IEC 60691:2015
(Main)Thermal-links - Requirements and application guide
Thermal-links - Requirements and application guide
IEC 60691:2015 is applicable to thermal-links intended for incorporation in electrical appliances, electronic equipment and component parts thereof, normally intended for use indoors, in order to protect them against excessive temperatures under abnormal conditions. This standard may be applicable to thermal-links for use under conditions other than indoors, provided that the climatic and other circumstances in the immediate surroundings of such thermal-links are comparable with those in this standard. This standard may be applicable to thermal-links in their simplest forms (e.g. melting strips or wires), provided that molten materials expelled during function cannot adversely interfere with the safe use of the equipment, especially in the case of hand-held or portable equipment, irrespective of its position. Annex H of this standard is applicable to thermal-link packaged assemblies where the thermal-link(s) has already been approved to this standard but packaged in a metallic or non-metallic housing and provided with terminals/wiring leads. This standard is applicable to thermal-links with a rated voltage not exceeding 690 V a.c. or d.c. and a rated current not exceeding 63 A. The objectives of this standard are: to establish uniform requirements for thermal-links, to define methods of test, to provide useful information for the application of thermal-links in equipment. This standard is not applicable to thermal-links used under extreme conditions such as corrosive or explosive atmospheres. This standard is not applicable to thermal-links to be used in circuits on a.c. with a frequency lower than 45 Hz or higher than 62 Hz. This fourth edition cancels and replaces the third edition published in 2002, Amendment 1:2006 and Amendment 2:2010. This fourth edition constitutes a technical revision. This fourth edition includes the following significant technical changes with respect to the previous edition:
- requirements for thermal-link packaged assemblies;
- renew the requirements and definitions for Th-test;
- change starting temperature for interrupt current test;
- clarify requirements for marking (packing label);
- minimum Proof Tracking Index 175 instead 120. Keywords: thermal protection of equipment, thermal-links The contents of the corrigendum of August 2016 have been included in this copy.
Protecteurs thermiques - Exigences et guide d'application
L'IEC 60691:2015 est applicable aux protecteurs thermiques destinés à être incorporés dans les appareils électriques, le matériel électronique et ses composants, normalement utilisés à l'intérieur d'un local, afin de les protéger contre les températures excessives lors de conditions anormales. La présente Norme peut s'appliquer aux protecteurs thermiques utilisés dans d'autres conditions que celles qui sont réunies à l'intérieur d'un local, pourvu que les conditions climatiques ou autres de l'entourage immédiat de tels protecteurs thermiques soient comparables à celles de la présente Norme. La présente Norme peut s'appliquer aux protecteurs thermiques dans leurs formes les plus simples (par exemple les lames ou les fils de fusion), pourvu que le matériau fondu, expulsé pendant le fonctionnement, ne soit pas préjudiciable à la sécurité du matériel, particulièrement dans le cas du matériel tenu à la main, ou mobile indépendamment de sa position. L'Annexe H de la présente Norme s'applique aux ensembles conditionnés de protecteurs thermiques déjà conformes à la présente Norme mais conditionnés dans un boîtier métallique ou non métallique et munis de bornes/conducteurs à fils. La présente Norme s'applique aux protecteurs thermiques dont la tension assignée n'excède pas 690 V en courant alternatif ou en courant continu, et dont le courant assigné n'excède pas 63 A. Les objectifs de la présente Norme sont les suivants: établir des exigences uniformes pour les protecteurs thermiques, définir des méthodes d'essai, fournir des renseignements utiles pour l'utilisation des protecteurs thermiques dans les matériels. La présente Norme n'est pas applicable aux protecteurs thermiques utilisés dans des conditions extrêmes, telles que des atmosphères corrosives ou explosives. La présente Norme n'est pas applicable aux protecteurs thermiques destinés à être utilisés dans des circuits en courant alternatif avec une fréquence inférieure à 45 Hz ou supérieure à 62 Hz. Cette quatrième édition annule et remplace la troisième édition parue en 2002, l'Amendement 1:2006 et l'Amendement 2:2010. Cette quatrième édition constitue une révision technique. Cette quatrième édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
- exigences relatives aux ensembles conditionnés de protecteurs thermiques;
- reformulation des exigences et des définitions relatives à l'essai Th;
- modification de la température initiale pour l'essai de courant de coupure;
- clarification des exigences de marquage (étiquette de conditionnement);
- Indice de tenue au cheminement minimum égal à 175 au lieu de 120. Mots clés: protection thermique des matériels, protecteurs thermiques Le contenu du corrigendum d'août 2016 a été pris en considération dans cet exemplaire.
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IEC 60691 ®
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Thermal-links – Requirements and application guide
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IEC 60691 ®
Edition 4.1 2019-01
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
colour
inside
Thermal-links – Requirements and application guide
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.120.50 ISBN 978-2-8322-6430-0
IEC 60691 ®
Edition 4.1 2019-01
CONSOLIDATED VERSION
REDLINE VERSION
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inside
Thermal-links – Requirements and application guide
– 2 – IEC 60691:2015+AMD1:2019 CSV
© IEC 2019
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
4 General requirements . 10
5 General notes on tests . 11
6 Classification . 13
6.1 Electrical conditions . 13
6.2 Thermal conditions. 14
6.3 Resistance to tracking . 14
7 Marking . 14
8 Documentation . 15
9 Constructional requirements . 15
9.1 General . 15
9.2 Lead secureness tests . 16
9.2.1 General . 16
9.2.2 Tensile test . 16
9.2.3 Thrust test . 17
9.2.4 Bending/twist test . 17
9.3 Contacts used for the current path . 18
9.4 Accessible mounting brackets or metal parts . 18
9.5 Insulating materials . 18
9.6 Resistance to tracking . 18
9.7 Creepage distances and clearances . 18
9.8 Temperature and humidity cycle conditioning . 19
9.9 Terminals and terminations . 19
10 Electrical requirements . 19
10.1 Dielectric strength . 19
10.2 Insulation resistance . 20
10.3 Interrupting current . 21
10.3.1 General . 21
10.3.2 Specific conditions . 21
10.4 Transient overload current . 22
10.5 Limited short-circuit test . 23
10.5.1 General . 23
10.5.2 Test method . 23
10.5.3 Fuse size (rating) . 23
10.5.4 Compliance . 24
11 Temperature tests . 24
11.1 General . 24
11.2 Holding temperature, T . 24
h
11.3 Rated functioning temperature, T . 25
f
11.4 Maximum temperature limit, T . 25
m
© IEC 2019
11.5 Ageing . 25
12 Resistance to rusting . 26
13 Manufacturer’s validation programme . 26
Annex A (normative) Application guide. 28
Annex B (normative) Alternative ageing test for thermal-links with T greater than
h
250 °C for use in electric irons . 29
Annex C (normative) Conductive heat ageing test . 30
C.1 Conductive heat ageing test . 30
C.2 Method . 30
C.3 Ageing . 31
C.4 Results . 32
C.5 Dielectric strength test . 32
C.6 Test oven . 32
Annex D (informative) Extended holding temperature evaluation . 34
D.1 Extended holding temperature conditioning test . 34
D.2 Load current interrupt test . 34
Annex E (normative) Seal ageing test . 36
Annex F (normative) Identification requirements . 38
Annex G (normative) Indelibility of markings . 39
Annex H (normative) Requirements for thermal-link packaged assemblies . 40
Bibliography . 43
Figure 1 – Bending/twist test . 17
Figure C.1 – Typical test fixture assembly . 32
Figure C.2 – Typical thermal-link test oven . 33
Figure D.1 – Typical terminal block support test fixture . 35
Figure E.1 – Conditioning time versus oven temperature for proposed temperature
index. 37
Figure G.1 – Apparatus for testing durability of markings . 39
Table 1 – Test schedule . 13
Table 2 – Strength of leads and terminal parts – Minimum required tensile and thrust
test forces . 17
Table 3 – Creepage distances and clearances (absolute minimum values) . 19
Table 4 – Test voltages for dielectric strength . 20
Table 5 – Test current for interrupting test . 21
Table 6 – Limited short-circuit test capacity . 23
Table H.1 – Push and pull force . 41
Table H.2 – Minimum nominal cross-sectional area of conductor . 42
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© IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
THERMAL-LINKS –
REQUIREMENTS AND APPLICATION GUIDE
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
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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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) 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.
This consolidated version of the official IEC Standard and its amendment has been
prepared for user convenience.
IEC 60691 edition 4.1 contains the fourth edition (2015-10) [documents 32C/512/FDIS and
32C/515/RVD] and its corrigendum (2016-08), and its amendment 1 (2019-01) [documents
32C/548/FDIS and 32C/559/RVD].
In this Redline version, a vertical line in the margin shows where the technical content is
modified by amendment 1. Additions are in green text, deletions are in strikethrough red
text. A separate Final version with all changes accepted is available in this publication.
© IEC 2019
International Standard IEC 60691 has been prepared by subcommittee 32C: Miniature fuses,
of IEC technical committee 32: Fuses.
This fourth edition constitutes a technical revision.
This fourth edition includes the following significant technical changes with respect to the
previous edition:
a) requirements for thermal-link packaged assemblies;
b) renew the requirements and definitions for T -test;
h
c) change starting temperature for interrupt current test;
d) clarify requirements for marking (packing label);
e) minimum Proof Tracking Index 175 instead 120.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The basis for this standard is the harmonization of the USA national standard, UL 1020, fifth
edition (withdrawn 2003), and IEC 60691:1993, together with its Amendment 1:1995 and
Amendment 2:2000.
