SIST EN 61033:2007

• Abstract:

  Describes three methods of test: 1) twisted coil test (method A); 2) helical coil test (method B); 3) wire bundle test (method C).

• Status: Published
• Publication Date: 30-Sep-2007
• ICS: 17.220.99 - Other standards related to electricity and magnetism
• ICS: 29.035.01 - Insulating materials in general
• Technical Committee: IZO - Insulating materials
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 13-Sep-2007
• Due Date: 18-Nov-2007
• Completion Date: 01-Oct-2007
• Ref Project: EN 61033:2006 - Test methods for the determination of bond strength of impregnating agents to an enamelled wire substrate

SIST EN 61033:2007 is the Slovenian adoption of EN 61033:2006, based on IEC 61033:1991 + A1:2006. It specifies three test methods for determining the bond strength of impregnating agents on an enamelled wire substrate, mainly for solvent-based varnishes and solventless resins used with enamelled winding wire. It is intended for laboratories, manufacturers and specifiers who need a common way to compare cured bond performance.

What does SIST EN 61033:2007 specify?

SIST EN 61033:2007 specifies laboratory test methods for bond strength testing on enamelled wire substrates. The scope covers three methods - twisted coil, helical coil and wire bundle - and allows one of them to be assigned as a referee method when the relevant specification sheet says so.

The document is organized into Clause 1, Clause 2 with three test methods, and Annex ZA. The methods are:

• Clause 2.1 - Method A: twisted coil test
• Clause 2.2 - Method B: helical coil test
• Clause 2.3 - Method C: wire bundle test

Annex ZA gives the normative references to international publications and their corresponding European publications. The figures support the specimen preparation, test fixtures and loading arrangements used in each method.

What are the key requirements of SIST EN 61033:2007?

SIST EN 61033:2007 measures the force needed to break an impregnated and cured specimen, then reports the bond strength as the median of five results in newtons. In practice, that means the same material can be checked at different test temperatures, and the result is tied to a defined specimen shape and loading setup rather than to a subjective judgment.

Common points across the three methods

• Clause 1 says bond strength may be affected by cure, test temperature, thermal ageing and the wire enamel chosen. This matters because test results are meaningful only when the preparation and test conditions are kept under control.
• For each test temperature, the standard calls for five specimens. That gives a small data set for calculating the median and spotting unusual results.
• The methods allow a manufacturer’s recommended cure schedule or an agreed schedule. In practice, the curing step must match the material being tested, or the result will not represent normal use.

Method A - twisted coil test

• Clause 2.1 uses an enamelled winding wire twisted into a coil, impregnated, cured and then pulled until it breaks. The maximum force is the measure of bond strength.
• Clause 2.1.2 gives a defined coil geometry and impregnation sequence. For the reader, this means Method A is a controlled way to compare materials on a twisted coil substrate, not a free-form sample.
• Clause 2.1.4 requires the loading rate to be adjusted so that the maximum force is reached in about one minute. That keeps the test comparable between laboratories.
• Clause 2.1.5 reports the median of the five measurements. The report in Clause 2.1.6 also records the impregnating agent, the substrate, the specimen preparation, the test temperatures, the minimum and maximum values, and any washing or surface preparation.

Method B - helical coil test

• Clause 2.2 uses a helical coil made from enamelled winding wire, coated with varnish and cured, then broken under tension. The measured force again stands for bond strength.
• Clause 2.2.2 specifies a mandrel-based coil preparation and controlled winding tension. This gives a repeatable specimen geometry, which is important when comparing results between suppliers or production lots.
• Clause 2.2.4 uses the same type of loading control as Method A, with the force peak reached in about one minute. Elevated-temperature testing is handled with a heating cabinet attached to the equipment.
• Clause 2.2.5 and 2.2.6 use the same median-based result and similar reporting items as Method A, so results from different materials can be documented in a consistent way.

Method C - wire bundle test

• Clause 2.3 uses a bundle of enamelled wires coated with varnish and cured, then pulls the central wire out of the bundle. The pull-out force measures bond strength.
• Clause 2.3.2 gives two specimen assembly procedures. In practice, the method checks how well the impregnating agent holds a compact wire bundle together under tensile loading.
• Clause 2.3.4 again requires the force peak to be reached in about one minute and allows elevated-temperature testing with a heating cabinet. This keeps the test aligned with the other methods.
• Clause 2.3.5 and 2.3.6 repeat the same median result format and report content, which makes the three methods comparable in documentation even though the specimens are different.

