IEC 60034-11:2020

Rotating electrical machines - Part 11: Thermal protection

IEC 60034-11:2020 is available as IEC 60034-11:2020 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.IEC 60034-11:2020 specifies requirements relating to the use of thermal protectors and thermal detectors incorporated into the stator windings or placed in other suitable positions in induction machines in order to protect them against serious damage due to thermal overloads. It applies to single-speed three-phase 50 Hz or 60 Hz cage induction motors in accordance with IEC 60034-1 and IEC 60034-12 that:
- have a rated voltage up to 1 000 V;
- are intended for direct-on-line or star-delta starting.
The main changes with respect to the previous edition are:
- the additional specification of winding temperature limits for temperature class 200 (N),
- the increased limits of maximum winding temperatures for overloads with rapid variation,
- the clarification that the motor winding may be permanently damaged after it has been exposed to temperatures
- a clarification of the definition of indirect thermal protection,
- a clarification on the test methods for larger motors.

Machines électriques tournantes - Partie 11: Protection thermique

IEC 60034-11:2020 est disponible sous forme de IEC 60034-11:2020 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.
L'IEC 60034-11:2020 spécifie les exigences relatives à l’utilisation de protecteurs et détecteurs thermiques incorporés dans les enroulements statoriques, ou autres emplacements adaptés, dans les machines à induction afin de les protéger contre de graves dommages dus aux surcharges thermiques. Elle s’applique aux moteurs triphasés à induction à cage à une seule vitesse fonctionnant à 50 Hz ou 60 Hz conformément à l’IEC 60034-1 et à l’IEC 60034-12 qui:
- ont une tension assignée jusqu’à 1 000 V;
- sont prévus pour un démarrage direct ou étoile-triangle.
Par rapport à l’édition précédente, les modifications majeures sont les suivantes
- spécification supplémentaire relative aux limites de température de l’enroulement pour la classe thermique 200 (N),
- augmentation des limites des températures maximales d’enroulement pour surcharges à évolution rapide,
- précision concernant l’enroulement du moteur qui peut être endommagé de façon permanente après une exposition aux températures,
- précision de la définition de protection thermique indirecte,
- précision, au 8.3, concernant les méthodes d’essai pour les moteurs plus importants.

General Information

• Status: Published
• Publication Date: 04-Oct-2020
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 29.160.01 - Rotating machinery in general
• Technical Committee: TC 2 - Rotating machinery
• Drafting Committee: WG 12 - TC 2/WG 12
• Current Stage: PPUB - Publication issued
• Start Date: 09-Oct-2020
• Completion Date: 05-Oct-2020

Relations

• Revises: IEC 60034-11:2004 - Rotating electrical machines - Part 11: Thermal protection
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 60034-11 ®
Edition 3.0 2020-10
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Rotating electrical machines –
Part 11: Thermal protection
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
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About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

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IEC 60034-11 ®
Edition 3.0 2020-10
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Rotating electrical machines –

Part 11: Thermal protection
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.160.01 ISBN 978-2-8322-8936-5

– 2 – IEC 60034-11:2020 RLV © IEC 2020
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Thermal protection limits . 7
5 Protection against thermal overloads with slow variation . 8
6 Protection against thermal overloads with rapid variation . 10
7 Restart after tripping . 12
8 Type tests . 13
8.1 General . 13
8.2 Verification of temperature due to the thermal overloads with slow variation . 13
8.3 Verification of temperature due to thermal overloads with rapid variation . 13
9 Routine tests . 13

Figure 1 – Example of thermal overload with slow variation and direct thermal
protection . 9
Figure 2 – Example of thermal overload with slow variation in the case of too intensive
intermittent periodic duty with starting (duty S4) and direct thermal protection . 9
Figure 3 – Example of thermal overload with rapid variation where the thermally critical
part has direct thermal protection . 11
Figure 4 – Example of thermal overload with rapid variation where the thermally critical
part has indirect thermal protection . 12

Table 1 – Maximum winding temperatures for overloads with slow variation . 8
Table 2 – Maximum winding temperatures for overloads with rapid variation . 10

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ROTATING ELECTRICAL MACHINES –

Part 11: Thermal protection
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.
This redline version of the official IEC Standard allows the user to identify the changes
made to the previous edition. A vertical bar appears in the margin wherever a change has
been made. Additions are in green text, deletions are in strikethrough red text.

