1、BRITISH STANDARD AEROSPACE SERIES Cables, electrical, aircraft use Test methods Part 804: Velocity of propagation The European Standard EN 3475-804:2002 has the status of a British Standard ICs 49.060 BS EN 3475-80412002 WkNb A%“ U- rn% E rn NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY C
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5、nity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 and 3 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
6、Date I Comments O BSI 25 June 2002 ISBN O 580 39910 9 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 3475-804 June 2002 ICs 49.060 English version Aerospace series - Cables, electrical, aircraft use - Test methods - Part 804: Velocity of propagation Srie arospatiale - Cbles lectriques usage ar
7、onautique - Mthodes dessais - Partie 804: Vitesse de propagation Luft- und Raumfahrt - Elektrischen Leitungen fr Luftfahrt Verwendung - Prfverfahren -Teil 804: Ausbreitungsgeschwindigkeit This European Standard was approved by CEN on 20 January 2002 CEN members are bound to comply with the CENKENELE
8、C 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 Management Centre or to any CEN m
9、ember. 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 member into its own language and notified to the Management Centre has the same status as the official versions. CEN member
10、s are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION EUROPISCHES KOMITEE FR
11、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 for CEN national Members. Ref. No. EN 3475-804:2002 E EN 3475-80412002 (E) Foreword This document (EN 3475-804:2002) has
12、 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 Standard has received the approval of the National Associations and the Official Services of the member countries of AECMA, prio
13、r 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 by December 2002, and conflicting national standards shall be withdrawn at the latest by December 2002. According to the
14、CENKENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spai
15、n, Sweden, Switzerland and the United Kingdom. 2 EN 3475-80412002 (E) 1 Scope This standard specifies a method for measuring the velocity of propagation in a cable. It shall be used together with EN 3475-100. 2 Normative references This European Standard incorporates by dated or undated reference pr
16、ovisions from other publications. These normative 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 i
17、t by amendment or revision. For undated references the latest edition of the publication referred to applies. EN 3475-100 Aerospace series - Cables, electrical, aircraft use - Test methods - Part 100: General 3 Preparation of specimens These shall be stripped and prepared for connection to the measu
18、ring device. 4 Method A real time reflectometer shall be used, delivering a reference signal, the rise time of which is equal to or less than 150 ps, fitted at the output to a precision coaxial air line, with a characteristic impedance of Z, (accuracy 1 %), and to an oscilloscope. The measurement sh
19、all be taken on a sample with a length of (3 f 0,Ol) m. The sample shall be prepared for the test so as to minimise mismatch at the cable input (using an appropriate connector or the shortest possible connections). The other end of the cable shall be open circuit. The sample shall be connected to th
20、e coaxial air line as follows: - coaxial cable; Centre and outer conductors connected to their counterparts in the coaxial air line. - symmetrical cables; Measurement in differential mode: each conductor of the pair shall be connected to one of the conductors of the coaxial air line; any screens sha
21、ll not be connected. The velocity of propagation in the cable shall be calculated from the measurement of propagation time t for go and return of the signal in the sample, by the formula: where : V is expressed in kilometres per second t is expressed in nanoseconds 5 The velocity of propagation shal
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