Equipment and measurement control

• All three methods use test equipment according to ISO 178. That tells the laboratory which type of tensile test machine and support arrangement to use.
• The figures define the supports, jigs and specimen layouts for each method. In practice, the setup is part of the test method, not an optional detail.

What terms does SIST EN 61033:2007 define?

• Impregnating agent - the varnish or resin applied to the enamelled wire substrate before curing.
• Enamelled wire substrate - the enamelled winding wire that forms the base specimen for the bond test.
• Bond strength - the force needed to break the impregnated specimen, reported in newtons.
• Twisted coil test - Method A, where a twisted coil specimen is impregnated and then broken in tension.
• Helical coil test - Method B, where a helical coil specimen is coated, cured and pulled to failure.
• Wire bundle test - Method C, where a bundle of wires is impregnated and the central wire is pulled out.
• Referee method - a method that a specification sheet may assign as the deciding test for a given material group.

Who uses SIST EN 61033:2007?

SIST EN 61033:2007 is used by manufacturers and test laboratories working with electrical insulating materials, especially impregnation varnishes, solventless resins and enamelled winding wire. Quality control teams use it to compare materials, monitor production and check whether cure or temperature changes affect bonding. Buyers and specifiers use it when they need a named test method in a product specification or purchase requirement.

It is also relevant to winding-wire suppliers, motor and transformer manufacturers, and any organization that needs a repeatable way to measure how strongly an impregnating agent bonds to an enamelled wire substrate.

What changed in SIST EN 61033:2007 from the previous edition?

The IEC prefatory material says this standard replaces IEC 290 (1969) and IEC 699 (1981). The European foreword says the IEC text was approved without modification, and Annex ZA was added by CENELEC.

Amendment 1 updated Method A. It tightened the winding dimensions and the twisting operation for the twisted coil specimen, and it adjusted the matching figure dimensions for the coil winder and coil twister.

Which standards are used with SIST EN 61033:2007?

• IEC 60317 Series - listed in Annex ZA as a normative reference; it provides the series of specifications for particular types of winding wires.
• EN 60317 Series - the European publication corresponding to IEC 60317 Series in Annex ZA.
• ISO 178 - used for the tensile test equipment and support arrangements in all three methods.
• IEC 317 - quoted in the body as a reference for enamelled winding wire.

What does the SIST EN 61033:2007 document contain?

The document contains three complete test methods with specimen preparation, impregnation, curing, loading and reporting steps. Figures 1 to 9 show the coil winders, twisting device, support arrangements, specimen shapes, the bundle-test jig and the tensile-machine fixture used in the methods.

It also gives the operating details that matter for a lab: specimen count, test-temperature handling, loading rate, and the way to record the result as a median value. The reporting clauses require material identification, specimen details, test temperatures and the minimum and maximum measured values for each temperature.

For the bundle test, the document includes two specimen assembly procedures, so a lab can choose the arrangement that fits its handling method. For elevated-temperature work, it explains how to use a heating cabinet without letting the specimen sit hot for longer than needed.

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01-november-2007
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Test methods for the determination of bond strength of impregnating agents to an
enamelled wire substrate (IEC 61033:1991 (EQV) + A1:2006)
Prüfverfahren zur Bestimmung der Verbackungsfestigkeit von Imprägniermitteln auf
einem Lackdraht-Substrat (IEC 61033:1991 (EQV) + A1:2006)
Méthodes d'essai pour la détermination du pouvoir agglomérant des agents
d'imprégnation sur fil émaillé (IEC 61033:1991 (EQV) + A1:2006)
Ta slovenski standard je istoveten z: EN 61033:2006
ICS:
17.220.99 Drugi standardi v zvezi z Other standards related to
elektriko in magnetizmom electricity and magnetism
29.035.01 Izolacijski materiali na Insulating materials in
splošno general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 61033
NORME EUROPÉENNE
December 2006
EUROPÄISCHE NORM
ICS 17.220.99; 29.035.01
English version
Test methods for the determination of bond strength
of impregnating agents to an enamelled wire substrate
(IEC 61033:1991 + A1:2006)
Méthodes d'essai pour la détermination  Prüfverfahren zur Bestimmung
du pouvoir agglomérant des agents der Verbackungsfestigkeit
d'imprégnation sur fil émaillé von Imprägniermitteln auf einem
(CEI 61033:1991 + A1:2006) Lackdraht-Substrat
(IEC 61033:1991 + A1:2006)
This European Standard was approved by CENELEC on 2006-11-01. 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 Central Secretariat 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 Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, the Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2006 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61033:2006 E
Foreword
The text of the International Standard IEC 61033:1991 + A1:2006, prepared by IEC TC 15, Standards on
specifications for electrical insulating materials, was submitted to the Unique Acceptance Procedure and
was approved by CENELEC as EN 61033 on 2006-11-01 without any modification.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2007-11-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2009-11-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 61033:1991 + A1:2006 was approved by CENELEC as a
European Standard without any modification.
__________
- 3 - EN 61033:2006
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.

