Test procedure for the determination of the temperature index of enamelled and tape wrapped winding wires

This International Standard specifies, in accordance with the provisions of IEC 60216-1, a
method for evaluating the temperature index of enamelled wire, varnished or unvarnished with
an impregnating agent, and of tape wrapped round and rectangular wire, in air at atmospheric
pressure by periodically monitoring changes in response to AC proof voltage tests. This
procedure does not apply to fibre-insulated wire or wire covered with tapes containing
inorganic fibres.
NOTE The data obtained according to this test procedure provide the designer and development engineer with
information for the selection of winding wire for further evaluation of insulation systems and equipment tests.

Prüfverfahren zur Bestimmung des Temperaturindex von Lackdrähten und bandumwickelten Drähten

Méthode d’essai pour la détermination de l’indice de température des fils de bobinage émaillés et enveloppés de ruban

L'IEC 60172:2015 spécifie, conformément aux dispositions de l'IEC 60216-1, une méthode pour l'évaluation de l'indice de température du fil émaillé, imprégné ou non imprégné avec un matériau d'imprégnation, et du fil de section circulaire ou rectangulaire, enveloppé de ruban, dans l'air à la pression atmosphérique, en contrôlant périodiquement les variations de réponse aux essais de tension d'épreuve en courant alternatif. Cette méthode ne concerne pas le fil avec revêtement fibreux ou le fil recouvert de rubans contenant des fibres non organiques. Cette quatrième édition annule et remplace la troisième édition parue en 1987, l'Amendement 1:1997 et l'Amendement 2:2010. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente: - Révision de l'Article 1 (Domaine d'application): intégration du texte approprié issu de l'ancien Article 2 (Objet); - Suppression de l'Article 2 (Objet): texte correspondant reporté dans les articles existants; - Nouvel Article 2 (Références normatives); - Révision de 5.1.1, 5.3 et 5.4 avec corrections apportées à l'Amendement 2 à la troisième édition; - Révision de l'Article 7 de manière à préciser les éprouvettes qui répondent aux exigences du Tableau 3 et du Tableau 4; - Révision des figures avec photos et graphiques haute résolution. Mots clés: fil émaillé, fil de section circulaire ou rectangulaire enveloppé de ruban, essais de tension d'épreuve en courant alternatif

Preskusni postopek za ugotavljanje temperaturnega indeksa emajlirane in s trakom ovite žice za navitja

Ta mednarodni standard v skladu z določbami standarda IEC 60216-1 določa metodo za vrednotenje temperaturnega indeksa emajlirane žice, premazane z impregnacijskim premazom ali ne, in traku, ovitega okrog pravokotne žice, v zraku pri atmosferskem tlaku z rednim spremljanjem sprememb v odziv na preskuse napetosti. Ta postopek se ne uporablja za žico, izolirano z vlakni, ali žico, prekrito s trakovi, ki vsebuje anorganska vlakna.
OPOMBA: Podatki, pridobljeni v skladu s tem preskusnim postopkom, zagotavljajo načrtovalcu in razvijalcu informacije za izbiro žice za navitja za dodatno vrednotenje izolacijskih sistemov ter preskusov opreme.

General Information

Status
Published
Publication Date
16-Aug-2015
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
06-Aug-2015
Due Date
11-Oct-2015
Completion Date
17-Aug-2015

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SLOVENSKI STANDARD
SIST EN 60172:2015
01-september-2015
1DGRPHãþD
SIST EN 60172:2001
SIST EN 60172:2001/A1:2001
SIST EN 60172:2001/A2:2010
Preskusni postopek za ugotavljanje temperaturnega indeksa emajlirane in s
trakom ovite žice za navitja

Test procedure for the determination of the temperature index of enamelled and tape

wrapped winding wires
Prüfverfahren zur Bestimmung des Temperaturindex von Lackdrähten und
bandumwickelten Drähten

Méthode d’essai pour la détermination de l’indice de température des fils de bobinage

