1、BRITISH STANDARD BS EN 61241-2-2:1996 Electrical apparatus for use in the presence of combustible dust Part 2: Test methods Section 2.2 Method for determining the electrical resistivity of dust in layers The European Standard EN 61241-2-2:1995 has the status of a British Standard ICS 29.260.20BSEN61
2、241-2-2:1996 This British Standard, having been prepared under the directionof the Electrotechnical Sector Board, was published underthe authority of the Standards Board and comes intoeffect on 15March1996 BSI 10-1999 The following BSI references relate to the work on this standard: Committee refere
3、nce GEL/31 Draft for comment90/32582 DC ISBN0 580 25239 6 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee GEL/31, Electrical apparatus for explosive atmospheres, upon which the following bodies were represented: Associati
4、on of British Mining Equipment Companies British Cables Makers Confederation British Electrical Systems Association (BEAMA Ltd.) British Gas plc British Lighting Association for the Preparation of Standards (Britlaps) Council for Electrical Equipment for Flammable Atmospheres (BEAMA Ltd.) Department
5、 of Trade and Industry (Standards Policy Unit) ERA Technology Ltd. Electric Trace Heating Industrial Council (Ethic) Electrical Contractors Association Electroheat Manufacturers Association of BEAMA (EMAB) Energy Industries Council Engineering Equipment and Materials Users Association GAMBICA (BEAMA
6、 Ltd.) Gland Manufacturers Technical Committee Health and Safety Executive Institute of Petroleum Lighting Industry Federation Ltd. Loss Prevention Council Marine Safety Agency Ministry of Defence National Inspection Council for Electrical Installation Contracting Rotating Electrical Machines Associ
7、ation (BEAMA Ltd.) Sira Limited Trades Union Congress United Kingdom Offshore Operators Association The following body was also represented in the drafting of the standard, through sub-committees and panels: Department of the Environment (Building Research Establishment) Amendments issued since publ
8、ication Amd. No. Date CommentsBSEN61241-2-2:1996 BSI 10-1999 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2 Introduction 3 1 Scope 3 2 Normative references 3 3 Definitions 3 4 Test apparatus 3 5 Test sample 4 6 Procedure 4 7 Test report 4 Annex ZA (normativ
9、e) Normative references to international publicationswiththeir corresponding European publications 6 Figure 1 Test cell 5 Figure 2 Circuit diagram 5 List of references Inside back coverBSEN61241-2-2:1996 ii BSI 10-1999 National foreword This British Standard has been prepared by Technical Committee
10、GEL/31 and is the English language version ofEN61241-2-2:1995 Electrical apparatus for use in the presence of combustible dust Part2: Test methods Section2: Method for determining the electrical resistivity of dust in layers published by the European Committee for Electrotechnical Standardization (C
11、ENELEC). It is identical with IEC1241-2-2:1993 incorporating corrigendum May1994, published by the International Electrotechnical Commission (IEC), except that inEN61241-1-1 “technical report” has been replaced by “standard” throughout the text. A British Standard does not purport to include all the
12、 necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-reference Publication referred to Corresponding British Standard ISO 4225:1980 a BS 6069
13、Characterization of air quality Part2:1994 Glossary a ISO 4225:1980 has been superseded by ISO4225:1994. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, theEN title page, pages2 to6, an inside back cover and a back cover. This standard has been updated
14、(see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN61241-2-2 August 1995 ICS 29.260.20 Descriptors: Electric equipment, explosive atmosphere, explosion proofing, fi
15、re protection, dust, combustible dust, test, resistivity English version Electrical apparatus for use in the presence of combustible dust Part2: Test methods Section2: Method for determining the electrical resistivity of dust in layers (IEC 1241-2-2:1993+corrigendum1994) Matriels lectriques destins
16、tre utiliss en prsence de poussires combustibles Partie2: Mthodes dessais Section2: Mthode de dtermination de la rsistivit lectrique des couches de poussires (CEI1241-2-2:1993+corrigendum1994) Elektrische Betriebsmittel zur Verwendung in Bereichen mit brennbarem Staub Teil2: Untersuchungsverfahren H
17、auptabschnitt2: Verfahren zur Bestimmung des elektrischen Widerstandes von Staubschttungen (IEC1241-2-2:1993+Corrigendum 1994) This European Standard was approved by CENELEC on1995-03-06. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for
18、 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 offic
19、ial 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 commi
20、ttees of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and UnitedKingdom. CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Euro
21、pisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels 1995 Copyright reserved to CENELEC members Ref. No.EN61241-2-2:1995 EEN61241-2-2:1995 2 BSI 10-1999 Foreword The text of the technical report IEC1241-2-2:1993 with its corrigendum May1994, prepared
22、by SC31H, Apparatus for use in the presence of ignitable dust, ofIECTC31, Electrical apparatus for explosive atmospheres, was submitted to the formal vote and was approved by CENELEC asEN61241-2-2 on1995-03-06 without any modification. The following dates were fixed: Annexes designated “normative” a
23、re part of the body of the standard. In this standard,Annex ZA is normative.Annex ZA has been added by CENELEC. latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 1996-03-01 latest date by which the national st
24、andards conflicting with the EN have to be withdrawn (dow) 1996-03-01EN61241-2-2:1995 BSI 10-1999 3 Introduction This standard 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,
25、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
26、 the apparatus prescribed in IEC1241-2-1 1) , heated to400 C. The test for explosivity will not always reveal the explosive nature of a dust so that a “fail to danger” situation could arise. NOTEPrecautions should be taken to safeguard the health of personnel conducting the tests against the risk of
27、 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. 1 Scope This standard specifies a method of test to determine, by application of a d.c.
