IEC 60071-5:2014

SLOVENSKI STANDARD
01-april-1998
Electrical apparatus for use in the presence of combustible dust - Part 2: Test
methods - Section 2: Method for determining the electrical resistivity of dust in
layers
Electrical apparatus for use in the presence of combustible dust - Part 2: Test methods -
Section 2: Method for determining the electrical resistivity of dust in layers
Matériels électriques destinés à être utilisés en présence de poussières combustibles -
Partie 2: Méthodes d'essais - Section 2: Méthode de détermination de la résistivité
électrique des couches de poussières
Ta slovenski standard je istoveten z: IEC/TS 61241-2-2
ICS:
29.260.20 (OHNWULþQLDSDUDWL]D Electrical apparatus for
HNVSOR]LYQDR]UDþMD explosive atmospheres
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

RAPPORT CEI
TECHNIQUE - TYPE 2 IEC
1241-2-2
TECHNICAL
Première édition
REPORT - TYPE 2 First edition
1993-08
Matériels électriques destinés à être utilisés
en présence de poussières combustibles -
Partie 2:
Méthodes d'essais -
Section 2: Méthode de détermination de
la résistivité électrique des couches de poussières
Electrical apparatus for use in the
presence of combustible dust -
Part 2:
Test methods -
2: Method for determining the electrical
Section
resistivity of dust in layers
réservés — Copyright — all rights reserved
© CEI 1993 Droits de reproduction
No part of this publication may be reproduced or util ized in
Aucune partie de cette publication ne peut être reproduite ni
any form or by any means, electronic or mechanical,
utilisée sous quelque forme que ce soit et par aucun pro-
including photocopying and microfilm, without permission
cédé, électronique ou mécanique, y compris la photocopie et
les microfilms, sans l'accord écrit de l'éditeur. in writing from the publisher.
Genève, Suisse
Bureau Central de la Commission Electrotechnique Internationale 3, rue de Varembé
Commission Electrotechnique Internationale CODE PRIX
International Electrotechnical Commission
PRICE CODE J
IEC MemnyHapoaHaa 3nelsrporexHHVecKaa KoMuccaa
catalogue en vigueur
Pour prix, voir •
•
For price, see current catalogue

IEC Publication 1241-2-2
Publication 1241-2-2 de la CEI
(First edition - 1993)
(Première édition - 1993)
Matériels électriques destinés Electrical apparatus
for use in the presence
à être utilisés en présence
of combustible dust
de poussières combustibles
Part 2: Test methods
Partie 2: Méthodes d’essais
Section 2: Method for determining
Section 2: Méthode de détermination
the electrical resistivity
de la résistivité électrique
of dust in layers
des couches de poussières
C O R R I G E N D U M 1
Page 14
Page 15
6.3 Calcul de la résistivit
6.3 Calculation of resistivity
Sous la seconde équation de l’article, au
Under the second equation in the clause,
lieu de:
instead of:
o
where
ρ est la résistivité en Ω;
ρ is the resistivity in Ω;
lire:
read:
o
where
Ω m;
ρ est la résistivité en • ρ Ω•m;
is the resistivity in
May 1994
Mai 1994
1241-2-2 © I EC:1993 - 5 -
INTERNATIONAL ELECTROTECHNICAL COMMISSION
ELECTRICAL APPARATUS FOR USE IN THE
DUST -
PRESENCE OF COMBUSTIBLE
Part 2: Test methods -
Section 2: Method for determining the electrical resistivity
of dust in layers
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization
comprising all national electrotechnical committees (IEC National Committees). The object of the IEC is to
promote international cooperation on all questions concerning standardization in the electrical and
electronic fields. To this end and in addition to other activities, the IEC publishes International Standards.
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. The 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 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.
They have the form of recommendations for international use published in the form of standards, technical
3)
reports or guides and they are accepted by the National Committees in that sense.
In order to promote international unification, IEC National Committees undertake to apply IEC International
4)
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
The main task of IEC technical committees is to prepare International Standards. In excep-
tional circumstances, a technical committee may propose the publication of a technical
report of one of the following types:
cannot be obtained for the publication of an Inter-
• type 1, when the required suppo rt
national Standard, despite repeated efforts;
• type 2, when the subject is still under technical development or where for any other
reason there is the future but not immediate possibility of an agreement on an Inter-
national Standard;
type 3, when a technical committee has collected data of a different kind from that
•
which is normally published as an International Standard, for example "state of the art".
Technical reports of types 1 and 2 are subject to review within three years of publication to
decide whether they can be transformed into International Standards. Technical reports of
type 3 do not necessarily have to be reviewed until the data they provide are considered
to be no longer valid or useful.
IEC 1241-2-2 which is a technical report of type 2, has been prepared by sub-committee 31H:
Apparatus for use in the presence of combustible dust, of IEC technical committee 31:
Electrical apparatus for explosive atmospheres.

1241-2-2 - 9 -
40 I EC:1993
INTRODUCTION
This technical repo rt is applicable to the determination of the electrical resistivity of dust in
layers.
The test method is not suitable for use with recognized explosives, gunpowder, dynamite,
or substances or mixtures of substances which may, under some circumstances, behave
in a similar manner. Where any doubt exists about the existence of a hazard due to
explosive properties, an indication may be obtained by placing a very small quantity of
the dust in question on the heated surface of the apparatus prescribed in IEC 1241-2-1*,
heated to 400 °C.
The test for explosivity will not always reveal the explosive nature of a dust so that a "fail
to danger* situation could arise.
NOTE - Precautions should be taken to safeguard the health of personnel conducting the tests against the
risk of fire, explosion and/or the effects, including toxic effects, of combustion.
This test method is applicable to the construction and application of electrical apparatus
for use in the presence of combustible dust.
Electrical apparatus for use in the presence of combustible dust – Part 2: Test
* IEC 1241-2-1: 1993,
methods – Section 1 (under consideration).

- 13 -
1241-2-2 ©IEC:1993
4 Test apparatus
Figures 1 and 2 give details for the construction of the test apparatus. The test cell (see
figure 1) is of open construction, and consists of two stainless steel bars with nominal
dimensions: length (W) - 100 mm, height (H) - 10 mm, breadth (B) - 20 mm to 40 mm.
These bars are placed at a nominal distance apart of (L) - 10 mm on a base with a thick-
ness between 5 mm and 10 mm.
NOTE - Glass or polytetrafluorethylene (PTFE) have been found to be suitable materials for the base.
Two glass bars, also with a nominal height of 10 mm, are placed across the ends of the
electrodes to keep the dust layer in place.
Figure 2 illustrates an example of a suitable electrical circuit for making the resistivity
measurement. It contains a 10 kf2 resistor to restrict the breakdown current to a maximum
value of 0,2 A at a maximum supply voltage of 2 000 V d.c. Other circuits with comparable
characteristics and accuracy may be used.
The current-to-voltage converter has six ranges to deal with the various values of supply
voltage and dust resistivity. A voltage inverter is present to provide a positive output.
All resistors are 5 %, 0,5 W high-stability carbon-film type.
5 Test sample
The test sample shall be homogeneous and representative of the dust received for testing.
When dust is received, it should be put in a closed vessel until tested, or it should be
conditioned, or it should be tested directly, and the moistu
...