EN 60343:1992
(Main)Recommended test methods for determining the relative resistance of insulating materials to breakdown by surface discharges
Recommended test methods for determining the relative resistance of insulating materials to breakdown by surface discharges
Assesses the relative resistance of solid insulating materials to breakdown when exposed to partial surface discharges at stresses and frequencies used in industrial service.
Empfohlene Prüfverfahren zur Bestimmung der relativen Beständigkeit isolierender Werkstoffe gegen Durchschlag infolge Oberflächenteilentladung
Méthodes d'essai recommandées pour la détermination de la résistance relative des matériaux isolants au claquage par les décharges superficielles
Détermine la résistance relative à la rupture diélectrique des matériaux isolants solides, lorsqu'ils sont soumis à des décharges superficielles partielles, sous des gradients et à des fréquences identiques à ceux qui sont utilisés en service industriel.
Recommended test methods for determining the relative resistance of insulating materials to breakdown by surface discharges (IEC 60343:1991)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-oktober-1998
Recommended test methods for determining the relative resistance of insulating
materials to breakdown by surface discharges (IEC 60343:1991)
Recommended test methods for determining the relative resistance of insulating
materials to breakdown by surface discharges
Empfohlene Prüfverfahren zur Bestimmung der relativen Beständigkeit isolierender
Werkstoffe gegen Durchschlag infolge Oberflächenteilentladung
Méthodes d'essai recommandées pour la détermination de la résistance relative des
matériaux isolants au claquage par les décharges superficielles
Ta slovenski standard je istoveten z: EN 60343:1992
ICS:
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.
NORME CEI
INTERNATIONALE IEC
INTERNATIONAL
Deuxième édition
STAN DARD
Second edition
1991-01
Méthodes d'essai recommandées pour la
détermination de la résistance relative des
matériaux isolants au claquage par les
décharges superficielles
Recommended test methods for determining the
relative resistance of insulating materials to
breakdown by surface discharges
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343 ©I EC - 3 -
CONTENTS
Page
FOREWORD 5
Clause
1 Scope 7
2 Normative references
3 Object and principle of test
4 Test arrangement 7
5 Electrical apparatus
6 Procedure
7 Factors to be taken into consideration 17
8 Test report 19
FIGURES
343 © I EC
INTERNATIONAL ELECTROTECHNICAL COMMISSION
RECOMMENDED TEST METHODS FOR DETERMINING
THE RELATIVE RESISTANCE OF INSULATING MATERIALS
TO BREAKDOWN BY SURFACE DISCHARGES
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.
This International Standard has been prepared by Sub-Committee 15B:
Endurance tests, of IEC Technical Committee No. 15: Insulating materials.
This second edition of IEC 343 replaces the first edition published in 1970.
The text of this standard is based on the following documents:
Six Months' Rule Report on Voting
15B000)65 15B000)70
this standard can be
Full information on the voting for the approval of,
found in the Voting Report indicated in the above table.
343 ©IEC - 7 -
RECOMMENDED TEST METHODS FOR DETERMINING
THE RELATIVE RESISTANCE OF INSULATING MATERIALS
TO BREAKDOWN BY SURFACE DISCHARGES
1 Scope
This International Standard concerns endurance tests with surface dis-
charges. It is intended to assess the relative resistance of solid insulating
materials to breakdown when exposed to surface discharges.
2 Normative references
The following standards contain provisions which, through reference in
this text, constitute provisions of this International Standard. At the time
of publication, the editions indicated were valid. All standards are subject
to revision, and parties to agreements based on this International Standard
are encouraged to investigate the possibility of applying the most recent
editions of the standards listed below. Members of IEC and ISO maintain
registers of currently valid International Standards.
IEC 60, High-voltage test techniques.
IEC 212: 1971, Standard conditions for use prior to and during the testing
of solid electrical insulating materials.
IEC 270: 1981, Partial discharge measurements.
3 Object and principle of test
Simple means are required for assessing the relative resistance of solid
insulating materials to breakdown when exposed to surface discharges while
stressed by electrical field strengths at frequencies used in industrial
service.
Experience shows that endurance tests, taking as a criterion the complete
puncture of the material in the presence of surface discharges from several
types of electrodes, provide a similar and reproducible classification of
materials with respect to this type of stressing, provided that dry air is
circulated around the electrodes and over the surface of the specimen
during the test.
