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1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS EN 50268-2:2000 The Eu
2、ropean Standard EN 50268-2:1999 has the status of a British Standard ICS 13.220.40; 29.060.20 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Common test methods for cables under fire conditions Measurement of smoke density of cables burning under defined conditions Part 2: Pr
3、ocedure This British Standard, having been prepared under the direction of the Electrotechnical Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 April 2000 BSI 04-2000 ISBN 0 580 34493 0 BS EN 50268-2:2000 Amendments issued since publication
4、Amd. No.DateComments National foreword This British Standard is the official English language version of EN 50268-2:1999. It supersedes BS 7622-2:1993 which is withdrawn. The UK participation in its preparation was entrusted by Technical Committee GEL/20, Electric cables, to Subcommittee GEL/20/3, I
5、nsulation and sheath, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European develo
6、pments and promulgate them in the UK. A list of organizations represented on this subcommittee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Cat
7、alogue under the section entitled International Standards Correspondence Index, or by using the Find facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their cor
8、rect application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 6, an inside back cover and a back cover. The BSI copyright notice displayed in
9、 this document indicates when the document was last issued. CENELEC European Committee for Electrotechnical Standardization Comite Europe en de Normalisation Electrotechnique Europa isches Komitee fu r Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels 1999 CENELEC Al
10、l rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 50268-2:1999 E EUROPEAN STANDARDEN 50268-2 NORME EUROPE ENNE EUROPA ISCHE NORM September 1999 ICS 13.220.40; 29.060.20Supersedes HD 606.2 S1:1992 English version Common test methods for cables u
11、nder fire conditions Measurement of smoke density of cables burning under defined conditions Part 2: Procedure Me thodes dessai communes aux ca bles soumis au feu Mesure de la densite de fume es de gage es par des ca bles bru lant dans des conditions de finies Partie 2: Proce dure Allgemeine Pru fve
12、rfahren fu r das Verhalten von Kabeln und isolierten Leitungen im Brandfall Messung der Rauchdichte von Kabeln und isolierten Leitungen beim Brennen unter definierten Bedingungen Teil 2: Pru fverfahren This European Standard was approved by CENELEC on 1999-04-01. CENELEC members are bound to comply
13、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 application to the Central Secret
14、ariat 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 has the same status as th
15、e official versions. CENELEC members are the national electrotechnical standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland,Italy,Luxembourg,Netherlands,Norway,Portugal,Spain,Sweden, Switzerland and United Kingdom. Page 2 EN 50268-2:1999 B
16、SI 04-2000 Foreword This European Standard was prepared by the Technical Committee CENELEC TC20, Electric cables, and agreed at its Dublin meeting (April 1997). The text of the draft was submitted to the Unique Acceptance Procedure and approved by CENELEC as EN 50268-1 on 1999-04-01. This European S
17、tandard supersedes HD 606.2 Sl:1992 The following dates were fixed: latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2000-04-01 latest date by which national standards conflicting with the EN have to be withd
18、rawn (dow) 2001-04-01 Annexes designated informative are given for information only. In this standard annexes A and B are informative. Contents Page Foreword2 1Scope3 2Normative references3 3Definitions3 4Test apparatus3 5Test assembly3 5.1Cable test pieces3 5.2Cable selection and assembly3 5.3Posit
19、ioning of test pieces3 6Test procedure4 7Evaluation of test results4 8Retest procedure4 Annex A (informative) Guidance on calculation of absorbance6 Annex B (informative) Recommended performance requirement6 Page 3 EN 50268-2:1999 BSI 04-2000 1 Scope EN 50268 specifies a method of test for measureme
20、nt of smoke density of cables burning under defined conditions. It is suitable for electric insulated conductor or cable, or optical cables. Part 1 specifies the apparatus and part 2 specifies procedure. This standard includes an informative annex of recommended requirements for compliance. NOTEExpe
21、rience has shown that the test protocol is not suitable for some cables that exceed 70 mm overall diameter. In such cases the manufacturer should be consulted. 2 Normative references This European Standard incorporates by dated or undated reference, provisions from other publications. These normativ
22、e references are cited at the appropriate 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 referenc
23、es the latest edition of the publication referred to applies. EN 50268-1, Common test methods for cables under fire conditions Measurement of smoke density of cables burning under defined conditions Part 1: Apparatus. EN 60695-4, Fire hazard testing Part 4: Terminology concerning fire tests. NOTEIEC
24、 60695 is in the course of re-numbering its parts and sections. This will also affect the equivalent ENs. 3 Definitions For the purposes of this part 2 of EN 50268 the definitions in EN 60695-4 apply. 4 Test apparatus The test procedure defined in this part 2 of EN 50268 shall be carried out using t
