1、BRITISH STANDARD BSEN 60068-2-68: 1996 IEC68-2-68: 1994 Environmental testing Part 2: Tests Test L: Dust and sand The European Standard EN60068-2-68:1996 has the status of a BritishStandard This Part should be read in conjunction with BSEN60068-1:1995 General and guidance ICS19.040BSEN60068-2-68:199
2、6 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 15September1996 BSI 04-1999 The following BSI references relate to the work on this standard: Committee referenceGEL/
3、50 Draft for comment 89/27022DC ISBN 0 580 26154 9 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee GEL/50, Environmental testing of electrotechnical products, upon which the following bodies were represented: Federation o
4、f the Electronics Industry GAMBICA (BEMA Ltd.) Ministry of Defence Society of Motor Manufacturers and Traders Limited The following bodies were also represented in the drafting of the standard, through subcommittees and panels: Biodeterioration Society Institute of Materials National Supervising Ins
5、pectorate (BSIPC) Society of Environmental Engineers Amendments issued since publication Amd. No. Date CommentsBSEN60068-2-68:1996 BSI 04-1999 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2 Text of EN60068-2-68 3 List of references Inside back coverBSEN6006
6、8-2-68:1996 ii BSI 04-1999 National foreword This British Standard has been prepared by Technical Committee GEL/50 and is the English language version of EN60068-2-68:1996, Environmental testing Part 2: Tests Test L: Dust and sand published by the European Committee for Electrotechnical Standardizat
7、ion (CENELEC). It is identical with IEC68-2-68:1994 published by the International Electrotechnical Commission (IEC). A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a
8、 British Standard does not of itself confer immunity from legal obligations. Cross-references Publication referred to Corresponding British Standard EN60068-1:1994 (IEC68-1:1988) BSEN60068 Environmental testing Part 1:1995 aGeneral and guidance EN60529:1991 (IEC529:1989) BSEN60529:1992 Specification
9、 for degrees of protection provided by enclosures (IPcode) HD478.2.5S1:1993 BS7527 Classification of environmental conditions (IEC721-2-5:1991) Part 2 Environmental conditions appearing in nature Section 2.5:1991 Dust, sand, salt mist a BSEN60068-1:1995 includes the corrigendum October 1988 and A1:1
10、993 to IEC68-1. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, theEN title page, pages 2 to 48, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated
11、in the amendment table on theinside front cover.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN60068-2-68 April 1996 ICS19.040 Descriptors: Environmental testing, electrotechnical products, test methods, non-abrasive fine dust, free settling dust, blown dust and sand English version Environment
12、al testing Part 2: Tests Test L: Dust and sand (IEC68-2-68:1994) Essais denvironnement Partie 2: Essais Essai L: Poussire et sable (CEI68-2-68:1994) Umweltprfungen Teil 2: Prfungen Prfung L: Staub und Sand (IEC68-2-68:1994) This European Standard was approved by CENELEC on 1996-03-05. CENELEC member
13、s 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 applicatio
14、n 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 ha
15、s the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CENELEC European
16、 Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels 1996 Copyright reserved to CENELEC members Ref. No. EN60068-2-68:1996EEN60068-2-68:1996 BSI 04-199
17、9 2 Foreword The text of the International Standard IEC68-2-68:1994, prepared by SC50B, Climatic tests, of IECTC50, Environmental testing, was submitted to the formal vote and was approved by CENELEC as EN60068-2-68 on1996-03-05 without any modification. The following dates were fixed: Annexes desig