– 4 – IEC 60034-11:2020 RLV © IEC 2020
International Standard IEC 60034-11 has been prepared by IEC technical committee 2: Rotating
machinery.
This third edition cancels and replaces the second edition, published in 2004. This edition
constitutes a technical revision.
The main changes with respect to the previous edition are
– the additional specification of winding temperature limits for temperature class 200 (N),
– the increased limits of maximum winding temperatures for overloads with rapid variation,
– the clarification that the motor winding may be permanently damaged after it has been
exposed to temperatures according to Table 2,
– a clarification of scope,
– a clarification of the definition of indirect thermal protection,
– a clarifying note in Clause 6,
– the conversion of note 3 in Clause 6 into normal text including changes in wording,
– the incorporation of note 3 in Clause 5 into Clause 2,
– a clarification on the test methods for larger motors in 8.3.
The text of this International Standard is based on the following documents:
FDIS Report on voting
2/2011/FDIS 2/2019/RVD
Full information on the voting for the approval of this International Standard can be found in the
report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 60034 series, published under the general title Rotating electrical
machines, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document 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.

INTRODUCTION
Thermal protection systems are based on the principle of protecting or monitoring the vulnerable
machine parts against excessive temperatures. This requires the selection of the appropriate
thermal protection device to suit both the type of protection required and the machine
component to be protected. This document does not detail the protection methods available or
specify the protection method to be used for particular applications, but instead it specifies the
temperature of the protected parts that should not be exceeded if a fault or machine abuse
occurs.
The requirements are not intended to guarantee a "normal" machine life for all conditions of
use, but rather to avoid both failure and accelerated premature thermal ageing of the winding
insulation. The requirements result from a compromise, since the level of protection should
neither be set so low that it causes nuisance tripping nor so high that it allows continuous
working at temperatures that will seriously affect the life of the winding insulation.
Normal insulation life can only be ensured by correct motor application and maintenance.
Frequent operation at above the normal temperature limits, see IEC 60034-1, which cannot be
prevented by built-in thermal protection without risking nuisance tripping may lead to a
noticeable reduction in machine life. It should be noted that The life of the winding insulation
is approximately halved for every 8 K to 10 K increase in the continuous operating temperature.
The requirement to incorporate thermal protection in a machine is a matter for agreement. The
application of this document should be is a matter of agreement between the user and the
machine manufacturer.
– 6 – IEC 60034-11:2020 RLV © IEC 2020
ROTATING ELECTRICAL MACHINES –

Part 11: Thermal protection
1 Scope
This part of IEC 60034 specifies requirements relating to the use of thermal protectors and
thermal detectors incorporated into the stator windings or placed in other suitable positions in
induction machines in order to protect them against serious damage due to thermal overloads.
It applies to machines manufactured in accordance with IEC 60034-12 with the voltage limits
specified in IEC 60034-12. The protection of bearings and other mechanical parts is not
included. It applies to single-speed three-phase 50 Hz or 60 Hz cage induction motors in
accordance with IEC 60034-1 and IEC 60034-12 that:
• have a rated voltage up to 1 000 V;
• are intended for direct-on-line or star-delta starting.
Not included are:
• direct protection of the rotor winding; the methods of protection only protect rotor windings
indirectly; for large motors (particularly 2 pole motors) and for motors starting large inertia
loads, special att
...

