IEC 60172:1987/AMD2:2010

IEC 60172 ®
Edition 3.0 2010-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
AMENDMENT 2
AMENDEMENT 2
Test procedure for the determination of the temperature index of enamelled
winding wires
Méthode d'essai pour la détermination de l'indice de température des fils de
bobinage émaillés
IEC 60172:1987/A2:2010
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IEC 60172 ®
Edition 3.0 2010-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
AMENDMENT 2
AMENDEMENT 2
Test procedure for the determination of the temperature index of enamelled
winding wires
Méthode d'essai pour la détermination de l'indice de température des fils de
bobinage émaillés
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
F
CODE PRIX
ICS 29.060.10 ISBN 978-2-88910-062-0
– 2 – 60172 Amend. 2 © IEC:2010
FOREWORD
This amendment has been prepared by IEC technical committee 55: Winding wires.
The text of this amendment is based on the following documents:
CDV Report on voting
55/1140/CDV 55/1174/RVC
Full information on the voting for the approval of this amendment can be found in the report on
voting indicated in the above table.
The committee has decided that the contents of this amendment and the base publication will
remain unchanged until the maintenance result date indicated on the IEC web site under
"http://webstore.iec.ch" in the data related to the specific publication. At this date, the
publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
_____________
5 Test specimens
5.1.1 Enamelled round wire with a nominal conductor diameter of 0,800 mm up to and
including 1,500 mm
Replace the title and text of this subclause by the following:
5.1.1 Enamelled round wire with a nominal conductor diameter of 0,224 mm up to and
including 2,65 mm
The grade of insulation used for determining the thermal index shall be grade 2 or grade 2B for
self-bonding winding wires.
Wire sizes 0,315 mm and 0,28 mm are permitted for use when the specification size range is
limited to 0,50 mm and finer.
NOTE For round enamelled winding wires, in order to avoid undue fragility of the test specimen, experience has
shown that nominal conductor diameters of 0,800 mm up to and including 2,65 mm are generally found convenient
to handle and test.
60172 Amend. 2 © IEC:2010 – 3 –
Replace the existing Table 1 by the following new Table 1:
Table 1 – Force and number of twists for specimens

Nominal diameter Force Number of twists
mm applied to per 125 mm
wire pairs
N
Over Up to and including
0,224 0,25 0,85 33
0,25 0,35 1,7 23
0,35 0,50 3,4 16
0,50 0,75 7,0 12
0,75 1,05 13,5 8
1,05 1,50 27,0 6
1,50 2,15 54,0 4
2,15 2,65 108,0 3
5.3 Number of test specimens
Replace the text of this subclause by the following new text:
Experience has shown that 20 specimens without impregnation and 10 specimens with
impregnation give results with an acceptable tolerance. A minimum of 10 specimens shall be
used.
5.4 Specimen holder
Replace the last sentence of this subclause by the following new sentence:
The holder shall be designed for at least 10 specimens to decrease handling time.
6 Temperature exposure
Replace the eighth paragraph of this clause by the following new paragraph:
Test specimens should be exposed to a minimum of three and preferably four exposure
temperatures. The lowest temperature, recommended at 20 °C above the desired thermal
class, should be one which results in a time frame to failure of more than 5000 h. The highest
exposure temperature must have a value of at least 100 h to be considered a valid data point.
Exposure temperatures should not be more than 20 °C apart. The accuracy of the temperature
index predicted from the results will increase as the exposure temperature approaches the
temperature to which the insulation is exposed in service.
7 Test voltage and its application
Replace the third paragraph of this clause by the following new paragraph:
The test specimens are removed from the ovens and cooled to room temperature. Each
specimen is subjected to a proof voltage according to the average thickness of the enamel as

– 4 – 60172 Amend. 2 © IEC:2010
specified in Table 3. For self-bonding wires, the self-bonding layer is included in the increase in
diameter due to the insulation.

Annex A
Replace Table A1 by the following new Table A.1:
Table A.1 – Commonly used test temperatures in degrees Celsius and
the corresponding Kelvin’s with its reciprocal and reciprocal squared values
θ T
–1 2 2 –2
X = 1/T (K ) X = 1/T (K )
ºC K
−3 −6
105 378
2,646 × 10 6,999 × 10
−3 −6
120 393
2,545 × 10 6,475 × 10
−3 −6
125 398
2,513 × 10 6,313 × 10
−3 −6
130 403
2,481 × 10 6,157 × 10
−3 −6
140 413
2,421 × 10 5,863 × 10
−3 −6
150 423
2,364 × 10 5,589 × 10
−3 −6
155 428
2,336 × 10 5,459 × 10
−3 −6
165 438
2,283 × 10 5,212 × 10
−3 −6
175 448
2,232 × 10 4,982 × 10
−3 −6
180 453
2,208 × 10 4,873 × 10
−3 −6
185 458
2,183 × 10 4,767 × 10
−3 −6
190 463
2,160 × 10 4,665 × 10
−3 −6
200 473
2,114 × 10 4,470 × 10
−3 −6
210 483
2,070 × 10 4,287 × 10
−3 −6
220 493
2,028 × 10 4,114 × 10
−3 −6
225 498
2,008 × 10 4,032 × 10
−3 −6
230 503
1,988 × 10 3,952 × 10
−3 −6
240 513
1,949 × 10 3,800 × 10
−3 −6
250 523
1,912 × 10 3,656 × 10
−3 −6
260 533
1,876 × 10 3,520 × 10
−3 −6
270 543
1,842 × 10 3,392 × 10
−3 −6
280 5
...