28、 voltage, the electrical resistivity of a layer of dust. It is intended to be used in the design, construction, testing, and application of electrical apparatus for use in the presence of combustible dust. The test method is not suitable for use with recognized explosives or substances having explos
29、ive properties. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this standard. At the time of publication, the editions indicated were valid. All normative documents are subject to revision, and parties to ag
30、reements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 565:1990, Test sieves Metal wire cloth, perforated
31、metal plate and electroformed sheet Nominal sizes of openings. ISO 4225:1980, Air quality General aspects Vocabulary. 3 Definitions For the purpose of this standard the following definitions apply. 3.1 dust small solid particles in the atmosphere which settle out under their own weight, but which ma
32、y remain suspended in air for some time NOTEThis definition includes what are defined in ISO4225 as “dust” and “grit”. 3.2 conductive dust dust with electrical resistivity equal to or less than10 37.m 3.3 non-conductive dust dust with electrical resistivity greater than10 37.m 3.4 electrical resisti
33、vity minimum value of the electrical resistance of a dust layer measured between electrodes spaced at unit distance apart, and each having unit area in contact with the dust NOTEFor the purpose of this standard, electrical resistivity is measured in ohm metre. 4 Test apparatus Figure 1 andFigure 2 g
34、ive details for the construction of the test apparatus. The test cell (seeFigure 1) is of open construction, and consists of two stainless steel bars with nominal dimensions: length (W) 100mm, height (H) 10mm, breadth(B) 20mm to40mm. These bars are placed at a nominal distance apart of (L) 10mm on a
35、 base with a thickness between5mm and10mm. NOTEGlass or polytetrafluorethylene (PTFE) have been found to be suitable materials for the base. Two glass bars, also with a nominal height of10mm, are placed across the ends of the electrodes to keep the dust layer in place. Figure 2 illustrates an exampl
36、e of a suitable electrical circuit for making the resistivity measurement. It contains a10k7 resistor to restrict the breakdown current to a maximum value of0,2A at a maximum supply voltage of2000Vd.c. Other circuits with comparable characteristics and accuracy may be used. 1) IEC1241-2-1:1993, Elec
37、trical apparatus for use in the presence of combustible dust Part2: Test methods Section 1 (underconsideration).EN61241-2-2:1995 4 BSI 10-1999 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 prov
38、ide a positive output. All resistors are5%,0,5W 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
39、be tested directly, and the moisture content measured at the same time and reported. The sample of dust to be tested shall, in general, be able to pass through a woven metal wire cloth, or a square hole perforated plate test sieve with a nominal size aperture of71 4m (supplementary size, see ISO565)
40、. If it is required to test coarser dust, a test sieve with a nominal size of aperture up to5004m may be used. State the nominal size of aperture of the sieve used in the report of the test. State the moisture content of the dust sample as tested in the report of the test, and describe the method of
41、 measurement. State in the test report any apparent changes in the properties of the dust, for example moisture content or particle shape, resulting from the preparation of the test sample, for example in sieving. 6 Procedure 6.1 Preliminary measurement Measure the resistance R oof the empty test ce
42、ll with the two glass bars in position. 6.2 Measurement of resistance Pour a weighed quantity of the test sample into the test cell. Remove excess dust by running a straight-edge along the top of the stainless steel electrodes. Collect and weigh the excess. Calculate the mass of dust in the test cel
43、l. Measure the resistance of the filled test cell R swith the following values of d.c.voltage applied: 110, 220, 300, 500, 1000, 1500, 2000 V Apply each value of voltage for at least10s, and longer if polarization is evident. The same sample of dust in the test cell may be used for all the tests at
44、any one of the values of voltage. 6.3 Calculation of resistivity Generally, R ois greater than10 R s , and the resistivity of the dust is calculated from the equation = 0,001 R sH W/L If R ois less than10 R s , the resistivity is calculated from the equation = 0,001 R s R o /R o R s H W/L Calculate
45、the resistivity for each value of the applied voltage. 7 Test report The test report shall include the results of the measurements, the name, source and chemical description (if not implicit in the name) of the dust tested, the particle size and moisture content of the test sample, and the date and
46、identification number of the test. Report the mass of the dust in the test cell, and the ambient temperature at the time of the test. The report shall state that the determination of electrical resistivity of the dust has been carried out in accordance with this standard. where is the resistivity in
47、 7.m R o is the resistance of empty test cell in 7; R s is the resistance of the filled test cell in 7; H is the height of the electrode in mm; W is the length of the electrode in mm; L is the space between electrodes in mm.EN61241-2-2:1995 BSI 10-1999 5 Figure 1 Test cell Figure 2 Circuit diagramEN
48、61241-2-2:1995 6 BSI 10-1999 Annex ZA (normative) Normative references to international publications with their corresponding European publications This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appro
49、priate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies (including amendments). NOTEWhen the international publication has been modified by CENELEC common modifications, indicated by (mod), the relevant EN/HD applies. Publication Yea