25、he test apparatus, i.e. test enclosure, photometric system and standard fire source, given in EN 50268-1. 5 Test assembly 5.1 Cable test pieces These shall consist of one or more samples of cable 1,00 m0,05 m long which shall be carefully straightened and then conditioned for at least 16 h at 23 8C5
26、 8C. 5.2 Cable selection and assembly 5.2.1 Selection of number of test pieces Overall diameter of the cable (D) Number of test pieces mmCablesBundlesd D 401 20 D # 402 10 D # 203 5 D # 10N1a, c 1 # D # 5N2b, c a N1=cables 45 D b N2=bundles 45 3 D c The value of N1and N2shall be rounded downwards to
27、 the integer to give the number of cables or bundles. d Each bundle shall consist of seven cables twisted together with a lay between 20 D and 30 D and bound with two turns of approximately 0,5 mm diameter wire in the centre and at every 100 mm each side from the centre (see Figure 1) 5.2.2 Assembly
28、 of test pieces The test pieces shall remain in situ during the test as follows: cables or bundles shall be bound together at the ends, and at 300 mm from each end, at which place they shall be clamped to the support by means of wire binders. NOTEDepending upon construction, small cables and flexibl
29、e cables may be subject to movement during the test. In these cases it is also recommended that the cables or bundles are bound with two turns of approximately 0,5 mm diameter wire in the centre and at every 100 mm each side from the centre. Alternatively, the cables or bundles may be tensioned at o
30、ne or both ends by means of an appropriate device, for example spring or weight. 5.3 Positioning of test pieces The tray containing the alcohol shall be supported above the ground surface to permit air circulation around and beneath the tray. The test pieces (cables or bundles) shall be laid touchin
31、g in a horizontal position and centred above the tray so that the distance between the underneath of the test pieces and the bottom of the tray is 150 mm5 mm (see Figure 2). Page 4 EN 50268-2:1999 BSI 04-2000 Key: 1. Wire binder 2. Centre 3. Number of test pieces = 7 Dimensions in millimetres Figure
32、 1 Method of binding for cable bundles 6 Test procedure NOTEBefore each test it may be necessary to clean the windows of the photometric system to regain 100 % light transmission after stabilization of the voltage (see also clause A.2 of annex A of EN 50268-1). 6.1 Immediately before commencing a te
33、st, the temperature within the cube shall be in the range of 25 8C5 8C when measured at the internal door surface at a height of 1,5 m to 2,0 m and a minimum of 0,2 m from the walls. 6.2 Before a test, carry out one blank test as defined in EN 50268-1, clause 8 to preheat the test enclosure if neces
34、sary. 6.3 For the test, the fire source shall be as defined in EN 50268-1, clause 6. 6.4 With the test samples supported above the tray, start the air circulation and ignite the alcohol. Make sure that all the persons leave the cube immediately, and that the door is closed. 6.5 The test is considere
35、d as ended when there is no decrease in light transmittance for 5 min after the fire source has extinguished or when the test duration reaches 40 min. 6.6 Record the minimum light transmittance. NOTEIf it is required to use information on smoke density for wider hazard evaluation or fire safety engi
36、neering purposes, it may be necessary to calculate absorbance levels. Guidance on such calculations is given in annex A. 6.7 Extract the combustion products at the end of each test. 7 Evaluation of test results The requirement shall be as given in the relevant cable specification. NOTEIf no value is
37、 given in the relevant cable specification it is recommended that the recommendation in annex B be adopted as a minimum. 8 Retest procedure In case of dispute a further two tests shall be undertaken using similar cables. Both of these test results shall comply with the requirements of clause 7. Page
38、 5 EN 50268-2:1999 BSI 04-2000 Key: A. Side view1. Support4. Back wall B. Plan view2. Metal tray5. Floor 3. Test piece Dimensions in millimetres Figure 2 Method of support of test pieces Page 6 EN 50268-2:1999 BSI 04-2000 Annex A (informative) Guidance on calculation of absorbance The absorbance (Ao
39、), i.e. the absorbance produced across the opposite faces of a cube of side 1 m when one unit of material is burned, is calculated from the expression. Ao= AmV nl where Amis the measured absorbance as calculated in EN 50268-1, 10.5 using the minimum light transmittance (lt) recorded by the photocell
40、 in 6.6 of this part 2; Vis the measured volume of the cube (in m3); nis the total number of samples of cable in the test assembly; NOTEWhere bundles are tested n is the number of bundles multiplied by the number of cable samples in each bundle. lis the measured length of the optical path (in m). Th
41、e absorbance value obtained is of significance if the system involves different cables/products and an overall assessment of smoke density level is required. Annex B (informative) Recommended performance requirement The performance requirements for a particular type or class of insulated conductor o
42、r cable should preferably be given in the individual cable standard. In the absence of any given requirement it is recommended that a value of 60 % light transmittance is adopted as a minimum for any cable tested against this standard. blank BS EN 50268-2:2000 BSI 389 Chiswick High Road London W4 4A
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