IEC 60034-12:2024

IEC 60034-12 ®
Edition 4.0 2024-05
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Rotating electrical machines –
Part 12: Starting performance of single-speed three-phase cage induction
motors
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IEC 60034-12 ®
Edition 4.0 2024-05
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Rotating electrical machines –
Part 12: Starting performance of single-speed three-phase cage induction
motors
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.160.01 ISBN 978-2-8322-8990-7

– 2 – IEC 60034-12:2024 RLV © IEC 2024
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Symbols . 8
5 Designation . 9
5.1 General . 9
5.2 Design N . 9
5.3 Design NE . 9
5.4 Designs NY and NEY . 9
5.5 Design H . 9
5.6 Design HE . 9
5.7 Designs HY and HEY . 10
6 Design N requirements . 10
6.1 Torque characteristics . 10
6.2 Locked rotor current and apparent power . 10
6.3 Starting requirements . 10
7 Design NE starting requirements . 11
8 Designs NY and NEY starting requirements . 11
9 Design H requirements . 11
9.1 Starting torque . 11
9.2 Locked rotor current and apparent power . 11
9.3 Starting requirements . 11
10 Design HE starting requirements . 12
11 Designs HY and HEY starting requirements . 12
12 Determination of current and torque from measurement. 12
12.1 Locked-rotor current and locked-rotor torque . 12
12.2 Breakdown torque . 12
12.3 Torque-speed curve and current-speed curve . 13
12.3.1 General . 13
12.3.2 Torque-speed and current-speed curves from direct measurement
(method a) . 13
12.3.3 Torque-speed and current-speed curves from acceleration (method b) . 13
12.3.4 Torque-speed and current-speed curves from measured input power
(method c) . 14
12.4 Correction of data for tests performed at reduced voltage and/or other than
rated frequency . 14
Annex A (informative) Current and torque characteristics with locked rotor . 20
Annex B (informative) Correction method for test done on reduced voltage . 24
Bibliography . 25

Figure A.1 – Locked-rotor current in multiples of rated current versus time . 20
Figure A.2 – Locked-rotor torque in multiples of rated torque versus time . 21
Figure A.3 – Locked-rotor torque in cNm versus rotor position in °; left: preferable
number of rotor slots, right: less preferable number of rotor slots . 21

Figure A.4 – Locked-rotor torque in cNm versus rotor position in ° . 22
Figure A.5 – Time -courses (in s) of rotational speed (upper left), torque (lower left),
phase voltage (upper right) and phase current (lower right) during a star-delta start-up . 23

Table 1 – Minimum values of torques for design N . 15
Table 2 – Maximum values of locked rotor apparent power for designs N and H . 16
Table 3 – Maximum values of locked rotor apparent power for designs NE and HE . 16
Table 4 – External moment of inertia (J) . 17
Table 5 – Minimum values of torques for design H . 18
Table 6 – Minimum values of torques for design N motors with type of protection 'Ex
eb – increased safety' . 18
Table 7 – External moment of inertia (J) for motors with type of protection 'Ex eb –
increased safety' . 19

– 4 – IEC 60034-12:2024 RLV © IEC 2024
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ROTATING ELECTRICAL MACHINES –

Part 12: Starting performance of single-speed
three-phase cage induction motors

FOREWORD
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This redline version of the official IEC Standard allows the user to identify the changes
made to the previous edition IEC 60034-12:2016. A vertical bar appears in the margin
wherever a change has been made. Additions are in green text, deletions are in
strikethrough red text.
IEC 60034-12 has been prepared by IEC technical committee 2: Rotating machinery. It is an
International Standard.
This fourth edition cancels and replaces the third edition published in 2016. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
Clause or
Change
subclause
Table 6 Aligned with the requirements for explosion protected motors from TC31 WG27
12 New clause on methods for measuring locked-rotor current and torque
Annex A New informative annex on the general current and torque characteristics with locked
rotor
Annex B New informative annex on correction of voltage and frequency

The text of this International Standard is based on the following documents:
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