NOTE  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.
Publication Year Title EN/HD Year

IEC 60317 Series Specifications for particular types of winding EN 60317 Series
wires
ISO 178 1975 Plastics - Determination of flexural properties - -
of rigid plastics
NORME
CEI
INTERNATIONALE IEC
INTERNATIONAL
Première édition
STANDARD
First edition
1991-04
Méthodes d'essai pour la détermination du
pouvoir agglomérant des agents d'imprégnation
sur fil émaillé
Test methods for the determination of bond
strength of impregnating agents to an enamelled
wire substrate
© IEC 1991 Droits de reproduction réservés — Copyright - all rights reserved
Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in
utilisée sous quelque forme que ce soit et par aucun any form or by any means, electronic or mechanical,
procédé, électronique ou mécanique, y compris la photo- including photocopying and microfilm, without permission in
copie et les microfilms, sans l'accord écrit de l'éditeur. writing from the publisher.
International Electrotechnical Commission 3, rue de Varembé Geneva, Switzerland
Telefax: [phone] e-mail: [e-mail] IEC web site http: //www.iec.ch
CODE PRIX
Commission Electrotechnique Internationale
M
PRICE CODE
International Electrotechnical Commission
IEC
MeNsayuaponuaR 3ileHTpoTexHH4ecHaa HOMHCCHA
Pour prix, vigueur
voir catalogue en
• • For price, see current catalogue

- 3 -
1033 © I E C
CONTENTS
Page
FOREWORD
PREFACE
INTRODUCTION
Clause
1 Scope
2 Methods of test
2.1 Method A: twisted coil test 7
2.2 Method B: helical coil test 11
2.3 Method C: Wire bundle test 13
Figures 18
©
1033 IE C - 5 -
INTERNATIONAL ELECTROTECHNICAL COMMISSION
TEST METHODS FOR THE DETERMINATION OF BOND STRENGTH OF
IMPREGNATING AGENTS TO AN ENAMELLED WIRE SUBSTRATE
FOREWORD
1) The formal decisions or agreements of the IEC on technical matters,
prepared by Technical Committees on which all the National Committees
having a special interest therein are represented, express, as nearly
as possible, an international consensus of opinion on the subjects
dealt with.
2)
They have the form of recommendations for international use and they
are accepted by the National Committees in that sense.
3) In order to promote international unification, the IEC expresses the
wish that all National Committees should adopt the text of the IEC
recommendation for their national rules in so far as national con-
ditions will permit. Any divergence between the IEC recommendation and
the corresponding national rules should, as far as possible, be clearly
indicated in the latter.
PREFACE
This standard has been prepared by Sub-Committee 15C: Specifications, of
IEC Technical Committee No. 15: Insulating materials.
The text of this standard is based on the following documents:
Six Months' Rule
Report on Voting
15C(C0)252
15C(CO)270
15C(CO)252A
Full information on the voting for the approval of this standard can be
found in the Voting Report indicated in the above table.
This standard replaces IEC 290, published in 1969, and IEC 699, published
in 1981.
The following IEC publication is quoted in this standard:
Publication No. 317: Specifications for particular types of winding
wires.
Other publication quoted:
ISO 178 (1975): Plastics - Determination of flexural properties of
rigid plastics.
1033 ©
I EC
TEST METHODS FOR THE DETERMINATION OF BOND STRENGTH OF
IMPREGNATING AGENTS TO
AN ENAMELLED WIRE SUBSTRATE
INTRODUCTION
This standard deals with three methods of test to determine the bond
strength of impregnating agents in conjunction with enamelled wire sub-
strates.
The methods are as follows:
1) Twisted coil test: method A
2) Helical coil test: method B
3) Wire bundle test: method C
1 Scope
This standard describes three methods of test to determine the bond
strength of impregnating agents such as solvent-based varnishes and
solventless resins to an enamelled wire substrate. Bond strength may be
affected by cure, by test temperature, by thermal ageing, and for any
impregnating agent, by the chosen type of wire enamel.
These three methods of test cover the prevailing standard practice of
testing bond strength. For a certain group of materials, one of these
methods may be assigned to be the referee method subject to a specifi-
cation in the relevant specification sheet.
2 Methods of test
2.1
Method A: twisted coil test
2.1.1
Principle
In this test, 0,315 mm diameter enamelled winding wire in the form of a
twisted coil is impregnated and cured. The maximum force to break this
specimen is a measure of the bond strength.
2.1.2
Specimen
Prepare a random wound coil from an enamelled winding wire (see note 1)
by means of a suitable winding equipment (see figure la). To prevent
opening of the coil after removal from the winding equipment, each end of
the winding wire, or short piece of enamelled wire may be wrapped around
the coil two or three times in opposite directions. For this purpose the
winding equipment is provided with appropriate notches (see figure lb).
For winding the coil, the following dimensions apply:

1033 © IEC - 9 -
winding diameter: 57 mm ±
1 mm
±
width of the slot: 6 mm 1 mm
number of turns: 100 (see note 2)
nominal wire diameter: 0,315 mm
NOTES
1 For enamelled winding wire see also IEC 317.
2 Instead of 100 turns, two times 50 turns may be used to provide a
bifilar winding that allows a.c. current heating of the coil if
desired.
Remove the coil from the winding equipment and stretch it into an oval
shape. Twist the coil two full turns around its longitudinal axis by means
of a twisting device (see figures 2a and 2b) . The twisted coil formed is
about 7 mm in diameter and 85 mm to 90 mm in length and serves as
substrate for the impregnating agent.
Unless otherwise specified in the purchase contract, treat the twisted coil
once with the impregnating agent. With the twisted coil in the vertical
position, immerse it in the impregnating agent for 5 min ± 1 min (see
note). Remove it slowly and uniformly at a maximum rate of 1 mm/s. Drain
horizontally for 10 min to 15 min and cure horizontally according to the
manufacturer's recommendation or to an agreed schedule. If more than one
treatment is to be given, dip, drain and cure the twisted coil vertically,
reversing the direction for each subsequent treatment.
Prepare five specimens for each test temperature.
NOTE - Some impregnating agents, such as high viscosity or thixotropic
products may require alternative processing methods.
2.1.3 Equipment
Use equipment according to ISO 178.
Dimensions of the supports of the test equipment shall comply with
figure 3.
2.1.4
Procedures
With the specimen properly positioned according to figure 3, adjust the
crosshead speed so that the maximum force is reached in about 1 min.
For tests at elevated temperatures (see note), a heating cabinet attached
to the equipment may be used. Before testing, the test specimen shall be
kept in the cabinet at the test temperature for a time just sufficient to
ensure that the test specimen reaches this temperature. Extended heating
of the specimen could affect the property.
NOTE - In case of current heating, the test temperature of the test
specimen should be determined by adequate means, e.g. thermocouple,
resistance measurements.
1033 © IEC - 11 -
2.1.5
Result
The bond strength is expressed as the median value of the five measure-
ments in newtons.
2.1.6 Report
Report the following:
reference to test method A of this standard;
- details of the impregnating agent;
-
details of the substrate (type of enamelled winding wire);
-
details of specimen preparation (single or bifilar coil, impregnating
details);
- test temperatures;
-
bond strength and the minimum and maximum measured values for
each test temperature;
-
if the winding wire or test specimens have been washed in any
manner so that they are no longer in an "as received" condition, such
procedure shall be noted in the report.
2.2
Method B: helical coil test
2.2.1
Principle
In this test,
1 mm diameter wire in the form of a helical coil is coated with
varnish and cured. The force necessary to break this coil is a measure of
the bond strength.
2.2.2
Specimen
Prepare a helical coil (see figure 4) from an enamelled winding wire (see
note) by means of a suitable winding equipment. For winding the coil, the
following dimensions apply:
nominal wire diameter:
1 mm
mandrel diameter: ±
6,3 mm 0,1 mm
length of coil:
75 mm ± 2 mm
±
winding tension:
10 N
...