IEC 60691:2023

Thermal-links - Requirements and application guide

IEC 60691:2023 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 document 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 document 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.

Protecteurs thermiques - Exigences et guide d'application

L'IEC 60691:2023 s'applique aux protecteurs thermiques destinés à être incorporés dans les appareils électriques, le matériel électronique et ses composants, normalement utilisés en intérieur, afin de les protéger contre les températures excessives lors de conditions anormales.
NOTE 1 Le matériel n'est pas prévu pour produire de la chaleur.
NOTE 2 L'efficacité de la protection contre les températures excessives dépend logiquement de la position et du mode de montage du protecteur thermique ainsi que du courant qui le traverse.
Le présent document peut s'appliquer aux protecteurs thermiques utilisés dans d'autres conditions que celles qui sont réunies en intérieur, tant que les conditions climatiques ou autres de l'environnement immédiat de tels protecteurs thermiques sont comparables à celles de la présente norme.

General Information

• Status: Published
• Publication Date: 27-Oct-2024
• ICS: 29.120.50 - Fuses and other overcurrent protection devices
• Technical Committee: SC 32C - Miniature fuses
• Drafting Committee: MT 9 - TC 32/SC 32C/MT 9
• Current Stage: PPUB - Publication issued
• Start Date: 17-Mar-2023
• Completion Date: 06-Mar-2023

Relations

• Amended By: IEC 60691:2023/AMD1:2024 - Amendment 1 - Thermal-links - Requirements and application guide
• Effective Date: 05-Sep-2023
• Revises: IEC 60691:2015 - Thermal-links - Requirements and application guide
• Effective Date: 05-Sep-2023
• Revises: IEC 60691:2015/COR1:2016 - Corrigendum 1 - Thermal-links - Requirements and application guide
• Effective Date: 05-Sep-2023
• Revises: IEC 60691:2015/AMD1:2019 - Amendment 1 - Thermal-links - Requirements and application guide
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 60691 ®
Edition 5.0 2023-03
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Thermal-links – Requirements and application guide
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
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About the IEC
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International Standards for all electrical, electronic and related technologies.

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IEC 60691 ®
Edition 5.0 2023-03
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Thermal-links – Requirements and application guide
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.120.50 ISBN 978-2-8322-6617-5

– 2 – IEC 60691:2023 RLV © IEC 2023
CONTENTS
FOREWORD .5
INTRODUCTION .2
1 Scope .8
2 Normative references .8
3 Terms and definitions .9
4 General requirements . 11
5 General notes on tests . 12
6 Classification . 14
6.1 Electrical conditions . 14
6.2 Thermal conditions . 14
6.3 Resistance to tracking . 14
7 Marking . 14
8 Documentation . 15
9 Constructional requirements . 16
9.1 General . 16
9.2 Lead secureness tests . 17
9.2.1 General . 17
9.2.2 Tensile test . 17
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 . 19
9.5 Insulating materials . 19
9.6 Resistance to tracking . 19
9.7 Creepage distances and clearances . 19
9.8 Temperature and humidity cycle conditioning . 20
9.9 Terminals and terminations . 20
10 Electrical requirements . 21
10.1 Dielectric strength. 21
10.2 Insulation resistance . 21
10.3 Interrupting current . 22
10.3.1 General . 22
10.3.2 Specific conditions. 22
10.4 Transient overload current . 24
10.5 Limited short-circuit test . 24
10.5.1 General . 24
10.5.2 Test method . 24
10.5.3 Fuse size (rating) . 25
10.5.4 Compliance . 25
11 Temperature tests . 25
11.1 General . 25
11.2 Holding temperature, T . 26
h
11.3 Rated functioning temperature, T . 26
f
11.4 Maximum temperature limit, T . 27
m
11.5 Ageing . 27

12 Resistance to rusting. 28
13 Manufacturer’s validation programme . 28

Annex A (normative) Application guide . 29
Annex B (normative) Alternative ageing test for thermal-links with T greater than
h
250 °C for use in electric irons . 30
Annex C (normative) Conductive heat ageing test . 31
C.1 Conductive heat ageing test . 31
C.2 Method . 31
C.2.1 General . 31
C.2.2 Typical test fixture assembly . 31
C.2.3 Temperature setting . 31
C.2.4 Temperature behaviour . 31
C.2.5 Temperature monitoring . 32
C.3 Ageing . 32
C.3.1 General . 32
C.3.2 Cooling operation . 32
C.3.3 Premature operation . 32
C.4 Results . 33
C.5 Dielectric strength test . 33
C.6 Test oven . 35
Annex D (informative) Extended holding temperature evaluation . 37
D.1 Extended holding temperature conditioning test . 37
D.2 Load current interrupt test . 37
Annex E (normative) Seal ageing test . 39
Annex F (normative) Identification requirements . 41
Annex G (normative) Indelibility of markings . 42
Annex H (normative) Requirements for thermal-link packaged assemblies . 43
Annex I (informative) Holding temperature . 48
Bibliography . 49