The following differing practices of a less permanent nature exist in the country indicated
below:
– Annex C is required to be declared in the USA;
– Annex E is required in the USA, if applicable;
– Annex F is required to be declared in the USA.
In this standard, the following type is used:
– compliance statements: in italic type.
The committee has decided that the contents of the base publication and its amendment 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.
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 document using a
colour printer.
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© IEC 2019
INTRODUCTION
Thermal-links, defined as non-resettable devices functioning once only without refunctioning,
are widely applied for the thermal protection of equipment in which, under fault (abnormal)
conditions, one or more parts may reach hazardous temperatures.
As these devices have several aspects in common with miniature fuse-links and are used for
obtaining a comparable degree of protection, this standard has endeavoured to lay down a
number of basic requirements for such devices.
© IEC 2019
THERMAL-LINKS –
REQUIREMENTS AND APPLICATION GUIDE
1 Scope
This International Standard is applicable to thermal-links intended for incorporation in
electrical appliances, electronic equipment and component parts thereof, normally intended
for use indoors, in order to protect them against excessive temperatures under abnormal
conditions.
NOTE 1 The equipment is not designed to generate heat.
NOTE 2 The effectiveness of the protection against excessive temperatures logically depends upon the position
and method of mounting of the thermal-link, as well as upon the current which it is carrying.
This standard may be applicable to thermal-links for use under conditions other than indoors,
provided that the climatic and other circumstances in the immediate surroundings of such
thermal-links are comparable with those in this standard.
This standard may be applicable to thermal-links in their simplest forms (e.g. melting strips or
wires), provided that molten materials expelled during function cannot adversely interfere with
the safe use of the equipment, especially in the case of hand-held or portable equipment,
irrespective of its position.
Annex H of this standard is applicable to thermal-link packaged assemblies where the
thermal-link(s) has already been approved to this standard but packaged in a metallic or non-
metallic housing and provided with terminals/wiring leads.
This standard is applicable to thermal-links with a rated voltage not exceeding 690 V a.c. or
d.c. and a rated current not exceeding 63 A.
The objectives of this standard are:
a) to establish uniform requirements for thermal-links,
b) to define methods of test,
c) to provide useful information for the application of thermal-links in equipment.
This standard is not applicable to thermal-links used under extreme conditions such as
corrosive or explosive atmospheres.
This standard is not applicable to thermal-links to be used in circuits on a.c. with a frequency
lower than 45 Hz or higher than 62 Hz.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60065:2014, Audio, video and similar electronic apparatus – Safety requirements
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© IEC 2019
IEC 60112:2003, Method for the determination of the proof and the comparative tracking
indices of solid insulating materials
IEC 60112:2003/AMD1:2009
IEC 60127-2:2014, Miniature fuses – Part 2: Cartridge fuse-links
IEC 60216-5:2008, Electrical insulating materials – Thermal endurance properties – Part 5:
Determination of relative thermal endurance index (RTE) of an insulating material
IEC 60664-1:2007, Insulation coordination for equipment within low-voltage systems – Part 1:
Principles, requirements and tests
IEC 60695-2-12:2010, Fire hazard testing – Part 2-12: Glowing/hot-wire based test methods –
Glow-wire flammability index (GWFI) test method for materials
IEC 60695-2-12:2010/AMD1:2014
IEC 60695-2-13:2010, Fire hazard testing – Part 2-13: Glowing/hot-wire based test methods –
Glow-wire ignition temperature (GWIT) test method for materials
IEC 60695-2-13:2010/AMD1:2014
IEC 60695-10-2:2014, Fire hazard testing – Part 10-2: Abnormal heat – Ball pressure test
method
IEC 60695-11-10:2013, Fire hazard testing – Part 11-10: Test flames – 50 W horizontal and
vertical flame test methods
IEC 60730-1:2013, Automatic electrical controls – Part 1: General requirements
IEC 61210:2010, Connecting devices – Flat quick-connect terminations for electrical copper
conductors – Safety requirements
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
clearance
shortest distance in air between two conductive parts
3.2
creepage distance
shortest distance along the surface of insulating material between two conductive parts
3.3
holding temperature
T
h
maximum temperature of the thermal-link at which it will not change its state of conductivity
during a specified time at the rated current
Note 1 to entry: The minimum permissible value of T is 35 °C.
h
3.4
homogeneous series
series of thermal-links having the same external dimensions and common overall construction,
deviating from each other only in such characteristics (including ratings) that, for a given test,
© IEC 2019
the testing of one or a reduced number of particular thermal-links of that series shall be taken
as representative for all the thermal-links of the series
3.5
interrupting current
I
b
value of the current that the thermal-link is capable of interrupting at rated voltage and under
specified circuit conditions
3.6
maximum temperature limit
T
m
temperature of the thermal-link stated by the manufacturer, up to which the mechanical and
electrical properties of the thermal-link, having changed its state of conductivity, will not be
impaired for a given time
3.7
pilot duty
rating assigned to a switching device that controls the coil of another electro-mechanical
device such as a solenoid, relay or contactor
3.8
portable equipment
equipment which is moved while in operation or which can easily be moved from one place to
another while connected to the supply
3.9
rated current
I
r
current used to classify a thermal-link
3.10
rated functioning temperature
T
f
temperature of the thermal-link which causes it to change its state of conductivity with a
detection current up to 10 mA as the only load
3.11
rated voltage
U
r
voltage used to classify a thermal-link
3.12
thermal element
metallic or non-metallic fusible material that is part of a thermal-link and is responsive to
temperature by a change of state such as from solid to liquid at the temperature for which it is
calibrated
3.13
thermal-link
non-resettable device incorporating a thermal element, which will open a circuit once only
when exposed for a sufficient length of time to a temperature in excess of that for which it has
been designed
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© IEC 2019
3.14
transient overload current
I
p
direct current pulse train which the thermal-link is able to withstand without impairing its
characteristics
3.15
type test
conformity testing on the basis of one or more specimens of a product representative of the
production
3.16
extended holding temperature
T
h-100
maximum temperature at which a thermal-link can be maintained while conducting the rated
load current at the rated voltage for a period of 100 weeks which will not cause the thermal-
link to open circuit in accordance with extended holding temperature evaluation
Note 1 to entry: This is a rating for user consideration during the investigation of the end product.
Note 2 to entry: Annex D specifies the extended holding temperature evaluation.
3.17
conductive heat ageing test
CHAT
test to evaluate a thermal-link for use in an appliance
Note 1 to entry: If it performs satisfactorily, the thermal-link will be assigned a CHAT rating. This rating is for end-
product user consideration during the investigation of the end-use product.
Note 2 to entry: Annex C specifies the conductive heat ageing test.
4 General requirements
4.1 Adequate protection of the equipment against excessive temperatures not only
depends upon the properties of the thermal-link but also to a large extent upon the mounting
of the thermal-link in the equipment. Therefore, in addition to good engineering practice, the
requirements of the application guide in Annex A shall be considered.
4.2 Thermal-links shall have adequate electrical and mechanical strength and shall be
constructed so as to withstand all conditions of handling likely to be encountered during
mounting and normal use, when used within the requirements of this standard.
4.3 When a thermal-link changes its state of conductivity, no arc or flame shall be
maintained, nor material expelled, that might impair the surrounding area or otherwise create
a risk of electric shock or fire. In addition, there shall be no emission of substances (e.g. gases,
liquids, dust, mist, vapour) which could cause a hazard.
For thermal-links using melting strips or wires, care should be taken to prevent molten
material from short-circuiting or bridging creepage distances and clearances in air, so as to
reduce the risk of impairing the insulation system of the equipment.
After it has functioned, the thermal-link shall not be damaged when subjected to temperatures
not exceeding T , in such a way that the safety of the equipment with regard to risk of electric
m
shock hazard and electrical breakdown is impaired. The thermal-link shall not reclose after it has
operated.
© IEC 2019
4.4 For requirements for thermal-link packaged assemblies, see Annex H.
5 General notes on tests
5.1 The test conditions are as follows.
5.1.1 Unless otherwise specified, only tests that are not required to be performed inside an
environmental chamber and/or test oven shall be carried out under the following atmospheric
conditions:
– temperature: 15 °C to 35 °C,
– relative humidity: 25 % to 75 %,
4 5
– air pressure: 8,6 × 10 Pa to 1,06 × 10 Pa.
The required atmospheric conditions during testing can be controlled when carrying out the
tests and during the duration of the tests. The required atmospheric conditions do not have to
be maintained in a test laboratory when tests are not performed.
5.1.2 Where the conditions given in 5.1.1 have a significant influence, they shall be kept
substantially constant during the tests.
5.1.3 If the temperature limits given in 5.1.1 are too wide for certain tests, these shall be
repeated, in case of doubt, at a temperature of (23 ± 1) °C.
5.2 In every test report, the ambient temperature shall be stated. If the standard conditions
for relative humidity or pressure are not fulfilled during the tests, a note to this effect shall be
added to the report.
5.3 If the result of a test is influenced, to an appreciable extent, by the position and method
of mounting of the specimen, the most unfavourable condition shall be chosen for the relevant
tests and recorded.
5.4 If a thermal-link has been specifically designed for use in a special type of equipment
and cannot be tested separately, the tests of this standard shall be performed in that
equipment or in the relevant part of it, or similar.
5.5 When testing a homogeneous series of thermal-links, all the tests shall be applied to
thermal-links with the lowest and highest T . Thermal-links with intermediate rated functioning
f
temperatures need only be subjected to tests according to 10.3, 11.3, 11.4 and 11.5.