émaillés et enveloppés de ruban
Ta slovenski standard je istoveten z: EN 60172:2015
ICS:
17.200.01 Termodinamika na splošno Thermodynamics in general
29.060.10 Žice Wires
SIST EN 60172:2015 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN 60172:2015
---------------------- Page: 2 ----------------------
SIST EN 60172:2015
EUROPEAN STANDARD EN 60172
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2015
ICS 29.060.10 Supersedes EN 60172:1994
English Version
Test procedure for the determination of the temperature index of
enamelled and tape wrapped winding wires
(IEC 60172:2015)

Méthode d'essai pour la détermination de l'indice de Prüfverfahren zur Bestimmung des Temperaturindex von

température des fils de bobinage émaillés et enveloppés de Lackdrähten und bandumwickelten Drähten

ruban (IEC 60172:2015)
(IEC 60172:2015)

This European Standard was approved by CENELEC on 2015-06-16. CENELEC members are bound to comply with the CEN/CENELEC

Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC

Management Centre or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation

under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the

same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,

Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,

Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2015 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.

Ref. No. EN 60172:2015 E
---------------------- Page: 3 ----------------------
SIST EN 60172:2015
EN 60172:2015
European foreword

The text of document 55/1518/FDIS, future edition 4 of IEC 60172, prepared by IEC/TC 55 "Winding

wires" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
EN 60172:2015.
The following dates are fixed:
(dop) 2016-03-16
• latest date by which the document has to be
implemented at national level by
publication of an identical national
standard or by endorsement
• latest date by which the national (dow) 2018-06-16
standards conflicting with the
document have to be withdrawn
This document supersedes EN 60172:1994.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such

patent rights.
Endorsement notice

The text of the International Standard IEC 60172:2015 was approved by CENELEC as a European

Standard without any modification.

In the official version, for Bibliography, the following notes have to be added for the standards indicated:

IEC 60317 (series) NOTE Harmonized as EN 60317 (series).
IEC 60455-3-5 NOTE Harmonized as EN 60455-3-5.
IEC 60464-3-2 NOTE Harmonized as EN 60464-3-2.
---------------------- Page: 4 ----------------------
SIST EN 60172:2015
EN 60172:2015
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following documents, in whole or in part, are normatively referenced in this document and are

indispensable for its application. For dated references, only the edition cited applies. For undated

references, the latest edition of the referenced document (including any amendments) applies.

NOTE 1 When an International Publication has been modified by common modifications, indicated by (mod), the relevant

EN/HD applies.

NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here:

www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60216-1 - Electrical insulating materials - Thermal EN 60216-1 -
endurance properties -- Part 1: Ageing
procedures and evaluation of test results
IEC 60216-3 - Electrical insulating materials - Thermal EN 60216-3 -
endurance properties -- Part 3: Instructions
for calculating thermal endurance
characteristics
---------------------- Page: 5 ----------------------
SIST EN 60172:2015
---------------------- Page: 6 ----------------------
SIST EN 60172:2015
IEC 60172
Edition 4.0 2015-05
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 978-2-8322-2676-6

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 7 ----------------------
SIST EN 60172:2015
– 2 – IEC 60172:2015 © IEC 2015
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 round wire with a nominal conductor diameter of 0,224 mm

up to and including 2,65 mm ............................................................................ 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 .................................................................. 14

6 Temperature exposure................................................................................................... 14

7 Test voltage and its application .................................................................................... 16

8 Calculations .................................................................................................................. 16

8.1 Specimen failure time ........................................................................................... 16

8.2 Time to failure ....................................................................................................... 17

8.3 Linearity of data .................................................................................................... 17

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 .......................................................................................................................... 26

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 – Specimen holder and electrical connection fixture ................................................ 14

Figure 10 – Thermal endurance graph – Temperature index ................................................. 18

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................................................... 15