Figure 1 – Bending/twist test . 18
Figure C.1 – Typical test fixture assembly . 34
Figure C.2 – Typical thermal-link test oven. 36
Figure D.1 – Typical terminal block support test fixture . 38
Figure E.1 – Conditioning time versus oven temperature for proposed temperature index . 40
Figure G.1 – Apparatus for testing durability of markings . 42

Table 1 – Test schedule . 13
Table 2 – Strength of leads and terminal parts – Minimum required tensile and thrust
test forces . 18
Table 3 – Creepage distances and clearances (absolute minimum values) . 20
Table 4 – Test voltages for dielectric strength . 21
Table 5 – Test current for interrupting test . 22
Table 6 – Limited short-circuit test capacity. 25

– 4 – IEC 60691:2023 RLV © IEC 2023
Table H.1 – Push and pull force . 45
Table H.2 – Minimum nominal cross-sectional area of conductor . 45
Table H.3 – Allowed values for the materials used in the thermal-link package . 47

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 technic
...

IEC 60691 ®
Edition 5.1 2024-10
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
colour
inside
Thermal-links – Requirements and application guide

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
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copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

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International Standards for all electrical, electronic and related technologies.

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IEC 60691 ®
Edition 5.1 2024-10
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
colour
inside
Thermal-links – Requirements and application guide
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.120.50 ISBN 978-2-8322-9972-2
REDLINE VERSION – 2 – IEC 60691:2023+AMD1:2024 CSV
© IEC 2024
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
4 General requirements . 11
5 General notes on tests . 12
6 Classification . 14
6.1 Electrical conditions . 14
6.2 Thermal conditions. 14
6.3 Resistance to tracking . 14
7 Marking . 14
8 Documentation . 15
9 Constructional requirements . 16
9.1 General . 16
9.2 Lead secureness tests . 17
9.2.1 General . 17
9.2.2 Tensile test . 17
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 . 19
9.5 Insulating materials . 19
9.6 Resistance to tracking . 19
9.7 Creepage distances and clearances . 19
9.8 Temperature and humidity cycle conditioning . 20
9.9 Terminals and terminations . 20
10 Electrical requirements . 21
10.1 Dielectric strength . 21
10.2 Insulation resistance . 21
10.3 Interrupting current . 22
10.3.1 General . 22
10.3.2 Specific conditions . 22
10.4 Transient overload current . 23
10.5 Limited short-circuit test . 24
10.5.1 General . 24
10.5.2 Test method . 24
10.5.3 Fuse size (rating) . 25
10.5.4 Compliance . 25
11 Temperature tests . 25
11.1 General . 25
11.2 Holding temperature, T . 26
h
11.3 Rated functioning temperature, T . 26
f
11.4 Maximum temperature limit, T . 26
m
11.5 Ageing . 27

© IEC 2024
12 Resistance to rusting . 27
13 Manufacturer’s validation programme . 28
Annex A (normative) Application guide. 29
Annex B (normative) Alternative ageing test for thermal-links with T greater than
h
250 °C for use in electric irons . 30
Annex C (normative) Conductive heat ageing test . 31
C.1 Conductive heat ageing test . 31
C.2 Method . 31
C.2.1 General . 31
C.2.2 Typical test fixture assembly . 31
C.2.3 Temperature setting. 31
C.2.4 Temperature behaviour . 31
C.2.5 Temperature monitoring . 32
C.3 Ageing . 32
C.3.1 General . 32
C.3.2 Cooling operation . 32
C.3.3 Premature operation . 32
C.4 Results . 33
C.5 Dielectric strength test . 33
C.6 Test oven . 33
Annex D (informative) Extended holding temperature evaluation . 35
D.1 Extended holding temperature conditioning test . 35
D.2 Load current interrupt test . 35
Annex E (normative) Seal ageing test . 37
Annex F (normative) Identification requirements . 39
Annex G (normative) Indelibility of markings . 40
Annex H (normative) Requirements for thermal-link packaged assemblies . 41
Annex I (informative) Holding temperature . 45
Bibliography . 46