5.6 The number of specimens is as follows.
5.6.1 The total number of specimens required is 48. Out of a total of 48 specimens, 15 are
kept as spares in case some of the tests have to be repeated. Out of a total of 48 specimens,
33 are divided into 11 groups assigned by alphabetical letters from A to K. Each group
consists of three specimens. Tests shall be performed in the order indicated in Table 1 but, if
so required, tests may be repeated, for example the test on marking (see Clause 7).
Additional samples may be needed according to Note 2 of Table 1.
For optional tests, additional samples should be required as per the applicable annexes.
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© IEC 2019
5.6.2 If, in any of the tests carried out in accordance with any relevant test clause, a failure
is reported, the cause of the failure will be identified and corrective action taken. Based on the
failure analysis report and the corrective action, as a minimum, the test sequence shall be
repeated on twice the number of revised specimens, and no further failures are allowed.
If no corrective actions are necessary, the test should be repeated with double the same size
and no further deviation is allowed.
5.6.3 For requirements for thermal-link packaged assemblies, see Annex H
5.7 The conductive heat ageing test of Annex C is applicable when declared by the
manufacturer.
The conductive heat ageing test may be omitted if the thermal-link is constructed without
contacts.
NOTE In the USA the conductive heat ageing test is required to be declared.
© IEC 2019
Table 1 – Test schedule
Clause or Test Specimen groups
Sub-clause
A B C D E F G H I J K
a
7 Marking (Rub test) X X
a
7 Marking (visual inspection only) X X
9 Constructional requirements
a
9.2.2 Tensile forces X
a
9.2.3 Thrust force X
a
9.2.4 Bending/twist force X
a
9.6 Resistance to tracking X
a
9.7 Creepage distances and clearances X X
9.8 Temperature and humidity cycle X X X X X
conditioning
10 Electrical requirements
10.1 Dielectric strength (if applicable) X X X X X
10.2 Insulation resistance (if applicable) X X X X X
10.3 Interrupting current X X
10.4 Transient overload current X X X
11 Temperature tests
11.2 Check on T X
h
11.3 Check on T X X
f
11.4 Check on T followed by dielectric X X
m
test and insulation resistance
11.5 Ageing X X X X X
step 1 (optional) 21 days
step 2 (mandatory) 21 days
step 3 (mandatory) 14 days
step 4 (mandatory) 7 days
step 5 (mandatory) 7 days
step 6 (mandatory) 24 hours
10.1 Dielectric strength X X X X X X X X
10.2 Insulation resistance X X X X X X X X
12 Resistance to rusting
a
12 Resistance to rusting (ferrous parts) X X X
If the conditions of voltage, power and current in 10.3.2.3, 10.3.2.4 and 10.3.2.5 are not covered by one test,
a minimum of three samples should be tested for each condition.
a
For homogeneous series, these tests may be omitted for intermediate ratings.
6 Classification
6.1 Electrical conditions
With regard to electrical conditions, the following terms are used:
a) voltage
1) AC
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© IEC 2019
2) DC
b) current
1) resistive
2) inductive
c) motor
d) pilot duty
e) electric discharge lamp
f) special
6.2 Thermal conditions
With regard to thermal conditions, the following symbols and abbreviations are used:
a) T
f
b) T
h
c) T
m
d) CHAT
e) T
h-100
6.3 Resistance to tracking
With regard to resistance to tracking, the following ranges are used:
a) proof tracking index from 175 to 249;
b) proof tracking index greater than or equal to 250.
NOTE These ranges are based on test methods for surface tracking laid down in IEC 60112.
7 Marking
7.1 Each thermal-link shall be marked with the following:
a) type or catalogue reference;
b) manufacturer’s name or trade mark;
c) rated functioning temperature T with or without the symbol T followed by the number of
f f
degrees Celsius (marked with °C or C);
d) date code which identifies the date of manufacture and which does not repeat for at least
10 years, and a factory location or code, stamped on the thermal-link or the smallest
packaging.
If there is only one factory, the factory location may be omitted.
Catalogue or reference numbers should define those parameters such as temperature, current
and voltage, which together classify a thermal-link.
7.2 The rated functioning temperature T may be omitted if a different type or catalogue
f
reference is employed for each different functioning temperature.
7.3 Marking shall be indelible and legible.
Compliance with the requirements for Indelibility of markings is checked by the test in
Annex G using the apparatus shown in Figure G.1. Legibility is checked by inspection. After
the ageing tests of 11.4, compliance is checked by inspection.
© IEC 2019
7.4 The marking in accordance with a), b), c) and d) in 7.1 shall be printed additionally on
the packing, together with a reference to this standard.
7.5 If the thermal-link is small in size, and not intended to be replaced, the markings in
accordance with b) to d) in 7.1 shall be printed on the packaging, together with a reference to
this standard.
Compliance is checked by inspection.
8 Documentation
The manufacturer shall provide in the technical documentation, catalogues or instructional
leaflets the following information, in addition to that required in Clause 7:
a) classification in accordance with Clause 6;
b) for each of the classifications;
1) characteristic temperatures T , T , T ;
f h m
2) characteristic currents I , I , I ;
r b p
3) rated voltage U ;
r
c) suitability for sealing in, or use with impregnating fluids or cleaning solvents;
d) information for mounting the thermal-link in the equipment.
e) thermal-links small in size and not intended to be replaced.
For reasons of safety, it should be made clear in the documentation that a thermal-link is a
non-repairable item and that, in case of replacement, an equivalent thermal-link from the
same manufacturer and having the same catalogue reference should be used, mounted in
exactly the same way.
f) the position of the metal screen, if it is located at a distance other than 12,7 mm away
from the live parts in the case of a thermal-link having an exposed element.
9 Constructional requirements
9.1 General
9.1.1 Thermal-links shall have adequate mechanical strength and stability so as to
withstand the stresses likely to be encountered during handling, normal use and fault
conditions of the relevant end-use equipment.
9.1.2 Tab terminals shall be constructed in accordance with IEC 61210 and the maximum
permissible temperature of the used Tab materials shall be in accordance with Table A.1 of
IEC 61210:2010 (Tabs / Integrated).
9.1.3 Current-carrying parts shall be constructed in such a way that contact pressure is not
transmitted through non-metallic material other than ceramic, or any material considered as
having sufficient dimensional stability over the range of temperatures to be expected, unless
there is sufficient resilience in the corresponding metal parts to compensate for any shrinkage
or distortion of the non-metallic material.
Current-carrying parts shall have the necessary mechanical strength, be capable of carrying
the rated current and shall be of a material that is acceptable for the particular application.
For current-carrying parts, temperature limits should shall be considered according to
Table 13 of IEC 60730-1:2013.
– 16 – IEC 60691:2015+AMD1:2019 CSV
© IEC 2019
9.1.4 Friction shall not be used to secure uninsulated live parts (including terminals) to
supporting surfaces if there is a risk of such parts turning or shifting their position, resulting in
the reduction of creepage distances and clearances to less than those required elsewhere in
this standard. The security of contact assemblies shall be such that alignment of contacts is
maintained.
9.1.5 Leads and terminal parts shall be secured so that stress on them during installation
and normal use does not impair operation of the thermal-link. Thermal-links using seals with
formed leads for use in appliances or components shall not be bent less than 3 mm from the
thermal-link seal.
Leads may be bent less than 3 mm from the seal if:
a) the thermal-link manufacturer's bending fixture and procedure does not transmit stress to
the thermal-link operating mechanism, and if;
b) formed test samples shall be subjected to the bending/twist lead secureness test of 9.2.4
and the rated functioning temperature test of 11.3.
9.1.6 Thermal-links with leads smaller than 0,21 mm shall be provided with application
instructions that instruct the user how to mount the device in equipment, taking into
consideration the device's temperature response. The instructions shall also include guidance
on the effects that movement and vibration in the equipment may have on the thermal-link's
terminals, connections and other mounting components.
9.1.7 A terminal for a soldered connection shall have provision, such as a hole, for holding
the conductor independently of solder.
9.1.8 When applicable, provision shall be made for securely mounting a thermal-link in
position.
9.1.9 Thermal-links intended to be embedded in windings and the like need not have
provision for mounting.
9.1.10 Bolts, screws, or other parts used for mounting an assembly having a thermal-link
shall be independent of those used for securing component parts of the assembly.
9.1.11 Compliance is checked by the lead secureness tests of 9.2. Mounting and
securement instructions shall be provided with thermal-links for the manufacturer of the end-
product in accordance with Annex A.
9.2 Lead secureness tests
9.2.1 General
If force applied to thermal-link wire leads causes breakdown of one or more parts leading
directly or indirectly to stress being applied to the operating mechanism, the tests described in
9.2.2, 9.2.3 and 9.2.4 shall be conducted. There shall be no displacement of parts that would
tend to reclose a thermal-link or reduce creepage distances or clearances as a result of the
tests specified in 9.2.2 and 9.2.3. There shall be no displacement of parts other than the wire
leads as a result of the test specified in 9.2.4.
9.2.2 Tensile test
The thermal-link shall be supported in any convenient manner in order not to damage it
and a tensile force as specified in Table 2 shall be applied to each lead for 1 min.
© IEC 2019
9.2.3 Thrust test
The thermal-link shall be supported using any convenient means such that it is not damaged
and a thrust force as specified in Table 2 shall be applied to each lead for 1 min at a distance
of 2 mm from the thermal-link.