18、nated “normative” are part of the body of the standard. Annexes designated “informative” are given for information only. In this standard, Annex ZA is normative and Annex A and Annex B are informative. Annex ZA has been added by CENELEC. Contents Page Introduction 3 1 General 3 1.1 Scope 3 1.2 Descr
19、iption of Test L 3 2 Normative references 3 3 Definitions 4 4 Test La: non-abrasive fine dust 5 4.1 Method La1: cyclic air pressure 5 4.2 Method La2: constant air pressure 7 4.3 Guidance for test La 10 5 Test Lb: free settling dust 16 5.1 Object 16 5.2 Method Lb 16 5.3 Guidance for test Lb 18 6 Test
20、 Lc: blown dust and sand 23 6.1 Method Lc1: recirculating chamber 23 6.2 Method Lc2: free blowing dust 27 6.3 Guidance for test Lc 29 Annex A (informative) Guidance 40 Annex B (informative) Bibliography 47 Page Annex ZA (normative) Normative references tointernational publications with their corresp
21、onding European publications 47 Figure 1 Structuring of test methods 34 Figure 2 Pressure cycle in the test chamber Category 1 34 Figure 3 Example of a suitable test chamber for method La1 35 Figure 4 Example of a suitable test chamber for method La2 36 Figure 5 Example of test apparatus for test Lb
22、 37 Figure 6 Principal layout of test apparatus for method Lc1 38 Figure 7 Example of dust injection system for method Lc2 39 Figure A.1 Particule size distribution 45 Figure A.2 Relative humidity according to temperature (example) 46 Table 1 Summary of test characteristics 4 Table 2 Typical dust an
23、d sand sedimentation rates 22 Table 3 Acceleration factor 22 Table A.1 Hardness scale 41 Table A.2 Comparison of test methods 44 latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 1997-03-01 latest date by whic
24、h the national standards conflicting with the EN have to be withdrawn (dow) 1996-03-01EN60068-2-68:1996 BSI 04-1999 3 Introduction The tests described in this part of IEC68-2 give information on effects for which the relevant specification may specify assessment criteria. Some of such effects are: a
25、) ingress of dust into enclosures; b) change of electrical characteristics (forexample, faulty contact, change of contact resistance, change of track resistance); c) seizure, or disturbance in motion of bearings, axles, shafts and other moving parts; d) surface abrasion (erosion); e) contamination o
26、f optical surfaces; contamination of lubricants; f) clogging of ventilating openings, bushings, pipes, filters, apertures necessary for operation etc. Different tests have been specified to consider diversified aspects which may be used to verify constructional integrity of electrotechnical products
27、 or to simulate the conditions of operation in service. The tests differ by the character of the air flow carrying the particulate matter, and by the type of such matter, resulting in a special methodology for each test. 1 General This survey indicates the general structure of the dust/sand tests in
28、cluded in this publication. The structuring and a summary of the characteristics of the different tests are given in Figure 1 and Table 1. It should be noted that the dust test of IEC529 has its equivalent in the proposed method La2. SeealsoAnnex A. 1.1 Scope This part of IEC68-2 specifies test meth
29、ods to determine the effects of dust and sand suspended in air, on electrotechnical products. The test methods of this standard are not intended for the testing of air filters. Only method Lc2 is suitable for the simulation of the erosion effects of high velocity (more than 100m/s) particles. 1.2 De
30、scription of Test L The dust and sand test is structured into three groups: 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this part of IEC68-2. At the time of publication, the editions indicated were valid.