4 Test arrangement
4.1
Test electrodes
The tests shall be made using a stainless steel cylindrical electrode and a
plate electrode. The precise grade of stainless steel is not important.
These electrodes shall be as follows:
343©IEC -9
4.1.1 Cylindrical electrode
A cylinder of 6 mm ± 0,3 mm diameter with the sharp edge removed to
leave a 1 mm radius. This electrode with a mass not exceeding 30 g shall
be normal to the surface of the specimen and rest upon it. With soft
materials, a gap not exceeding 100 pm between this electrode and the
specimen is permitted to avoid possible mechanical damage.
It is convenient to introduce very thin specimens (thickness less than
100 pm) between electrodes fixed 100 pm apart.
When necessary to reduce specimen capacitance and minimize thermal
heating, cylindrical electrodes of less than 6 mm are permissible provided
the radius of the electrode edge is maintained at 1 mm.
Figure 1 shows examples of two electrode arrangements which may be
used. The arrangement shown in figure lb avoids the electrode being
seated slightly canted on the specimen when a gap between electrode and
specimen is not necessary. Other arrangements are possible.
4.1.2 Plate electrode
A plate having an area greater than the area covered by discharges from
the cylindrical electrode at the test voltage (see 4.2) .
4.1 .3 Electrode arrangement
The electrode arrangement, whenever possible, should have axial sym-
metry. The air inlet shall be in a position to obtain an air distribution as
uniform as possible on the different electrodes to ensure reproducible
results. The test may be made with one or several electrodes above the
test sample. If several electrodes are used, the inter-electrode separation
shall be sufficient to avoid interaction between the discharges from
adjacent electrodes and not less than 50 mm (see figure 2) .
4.2 Test specimen
Whenever possible, tests should be made on specimens of one or more of
the following nominal thicknesses: 3,0 mm, 1,6 mm, 1,0 mm, 500 pm,
100 pm and 25 pm. For each nominal thickness, not less than nine speci-
mens (sample areas exposed to discharges) shall be tested at each voltage.
The specimen shall be of adequate area to avoid flashover and of uniform
thickness, in accordance with normal industry tolerances. The upper
surface of the specimen exposed to discharges shall be free from contami-
nation.
To prevent small discharges between the specimen and the plate electrode
it may be necessary to apply a conducting electrode to the lower surface
of the specimen. Care shall be taken when selecting an electrode material
to ensure that it does not react with or significantly change the specimen
properties.
343 © IEC - 11 -
The following materials are in common usage:
a)
vacuum deposited aluminium, silver or gold. It may be necessary
to condition the specimen after the electrode has been applied;
b) tin or aluminium foil„ 0,025 mm thick and of the same size as the
test specimen. The foil may be stuck to the specimen with a suitable
petroleum or silicone grease. The amount of grease for this purpose
should be a minimum. One must also avoid getting grease on the
opposite side of the specimen. The grease shall have no harmful effect
on the specimen due to chemical deterioration;
c) conducting silver paint.
Tests shall be carried out on test specimens which have been conditioned
so that they are substantially in equilibrium in accordance with IEC 212.
NOTE - Special tests may be made on stacks of thin film material, but
the results are likely to be very different from tests with a single
layer of the same material of equal thickness.
4.3 Test conditions
The test is normally carried out on specimens without applied strain but
specimens may be subjected to mechanical strain during exposure to dis-
charges, either by applying tension or by bending sheet specimens over a
curved plate electrode. Where mechanical strain is applied, 0,5 % defor-
mation shall be used for rigid materials and 5 for flexible materials.
Tests shall normally be made in air dried to a relative humidity not
exceeding 20 % (relative humidity of 20 or less can be obtained by
passing the air through a drying column containing a suitable desiccant
such as CaCl 2 ) .
The degree of dryness of the air and its rate of flow across the upper
surface of the specimens shall be sufficient to ensure that under the test
conditions the measured life is not influenced by local concentrations of
degradation products (a flow rate of 0,5 I/min per specimen has frequently
been found satisfactory) .
NOTES
1 Tests are normally made at a temperature of 23 °C ± 2 °C. It may
be advantageous to
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