SIST HD 438 S1:1998
(Main)Method of test for electrical resistance and resistivity of insulating materials at elevated temperatures
Method of test for electrical resistance and resistivity of insulating materials at elevated temperatures
Covers procedures for the determination of insulation resistance and volume resistivity of insulating materials at temperatures up to at least 800 °C.
Prüfverfahren für den elektrischen Durchgangswiderstand und den spezifischen Widerstand von Isolierstoffen, bei erhöhten Temperaturen
Méthode d'essai pour la résistance d'isolement et la résistivité transversale des matériaux isolants à des températures élevées
Couvre les méthodes de détermination de la résistance d'isolement et de la résistance transversale des matériaux isolants à des températures allant au moins jusqu'à 800 °C.
Method of test for electrical resistance and resistivity of insulating materials at elevated temperatures (IEC 60345:1971)
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Standards Content (Sample)
SLOVENSKI STANDARD
SIST HD 438 S1:1998
01-oktober-1998
Method of test for electrical resistance and resistivity of insulating materials at
elevated temperatures (IEC 60345:1971)
Method of test for electrical resistance and resistivity of insulating materials at elevated
temperatures
Prüfverfahren für den elektrischen Durchgangswiderstand und den spezifischen
Widerstand von Isolierstoffen, bei erhöhten Temperaturen
Méthode d'essai pour la résistance d'isolement et la résistivité transversale des
matériaux isolants à des températures élevées
Ta slovenski standard je istoveten z: HD 438 S1:1984
ICS:
29.035.01 Izolacijski materiali na Insulating materials in
splošno general
SIST HD 438 S1:1998 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST HD 438 S1:1998
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SIST HD 438 S1:1998
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SIST HD 438 S1:1998
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SIST HD 438 S1:1998
NORME CEI
INTERNATIONALE IEC
345
INTERNATIONAL
Première édition
STAN DARD
First edition
1971
Méthode d'essai pour la résistance d'isolement
et la résistivité transversale des matériaux isolants
à des températures élevées
Method of test for electrical resistance
and resistivity of insulating materials
at elevated temperatures
© CEI 1971 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
utilisée sous quelque forme que ce soit et par aucun procédé, in any form or by any means, electronic or mechanical,
électronique ou mécanique, y compris la photocopie et les including photocopying and microfilm, without permission
microfilms, sans l'accord écrit de l'éditeur. in writing from the publisher
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Pour prix, voir catalogue en vigueur
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For price, see current catalogue
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SIST HD 438 S1:1998
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INTERNATIONAL ELECTROTECHNICAL COMMISSION
METHOD OF TEST FOR ELECTRICAL RESISTANCE AND RESISTIVITY
OF INSULATING MATERIALS AT ELEVATED TEMPERATURES
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 this intern
ational unification, the IEC expresses the wish that all National Committees having as
yet no national rules, when preparing such rules, should use the IEC recommendations the fundamental basis for these
as
rules in so far
as national conditions will permit.
4) The desirability is recognized of extending international agreement on these matters through an endeavour to harmonize
national standardization rules with these recommendations in so far
as national conditions will permit. The National
Committees pledge their influence towards that end.
PREFACE
This Recommendation has been prepared by Sub-Committee 15A, Short-Time Tests, of IEC Technical
Committee No. 15, Insulating Materials.
A first draft was discussed at the meeting held in Venice in 1963. A new draft was discussed at the
meeting held in Tel-Aviv in 1966. As a result of this latter meeting, a final draft was submitted to the
National Committees for approval under the Six Months' Rule in September 1968.
The following countries voted explicitly in favour of publication:
Australia Korea (Democratic People's Republic of)
Belgium Netherlands
Canada Romania
Czechoslovakia South Africa
Denmark Sweden
Finland Switzerland
France Turkey
Germany Union of Soviet Socialist Republics
Israel United Kingdom
Italy Yugoslavia
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SIST HD 438 S1:1998
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METHOD OF TEST FOR ELECTRICAL RESISTANCE AND RESISTIVITY
OF INSULATING MATERIALS AT ELEVATED TEMPERATURES
1. Scope
This test method covers procedures for the determination of insulation resistance and volume
resistivity of insulating materials at temperatures up to at least 800 °C.
The measurements shall be made in accordance with I E C Publication 93, Recommended Methods
of Test for Volume and Surface Resistivities of Electrical Insulating Materials, and with I EC Publi-
cation 167, Methods of Test for the Determination of the Insulation Resistance of Solid Insulating
Materials, utilizing the following special procedures.
2. Preparation of specimens and electrodes
For insulation resistance measurements, the specimens may be of any suitable size and shape and
volume resistivity is measured,
may have electrodes already attached (see I E C Publication 167). When
the specimens shall preferably be in the form of disks, a three electrode system shall be used, one of
which is a guarded electrode. The thickness variation between any two places on the disk shall
be no greater than 5% of the mean thickness. The specimen electrodes shall preferably be circular
and consist of fired-on conducting paint or a conducting coating evaporated or sprayed onto the
specimen faces. Gold or platinum are suitable electrode metals. Silver should not be used since it
migrates at elevated temperatures. Thin layers of gold may lose their conductivity since the gold
may agglomerate at the higher temperatures. It is difficult to apply evaporated or sprayed-on
electrodes to porous test specimens and the results obtained with them are of doubtful value. To
minimize surface effects at the edges of the specimen (due sometimes to handling in specimen
preparation), it is recommended that if no guarded electrode is used, the minimum distance from
the electrodes to the specimen edge shall be 0.5 cm.
3. Test equipment
3.1 Resistance measurement (see Figure 1, page 12)
The resistance between electrodes shall be measured with a suitable device having the required
sensitivity and accuracy (see I E C Publication 93).
3.2
Heating chamber
For heating the specimen, a suitable electric oven or furnace shall be used. The construction shall
be such that the specimen is subjected to a uniform temperature throughout its total volume with
temperature fluctuations as small as possible. An adequate muffle should be provided to shield the
specimen from direct radiation by the heating elements. This muffle may be made of a ceramic such
as aluminum oxide or equivalent. A grounded metallic shield of silver, stainless steel or equivalent
metal shall also be provided within the oven. The shield shall act as a guard to prevent leakage
currents between the heating circuit and the measuring circuit. In the case of very high resistance
specimens, it may be necessary to disconnect the heating element to prevent interference during the
measurement,
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SIST HD 438 S1:1998
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3.3 Specimen holder
The specimens shall be mounted securely between two electrode backing plates within the heating
chamber. These backing plates and their respective leads should be made of a metal which is mechani-
cally stable and resistive to oxidation. High-heat-resistant alloys such as stainless steel may also
be utilized. Alternatively, the tests may be performed in an inert atmosphere. The backing plates
shall be of sufficient thickness to prevent warping and to provide heat equalization between the
specimen and the electrode backing plates. The contact faces of the plates should be equal in size to
the specimen electrodes, and one electrode backing plate should be movable so as to allow insertion
and removal of the test specimen.
3.4 Measuring leads
Insulated measuring leads should be brought into the furnace through high-resistance ceramic
insulators located in a cool zone and adequately guarded so as to prevent leakage current from
affecting the test results.
Note. — Alternatively, the leads may be passed through holes in the top or in a wall of the furnace (which should be
earthed). If stiff leads are used, they can be supported externally so as not to touch anything but their supports.
The supports will be relatively cool and thus can be made of any rigid insulating material.
3.5 Temperature control
A means of temperature control shall be
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