31、 All normative documents are subject to revision, and parties to agreements based on this part of IEC68-2 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 Intern
32、ational Standards. IEC529:1989, Degrees of protection provided by enclosures (IP code). IEC721-2-5:1991, Classification of environmental conditions Part 2: Environmental conditions appearing in nature Section 5: Dust, sand, salt mist. La: non-abrasive fine dust. A test which is primarily oriented to
33、wards investigation of the seals of the test specimen. The test specimen is exposed to a very fine dust in the form of talc or an equivalent. The effects of temperature cycling resulting in a pressure difference between the inside and outside of the specimen may be reproduced. Lb: free settling dust
34、. A test which is oriented towards investigation of the effects when simulating conditions at sheltered locations. The test specimen is exposed to a low-density dust atmosphere created by the intermittent injection of a small quantity of dust which is allowed to fall by gravity onto the specimen. Lc
35、: blown dust and sand. A test which is oriented towards investigation of the seals and the effect of erosion when simulating outdoor and vehicle conditions. The test specimen is exposed to either a turbulent or a laminar air flow to which is added a quantity of dust, sand or a dust/sand mixture.EN60
36、068-2-68:1996 4 BSI 04-1999 3 Definitions For the purpose of this part of IEC68-2 the following definitions apply. 3.1 dust particulate matter of unspecified origin or composition whose size ranges from 14m to 1504m (seenoteto3.7) Table 1 Summary of test characteristics 3.2 dust concentration total
37、mass of dust particles per unit volume of air 3.3 humidity relative humidity is defined as the ratio of the actual vapour pressure in the air at any temperature to the maximum of saturation vapour pressure at the same temperature 3.4 hygroscopic having a tendency to absorb moisture 3.5 particle size
38、 general dimension of the dust and sand particles based on the premise that the particles are spheres; commonly measured by sieving, by calculating settling velocities, or by determining areas of microscopic images 3.6 sand grains vary from spherical to angular whose size lies between 1004m and 2000
39、4m, but for environmental testing, the range is usually restricted from 1504m to 8504m (see note to 3.7) 3.7 sieve (square-meshed) intended for the particle size analysis of the material to be sieved, which conforms to a test sieve standard specification Procedure Dust/sand type Particle size Dust/s
40、and concentration Notes Test La Method La1 Talc or FE powder 754m 600g/m2/h (grams per square metre per hour) deposit on reference surface Test includes a cycling of the air pressure in the chamber Method La2 Talc or FE powder 754m 2kg/m3 3 (chamber volume) Air pressure in the specimen may be reduce
41、d Test Lb Olivine or 754m 6g/m 2 /d (grams per square metre per day) deposit on reference surface Free settling dust quartz or feldspar Test Lc Method Lc1 Olivine or 754mor 1g/m 3or Blown dust and sand quartz or 1504mor 3g/m 3or Recirculating chamber feldspar 8504m 10g/m 3 Method Lc2 Olivine or 754m
42、or 1g/m 3or Free blowing dust quartz or 1504mor 3g/m 3or feldspar 8504m 10g/m 3EN60068-2-68:1996 BSI 04-1999 5 NOTEIn test Lc of this standard the word “dust” has been used to include “sand”. 4 Test La: non-abrasive fine dust 4.1 Method La 1: cyclic air pressure 4.1.1 Object The object of this test
43、is to determine the degree of protection against ingress of fine dust into electrotechnical products. 4.1.2 General description Method La1 is a dust test in which the specimen is exposed to a dust-laden air flow containing non-abrasive powder of particle size 754m (see4.3). The test does not simulat
44、e natural or induced environments. A vertical air flow downwards is specified for the test. For enclosures of a specific category the pressure in the dust chamber is varied cyclically in order to encourage the ingress of powder. 4.1.3 Description of test apparatus The test chamber shall expose the t
45、est specimen to a mainly vertical, non-laminar air flow containing a specified quantity of test dust. For this purpose, the test dust shall be agitated and blown into a sealed chamber. It shall be possible to cycle the chamber pressure as required by 4.1.4.6. Dust settled in the base of the test cha
46、mber shall be brought back into circulation. The volume of the specimen shall be no more than25% of the test chamber volume and its base shall be no more than50% of the horizontal working space surface of the test chamber. If the size of the specimen does not comply with this standard, the relevant
47、specification shall prescribe which of the following procedures shall be applied: a) testing of individually enclosed sections of the product; b) testing of representative parts of the product comprising components such as doors, ventilating openings, seats, shaft seals etc, with the delicate parts
48、of the product such as terminals, collector rings etc, in position at the time of testing; c) testing of smaller products having the same design details as full scale products. An example of a suitable test apparatus is given in Figure 3. 4.1.4 Test conditions 4.1.4.1 Test dust The test dust consist
49、s of dry fine-granular non-abrasive powder which shall be able to pass through a square-meshed sieve with a nominal wire diameter of 504m and a nominal width between wires of 754m. Talc can be used for this test as analysis shows that it meets these requirements (see 4.3.4.2). The test dust shall not be used for more than 20 tests. Care should be taken to keep the powder dry to maintain its fine granularity. It shall be dried by heating for 2h at+80C before use. 4.1.4.2 Dust concentration The quantity of test dust used
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