9.2.4 Bending/twist test
The thermal-link shall be rigidly supported such that it is not damaged. Each lead shall be
bent through 90° at a location 10 mm from the body of the thermal-link and then twisted
through 180° as shown in Figure 1.
Thermal-link
rigidly supported
10 mm
Step 1: Bend
180°
Step 2: Twist
IEC
Figure 1 – Bending/twist test
Table 2 – Strength of leads and terminal parts –
Minimum required tensile and thrust test forces
Nominal cross-sectional area of the lead, A, Tensile force Thrust force
mm N N
Up to and including 0,05 1 0,25
Over 0,05 up to and including 1,2
20 × A 5 × A
Over 1,2 40 8
NOTE A is the nominal cross-sectional area of the terminal in mm .
90°
– 18 – IEC 60691:2015+AMD1:2019 CSV
© IEC 2019
9.3 Contacts used for the current path
Contacts used for the current path in a thermal-link shall withstand the voltage stress
determined by the voltage source in the circuit. Current-carrying elements or contacts,
together with their terminals, are usually isolated from metal parts such as mounting brackets,
metal enclosures and the like, by insulating material.
9.4 Accessible mounting brackets or metal parts
If mounting brackets or metal parts of the thermal-link's enclosure are accessible or
connected through low impedances to metal enclosures of the equipment accessible to the
user from the outside, the insulation between the current-carrying elements of the thermal-link
and such conductive encl
...
IEC 60691 ®
Edition 4.0 2015-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Thermal-links – Requirements and application guide
Protecteurs thermiques – Exigences et guide d'application
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IEC 60691 ®
Edition 4.0 2015-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Thermal-links – Requirements and application guide
Protecteurs thermiques – Exigences et guide d'application
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.120.50 ISBN 978-2-8322-2921-7
– 2 – IEC 60691:2015 © IEC 2015
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
4 General requirements . 10
5 General notes on tests . 11
6 Classification . 13
6.1 Electrical conditions . 13
6.2 Thermal conditions. 14
6.3 Resistance to tracking . 14
7 Marking . 14
8 Documentation . 15
9 Constructional requirements . 15
9.1 General . 15
9.2 Lead secureness tests . 16
9.2.1 General . 16
9.2.2 Tensile test . 16
9.2.3 Thrust test . 17
9.2.4 Bending/twist test . 17
9.3 Contacts used for the current path . 18
9.4 Accessible mounting brackets or metal parts . 18
9.5 Insulating materials . 18
9.6 Resistance to tracking . 18
9.7 Creepage distances and clearances . 18
9.8 Temperature and humidity cycle conditioning . 19
9.9 Terminals and terminations . 19
10 Electrical requirements . 19
10.1 Dielectric strength . 19
10.2 Insulation resistance . 20
10.3 Interrupting current . 21
10.3.1 General . 21
10.3.2 Specific conditions . 21
10.4 Transient overload current . 22
10.5 Limited short-circuit test . 23
10.5.1 General . 23
10.5.2 Test method . 23
10.5.3 Fuse size (rating) . 23
10.5.4 Compliance . 24
11 Temperature tests . 24
11.1 General . 24
11.2 Holding temperature, T . 24
h
11.3 Rated functioning temperature, T . 25
f
11.4 Maximum temperature limit, T . 25
m
11.5 Ageing . 25
12 Resistance to rusting . 26
13 Manufacturer’s validation programme . 26
Annex A (normative) Application guide. 28
Annex B (normative) Alternative ageing test for thermal-links with T greater than
h
250 °C for use in electric irons . 29
Annex C (normative) Conductive heat ageing test . 30
C.1 Conductive heat ageing test . 30
C.2 Method . 30
C.3 Ageing . 31
C.4 Results . 32
C.5 Dielectric strength test . 32
C.6 Test oven . 32
Annex D (informative) Extended holding temperature evaluation . 34
D.1 Extended holding temperature conditioning test . 34
D.2 Load current interrupt test . 34
Annex E (normative) Seal ageing test . 36
Annex F (normative) Identification requirements . 38
Annex G (normative) Indelibility of markings . 39
Annex H (normative) Requirements for thermal-link packaged assemblies . 40
Bibliography . 43
Figure 1 – Bending/twist test . 17
Figure C.1 – Typical test fixture assembly . 32
Figure C.2 – Typical thermal-link test oven . 33
Figure D.1 – Typical terminal block support test fixture . 35
Figure E.1 – Conditioning time versus oven temperature for proposed temperature
index. 37
Figure G.1 – Apparatus for testing durability of markings . 39
Table 1 – Test schedule . 13
Table 2 – Strength of leads and terminal parts – Minimum required tensile and thrust
test forces . 17
Table 3 – Creepage distances and clearances (absolute minimum values) . 19
Table 4 – Test voltages for dielectric strength . 20
Table 5 – Test current for interrupting test . 21
Table 6 – Limited short-circuit test capacity . 23
Table H.1 – Push and pull force . 41
Table H.2 – Minimum nominal cross-sectional area of conductor . 42
– 4 – IEC 60691:2015 © IEC 2015
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
THERMAL-LINKS –
REQUIREMENTS AND APPLICATION GUIDE
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, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for 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) 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 60691 has been prepared by subcommittee 32C: Miniature fuses,
of IEC technical committee 32: Fuses.
This fourth edition cancels and replaces the third edition published in 2002, Amendment 1:
2006 and Amendment 2: 2010. This fourth edition constitutes a technical revision.
This fourth edition includes the following significant technical changes with respect to the
previous edition:
a) requirements for thermal-link packaged assemblies;
b) renew the requirements and definitions for T -test;
h
c) change starting temperature for interrupt current test;
d) clarify requirements for marking (packing label);
e) minimum Proof Tracking Index 175 instead 120.
The text of this standard is based on the following documents:
FDIS Report on voting
32C/512/FDIS 32C/515/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.
The basis for this standard is the harmonization of the USA national standard, UL 1020, fifth
edition (withdrawn 2003), and IEC 60691:1993, together with its Amendment 1:1995 and
Amendment 2:2000.
The following differing practices of a less permanent nature exist in the country indicated
below:
– Annex C is required to be declared in the USA;
– Annex E is required in the USA, if applicable;
– Annex F is required to be declared in the USA.
In this standard, the following type is used:
– compliance statements: in italic type.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC website 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.
The contents of the corrigendum of August 2016 have been included in this copy.
– 6 – IEC 60691:2015 © IEC 2015
INTRODUCTION
Thermal-links, defined as non-resettable devices functioning once only without refunctioning,
are widely applied for the thermal protection of equipment in which, under fault (abnormal)
conditions, one or more parts may reach hazardous temperatures.
As these devices have several aspects in common with miniature fuse-links and are used for
obtaining a comparable degree of protection, this standard has endeavoured to lay down a
number of basic requirements for such devices.
THERMAL-LINKS –
REQUIREMENTS AND APPLICATION GUIDE
1 Scope
This International Standard is applicable to thermal-links intended for incorporation in
electrical appliances, electronic equipment and component parts thereof, normally intended
for use indoors, in order to protect them against excessive temperatures under abnormal
conditions.
NOTE 1 The equipment is not designed to generate heat.
NOTE 2 The effectiveness of the protection against excessive temperatures logically depends upon the position
and method of mounting of the thermal-link, as well as upon the current which it is carrying.
This standard may be applicable to thermal-links for use under conditions other than indoors,
provided that the climatic and other circumstances in the immediate surroundings of such
thermal-links are comparable with those in this standard.
This standard may be applicable to thermal-links in their simplest forms (e.g. melting strips or
wires), provided that molten materials expelled during function cannot adversely interfere with
the safe use of the equipment, especially in the case of hand-held or portable equipment,
irrespective of its position.
Annex H of this standard is applicable to thermal-link packaged assemblies where the
thermal-link(s) has already been approved to this standard but packaged in a metallic or non-
metallic housing and provided with terminals/wiring leads.
This standard is applicable to thermal-links with a rated voltage not exceeding 690 V a.c. or
d.c. and a rated current not exceeding 63 A.
The objectives of this standard are:
a) to establish uniform requirements for thermal-links,
b) to define methods of test,
c) to provide useful information for the application of thermal-links in equipment.
This standard is not applicable to thermal-links used under extreme conditions such as
corrosive or explosive atmospheres.
