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1、BRITISH STANDARDCommon test methods for cables under fire conditions Measurement of smoke density of cables burning under defined conditions Part 1: ApparatusThe European Standard EN 50268-1:1999 has the status of aBritish StandardICS 13.220.40; 29.060.20| BS EN50268-1:2000|NO COPYING WITHOUT BSI PE
2、RMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBS EN 50268-1:2000National forewordThis British Standard is the official English language version of EN 50268-1:1999. It supersedes BS 7622-1:1993, which is withdrawn.The UK participation in its preparation was entrusted by Technical Committee GEL/20, Ele
3、ctric cables, to Subcommittee GEL/20/3, Insulation and sheath, which has the responsibility to: aid enquirers to understand the text; present to the responsible European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related intern
4、ational and European developments and promulgate them in the UK.A list of organizations represented on this subcommittee can be obtained on request to its secretary.Cross-referencesThe British Standards which implement international or European publications referred to in this document may be found
5、in the BSI Standards Catalogue under the section entitled International Standards Correspondence Index, or by using theFind 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 res
6、ponsible for their correct application.Compliance with a British Standard does not of itself confer immunity from legal obligations.Summary of pagesThis document comprises a front cover, an inside front cover, the EN title page, pages 2 to 7 and a back cover.The BSI copyright notice displayed in thi
7、s document indicates when the document was last issued.Amd. No.DateCommentsThis British Standard, having been prepared under the direction of the ElectrotechnicalSector Committee, was published under the authority of the Standards Committee and comes into effect on 15 April 2000BSI 04-2000ISBN 0 580
8、 34494 0Amendments issued since publicationEUROPEAN STANDARDEN 50268-1NORME EUROPE ENNEEUROPA ISCHE NORMSeptember 1999ICS 13.220.40; 29.060.20Supersedes HD 606.1 S1:1992English versionCommon test methods for cables under fire conditions Measurement of smoke density of cables burning under defined co
9、nditions Part 1: ApparatusMe thodes dessai communes aux ca bles soumis au feu Mesure de la densite de fume es de gage espar des ca bles bru lant dans des conditions de finies Partie 1: AppareillageAllgemeine Pru fverfahren fu r das Verhalten von Kabeln und isolierten Leitungen im Brandfall Messung d
10、er Rauchdichte von Kabeln und isolierten Leitungen beim Brennen unter definierten Bedingungen Teil 1: Pru feinrichtungThis European Standard was approved by CENELEC on 1997-04-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving
11、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 official versio
12、ns (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 committees of Au
13、stria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.CENELECEuropean Committee for Electrotechnical Standardization Comite Europe en de Normalisation Electrotechniq
14、ue Europa isches Komitee fu r Elektrotechnische NormungCentral Secretariat: rue de Stassart 35, B-1050 Brussels1999 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELECmembers.Ref. No. EN 50268-1:1999 EPage 7EN 50268-1:1999BSI 04-2000ForewordThis European St
15、andard was prepared by the TechnicalCommittee CENELEC TC20, Electric cables, andContentsPageagreed 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 Standard supersedes HD 606.1
16、Sl:1992The following dates were fixed:Foreword 21Scope 32Normative references 33Definitions 34Details of test enclosure 35Photometric system 3 latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement latest date by which n
17、ational standards conflicting with the EN have to be withdrawn(dop) 2000-04-01(dow) 2001-04-016Standard fire source 47Smoke mixing 48Blank test 48.1Purpose 48.2Procedure 49Qualification of test apparatus 410Qualification burning test 4Annexes designated informative are given for information only. In
18、 this standard annexes A and B are informative.10.1 Purpose 410.2 Preparation of cube 410.3 Qualification smoke sources 410.4 Test procedure 410.5 Calculation 410.6 Requirements 5Annex A (informative) Guidance notes 7Annex B (informative) Bibliography 71 ScopeEN 50268 specifies a method of test for
19、measurement of smoke density of cables burning under defined conditions. It is suitable for electric insulated conductor or cable, or optical cables. This part 1 details the apparatus. The procedure, together with an informative annex of recommended requirements for compliance, is given in part 2.NO
20、TE Experience has shown that the test protocol is not suitable for some cables that exceed 70 mm overall diameter. In suchcases the manufacturer should be consulted.2 Normative referencesThis European Standard incorporates by dated or undated reference, provisions from other publications. These norm
21、ative 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 onlywhen incorporated in it by amendment or revision. For undated refer
22、ences the latest edition of the publication referred to applies.EN 60695-4, Fire hazard testing Part 4: Terminology concerning fire tests.NOTE IEC 60695 is in the course of re-numbering its parts and sections. This will also affect the equivalent ENs.3 DefinitionsFor the purposes of this part 1 of E
23、N 50268 the definitions in EN 60695-4 apply.4 Details of test enclosureThe equipment shall comprise a cubic enclosure with inside dimensions of 3 000 mm30 mm and constructed of a suitable material fixed on to a steel angle frame. One side shall have a door, with a glass inspection window. Transparen
24、t sealed windows (minimum size 100 mm 3 100 mm) shall be provided on two opposite sides to permit the transmission of a beam of light from the horizontal photometric system. The distance from the floor to the centre of these windows shall be 2 150 mm 100 mm (see Figure 1 for plan view).The walls of
