1、Cables, electrical, aircraft use Test methods Part 806: Attenuation The European Standard EN 3475-8062002 has the status of a British Standard ICs 49.060 BS EN 3475-80612002 BS EN 3475-806:2002 National foreword This British Standard is the official English language version of The UKparticipation in
2、 its preparation was entrusted by Technical Committee ACE/6, Aerospace avionic electrical and fibre optic technology, to Subcommittee, ACE/6/2, Aerospace - Cables, which has the responsibility to: EN 3475-80612002. This British Standard, having been prepared under the direction of the Engineering Se
3、ctor Policy and Strategy Committee, was published under the authority of the Standards Policy and Strategy Committee on 25 June 2002 - - 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 i
4、nterests informed; monitor related international 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. Cros s-r e ferenc es The British Standards which implement international or European publi
5、cations referred to in this document may be found in the BSI Standards Catalogue 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 prov
6、isions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not ofitself 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 5
7、and a back cover. The BSI copyright date displayed in this document indicates when the document was last issued. Amendments issued since publication Amd.No. I Date I Comments O BSI 25 June 2002 ISBN O 580 39908 7 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 3475-806 June 2002 ICs 49.060 Engl
8、ish version Aerospace series - Cables, electrical, aircraft use - Test methods - Part 806: Attenuation Srie arospatiale - Cbles lectriques usage aronautique - Mthodes dessais - Partie 806: Affaiblissement Luft- und Raumfahrt - Elektrischen Leitungen fr Luftfahrt Verwendung - Prfverfahren - Teil 806:
9、 Dmpfung This European Standard was approved by CEN on 20 January 2002 CEN members are bound to comply with the CENKENELEC 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 bibliographi
10、cal references concerning such national standards may be obtained on application to the Management Centre or to any CEN 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 CEN me
11、mber into its own language and notified to the Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway
12、, Portugal, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION EUROPISCHES KOMITEE FR NORMUNG COMIT EUROPEN DE NORMALISATION Management Centre: rue de Stassart, 36 B-1050 Brussels O 2002 CEN All rights of exploitation in any form and by any means reserved worldwide
13、 for CEN national Members. Ref. No. EN 3475-806:2002 E EN 3475-80612002 (E) Foreword This document (EN 3475-806:2002) has been prepared by the European Association of Aerospace Manufacturers (AECMA). After enquiries and votes carried out in accordance with the rules of this Association, this Standar
14、d has received the approval of the National Associations and the Official Services of the member countries of AECMA, prior to its presentation to CEN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest
15、by December 2002, and conflicting national standards shall be withdrawn at the latest by December 2002. According to the CENKENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, D
16、enmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. 2 EN 3475-80612002 (E) - / a/ b F 1 Scope Indicator This standard specifies methods for measuring the attenuation of a cable. It sha
17、ll be used together with EN 3475-100. 2 Normative references This European Standard incorporates by dated or undated reference provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated reference
18、s, 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. EN 3475-100 Aerospace series - Cables, electrical, aircraft u
19、se - Test methods - Part 100: General 3 Preparation of specimens Connectors shall be fitted on each end of the test specimens (coaxial cables) or the test specimens shall be stripped (balanced cables) and connected to the measuring device. 4 Methods 4.1 Insertion method Measurement of attenuation is
20、 carried out by transmission in harmonic mode at the frequencies indicated in the product standard, inserting a cable sample in a suitable circuit and by compensating the attenuation caused by this cable by means of a calibrated attenuator. The sample shall be of a length i such that it produces, un
21、less otherwise stipulated in the product standard, an attenuation equivalent to at least 3 dB. Figure 1 shows a basic arrangement. The generator is adjusted to the measuring frequency F and its output level is held constant throughout measurement. The indicator consists either of a measurement recei
22、ver or a detector followed by a d.c. or low frequency voltmeter if the generator is modulated. I Fixled Adaptor attenuator Figure 1 3 EN 3475-80612002 (E) The adaptor devices shown in figure 1 are intended to ensure correct connection between the measuring line and the cable to be tested. Since the
23、measuring line is a coaxial cable, these devices shall not be used if the cable to be tested has a coaxial structure of the same rated characteristic impedance as the line: these are impedance transformers in the case of coaxial cables with different rated characteristic impedance: these are balance
24、d transformers in the case of symmetrical cables (pairs). First note the output level on the indicator which corresponds to a value NI on the calibrated variable attenuator. Then connect the test sample between a and b and readjust the variable attenuator so as to obtain the same indicator level as
25、in the previous operation; if N2 is the new value shown on the variable attenuator, attenuation is: in decibels per metre at 20 “C NI -N2 a= L1+ 0,002 (t - 20) where tis the temperature, in degrees Celsius, of the test specimens. 4.2 The attenuation constant shall be determined from the ratio of the
26、 input and output voltage or power. Both quantities may be measured in turn by a single measuring receiver or simultaneously with a network analyser or two channel powermeters. In the case of a balanced cable, the measurement shall be carried out in a balanced condition. If the measuring test equipm
27、ent is an unbalanced one, both ends of the pair shall be connected to the test equipment by means of baluns. The baluns shall be selected to match the test equipment to the cable nominal impedance at the test frequency. Comparison of input and output voltage or power (insertion loss 2 3 db) Layout T
28、he test equipment shall be assembled generally in accordance with one of the two circuit arrangements shown in figure 2 or figure 3. a b I I X+ 8 9 Figure 2 - Layout of test circuit for comparison -Test set up A Where: 1 : generator 2 : attenuator 6 dB 5 : testspecimen 6 : insertion unit 8 : termina
29、ting load 9 : network analyser 10 : matching baluns (measurement on a balanced cable with an unbalanced measuring test equipment) 4 EN 3475-80612002 (E) a b I 5 6 8 Figure 3 - Layout of test circuit for comparison -Test set up B Where: 1 : generator 2 : attenuator 6 dB 5 : testspecimen 6 : insertion
30、 unit 7 : measuring receiver 8 : terminating load 9 : network analyser 10 : matching baluns (measurement on a balanced cable with an unbalanced measuring test equipment) Procedure For test set up A, the test circuit shall be calibrated at the test frequency with the test ports connected together. Th
31、e test specimen shall then be inserted into the circuit and the ratio of the input and output voltage or power shall be recorded, reading a in decibels. Expression of results The attenuation constant shall be determined as follows: a Testset upA a = , in decibels per metre at 20 “C L I + 0,002 (f -
32、20) , in decibels per metre at 20 “C al - a2 Testset upB a = L I + 0,002 (f-20) Where: a is the test circuit A reading in decibels al is the circuit B reading without the test specimen in decibels a2 is the circuit B reading with the test specimen in decibels L is the length of the test specimen in
33、metres t is the temperature of the test specimen in degrees Celsius 5 The values obtained shall not exceed the values specified in the product standard. Req u i remen t 5 BS EN 3475-80612002 B SI 389 Chiswick High Road London w4 4AL BSI -British Standards Institution BSI is the independent national
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