This standard is not applicable to thermal-links to be used in circuits on a.c. with a frequency
lower than 45 Hz or higher than 62 Hz.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60065:2014, Audio, video and similar electronic apparatus – Safety requirements
– 8 – IEC 60691:2015 © IEC 2015
IEC 60112:2003, Method for the determination of the proof and the comparative tracking
indices of solid insulating materials
IEC 60112:2003/AMD1:2009
IEC 60127-2:2014, Miniature fuses – Part 2: Cartridge fuse-links
IEC 60216-5:2008, Electrical insulating materials – Thermal endurance properties – Part 5:
Determination of relative thermal endurance index (RTE) of an insulating material
IEC 60664-1:2007, Insulation coordination for equipment within low-voltage systems – Part 1:
Principles, requirements and tests
IEC 60695-2-12:2010, Fire hazard testing – Part 2-12: Glowing/hot-wire based test methods –
Glow-wire flammability index (GWFI) test method for materials
IEC 60695-2-12:2010/AMD1:2014
IEC 60695-2-13:2010, Fire hazard testing – Part 2-13: Glowing/hot-wire based test methods –
Glow-wire ignition temperature (GWIT) test method for materials
IEC 60695-2-13:2010/AMD1:2014
IEC 60695-10-2:2014, Fire hazard testing – Part 10-2: Abnormal heat – Ball pressure test
method
IEC 60695-11-10:2013, Fire hazard testing – Part 11-10: Test flames – 50 W horizontal and
vertical flame test methods
IEC 60730-1:2013, Automatic electrical controls – Part 1: General requirements
IEC 61210:2010, Connecting devices – Flat quick-connect terminations for electrical copper
conductors – Safety requirements
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
clearance
shortest distance in air between two conductive parts
3.2
creepage distance
shortest distance along the surface of insulating material between two conductive parts
3.3
holding temperature
T
h
maximum temperature of the thermal-link at which it will not change its state of conductivity
during a specified time at the rated current
Note 1 to entry: The minimum permissible value of T is 35 °C.
h
3.4
homogeneous series
series of thermal-links having the same external dimensions and common overall construction,
deviating from each other only in such characteristics (including ratings) that, for a given test,
the testing of one or a reduced number of particular thermal-links of that series shall be taken
as representative for all the thermal-links of the series
3.5
interrupting current
I
b
value of the current that the thermal-link is capable of interrupting at rated voltage and under
specified circuit conditions
3.6
maximum temperature limit
T
m
temperature of the thermal-link stated by the manufacturer, up to which the mechanical and
electrical properties of the thermal-link, having changed its state of conductivity, will not be
impaired for a given time
3.7
pilot duty
rating assigned to a switching device that controls the coil of another electro-mechanical
device such as a solenoid, relay or contactor
3.8
portable equipment
equipment which is moved while in operation or which can easily be moved from one place to
another while connected to the supply
3.9
rated current
I
r
current used to classify a thermal-link
3.10
rated functioning temperature
T
f
temperature of the thermal-link which causes it to change its state of conductivity with a
detection current up to 10 mA as the only load
3.11
rated voltage
U
r
voltage used to classify a thermal-link
3.12
thermal element
metallic or non-metallic fusible material that is part of a thermal-link and is responsive to
temperature by a change of state such as from solid to liquid at the temperature for which it is
calibrated
3.13
thermal-link
non-resettable device incorporating a thermal element, which will open a circuit once only
when exposed for a sufficient length of time to a temperature in excess of that for which it has
been designed
– 10 – IEC 60691:2015 © IEC 2015
3.14
transient overload current
I
p
direct current pulse train which the thermal-link is able to withstand without impairing its
characteristics
3.15
type test
conformity testing on the basis of one or more specimens of a product representative of the
production
3.16
extended holding temperature
T
h-100
maximum temperature at which a thermal-link can be maintained while conducting the rated
load current at the rated voltage for a period of 100 weeks which will not cause the thermal-
link to open circuit in accordance with extended holding temperature evaluation
Note 1 to entry: This is a rating for user consideration during the investigation of the end product.
Note 2 to entry: Annex D specifies the extended holding temperature evaluation.
3.17
conductive heat ageing test
CHAT
test to evaluate a thermal-link for use in an appliance
Note 1 to entry: If it performs satisfactorily, the thermal-link will be assigned a CHAT rating. This rating is for end-
product user consideration during the investigation of the end-use product.
Note 2 to entry: Annex C specifies the conductive heat ageing test.
4 General requirements
4.1 Adequate protection of the equipment against excessive temperatures not only
depends upon the properties of the thermal-link but also to a large extent upon the mounting
of the thermal-link in the equipment. Therefore, in addition to good engineering practice, the
requirements of the application guide in Annex A shall be considered.
4.2 Thermal-links shall have adequate electrical and mechanical strength and shall be
constructed so as to withstand all conditions of handling likely to be encountered during
mounting and normal use, when used within the requirements of this standard.
4.3 When a thermal-link changes its state of conductivity, no arc or flame shall be
maintained, nor material expelled that might impair the surrounding area or otherwise create a
risk of electric shock or fire.
For thermal-links using melting strips or wires, care should be taken to prevent molten
material from short-circuiting or bridging creepage distances and clearances in air, so as to
reduce the risk of impairing the insulation system of the equipment.
After it has functioned, the thermal-link shall not be damaged when subjected to temperatures
not exceeding T , in such a way that the safety of the equipment with regard to risk of electric
m
shock hazard and electrical breakdown is impaired. The thermal-link shall not reclose after it has
operated.
4.4 For requirements for thermal-link packaged assemblies, see Annex H.
5 General notes on tests
5.1 The test conditions are as follows.
5.1.1 Unless otherwise specified, only tests that are not required to be performed inside an
environmental chamber and/or test oven shall be carried out under the following atmospheric
conditions:
– temperature: 15 °C to 35 °C,
– relative humidity: 25 % to 75 %,
4 5
– air pressure: 8,6 × 10 Pa to 1,06 × 10 Pa.
The required atmospheric conditions during testing can be controlled when carrying out the
tests and during the duration of the tests. The required atmospheric conditions do not have to
be maintained in a test laboratory when tests are not performed.
5.1.2 Where the conditions given in 5.1.1 have a significant influence, they shall be kept
substantially constant during the tests.
5.1.3 If the temperature limits given in 5.1.1 are too wide for certain tests, these shall be
repeated, in case of doubt, at a temperature of (23 ± 1) °C.
5.2 In every test report, the ambient temperature shall be stated. If the standard conditions
for relative humidity or pressure are not fulfilled during the tests, a note to this effect shall be
added to the report.
5.3 If the result of a test is influenced, to an appreciable extent, by the position and method
of mounting of the specimen, the most unfavourable condition shall be chosen for the relevant
tests and recorded.
5.4 If a thermal-link has been specifically designed for use in a special type of equipment
and cannot be tested separately, the tests of this standard shall be performed in that
equipment or in the relevant part of it, or similar.
5.5 When testing a homogeneous series of thermal-links, all the tests shall be applied to
thermal-links with the lowest and highest T . Thermal-links with intermediate rated functioning
f
temperatures need only be subjected to tests according to 10.3, 11.3, 11.4 and 11.5.
5.6 The number of specimens is as follows.
5.6.1 The total number of specimens required is 48. Out of a total of 48 specimens, 15 are
kept as spares in case some of the tests have to be repeated. Out of a total of 48 specimens,
33 are divided into 11 groups assigned by alphabetical letters from A to K. Each group
consists of three specimens. Tests shall be performed in the order indicated in Table 1 but, if
so required, tests may be repeated, for example the test on marking (see Clause 7).
Additional samples may be needed according to Note 2 of Table 1.
For optional tests, additional samples should be required as per the applicable annexes.
– 12 – IEC 60691:2015 © IEC 2015
5.6.2 If, in any of the tests carried out in accordance with any relevant test clause, a failure
is reported, the cause of the failure will be identified and corrective action taken. Based on the
failure analysis report and the corrective action, as a minimum, the test sequence shall be
repeated on twice the number of revised specimens, and no further failures are allowed.
If no corrective actions are necessary, the test should be repeated with double the same size
and no further deviation is allowed.
5.6.3 For requirements for thermal-link packaged assemblies, see Annex H
5.7 The conductive heat ageing test of Annex C is applicable when declared by the
manufacturer.
The conductive heat ageing test may be omitted if the thermal-link is constructed without
contacts.
NOTE In the USA the conductive heat ageing test is required to be declared.
Table 1 – Test schedule
Clause or Test Specimen groups
Sub-clause
A B C D E F G H I J K
a
7 Marking (Rub test) X X
a
7 Marking (visual inspection only) X X
9 Constructional requirements
a
9.2.2 Tensile forces X
a
9.2.3 Thrust force X
a
9.2.4 Bending/twist force X
a
9.6 Resistance to tracking X
a
X X
9.7 Creepage distances and clearances
X X X X X
9.8 Temperature and humidity cycle
conditioning
10 Electrical requirements
10.1 Dielectric strength (if applicable) X X X X X
10.2 Insulation resistance (if applicable) X X X X X
10.3 Interrupting current X X
10.4 Transient overload current X X X
11 Temperature tests
11.2 Check on T X
h
11.3 Check on T X X
f
11.4 Check on T followed by dielectric X X
m
test and insulation resistance
11.5 Ageing X X X X X
step 1 (optional) 21 days
step 2 (mandatory) 21 days
step 3 (mandatory) 14 days
step 4 (mandatory) 7 days
step 5 (mandatory) 7 days
step 6 (mandatory) 24 hours
10.1 Dielectric strength X X X X X X X X
10.2 Insulation resistance X X X X X X X X
12 Resistance to rusting
a
X X X
12 Resistance to rusting (ferrous parts)
If the conditions of voltage, power and current in 10.3.2.3, 10.3.2.4 and 10.3.2.5 are not covered by one test,
a minimum of three samples should be tested for each condition.
a
For homogeneous series, these tests may be omitted for intermediate ratings.
6 Classification
6.1 Electrical conditions
With regard to electrical conditions, the following terms are used:
a) voltage
1) AC
– 14 – IEC 60691:2015 © IEC 2015
2) DC
b) current
1) resistive
2) inductive
c) motor
d) pilot duty
e) electric discharge lamp
f) special
6.2 Thermal conditions
With regard to thermal conditions, the following symbols and abbreviations are used:
a) T
f
b) T
h
c) T
m
d) CHAT
e) T
h-100
6.3 Resistance to tracking
With regard to resistance to tracking, the following ranges are used:
a) proof tracking index from 175 to 249;
b) proof tracking index greater than or equal to 250.
NOTE These ranges are based on test methods for surface tracking laid down in IEC 60112.
