Filters can include also other components
such as resistors and/or varistors or similar components.
This document applies to passive filter units for electromagnetic interference suppression for
which safety tests are appropriate. This implies that filters specified according to this document
will either be connected to mains supplies, when compliance with the mandatory tests of
Table B.1 is necessary, or used in other circuit positions where the equipment specification
specifies that some or all of these safety tests are required.
This document applies to passive filter units, which will be connected to an AC mains or other
supply (DC or AC) with a nominal voltage not exceeding 1 000 V AC, with a nominal frequency
not exceeding 400 Hz, or 1 500 V DC.
NOTE For AC use, IEC 60384-14 applies to capacitors which will be connected to AC mains with a nominal
frequency not exceeding 100 Hz.
This document covers appliance filters (US) but does not cover facility filters, cord-connected
filters or direct plug-in filters. These other filters will be covered by another sectional
specification.
2 Normative references
The following documents are referred to in the text in such a way that some or al
...