1、BSI BS*EN*bOOb8- 2-68 9b Lb24bb9 05bLLL 004 BRITISH STANDARD Environmental testing Part 2. Tests Test L. Dust and sand The European Standard EN 60068-2-68 : 1996 has the status of a British Standard This Part should be read in conjunction with BS EN 600681 : 1995 Geneml and guidance ICs 19.040 NO CO
2、PYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW 3s EN 1996 1994 iOO68-2-68 : EC68-2-68: - BSI BS*EN*b0068- 2-68 96 m 3624669 056L732 T4O 9 Amd.No. The foliowing BSI references relate to the work on this standard. Committee reference GEL150 Draft for comment 89i27022 DC BS EN 60068-
3、2-68 1996 Date Text affeckd Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee GEUM, Environmental testing of electrotechnical products, upon which the following bodies were represented Federation of the Electronics Industry
4、 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 htitute of Materials National Supervising Inspectorate (BSI -PC) Society
5、of Environmental Engineers This British Standard, having been prepared under the direction of the Electrotechnical Sector Board, was published under the authority of the Standards Board and comes into effect on 15 September 1996 O BSI 1996 Amendments issued since publication I ISBN O 580 26154 9 I B
6、SI BS*EN*60068- 2-68 96 = 1624669 0563733 987 = BS EN 60068-2-68 : 1996 Contents page Committees responsible Imide front cover National foreword ii Foreword 2 Text of EN 600682-68 3 O BSI 1996 i BSI BS*EN*h0068- 2-68 96 H 1624669 0561714 813 H BS EN 60068-2-68 : 1996 National foreword This British S
7、tandard has been prepared by Technical Committee GEIJ50 and is the English language version of EN 600682-68 : 1996, Enwironmtal testing Part 2: Tests - Test L: Dust and sand published by the European Committee for Electrotechnical Stankdization (CENELEC). It is identical with IEC 68-2-68 : 1994 publ
8、ished by the Intemational Electrotechnical Commission (IEC). Cross-references Publication referred to Corresponding British Standard EN 600681 : 1994 (IEC 681 : 1988) EN 60529 : 1991 (IEC 529 : 1989) HD 478.2.5 S1: 1993 (IEC 721-2-5 : 1991) BS EN 60068 Environmental testing Part 1 : 199521 Geneml an
9、d guidance BS EN 60529 : 1992 Speci,fzcation for degrees of protection lyravided by enclosures (P code) BS 7527 Clmfication of enwkcmnental w?u?itions Part 2 Enuironmentu conditions appearing in nature Section 2.5 : 1991 Dust, sand, sait mist Compliance with a British Standard does not of itself con
10、fer immunity from legal obligations. 1) Undated in the text. 2) BS EN 6006 b) change of electrical characteristics (for example, 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) surfa
11、ce abrasion (erosion): e) contamination of 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 construction
12、al integrity of electrotechnical products 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. - - BSI BS*EN*b0068- 2-68 96 m 3624667
13、 0.561718 469 m Page 4 EN 60068-2-68 : 1996 ENVIRONMENTAL TESTING - Part 2: Tests - Test L: Dust and sand 1 General This survey indicates the general structure of the dustkand tests included in this publication. The structuring and a summary of the characteristics of the different tests are given in
14、 figure 1 and table I. It should be noted that the dust test of IEC 529 has its equivalent in the proposed method La2. See also annex A. 1.1 Scope This pari of IEC 68-2 specifies test methods to determine the effects of dust and sand suspended in air, on electrotechnical products. The test methods o
15、f 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 100 m/s) particles. 1.2 Description of Test L The dust and sand test is structured into three groups: La: non-abrasive fine dust. A test
16、which is primarily oriented towards 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 repr
17、oduced. Lb: free settling dust. 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 b
18、y gravity onto the specimen. Lc: 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, s
19、and or a dustkand mixture. BSI BS*EN*bOObB- 2-68 96 1624669 0561719 3T5 Dussand concentration 600 glrnzih (grams per square metre per hour) deposit on reference surface 2 kg/mJ (chamber volume) Page 5 EN 60068-2-68 : 1996 Notes Test includes a cycling of the air pressure in the chamber Air pressure
20、in the specimen may be reduced Table i - Summary of test characteristics Method La1 Method La2 Dustlsand I Procedure Talc or FE powder Talc or FE powder I Test La 1 Test Lb Test Lc Method Lcl Method Lc2 Olivine or quartz or feldspar Olivine or quartz or feldspar Olivine or quartz or feldspar 1 gim3
21、or 3 glmJ or 10 glm3 Particle size Free blowing dust 75 pm 75 pm 75 pm 75pm or 150pm or 450 pm 75pm or 450 pm or (850 pm metre per day) deposit 1 gim3 or 3 glm3 or 10 glms Blown dust and sand Recirculating chamber 2 Normative references The following normative documents contain provisions which, thr
22、ough reference in this text, constitute provisions of this part of IEC 68-2. At the time of publication, the editions indicated were valid. All normative documents are subject to revision, and parties to agreements based on this part of IEC 68-2 are encouraged to investigate the possibility of apply
23、ing the most recent editions of the normative documents indicated below. Members of IEC and IS0 maintain registers of currently valid International Standards. IEC 529: 1989, Degrees of protection provided by enclosures (IP code) IEC 721 -2-5: 1991, Classification of environmental conditions - Pari 2
24、: Environmental conditions appearing in nature - Section 5: Dust, sand, salt mist 3 Definitions For the purpose of this part of IEC 68-2 the following definitions apply. 3.1 from 1 pm to 150 pm (see note to 3.7). dust: Particulate matter of unspecified origin or composition whose size ranges 3.2 dus
25、t concentration: Total mass of dust particles per unit volume of air. BSI BS*EN*bOOh- 2-68 96 1624669 0561720 O17 Page 6 EN 60068-2-68 : 1996 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 pressu
26、re at the same temperature. 3.4 hygroscopic: Having a tendency to absorb moisture. 3.5 particle size: 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 mic
