1、BS EN3475-811:2009ICS 49.060NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDAerospace series Cables, electrical,aircraft use TestmethodsPart 811: Unbalance attenuationThis British Standardwas published under theauthority of the StandardsPolicy and StrategyCommit
2、tee on 30 April2009 BSI 2009ISBN 978 0 580 57578 5Amendments/corrigenda issued since publicationDate CommentsBS EN 3475-811:2009National forewordThis British Standard is the UK implementation of EN 3475-811:2009.The UK participation in its preparation was entrusted to TechnicalCommittee ACE/6, Aeros
3、pace avionic electrical and fibre optictechnology.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its correct application.Compliance with
4、 a British Standard cannot confer immunityfrom legal obligations.BS EN 3475-811:2009EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 3475-811March 2009ICS 49.060English VersionAerospace series - Cables, electrical, aircraft use - Testmethods - Part 811: Unbalance attenuationSrie arospatiale - Cbles
5、 lectriques usagearonautique - Mthode dessai - Partie 811:Affaiblissement de dissymtrieLuft- und Raumfahrt - Elektrische Leitungen frLuftfahrtverwendung - Prfverfahren - Teil 811:UnsymmetriedmpfungThis European Standard was approved by CEN on 30 August 2008.CEN members are bound to comply with the C
6、EN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the CEN Management Centre or t
7、o any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial versions
8、.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, S
9、weden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: Avenue Marnix 17, B-1000 Brussels 2009 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref
10、. No. EN 3475-811:2009: EBS EN 3475-811:2009EN 3475-811:2009 (E) 2 Contents Page Foreword 3 1 Scope 4 2 Normative references 4 3 Terms and definitions .4 4 Preparation of specimens .5 5 Apparatus .5 6 Methods 6 6.1 Calibration 6 6.2 LCL measurement6 6.3 LCTL measurement .7 7 Requirements .7 BS EN 34
11、75-811:2009EN 3475-811:2009 (E) 3 Foreword This document (EN 3475-811:2009) has been prepared by the Aerospace and Defence Industries Association of Europe - Standardization (ASD-STAN). After enquiries and votes carried out in accordance with the rules of this Association, this Standard has received
12、 the approval of the National Associations and the Official Services of the member countries of ASD, 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 by September 200
13、9, and conflicting national standards shall be withdrawn at the latest by September 2009. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent righ
14、ts. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Ita
15、ly, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 3475-811:2009EN 3475-811:2009 (E) 4 1 Scope This standard specifies methods for measuring unbalance attenuation signal in common mode
16、 converted into differential mode caused by the characteristics of symmetry of transmission cables. Terms relative to this attenuation are defined in Clause 3. It shall be used together with EN 3475-100. 2 Normative references The following referenced documents are indispensable for the application
17、of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 3475-100, Aerospace series Cables, electrical, aircraft use Test methods Part 100: General. 3 Terms and definitions For
18、 the purposes of this document, the following terms and definitions apply. 3.1 longitudinal conversion loss (LCL) longitudinal conversion loss is defined as being the logarithmic ratio of the signal injected in common mode at the near end with the resulting differential signal at the near end from a
19、 symmetrical pair The LCL is equal to the attenuation of dissymmetry to the near end when the cable under test is finished with the same impedance that defines for the measurement of the asymmetrical attenuation. (See Figure 1). Z DUT Z/4Z VTELLCL = 20 log10TLVEdB NOTE DUT Device Under Test Figure 1
20、 3.2 longitudinal conversion transfer loss (LCTL) longitudinal conversion transfer loss is defined as being the logarithmic ratio of the signal injected in common mode at the near end with the resulting differential signal at the far end distant from a symmetrical pair The LCTL is equal to the atten
21、uation of dissymmetry at the far end added with the attenuation from the cable under test when this one is terminated with the same impedance that defines for the measurement of the attenuation of dissymmetry. (See Figure 2) BS EN 3475-811:2009EN 3475-811:2009 (E) 5 DUT Z/4Z EL1ZVT2Z/4 VL211 22LCTL
22、= 20 log1021TLVEdB Figure 2 4 Preparation of specimens Test specimen shall be of (100 1) metres length. The ends of the cable under test must be prepared in such way that the assembly of the pairs/quads is maintained. For unscreened twisted pair cables, it is mandatory to create a defined return com
23、mon-mode path. This is normally achieved by earthing all other pairs. However, the cable under test may be wound onto a metal drum. In this case the drum, the adjacent pairs and screens, if present, should be earthed. 5 Apparatus HF Network Analyser Two impedance transformers with centre tap on the
24、secondary windings available (3 ports baluns) Coaxial cables Different resistors terminations The baluns should have the following characteristics: primary impedance: 50 unbalanced secondary impedance: 100 balanced common-mode port impedance: high impedance insertion loss: 3 dB maximum return loss s
25、econdary: 20 dB minimum return loss, common mode: 10 dB minimum longitudinal balance: 60 dB minimum output signal balance: 50 dB minimum common-mode rejection: 50 dB minimum BS EN 3475-811:2009EN 3475-811:2009 (E) 6 6 Methods 6.1 Calibration a) For the reference line calibration over the whole speci
26、fied frequency range the same coaxial cables used for the measurements shall be used by connecting them between the analyser output and the input. b) Two identical baluns shall be used for the measurements. The baluns shall be connected back to back on the symmetrical output side and their attenuati
27、on measured over the specified frequency range. A short length connection shall be used (see Figure 3). The calculated insertion loss is recorded as Ilbal,DM. U0Udiff U150 50 Figure 3 c) The attenuation of the common signals of the test balun is measured by connecting the common-mode port terminals
28、to the differential output terminals of the test balun (see Figure 4). The output terminals of the test balun are short-circuited and connected to the inner conductor of the coaxial test lead. The outer shield of the coaxial test lead should be bonded to the ground plane. The measured insertion loss
29、 is recorded as Ilbal,CM. U0U150 50 Figure 4 Finally the computing correction is: Cor_LCLcal = 3 dB Ilbal,DM Ilbal,CM 6.2 LCL measurement The DUT pair under test should be connected to the differential mode balun output terminals. All unused pairs should be terminated with the suitable resistors as
30、shown in Figure 5. The loads and the cable shielding should be connected on the same ground plane. BS EN 3475-811:2009EN 3475-811:2009 (E) 7 Figure 5 6.3 LCTL measurement The DUT pair under test should be connected to the differential mode balun output terminals, and the far-end to the second differ
31、ential mode balun. All unused pairs should be terminated with the suitable resistors as shown in Figure 6. The loads and the cable shielding should be connected on the same ground plane. Figure 6 7 Requirements The LCL or LCTL values obtained shall not exceed the values specified in the product stan
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