---------------------- Page: 8 ----------------------
SIST EN 60172:2015
IEC 60172:2015 © IEC 2015 – 3 –

Table 4 – Proof voltage for tape-wrapped round and for enamelled or tape-wrapped

rectangular wire .................................................................................................................... 16

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

---------------------- Page: 9 ----------------------
SIST EN 60172:2015
– 4 – IEC 60172:2015 © IEC 2015
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
TEST PROCEDURE FOR THE DETERMINATION OF THE TEMPERATURE
INDEX OF ENAMELLED AND TAPE WRAPPED WINDING WIRES
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 60172 has been prepared by IEC Technical Committee 55:

Winding wires.
This fourth edition cancels and replaces the third edition published in 1987,

Amendment 1:1997 and Amendment 2:2010. This edition constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:

– Revision of Clause 1, Scope, to incorporate appropriate text from former Clause 2, Object;

– Deletion of Clause 2, Object, by placement of its text into existing clauses;
– New Clause 2, Normative references;

– Revision of 5.1.1, 5.3 and 5.4 with corrections to Amendment 2 to the third edition;

– Revision of Clause 7 as to clarify which specimens comply with Table 3 and Table 4;

– Revision of figures with high-resolution photos and graphs.
---------------------- Page: 10 ----------------------
SIST EN 60172:2015
IEC 60172:2015 © IEC 2015 – 5 –
The text of this standard is based on the following documents:
FDIS Report on voting
55/1518/FDIS 55/1524/RVD

Full information on the voting for the approval of this standard can be found in the report on

voting indicated in the above table.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

The committee has decided that the contents of this publication will remain unchanged until

the stability date indicated on the IEC website 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.

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.
---------------------- Page: 11 ----------------------
SIST EN 60172:2015
– 6 – IEC 60172:2015 © IEC 2015
TEST PROCEDURE FOR THE DETERMINATION OF THE TEMPERATURE
INDEX OF ENAMELLED AND TAPE WRAPPED WINDING WIRES
1 Scope

This International Standard specifies, in accordance with the provisions of IEC 60216-1, a

method for evaluating the temperature index of enamelled wire, varnished or unvarnished with

an impregnating agent, and of tape wrapped round and rectangular wire, in air at atmospheric

pressure by periodically monitoring changes in response to AC proof voltage tests. This

procedure does not apply to fibre-insulated wire or wire covered with tapes containing

inorganic fibres.

NOTE The data obtained according to this test procedure provide the designer and development engineer with

information for the selection of winding wire for further evaluation of insulation systems and equipment tests.

2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and

are indispensable for its application. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any
amendments) applies.

IEC 60216-1, Electrical insulating materials – Thermal endurance properties – Part 1: Ageing

procedures and evaluation of test results

IEC 60216-3, Electrical insulating materials – Thermal endurance properties – Part 3:

Instructions for calculating thermal endurance characteristics
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
temperature index

numerical value of the Celsius temperature expressed in degrees Celsius characterizing the

thermal capability of an insulating material or an insulation system

Note 1 to entry: In case of insulating materials, the temperature index is derived from the thermal endurance

relationship at a given time, normally 20 000 hours. It may be used as basis for determination of the material’s

temperature class.

Note 2 to entry: In case of insulation systems, the temperature index may be derived from known service

experience or from a known comparative functional evaluation of an evaluated and established reference insulation

system as basis.
[SOURCE: IEC 60050-212:2010, 212-12-11]
3.2
specimen failure time

number of hours at the exposure temperature that have elapsed at the time a specimen

fails the proof test
---------------------- Page: 12 ----------------------
SIST EN 60172:2015
IEC 60172:2015 © IEC 2015 – 7 –
3.3
time to failure

number of hours to failure calculated from the specimen failure times for a set of

specimens at one exposure temperature
4 Summary of procedure

A set of specimens in accordance with Clause 5 is subjected to a testing cycle. This cycle

consists of a heat-storing period at a temperature given in Clause 6, followed by a proof

voltage test at room temperature in accordance with Clause 7.