27、roscopic images. 3.6 sand: Grains vary from spherical to angular whose size lies between 100 pm and 2 O00 pm, but for environmental testing, the range is usually restricted from 150 pm to 850 pm (see note to 3.7). I 3.7 sieved, which conforms to a test sieve standard specification. sieve (square-mes
28、hed): Intended for the particle size analysis of the material to be I l NOTE - In test Lc of this standard the word dust has been used to include sand. I 4 Test La: non-abrasive fine dust I 4.1 Method Lal: cyclic air pressure I 4.1.1 Object The object of this test is to determine the degree of prote
29、ction 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 75 pm (see 4.3). The test does not simulate natural or induced environments
30、. 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 test specimen to a mainly vertical
31、, 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. I i 1 Dust settled in the base of the test chamber shall be brought back
32、into circulation. BSI BS%EN*bOOb8- 2-64 96 W Lb24bb 05bL72L T53 Page 7 EN 60068-2-68 : 1996 The volume of the specimen shall be no more than 25 o/o of the test chamber volume and its base shall be no more than 50 /O of the horizontal working space surface of the test chamber. If the size of the spec
33、imen does not comply with this standard, the relevant 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 open
34、ings, seats, shaft seals etc, with the delicate parts 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 T
35、est conditions 4.1.4.1 Test dust The test dust consists of dry fine-granular non-abrasive powder which shall be able to pass through a square-meshed sieve with a nominal wire diameter of 50 pm and a nominal width between wires of 75 pm. Talc can be used for this test as analysis shows that it meets
36、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 2 h at +80 “C before use. 4.1.4.2 Dust concentration The quantity of test dust used for the test sh
37、all be sufficient to obtain a uniform deposition on the reference surface in the chamber of (600 f 200) g/mYh. 4.1.4.3 Air flow The air flow in the test chamber shall be mainly vertical from top to bottom and it should not be laminar. 4.1.4.4 Air velocity The air velocity shall give the possibility
38、to generate a homogeneous distribution of the dust in the test chamber. 4.1.4.5 Humidity The relative humidity in the test chamber shall be less than 25 %. This may be achieved by raising the test chamber air temperature. (see clause A.3). BSI BS*EN*60068- 2-68 96 1624669 0561722 T Page 8 EN 60068-2
39、-68 : 1996 4.1.4.6 Depending on the operating conditions there are two different categories of specimen enclosures. Air pressure in the specimen Category 7: enclosures where an air pressure different from the environmental atmos- pheric air pressure may occur, for example caused by thermal cycling e
40、ffects during operation. Category 2: Enclosures where the air pressure is that of the ambient air pressure. The relevant specification shall state the category of the enclosure and the pressure reduction. 4.1.4.6.1 A specimen with a category 1 enclosure shall be introduced into the test chamber and
41、mounted in its normal operating position. It shall be submitted to periods of reduced pressure specified in figure 2. The pressure reduction below ambient shall be 2 kPa (20 mbar) or 5 kPa (50 mbar), as prescribed in the relevant specification. The dust shall be injected during each single cycle as
42、shown in figure 2. 4.1.4.6.2 A specimen with a category 2 enclosure shall be introduced into the test chamber and mounted in its normal operating position. The vacuum pump shall not be operating in such a case. 4.1.4.7 Severities The test severity defined by air pressure in the chamber and duration
43、of test, depending on the category of enclosure (see 4.1.4.6) shall be prescribed by the relevant specif ication. Category 7: pressure reduction of 2 kPa (20 mbar) or 5 kPa (50 mbar), as required by the relevant specification, for a duration of 2 h. Category 2: atmospheric pressure for a duration of
44、 4 h. 4.1.5 Preconditioning The relevant specification may call for a preconditioning. 4.1.6 initiai measurements The specimen shall be submitted to visual, dimensional and functionai checks prescribed by the relevant specification. 4.1.7 Testing The test chamber air shall be at a temperature high e
45、nough to ensure a relative humidity of 25 % or less. The specimen, while being at the ambient temperature of the laboratory, shall be introduced into the test chamber in the unpacked, switched-off, “ready for use“ state, in its normal operating position or as otherwise specified in the relevant spec
46、ifi- cation. In the case of multiple specimens, care shall be taken that the specimens neither touch each other nor shield each other against the influence of dust. BSI BS%EN*h0068- 2-68 Yb lb24bbY 05b1723 82b = Page 9 EN 60068-2-68 : 1996 The relevant specification may call for the specimen to be s
47、witched on and/or operated during the test. Dust shall be introduced into the chamber so that the specified concentration is maintained during the time specified for injection (category 1) or throughout the test duration (category 2). At the end of the conditioning, the specimen shall remain in the
48、closed test chamber until the dust has settled. 4.1.8 Intermediate measurements The relevant specification may call for measurements during or at the end of conditioning while the specimen is still in the test chamber. If such measurements are required, the relevant specification shall define the me
49、asurements and the period or periods after which they shall be carried out. 4.1.9 Recovery Unless otherwise required by the relevant specification, the specimen shall remain under standard atmospheric conditions for recovery for 2 h. 4.1 .l O Cleaning The relevant specification may prescribe removal of external surface dust to be carried out prior to final measurements. 4.1.1 1 Final measurements After recovery the specimen shall be submitted to visual, dimensional and functional checks prescribed by the relevant specification. 4.1 .12 Information to b
