IEC 60172:2020

IEC 60172 ®
Edition 5.0 2020-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Test procedure for the determination of the temperature index of enamelled and
tape wrapped winding wires
Méthode d’essai pour la détermination de l’indice de température des fils de
bobinage émaillés et enveloppés de ruban

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IEC 60172 ®
Edition 5.0 2020-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Test procedure for the determination of the temperature index of enamelled and

tape wrapped winding wires
Méthode d’essai pour la détermination de l’indice de température des fils de

bobinage émaillés et enveloppés de ruban

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.060.10 ISBN 978-2-8322-9086-6

– 2 – IEC 60172:2020 © IEC 2020
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Summary of procedure . 7
5 Test specimens . 7
5.1 Preparation . 7
5.1.1 Enamelled non-tape wrapped round wire . 7
5.1.2 Tape wrapped round wire and enamelled or tape wrapped rectangular
wire . 10
5.2 Varnish impregnation . 12
5.3 Notes on number of test specimens . 13
5.4 Specimen holder . 13
5.4.1 For specimens according to 5.1.1 . 13
5.4.2 For specimens according to 5.1.2 . 13
6 Temperature exposure. 14
7 Test voltage and its application . 15
8 Calculations . 16
8.1 Specimen failure time . 16
8.2 Time to failure . 16
8.3 Linearity of data . 16
8.4 Calculating and plotting thermal endurance and temperature index . 17
9 Report . 18
Annex A (normative) Method for calculation of the regression line . 19
Annex B (normative) Correlation coefficient . 24
Bibliography . 25

Figure 1 – Device used to form enamelled round wire test specimen . 8
Figure 2 – Spacer . 8
Figure 3 – Twist forming jig . 9
Figure 4 – Test specimen set up in forming jig . 9
Figure 5 – Test specimen formed with loop cut . 10
Figure 6 – Jig for bending large magnet wire, dielectric test specimen . 11
Figure 7 – Forming jig and test specimen . 12
Figure 8 – Specimen holder . 13
Figure 9 – Thermal endurance graph – Temperature index . 17
Figure A.1 – Plot of regression line based on sample calculation (Table A.2) . 23

Table 1 – Force and number of twists for specimens . 8
Table 2 – Proof voltage for round enamelled wire . 10
Table 3 – Recommended exposure times in days per cycle. 14
Table 4 – Proof voltage for tape-wrapped round and for enamelled or tape-wrapped
rectangular wire . 15

Table A.1 – Commonly used test temperatures in degrees Celsius and the
corresponding kelvins with its reciprocal and reciprocal squared values . 21
Table A.2 – Sample calculation . 22

– 4 – IEC 60172:2020 © IEC 2020
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
TEST PROCEDURE FOR THE DETERMINATION OF THE TEMPERATURE
INDEX OF ENAMELLED AND TAPE WRAPPED WINDING WIRES

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