25、the enclosure shall include orifices at ground level, i.e. not greater than 100 mm above the level of the chamber floor, for the passage of cables etc., and to permit the enclosure to be at atmospheric pressure. No orifice shall be directly behind the fire source or on the same wall. A minimum of tw
26、o orifices shall be provided and the total area of the orificesopen during the test shall be 50 cm2 10 cm2. The ambient temperature outside the enclosure shall be20 8C10 8C and the enclosure shall not be directly exposed to sunlight or extreme climatic changes. NOTE It should normally be possible to
27、 extract fumes from theenclosure after each test through a duct complete with valvewhich should be closed during the test. The duct may include a fan to increase the rate of extraction. It is recommended that the door of the enclosure be opened to assist the extraction process.A draught screen, 1 50
28、0 mm long and 1 000 mm high, shall be placed in the enclosure, at the position shown in Figure 1. It shall abut the back wall at a point750 mm from the side wall, and shall be curved to intersect the centre line of the enclosure at a point 1400 mm from the back wall.5 Photometric system5.1 The photo
29、metric system is illustrated in Figure 2. The light source and the receiver shall be placed externally in the centre of both windows in the two opposite walls of the cube without making physical contact. The light beam shall traverse the cube through the glass windows in the side walls.5.2 The light
30、 source shall be a halogen lamp with a tungsten filament with a clear quartz bulb having the following characteristics:nominal power: 100 Wnominal voltage: 12 V d.c.nominal luminous flux: 2 000 lm to 3 000 lm nominal colour temperature: 2 800 K to 3 200 KThe bulb shall be supplied with a voltage of1
31、2,0 V0,1 V (mean value). During the test the voltage shall be stabilized to a range of 0,01 V (see A.2c) for additional guidance). The lamp shall be mounted in a housing and the beam adjusted by a lens system togive an evenly illuminated circular area of 1,5 m 0,1 m diameter on the interior of the o
32、pposite wall.5.3 The receptor photocell shall be of the selenium or silicon type with a spectral response matching the International Commission on Illumination (CIE) photopic observer (equivalent to the human eye).The photocell shall be mounted at the end of150 mm 10 mm tube with a dust protection w
33、indow at the other end. The inside of the tube shall be matt black to prevent reflections. The photocell shall be connected to a potentiometric recorder to produce a linear proportional output. The cell shall beresistance-loaded to operate in its linear range and the input impedance of the recorder
34、shall be at least 104 times greater than the load resistance of the cell which shall not exceed 100 V.5.4 The photometric system shall be energized before the blank test. When stability has been attained, the zero and full scale reading of the recorder shall be adjusted for light on the detector cor
35、responding to 0 % (absence of light) and 100 % luminous transmission.NOTE Periodically, for example at the beginning of a test series, the performance of the photocell should be verified by placing standard neutral density filters in the light beam, It is essential that these filters cover the entir
36、e optical entry port of the photocell and the values of absorbance (or optical density) measured by the photocell fall within 5 % of the calibrated value of the filter. The filters should also permit the verification of the linearity of response of the detector which should be proportional to the ab
37、sorbance of light in the range used.6 Standard fire sourceThe standard fire source shall be 1,00 litre 0,01 litre of alcohol having the following composition by volume:ethanol: 90 % 1 % methanol: 4 %1 % water:6 %1 % When a denaturing agent is added to the alcohol, it shall have no effect on the smok
38、e emission of any cable under test.The alcohol shall be contained in a tray made from galvanised or stainless steel with jointed sealed edges, a trapezoidal trunk section and the following interior dimensions (see Figure 3):bottom base: 210 mm 3 110 mm top base: 240 mm 3 140 mm height:80 mmAll dimen
39、sions 2 mmThickness of tray: 1,0 mm 0,1 mmThe tray shall be supported at a height of100 mm 10 mm from the floor to permit air circulation around and beneath the tray.7 Smoke mixingIn order to ensure uniform distribution of the smoke, a table-type fan shall be placed on the floor of the cube as shown
40、 in Figure 1, the fan axis being between200 mm and 300 mm from the floor and the distance from the wall being 500 mm 50 mm. The fan shall have a blade sweep of 300 mm 60 mm and a flow rate of 7 m3/min to 15 m3/min. Air shall then be blown horizontally by the fan during the tests but the ignition sou
41、rce shall be protected by the screen as shown.NOTE Suitable fans may be found by reference to IEC 60879, Performance and construction of electric circulating fans and regulators.8 Blank test8.1 PurposeThe purpose of the blank test is to condition the interior of the cube to the specified temperature
42、 range, when necessary, prior to carrying out tests.8.2 Procedure8.2.1 Burn approximately 1 litre of alcohol as detailed in clause 6, in order to preheat the test enclosure.8.2.2 Purge the inside of the cube of all combustion products by operating the extraction system.9 Qualification of test appara
43、tusIn order to ensure that the combination of the test cube and the optical system produce results consistent with other test cubes when identical cables are burned under the same conditions, the test apparatus shall be subject to qualification. Qualification shall be achieved by carrying out the Qu
44、alification Burning Test(clause 10). The test apparatus shall meet the stated requirements.10 Qualification burning test10.1 PurposeThe purpose of the qualification burning test is to verify that the smoke produced in the cube gives standard absorbance values within the limits quoted in10.6 for both of the alcohol/toluene smoke sources described in 10.3.10.2 Preparation of cubeClean the windows of the photometric system to regain 100 % transmission after stabilization of the voltage.Immediately