This cycle is repeated until a sufficient number of specimens has failed. The time to failure is

calculated in accordance with Clause 8. The test is carried out at three or more

temperatures. A regression line is calculated in accordance with 8.4 and the time to failure

values plotted on thermal endurance graph paper as a function of the exposure
temperature.

The temperature in degrees Celsius, corresponding to the point of intersection of the

regression line with the ordinate of 20 000 h endurance represents the temperature index of

the winding wire under test.
5 Test specimens
5.1 Preparation

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.
Specimens shall be prepared as follows:

a) A wire specimen approximately 400 mm in length shall be twisted together over a distance

of 125 mm with a device as shown in Figure 1. The force (weight) applied to the wire pair

while being twisted and the number of twists are specified in Table 1.
---------------------- Page: 13 ----------------------
SIST EN 60172:2015
– 8 – IEC 60172:2015 © IEC 2015
IEC
Figure 1 – Device used to form enamelled round wire test specimen
Table 1 – Force and number of twists for specimens
Nominal diameter Force applied to wire pair Number of twists per
125 mm
mm 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 3,50 108,0 3

b) Spacers may be prepared as shown in Figure 2. Such thermally stable insulating

materials as ceramic or silicone glass fibre laminate may be used. The spacers are

marked with a suitable identifying letter or number.
3 19
Drill two holes to match wire diameter
IEC
Material: Silicone glass laminate
Dimensions in millimetres
Figure 2 – Spacer
---------------------- Page: 14 ----------------------
SIST EN 60172:2015
IEC 60172:2015 © IEC 2015 – 9 –

c) The test specimens may be shaped in a jig, an engineering drawing of which is shown

in Figure 3. A specimen is placed in the jig and a spacer, placed on the parallel leads

of the twisted pair, is brought up to the face of the jig as shown in Figure 4. The leads

are then bent parallel to hold the spacer in position. The forming jig provides more

uniform test specimens. If a specimen holder is used, the spacers are unnecessary.

R3,2
R1,2
R3,2
6,5 ∅ pin, press fit
IEC
R = Radius of bend
Dimensions in millimetres
Figure 3 – Twist forming jig
Forming jig
Push spacer to top
Enamelled wire twist
Bend ends parallel to hold spacer
IEC
Figure 4 – Test specimen set up in forming jig

d) The loop at the end of the twisted section shall be cut at two places (not one) to

provide the maximum spacing between the cut ends as shown in Figure 5. Any bending

of the wires, at this end or the other untwisted end, to ensure adequate separation

insulation.
between the wires shall avoid sharp bends or damage to the
---------------------- Page: 15 ----------------------
SIST EN 60172:2015
– 10 – IEC 60172:2015 © IEC 2015
Cut loop in two places
IEC
Figure 5 – Test specimen formed with loop cut

e) In order to ensure homogeneity of the batch of test specimens, it is recommended that

test specimens be subjected to a test voltage three times the value given in
Table 2 for 1 s.
Table 2 – Proof voltage for round enamelled wire
Voltage
Increase in diameter due to the insulation
(rms)
(mm)
Over Up to and including
– 0,015 300
0,015 0,024 300
0,024 0,035 400
0,035 0,050 500
0,050 0,070 700
0,070 0,090 1 000
0,090 0,130 1 200
5.1.2 Tape wrapped round wire and enamelled or tape wrapped rectangular wire

NOTE This procedure applies to any convenient dimension of round or rectangular wire. However, selecting wires

having dimensions that minimize the bending force needed to shape the test specimen will make the procedure

easier to perform. Wire with high stiffness will yield specimens with poor wire-to-wire contact areas.