Figure 1 – Bending/twist test . 18
Figure C.1 – Typical test fixture assembly . 33
Figure C.2 – Typical thermal-link test oven . 34
Figure D.1 – Typical terminal block support test fixture . 36
Figure E.1 – Conditioning time versus oven temperature for proposed temperature index . 38
Figure G.1 – Apparatus for testing durability of markings . 40

Table 1 – Test schedule . 13
Table 2 – Strength of leads and terminal parts – Minimum required tensile and thrust
test forces . 18
Table 3 – Creepage distances and clearances (absolute minimum values) . 20
Table 4 – Test voltages for dielectric strength . 21
Table 5 – Test current for interrupting test . 22
Table 6 – Limited short-circuit test capacity . 24
Table H.1 – Push and pull force . 43

REDLINE VERSION – 4 – IEC 60691:2023+AMD1:2024 CSV
© IEC 2024
Table H.2 – Minimum nominal cross-sectional area of conductor . 43
Table H.3 – Allowed values for the materials used in the thermal-link package . 44

© IEC 2024
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
...

IEC 60691 ®
Edition 5.0 2023-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Thermal-links – Requirements and application guide
Protecteurs thermiques – Exigences et guide d'application
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
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International Standards for all electrical, electronic and related technologies.
About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.
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and French, with equivalent terms in 19 additional languages.
a month by email.
Also known as the International Electrotechnical Vocabulary
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IEC 60691 ®
Edition 5.0 2023-03
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 978-2-8322-6469-0
– 2 – IEC 60691:2023 © IEC 2023
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
4 General requirements . 11
5 General notes on tests . 12
6 Classification . 14
6.1 Electrical conditions . 14
6.2 Thermal conditions. 14
6.3 Resistance to tracking . 14
7 Marking . 14
8 Documentation . 15
9 Constructional requirements . 16
9.1 General . 16
9.2 Lead secureness tests . 17
9.2.1 General . 17
9.2.2 Tensile test . 17
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 . 19
9.5 Insulating materials . 19
9.6 Resistance to tracking . 19
9.7 Creepage distances and clearances . 19
9.8 Temperature and humidity cycle conditioning . 20
9.9 Terminals and terminations . 20
10 Electrical requirements . 21
10.1 Dielectric strength . 21
10.2 Insulation resistance . 21
10.3 Interrupting current . 22
10.3.1 General . 22
10.3.2 Specific conditions . 22
10.4 Transient overload current . 23
10.5 Limited short-circuit test . 24
10.5.1 General . 24
10.5.2 Test method . 24
10.5.3 Fuse size (rating) . 25
10.5.4 Compliance . 25
11 Temperature tests . 25
11.1 General . 25
11.2 Holding temperature, T . 26
h
11.3 Rated functioning temperature, T . 26
f
11.4 Maximum temperature limit, T . 26
m
11.5 Ageing . 27

12 Resistance to rusting . 27
13 Manufacturer’s validation programme . 28
Annex A (normative) Application guide. 29
Annex B (normative) Alternative ageing test for thermal-links with T greater than
h
250 °C for use in electric irons . 30
Annex C (normative) Conductive heat ageing test . 31
C.1 Conductive heat ageing test . 31
C.2 Method . 31
C.2.1 General . 31
C.2.2 Typical test fixture assembly . 31
C.2.3 Temperature setting. 31
C.2.4 Temperature behaviour . 31
C.2.5 Temperature monitoring . 32
C.3 Ageing . 32
C.3.1 General . 32
C.3.2 Cooling operation . 32
C.3.3 Premature operation . 32
C.4 Results . 33
C.5 Dielectric strength test . 33
C.6 Test oven . 33
Annex D (informative) Extended holding temperature evaluation . 35
D.1 Extended holding temperature conditioning test . 35
D.2 Load current interrupt test . 35
Annex E (normative) Seal ageing test . 37
Annex F (normative) Identification requirements . 39
Annex G (normative) Indelibility of markings . 40
Annex H (normative) Requirements for thermal-link packaged assemblies . 41
Annex I (informative) Holding temperature . 45
Bibliography . 46

Figure 1 – Bending/twist test .
...