7 Marking
7.1 Each thermal-link shall be marked with the following:
a) type or catalogue reference;
b) manufacturer’s name or trade mark;
c) rated functioning temperature T with or without the symbol T followed by the number of
f f
degrees Celsius (marked with °C or C);
d) date code which identifies the date of manufacture and which does not repeat for at least
10 years, and a factory location or code, stamped on the thermal-link or the smallest
packaging.
If there is only one factory, the factory location may be omitted.
Catalogue or reference numbers should define those parameters such as temperature, current
and voltage, which together classify a thermal-link.
7.2 The rated functioning temperature T may be omitted if a different type or catalogue
f
reference is employed for each different functioning temperature.
7.3 Marking shall be indelible and legible.
Compliance with the requirements for Indelibility of markings is checked by the test in
Annex G using the apparatus shown in Figure G.1. Legibility is checked by inspection. After
the ageing tests of 11.4, compliance is checked by inspection.
7.4 The marking in accordance with a), b), c) and d) in 7.1 shall be printed additionally on
the packing, together with a reference to this standard.
7.5 If the thermal-link is small in size, and not intended to be replaced, the markings in
accordance with b) to d) in 7.1 shall be printed on the packaging, together with a reference to
this standard.
Compliance is checked by inspection.
8 Documentation
The manufacturer shall provide in the technical documentation, catalogues or instructional
leaflets the following information, in addition to that required in Clause 7:
a) classification in accordance with Clause 6;
b) for each of the classifications;
1) characteristic temperatures T , T , T ;
f h m
2) characteristic currents I , I , I ;
r b p
3) rated voltage U ;
r
c) suitability for sealing in, or use with impregnating fluids or cleaning solvents;
d) information for mounting the thermal-link in the equipment.
e) thermal-links small in size and not intended to be replaced.
For reasons of safety, it should be made clear in the documentation that a thermal-link is a
non-repairable item and that, in case of replacement, an equivalent thermal-link from the
same manufacturer and having the same catalogue reference should be used, mounted in
exactly the same way.
f) the position of the metal screen, if it is located at a distance other than 12,7 mm away
from the live parts in the case of a thermal-link having an exposed element.
9 Constructional requirements
9.1 General
9.1.1 Thermal-links shall have adequate mechanical strength and stability so as to
withstand the stresses likely to be encountered during handling, normal use and fault
conditions of the relevant end-use equipment.
9.1.2 Tab terminals shall be constructed in accordance with IEC 61210 and the maximum
permissible temperature of the used Tab materials shall be in accordance with Table A.1 of
IEC 61210:2010 (Tabs / Integrated).
9.1.3 Current-carrying parts shall be constructed in such a way that contact pressure is not
transmitted through non-metallic material other than ceramic, or any material considered as
having sufficient dimensional stability over the range of temperatures to be expected, unless
there is sufficient resilience in the corresponding metal parts to compensate for any shrinkage
or distortion of the non-metallic material.
Current-carrying parts shall have the necessary mechanical strength, be capable of carrying
the rated current and shall be of a material that is acceptable for the particular application.
For current-carrying parts, temperature limits should be considered according to Table 13 of
IEC 60730-1:2013.
– 16 – IEC 60691:2015 © IEC 2015
9.1.4 Friction shall not be used to secure uninsulated live parts (including terminals) to
supporting surfaces if there is a risk of such parts turning or shifting their position, resulting in
the reduction of creepage distances and clearances to less than those required elsewhere in
this standard. The security of contact assemblies shall be such that alignment of contacts is
maintained.
9.1.5 Leads and terminal parts shall be secured so that stress on them during installation
and normal use does not impair operation of the thermal-link. Thermal-links using seals with
formed leads for use in appliances or components shall not be bent less than 3 mm from the
thermal-link seal.
Leads may be bent less than 3 mm from the seal if:
a) the thermal-link manufacturer's bending fixture and procedure does not transmit stress to
the thermal-link operating mechanism, and if;
b) formed test samples shall be subjected to the bending/twist lead secureness test of 9.2.4
and the rated functioning temperature test of 11.3.
9.1.6 Thermal-links with leads smaller than 0,21 mm shall be provided with application
instructions that instruct the user how to mount the device in equipment, taking into
consideration the device's temperature response. The instructions shall also include guidance
on the effects that movement and vibration in the equipment may have on the thermal-link's
terminals, connections and other mounting components.
9.1.7 A terminal for a soldered connection shall have provision, such as a hole, for holding
the conductor independently of solder.
9.1.8 When applicable, provision shall be made for securely mounting a thermal-link in
position.
9.1.9 Thermal-links intended to be embedded in windings and the like need not have
provision for mounting.
9.1.10 Bolts, screws, or other parts used for mounting an assembly having a thermal-link
shall be independent of those used for securing component parts of the assembly.
9.1.11 Compliance is checked by the lead secureness tests of 9.2. Mounting and
securement instructions shall be provided with thermal-links for the manufacturer of the end-
product in accordance with Annex A.
9.2 Lead secureness tests
9.2.1 General
If force applied to thermal-link wire leads causes breakdown of one or more parts leading
directly or indirectly to stress being applied to the operating mechanism, the tests described in
9.2.2, 9.2.3 and 9.2.4 shall be conducted. There shall be no displacement of parts that would
tend to reclose a thermal-link or reduce creepage distances or clearances as a result of the
tests specified in 9.2.2 and 9.2.3. There shall be no displacement of parts other than the wire
leads as a result of the test specified in 9.2.4.
9.2.2 Tensile test
The thermal-link shall be supported in any convenient manner in order not to damage it
and a tensile force as specified in Table 2 shall be applied to each lead for 1 min.
9.2.3 Thrust test
The thermal-lin
...
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STANDARD
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Thermal-links – Requirements and application guide
Protecteurs thermiques – Exigences et guide d'application
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IEC 60691 ®
Edition 4.1 2019-01
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Thermal-links – Requirements and application guide
Protecteurs thermiques – Exigences et guide d'application
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.120.50 ISBN 978-2-8322-8954-9
IEC 60691 ®
Edition 4.1 2019-01
CONSOLIDATED VERSION
REDLINE VERSION
VERSION REDLINE
colour
inside
Thermal-links – Requirements and application guide
Protecteurs thermiques – Exigences et guide d'application
– 2 – IEC 60691:2015+AMD1:2019 CSV
© IEC 2019
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
4 General requirements . 10
5 General notes on tests . 11
6 Classification . 13
6.1 Electrical conditions . 13
6.2 Thermal conditions. 14
6.3 Resistance to tracking . 14
7 Marking . 14
8 Documentation . 15
9 Constructional requirements . 15
9.1 General . 15
9.2 Lead secureness tests . 16
9.2.1 General . 16
9.2.2 Tensile test . 16
9.2.3 Thrust test . 17
9.2.4 Bending/twist test . 17
9.3 Contacts used for the current path . 18
9.4 Accessible mounting brackets or metal parts . 18
9.5 Insulating materials . 18
9.6 Resistance to tracking . 18
9.7 Creepage distances and clearances . 18
9.8 Temperature and humidity cycle conditioning . 19
9.9 Terminals and terminations . 19
10 Electrical requirements . 19
10.1 Dielectric strength . 19
10.2 Insulation resistance . 20
10.3 Interrupting current . 21
10.3.1 General . 21
10.3.2 Specific conditions . 21
10.4 Transient overload current . 22
10.5 Limited short-circuit test . 23
10.5.1 General . 23
10.5.2 Test method . 23
10.5.3 Fuse size (rating) . 23
10.5.4 Compliance . 24
11 Temperature tests . 24
11.1 General . 24
11.2 Holding temperature, T . 24
h
11.3 Rated functioning temperature, T . 25
f
11.4 Maximum temperature limit, T . 25
m
© IEC 2019
11.5 Ageing . 25
12 Resistance to rusting . 26
13 Manufacturer’s validation programme . 26
Annex A (normative) Application guide. 28
Annex B (normative) Alternative ageing test for thermal-links with T greater than
h
250 °C for use in electric irons . 29
Annex C (normative) Conductive heat ageing test . 30
C.1 Conductive heat ageing test . 30
C.2 Method . 30
C.3 Ageing . 31
C.4 Results . 32
C.5 Dielectric strength test . 32
C.6 Test oven . 32
Annex D (informative) Extended holding temperature evaluation . 34
D.1 Extended holding temperature conditioning test . 34
D.2 Load current interrupt test . 34
Annex E (normative) Seal ageing test . 36
Annex F (normative) Identification requirements . 38
Annex G (normative) Indelibility of markings . 39
Annex H (normative) Requirements for thermal-link packaged assemblies . 40
Bibliography . 43
Figure 1 – Bending/twist test . 17
Figure C.1 – Typical test fixture assembly . 32
Figure C.2 – Typical thermal-link test oven . 33
Figure D.1 – Typical terminal block support test fixture . 35
Figure E.1 – Conditioning time versus oven temperature for proposed temperature
index. 37
Figure G.1 – Apparatus for testing durability of markings . 39
Table 1 – Test schedule . 13
Table 2 – Strength of leads and terminal parts – Minimum required tensile and thrust
test forces . 17
Table 3 – Creepage distances and clearances (absolute minimum values) . 19
Table 4 – Test voltages for dielectric strength . 20
Table 5 – Test current for interrupting test . 21
Table 6 – Limited short-circuit test capacity . 23
Table H.1 – Push and pull force . 41
Table H.2 – Minimum nominal cross-sectional area of conductor . 42
– 4 – IEC 60691:2015+AMD1:2019 CSV
© IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
THERMAL-LINKS –
REQUIREMENTS AND APPLICATION GUIDE
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
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with the International Organization for Standardization (ISO) in accordance with conditions determined by
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
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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.
