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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
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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
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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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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
...