1、STD-AECMA PREN 3475-BU7-ENGL L997 3032332 00332L7 TbD Edition approved for publication AECMA STANDARD NORME AECMA AECMA NORM C2 Chairman Comments should be sent within six months after the date of publication to prEN 3475-807 Edition P 1 June 1997 PUBLISHED BY THE EUROPEAN ASSOCIATION OF AEROSPACE I
2、NDUSTRIES (AECMA) Gulledelle 94 - 8-1200 BRUXELLES - Tel. (+32) 2 775 81 10 - Fax. (+32) 2 775 81 11 ICs : Descriptors : ENGLISH VERSION Aerospace series Cables, electrical, aircraft use Test methods Part 807 : Transfer impedance Srie arospatiale Luft- und Raumfahrt Mthodes dessais Prfverfahren Cble
3、s lectriques usage aronautique Partie 807 : Impdance de transfert Elektrischen Leitungen fr Luftfahrt Verwendung Teil 807 : Kupplungswiderstand This “Aerospace Series Prestandard has been drawn up under the responsibility of AECMA (The European Association of Aerospace Industries). It is published o
4、n green paper for the needs of AECMA-Members. It has been technically approved by the experts of the concerned Technical Committee following comment by the Member countries. Subsequent to the publication of this Prestandard, the technical content shall not be changed to an extent that interchangeabi
5、lity is affected, physically or functionally, without re-identification of the standard. After examination and signature of the AECMA Standard Checking Centre (NPS) and formal agreement of the Official Services of the Member countries it will be submitted as a draft European Standard to CEN (Europea
6、n Committee for Standardization) for formal vote. 1997-06-30 I I aecma 1997 AECMA Gulledelle 94 B-1200 BRUXELLES Mr Pezzetta STD-AECMA PREN 3475-807-ENGL 1997 LOL23LL OL32L 9T7 111 Page 3 prEN 3475-807 : 1997 1 Scope This standard specifies methods for measuring the transfer impedance of a cable. It
7、 shall 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 refer
8、ences, 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, aircra
9、ft use - Test methods - Part 100 : General 1) 3 Preparation of specimens These shall be stripped and prepared for connection to the measuring device required for the method chosen. 4 Methods 4.1 Simple method valid up to Method A : cable leakage method Q/m and 10 MHz Matching - resistance lo (to 1 %
10、I - Copper box - Insulating supports - Test cable Place the length of test cable (approximately 1 m) in a sealed copper box with two lead-throughs as shown in figure 1 (dimensions 500 mm x 660 mm). The lead-throughs for the generator and microvoltmeter detector are as shown in figure 2. So that : Vg
11、 = the generator voltage after the attenuator (input to cable) Generator input Output to microvoltmeter Figure 1 V = voltage detected Z, = value in ohms of characteristic impedance in common mode L = length of cable in metres ; therefore : v. z, ZT = - vs. L 1) Published as AECMA Prestandard at the
12、date of publication of this standard Previous page is blank ,STD.AECMA PREN 3475-807-ENLL 1997 1012311 0013219 833 m Page 4 prEN 3475-807 : 1997 Cable screening I IV r“ For multicore cables, the two conductors shall be connected to each other at both ends. For multiscreened cables, these shall be co
13、nnected to each other at both ends. Wall of the copper box Figure 2 The test cable shall be connected via its characteristic impedance Z,. Select a generator with the closest possible impedance to Z,. 4.2 Valid up to f = - , where : f is the frequency, in megahertz L is the cable length, in metres T
14、he conductors inside the screening, the transfer impedance of which is specified in the product standard, shall be connected together at both ends (figure 3). Method B : method of susceptible cable 30 L Cylindrical copper tube I Copper disc soldered to tube and to cable screening 7 I I G Coaxial out
15、put - Metal sleeve soldered Clamp-on probe for direct for measurement of U, to cable screening measurement of current lext. Figure 3 G is a variable frequency power generator. V is a selective voltmeter (field intensity meter) with input impedance 21. The value of I& is obtained either by direct mea
16、surement using a clamp-on current tester or by measuring Ut, by the formula : R is a power limiting resistor U1 is the generator output voltage - STD.AECMA PREN 3475-807-ENGL 1777 m 1012311 Oil13220 555 W Page 5 prEN 3475-807 : 1997 The short circuited elements are considered in the same way as the
17、conductor of a coaxial cable. See figure 4. The length of the cable inside the copper tube is L. The transfer impedance of the cable screening ZT is defined by the following theoretical formula : Figure 4 in which Vint. is the interference voltage appearing between the conductor and the screening. 5 Requirement The transfer impedance values ZT shall be below the values specified in the product standard.