This consolidated version of the official IEC Standard and its amendment has been
prepared for user convenience.
IEC 60691 edition 4.1 contains the fourth edition (2015-10) [documents 32C/512/FDIS
and 32C/515/RVD] and its corrigendum (2016-08), and its amendment 1 (2019-01)
[documents 32C/548/FDIS and 32C/559/RVD].
In this Redline version, a vertical line in the margin shows where the technical content
is modified by amendment 1. Additions are in green text, deletions are in strikethrough
red text. A separate Final version with all changes accepted is available in this
publication.
© IEC 2019
International Standard IEC 60691 has been prepared by subcommittee 32C: Miniature fuses,
of IEC technical committee 32: Fuses.
This fourth edition constitutes a technical revision.
This fourth edition includes the following significant technical changes with respect to the
previous edition:
a) requirements for thermal-link packaged assemblies;
b) renew the requirements and definitions for T -test;
h
c) change starting temperature for interrupt current test;
d) clarify requirements for marking (packing label);
e) minimum Proof Tracking Index 175 instead 120.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The basis for this standard is the harmonization of the USA national standard, UL 1020, fifth
edition (withdrawn 2003), and IEC 60691:1993, together with its Amendment 1:1995 and
Amendment 2:2000.
The following differing practices of a less permanent nature exist in the country indicated
below:
– Annex C is required to be declared in the USA;
– Annex E is required in the USA, if applicable;
– Annex F is required to be declared in the USA.
In this standard, the following type is used:
– compliance statements: in italic type.
The committee has decided that the contents of the base publication and its amendment 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.
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 document using a
colour printer.
– 6 – IEC 60691:2015+AMD1:2019 CSV
© IEC 2019
INTRODUCTION
Thermal-links, defined as non-resettable devices functioning once only without refunctioning,
are widely applied for the thermal protection of equipment in which, under fault (abnormal)
conditions, one or more parts may reach hazardous temperatures.
As these devices have several aspects in common with miniature fuse-links and are used for
obtaining a comparable degree of protection, this standard has endeavoured to lay down a
number of basic requirements for such devices.
© IEC 2019
THERMAL-LINKS –
REQUIREMENTS AND APPLICATION GUIDE
1 Scope
This International Standard is applicable to thermal-links intended for incorporation in
electrical appliances, electronic equipment and component parts thereof, normally intended
for use indoors, in order to protect them against excessive temperatures under abnormal
conditions.
NOTE 1 The equipment is not designed to generate heat.
NOTE 2 The effectiveness of the protection against excessive temperatures logically depends upon the position
and method of mounting of the thermal-link, as well as upon the current which it is carrying.
This standard may be applicable to thermal-links for use under conditions other than indoors,
provided that the climatic and other circumstances in the immediate surroundings of such
thermal-links are comparable with those in this standard.
This standard may be applicable to thermal-links in their simplest forms (e.g. melting strips or
wires), provided that molten materials expelled during function cannot adversely interfere with
the safe use of the equipment, especially in the case of hand-held or portable equipment,
irrespective of its position.
Annex H of this standard is applicable to thermal-link packaged assemblies where the
thermal-link(s) has already been approved to this standard but packaged in a metallic or non-
metallic housing and provided with terminals/wiring leads.
This standard is applicable to thermal-links with a rated voltage not exceeding 690 V a.c. or
d.c. and a rated current not exceeding 63 A.
The objectives of this standard are:
a) to establish uniform requirements for thermal-links,
b) to define methods of test,
c) to provide useful information for the application of thermal-links in equipment.
This standard is not applicable to thermal-links used under extreme conditions such as
corrosive or explosive atmospheres.
This standard is not applicable to thermal-links to be used in circuits on a.c. with a frequency
lower than 45 Hz or higher than 62 Hz.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60065:2014, Audio, video and similar electronic apparatus – Safety requirements
– 8 – IEC 60691:2015+AMD1:2019 CSV
© IEC 2019
IEC 60112:2003, Method for the determination of the proof and the comparative tracking
indices of solid insulating materials
IEC 60112:2003/AMD1:2009
IEC 60127-2:2014, Miniature fuses – Part 2: Cartridge fuse-links
IEC 60216-5:2008, Electrical insulating materials – Thermal endurance properties – Part 5:
Determination of relative thermal endurance index (RTE) of an insulating material
IEC 60664-1:2007, Insulation coordination for equipment within low-voltage systems – Part 1:
Principles, requirements and tests
IEC 60695-2-12:2010, Fire hazard testing – Part 2-12: Glowing/hot-wire based test methods –
Glow-wire flammability index (GWFI) test method for materials
IEC 60695-2-12:2010/AMD1:2014
IEC 60695-2-13:2010, Fire hazard testing – Part 2-13: Glowing/hot-wire based test methods –
Glow-wire ignition temperature (GWIT) test method for materials
IEC 60695-2-13:2010/AMD1:2014
IEC 60695-10-2:2014, Fire hazard testing – Part 10-2: Abnormal heat – Ball pressure test
method
IEC 60695-11-10:2013, Fire hazard testing – Part 11-10: Test flames – 50 W horizontal and
vertical flame test methods
IEC 60730-1:2013, Automatic electrical controls – Part 1: General requirements
IEC 61210:2010, Connecting devices – Flat quick-connect terminations for electrical copper
conductors – Safety requirements
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
clearance
shortest distance in air between two conductive parts
3.2
creepage distance
shortest distance along the surface of insulating material between two conductive parts
3.3
holding temperature
T
h
maximum temperature of the thermal-link at which it will not change its state of conductivity
during a specified time at the rated current
Note 1 to entry: The minimum permissible value of T is 35 °C.
h
3.4
homogeneous series
series of thermal-links having the same external dimensions and common overall construction,
deviating from each other only in such characteristics (including ratings) that, for a given test,
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the testing of one or a reduced number of particular thermal-links of that series shall be taken
as representative for all the thermal-links of the series
3.5
interrupting current
I
b
value of the current that the thermal-link is capable of interrupting at rated voltage and under
specified circuit conditions
3.6
maximum temperature limit
T
m
temperature of the thermal-link stated by the manufacturer, up to which the mechanical and
electrical properties of the thermal-link, having changed its state of conductivity, will not be
impaired for a given time
3.7
pilot duty
rating assigned to a switching device that controls the coil of another electro-mechanical
device such as a solenoid, relay or contactor
3.8
portable equipment
equipment which is moved while in operation or which can easily be moved from one place to
another while connected to the supply
3.9
rated current
I
r
current used to classify a thermal-link
3.10
rated functioning temperature
T
f
temperature of the thermal-link which causes it to change its state of conductivity with a
detection current up to 10 mA as the only load
3.11
rated voltage
U
r
voltage used to classify a thermal-link
3.12
thermal element
metallic or non-metallic fusible material that is part of a thermal-link and is responsive to
temperature by a change of state such as from solid to liquid at the temperature for which it is
calibrated
3.13
thermal-link
non-resettable device incorporating a thermal element, which will open a circuit once only
when exposed for a sufficient length of time to a temperature in excess of that for which it has
been designed
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3.14
transient overload current
I
p
direct current pulse train which the thermal-link is able to withstand without impairing its
characteristics
3.15
type test
conformity testing on the basis of one or more specimens of a product representative of the
production
3.16
extended holding temperature
T
h-100
maximum temperature at which a thermal-link can be maintained while conducting the rated
load current at the rated voltage for a period of 100 weeks which will not cause the thermal-
link to open circuit in accordance with extended holding temperature evaluation
Note 1 to entry: This is a rating for user consideration during the investigation of the end product.
Note 2 to entry: Annex D specifies the extended holding temperature evaluation.
3.17
conductive heat ageing test
CHAT
test to evaluate a thermal-link for use in an appliance
Note 1 to entry: If it performs satisfactorily, the thermal-link will be assigned a CHAT rating. This rating is for end-
product user consideration during the investigation of the end-use product.
Note 2 to entry: Annex C specifies the conductive heat ageing test.
4 General requirements
4.1 Adequate protection of the equipment against excessive temperatures not only
depends upon the properties of the thermal-link but also to a large extent upon the mounting
of the thermal-link in the equipment. Therefore, in addition to good engineering practice, the
requirements of the application guide in Annex A shall be considered.
4.2 Thermal-links shall have adequate electrical and mechanical strength and shall be
constructed so as to withstand all conditions of handling likely to be encountered during
mounting and normal use, when used within the requirements of this standard.
4.3 When a thermal-link changes its state of conductivity, no arc or flame shall be
maintained, nor material expelled, that might impair the surrounding area or otherwise create
a risk of electric shock or fire. In addition, there shall be no emission of substances (e.g.
gases, liquids, dust, mist, vapour) which could cause a hazard.
For thermal-links using melting strips or wires, care should be taken to prevent molten
material from short-circuiting or bridging creepage distances and clearances in air, so as to
reduce the risk of impairing the insulation system of the equipment.
After it has functioned, the thermal-link shall not be damaged when subjected to temperatures
not exceeding T , in such a way that the safety of the equipment with regard to risk of electric
m
shock hazard and electrical breakdown is impaired. The thermal-link shall not reclose after it has
operated.
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4.4 For requirements for thermal-link packaged assemblies, see Annex H.
5 General notes on tests
5.1 The test conditions are as follows.
5.1.1 Unless otherwise specified, only tests that are not required to be performed inside an
environmental chamber and/or test oven shall be carried out under the following atmospheric
conditions:
– temperature: 15 °C to 35 °C,
– relative humidity: 25 % to 75 %,
4 5
– air pressure: 8,6 × 10 Pa to 1,06 × 10 Pa.