Specimens shall be prepared as follows:

a) Two straight specimens of wire each of 250 mm length shall be cut from the supply spool.

b) 10 mm to 15 mm of the insulation shall be removed from one end of each piece of wire to

provide for electrical connection.

c) Each specimen shall be formed in a jig, as shown in Figure 6. This produces a straight

centre section of about 150 mm with bent ends, which provide the necessary flare at both

ends of the final specimen.
---------------------- Page: 16 ----------------------
SIST EN 60172:2015
IEC 60172:2015 © IEC 2015 – 11 –
IEC
All parts 12,5 mm thick
a) Fixed template
compound plate stock
Phenolic impregnated fabric
IEC
b) Movable template (same dimensions as a))
IEC
IEC
a mounting screws for fixed template
b mounting screws for movable template (template shall be free to slide)
c mounting screw for clamping lever (lever shall be free to rotate)
c) Platine
d) Clamping lever
Dimensions in millimetres
Figure 6 – Jig for bending large magnet wire, dielectric test specimen

d) The two formed specimens shall be placed together back-to-back and tightly wrapped with

glass yarn over the straight centre section of the specimen, as shown in Figure 7.

---------------------- Page: 17 ----------------------
SIST EN 60172:2015
– 12 – IEC 60172:2015 © IEC 2015
Forming jig
Test specimen
IEC
Figure 7 – Forming jig and test specimen

Care shall be taken that the centre section shows a close contact between the two pieces.

After tying, further bending of the ends shall be avoided. Pre-annealing of the specimen prior

to testing or impregnating will remove stress and craze marks and therefore may be desirable

with certain material.
e) Prior to testing the specimen shall be proof-tested at 1 000 V a.c.
5.2 Varnish impregnation

Experience has shown that insulated wire according to IEC 60317 and impregnating agents

according to IEC 60455-3-5 or IEC 60464-3-2 can affect one another during the thermal

ageing process.

NOTE 1 Testing varnished specimens will allow for evaluation of the compatibility of the wire insulation with an

impregnating agent. Thus the temperature indices of different combinations can be compared.

Interaction between wire insulation and such agent may increase or decrease the relative

thermal life of this combination compared with the life of the wire tested without impregnation.

Therefore, with impregnated specimens, this test procedure may give an indication of the

thermal endurance of a combination of wire insulation and impregnating agent.
If such impregnation is required, the following procedure shall be applied:

With the specimen in the vertical position, it shall be immersed in the impregnating agent for

(60 ± 10) s (see note). It shall be removed slowly and uniformly at a rate of about 1 mm/s. It

shall be drained horizontally for 10 min to 15 min and cured horizontally according to the

manufacturer's recommendation or to an agreed schedule. If more than one treatment is to be

given, immerse, drain and cure the specimen vertically reversing the specimen for each

subsequent treatment.
---------------------- Page: 18 ----------------------
SIST EN 60172:2015
IEC 60172:2015 © IEC 2015 – 13 –

NOTE 2 Some impregnating agents, such as high viscosity or thixotropic products require alternative processing

methods.
5.3 Notes on number of test specimens

The accuracy of the test results depends largely upon the number of test specimens aged at

each temperature. A greater number of test specimens is required to achieve an acceptable

degree of accuracy if there is a wide spread in results among the specimens exposed at each

temperature.

Experience has shown that twenty specimens without impregnation and ten specimens with

impregnation give results with an acceptable tolerance. A minimum of ten specimens shall be

used.
5.4 Specimen holder
5.4.1 For specimens according to 5.1.1

Since individual handling of the twisted specimens may result in premature failures, it is

recommended that the specimens be placed in a suitable holder, as shown in Figure 8. The

holder should be designed in a manner that will protect the twisted specimens from external

mechanical damage and warping. The holder will be so constructed as to allow the ends of

the twist to protrude from the holder to make electrical connection for the proof testing as

shown in Figure 9. The holder shall be designed for at least ten specimens to decrease

handling time.
IEC
Figure 8 – Specimen holder
---------------------- Page: 19 ----------------------
SIST EN 60172:2015
– 14 – IEC 60172:2015 © IEC 2015
IEC
Figure 9 – Specimen holder and electrical connecti
...

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