IEC 60034-11 ®
Edition 3.0 2020-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Rotating electrical machines –
Part 11: Thermal protection
Machines électriques tournantes –
Partie 11: Protection thermique

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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About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
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.

IEC publications search - webstore.iec.ch/advsearchform Electropedia - www.electropedia.org
The advanced search enables to find IEC publications by a The world's leading online dictionary on electrotechnology,
variety of criteria (reference number, text, technical containing more than 22 000 terminological entries in English
committee,…). It also gives information on projects, replaced and French, with equivalent terms in 16 additional languages.
and withdrawn publications. Also known as the International Electrotechnical Vocabulary

(IEV) online.
IEC Just Published - webstore.iec.ch/justpublished
Stay up to date on all new IEC publications. Just Published IEC Glossary - std.iec.ch/glossary
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once a month by email. French extracted from the Terms and Definitions clause of
IEC publications issued since 2002. Some entries have been
IEC Customer Service Centre - webstore.iec.ch/csc collected from earlier publications of IEC TC 37, 77, 86 and
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IEC 60034-11 ®
Edition 3.0 2020-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Rotating electrical machines –

Part 11: Thermal protection
Machines électriques tournantes –

Partie 11: Protection thermique

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.160.01 ISBN 978-2-8322-8844-3

– 2 – IEC 60034-11:2020 © IEC 2020
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Thermal protection limits . 7
5 Protection against thermal overloads with slow variation . 8
6 Protection against thermal overloads with rapid variation . 9
7 Restart after tripping . 11
8 Type tests . 12
8.1 General . 12
8.2 Verification of temperature due to the thermal overloads with slow variation . 12
8.3 Verification of temperature due to thermal overloads with rapid variation . 12
9 Routine tests . 12

Figure 1 – Example of thermal overload with slow variation and direct thermal
protection . 8
Figure 2 – Example of thermal overload with slow variation in the case of too intensive
intermittent periodic duty with starting (duty S4) and direct thermal protection . 9
Figure 3 – Example of thermal overload with rapid variation where the thermally critical
part has direct thermal protection . 10
Figure 4 – Example of thermal overload with rapid variation where the thermally critical
part has indirect thermal protection . 11

Table 1 – Maximum winding temperatures for overloads with slow variation . 8
Table 2 – Maximum winding temperatures for overloads with rapid variation . 9

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ROTATING ELECTRICAL MACHINES –

Part 11: Thermal protection
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 60034-11 has been prepared by IEC technical committee 2: Rotating
machinery.
This third edition cancels and replaces the second edition, published in 2004. This edition
constitutes a technical revision.
The main changes with respect to the previous edition are
– the additional specification of winding temperature limits for temperature class 200 (N),
– the increased limits of maximum winding temperatures for overloads with rapid variation,
– the clarification that the motor winding may be permanently damaged after it has been
exposed to temperatures according to Table 2,
– a clarification of scope,
– a clarification of the definition of indirect thermal protection,
– a clarifying note in Clause 6,
– the conversion of note 3 in Clause 6 into normal text including changes in wording,

– 4 – IEC 60034-11:2020 © IEC 2020
– the incorporation of note 3 in Clause 5 into Clause 2,
– a clarification on the test methods for larger motors in 8.3.
The text of this International Standard is based on the following documents:
FDIS Report on voting
2/2011/FDIS 2/2019/RVD
Full information on the voting for the approval of this International Standard can be found in the
report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 60034 series, published under the general title Rotating electrical
machines, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
INTRODUCTION
Thermal protection systems are based on the principle of protecting or monitoring the vulnerable
machine parts against excessive temperatures. This requires the selection of the appropriate
thermal protection device to suit both the type of protection required and the machine
component to be protected. This document does not detail the protection methods available or
specify the protection method to be used for particular applications, but instead it specifies the
temperature of the protected parts that should not be exceeded if a fault or machine abuse
occurs.
The requirements are not intended to guarantee a "normal" machine life for all conditions of
use, but rather t
...