The required atmospheric conditions during testing can be controlled when carrying out the
tests and during the duration of the tests. The required atmospheric conditions do not have to
be maintained in a test laboratory when tests are not performed.
5.1.2 Where the conditions given in 5.1.1 have a significant influence, they shall be kept
substantially constant during the tests.
5.1.3 If the temperature limits given in 5.1.1 are too wide for certain tests, these shall be
repeated, in case of doubt, at a temperature of (23 ± 1) °C.
5.2 In every test report, the ambient temperature shall be stated. If the standard conditions
for relative humidity or pressure are not fulfilled during the tests, a note to this effect shall be
added to the report.
5.3 If the result of a test is influenced, to an appreciable extent, by the position and method
of mounting of the specimen, the most unfavourable condition shall be chosen for the relevant
tests and recorded.
5.4 If a thermal-link has been specifically designed for use in a special type of equipment
and cannot be tested separately, the tests of this standard shall be performed in that
equipment or in the relevant part of it, or similar.
5.5 When testing a homogeneous series of thermal-links, all the tests shall be applied to
thermal-links with the lowest and highest T . Thermal-links with intermediate rated functioning
f
temperatures need only be subjected to tests according to 10.3, 11.3, 11.4 and 11.5.
5.6 The number of specimens is as follows.
5.6.1 The total number of specimens required is 48. Out of a total of 48 specimens, 15 are
kept as spares in case some of the tests have to be repeated. Out of a total of 48 specimens,
33 are divided into 11 groups assigned by alphabetical letters from A to K. Each group
consists of three specimens. Tests shall be performed in the order indicated in Table 1 but, if
so required, tests may be repeated, for example the test on marking (see Clause 7).
Additional samples may be needed according to Note 2 of Table 1.
For optional tests, additional samples should be required as per the applicable annexes.
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5.6.2 If, in any of the tests carried out in accordance with any relevant test clause, a failure
is reported, the cause of the failure will be identified and corrective action taken. Based on the
failure analysis report and the corrective action, as a minimum, the test sequence shall be
repeated on twice the number of revised specimens, and no further failures are allowed.
If no corrective actions are necessary, the test should be repeated with double the same size
and no further deviation is allowed.
5.6.3 For requirements for thermal-link packaged assemblies, see Annex H
5.7 The conductive heat ageing test of Annex C is applicable when declared by the
manufacturer.
The conductive heat ageing test may be omitted if the thermal-link is constructed without
contacts.
NOTE In the USA the conductive heat ageing test is required to be declared.
© IEC 2019
Table 1 – Test schedule
Clause or Test Specimen groups
Sub-clause
A B C D E F G H I J K
a
7 Marking (Rub test) X X
a
7 Marking (visual inspection only) X X
9 Constructional requirements
a
9.2.2 Tensile forces X
a
9.2.3 Thrust force X
a
9.2.4 Bending/twist force X
a
9.6 Resistance to tracking X
a
9.7 Creepage distances and clearances X X
9.8 Temperature and humidity cycle X X X X X
conditioning
10 Electrical requirements
10.1 Dielectric strength (if applicable) X X X X X
10.2 Insulation resistance (if applicable) X X X X X
10.3 Interrupting current X X
10.4 Transient overload current X X X
11 Temperature tests
11.2 Check on T X
h
11.3 Check on T X X
f
11.4 Check on T followed by dielectric X X
m
test and insulation resistance
11.5 Ageing X X X X X
step 1 (optional) 21 days
step 2 (mandatory) 21 days
step 3 (mandatory) 14 days
step 4 (mandatory) 7 days
step 5 (mandatory) 7 days
step 6 (mandatory) 24 hours
10.1 Dielectric strength X X X X X X X X
10.2 Insulation resistance X X X X X X X X
12 Resistance to rusting
a
12 Resistance to rusting (ferrous parts) X X X
If the conditions of voltage, power and current in 10.3.2.3, 10.3.2.4 and 10.3.2.5 are not covered by one test,
a minimum of three samples should be tested for each condition.
a
For homogeneous series, these tests may be omitted for intermediate ratings.
6 Classification
6.1 Electrical conditions
With regard to electrical conditions, the following terms are used:
a) voltage
1) AC
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2) DC
b) current
1) resistive
2) inductive
c) motor
d) pilot duty
e) electric discharge lamp
f) special
6.2 Thermal conditions
With regard to thermal conditions, the following symbols and abbreviations are used:
a) T
f
b) T
h
c) T
m
d) CHAT
e) T
h-100
6.3 Resistance to tracking
With regard to resistance to tracking, the following ranges are used:
a) proof tracking index from 175 to 249;
b) proof tracking index greater than or equal to 250.
NOTE These ranges are based on test methods for surface tracking laid down in IEC 60112.
7 Marking
7.1 Each thermal-link shall be marked with the following:
a) type or catalogue reference;
b) manufacturer’s name or trade mark;
c) rated functioning temperature T with or without the symbol T followed by the number of
f f
degrees Celsius (marked with °C or C);
d) date code which identifies the date of manufacture and which does not repeat for at least
10 years, and a factory location or code, stamped on the thermal-link or the smallest
packaging.
If there is only one factory, the factory location may be omitted.
Catalogue or reference numbers should define those parameters such as temperature, current
and voltage, which together classify a thermal-link.
7.2 The rated functioning temperature T may be omitted if a different type or catalogue
f
reference is employed for each different functioning temperature.
7.3 Marking shall be indelible and legible.
Compliance with the requirements for Indelibility of markings is checked by the test in
Annex G using the apparatus shown in Figure G.1. Legibility is checked by inspection. After
the ageing tests of 11.4, compliance is checked by inspection.
© IEC 2019
7.4 The marking in accordance with a), b), c) and d) in 7.1 shall be printed additionally on
the packing, together with a reference to this standard.
7.5 If the thermal-link is small in size, and not intended to be replaced, the markings in
accordance with b) to d) in 7.1 shall be printed on the packaging, together with a reference to
this standard.
Compliance is checked by inspection.
8 Documentation
The manufacturer shall provide in the technical documentation, catalogues or instructional
leaflets the following information, in addition to that required in Clause 7:
a) classification in accordance with Clause 6;
b) for each of the classifications;
1) characteristic temperatures T , T , T ;
f h m
2) characteristic currents I , I , I ;
r b p
3) rated voltage U ;
r
c) suitability for sealing in, or use with impregnating fluids or cleaning solvents;
d) information for mounting the thermal-link in the equipment.
e) thermal-links small in size and not intended to be replaced.
For reasons of safety, it should be made clear in the documentation that a thermal-link is a
non-repairable item and that, in case of replacement, an equivalent thermal-link from the
same manufacturer and having the same catalogue reference should be used, mounted in
exactly the same way.
f) the position of the metal screen, if it is located at a distance other than 12,7 mm away
from the live parts in the case of a thermal-link having an exposed element.
9 Constructional requirements
9.1 General
9.1.1 Thermal-links shall have adequate mechanical strength and stability so as to
withstand the stresses likely to be encountered during handling, normal use and fault
conditions of the relevant end-use equipment.
9.1.2 Tab terminals shall be constructed in accordance with IEC 61210 and the maximum
permissible temperature of the used Tab materials shall be in accordance with Table A.1 of
IEC 61210:2010 (Tabs / Integrated).
9.1.3 Current-carrying parts shall be constructed in such a way that contact pressure is not
transmitted through non-metallic material other than ceramic, or any material considered as
having sufficient dimensional stability over the range of temperatures to be expected, unless
there is sufficient resilience in the corresponding metal parts to compensate for any shrinkage
or distortion of the non-metallic material.
Current-carrying parts shall have the necessary mechanical strength, be capable of carrying
the rated current and shall be of a material that is acceptable for the particular application.
For current-carrying parts, temperature limits should shall be considered according to
Table 13 of IEC 60730-1:2013.
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9.1.4 Friction shall not be used to secure uninsulated live parts (including terminals) to
supporting surfaces if there is a risk of such parts turning or shifting their position, resulting in
the reduction of creepage distances and clearances to less than those required elsewhere in
this standard. The security of contact assemblies shall be such that alignment of contacts is
maintained.
9.1.5 Leads and terminal parts shall be secured so that stress on them during installation
and normal use does not impair operation of the thermal-link. Thermal-links using seals with
formed leads for use in appliances or components shall not be bent less than 3 mm from the
thermal-link seal.
Leads may be bent less than 3 mm from the seal if:
a) the thermal-link manufacturer's bending fixture and procedure does not transmit stress to
the thermal-link operating mechanism, and if;
b) formed test samples shall be subjected to the bending/twist lead secureness test of 9.2.4
and the rated functioning temperature test of 11.3.
9.1.6 Thermal-links with leads smaller than 0,21 mm shall be provided with application
instructions that instruct the user how to mount the device in equipment, taking into
consideration the device's temperature response. The instructions shall also include guidance
on the effects that movement and vibration in the equipment may have on the thermal-link's
terminals, connections and other mounting components.
9.1.7 A terminal for a soldered connection shall have provision, such as a hole, for holding
the conductor independently of solder.
9.1.8 When applicable, provision shall be made for securely mounting a thermal-link in
position.
9.1.9 Thermal-links intended to be embedded in windings and the like need not have
provision for mounting.
9.1.10 Bolts, screws, or other parts used for mounting an assembly having a thermal-link
shall be independent of those used for securing component parts o
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