1、AECMA STANDARD NORME AECMA AECMA NORM Edition approved for publication 15 November 2003 prEN 3475-408 Edition P 1 November 2003 Comments should be sent within six months after the date of publication to Electrical Domain AECMA-STAN ICs: Descriptors: Aerospace industry, aircraft equipment, electrical
2、 cables, test ENGLISH VERSION Aerospace series Cables, electrical, aircraft use Test methods Part 408: Fire resistance Srie arospatiale Luft- und Raumfahrt Mthodes dessais Prfverfahren Cbles lectriques usage aronautique Partie 408: Rsistance au feu Elektrische Leitungen fr Luftfahrtvewendung Teil 40
3、8: Feuerbestndigkeit This “Aerospace Series“ frestandard has been drawn up under the responsibility of AECMA-STAN (The European Association of Aerospace Industries - Standardization). It is published for the needs of the European Aerospace Industry. It has been technically approved by the experts of
4、 the concerned Domain following member comments. Subsequent to the publication of this pre-standard, the technical content shall not be changed to an extent that interchangeability is affected, physically or functionally, without re-identification of the standard. After examination and review by use
5、rs and formal agreement of AECMA-STAN, it will be submitted as a draft European Standard (prEN) to CEN (European Committee for Standardization) for formal vote and transformation to full European Standard (EN). The CEN national members have then to implement the EN at national level by giving the EN
6、 the status of a national standard and by withdrawing any national standards conflicting with the EN. I I Copyright 2003 O by AECMA-STA1 Page 2 prEN 3475-408: 2003 Foreword This standard was reviewed by the Domain Technical Coordinator of AECMA-STANS Electrical Domain. After inquiries and votes carr
7、ied out in accordance with the rules of AECMA-STAN defined in AECMA- STANS General Process Manual, this standard has received approval for Publication. Contents Page 1 Scope 3 2 Normative references . 3 3 Preparation of specimens . 3 4 Apparatus 3 5 Method 4 6 Requirements 6 Page 3 prEN 3475-408: 20
8、03 1 Scope This standard specifies a method of testing the fire resistance of “fire-proof electrical cables. It 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 refere
9、nces 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 it by amendment or revision. For undated references the l
10、atest edition of the publication referred to applies. IS0 2685: 1998, Aircraft - Environmental test procedure for airborne equipment - Resistance to fire in designated fire zones EN 3475-100, Aerospace series - Cables, electrical, aircraft use - Test methods - Part 700: General EN 3909, Aerospace se
11、ries - Test fluids, for electric components and sub-assemblies 1) 3 Preparation of specimens 6 test specimens, 0,75 m minimum length, shall be selected at random from a quantity of cable. 4 Apparatus 4.1 List of apparatus The following shall be required for this test: a burner, a test fixture, and t
12、est fluids. 4.2 Burner The burner shall be as described in Annex A of IS02685 or any other burner or assembly of burners satisfying the following conditions: - the minimum width of the burner shall be 50 mm; - cable length exposed to the flame: 152 mm; - diameter or width of the flame at the base of
13、 the burner(s) 2 2 D (D diameter of the cable under test); - flame temperature: (1 100 f 80) OC; - heat flux density received by the calorimeter described in Annex B of IS0 2685: (1 16 f IO) kW/m2. 4.3 Test fixture Refer to Figures 1 and 2. The distance between the burner nose and the cable under te
14、st shall be as specified in IS0 2685 Annex A. The frame of the test fixture shall be vibrated with the following characteristics: - direction perpendicular to the axis of the cable; - frequency: (30 f 5) Hz; - minimum acceleration: 4 g. 1) Published as AECMA Prestandard at the date of publication of
15、 this standard Page 4 prEN 3475-408: 2003 4.4 Fluids The test fluids listed below shall be in accordance with EN 3909. - aircraft fuel (kerosene); - hydraulic fluid (phosphate base); - lubricant (synthetic oil); - cleaning product (isopropylic alcohol); - de-icing fluid (ethylene glycol). 5 Method 5
16、.1 Preparation The test shall be conducted in still air. The centre section of each of the specimens shall be immersed over a length of 0,5 m for 24 h at ambient temperature, one sample in each of the test fluids. After removal from the test fluid any surplus fluid shall be removed with a lint free
17、cloth. The sample shall stand for 1 h. Each sample shall be mounted onto a frame as shown in Figure 1. Each sample shall be wrapped once around with two nickel-chrome ribbons with their inner edges spaced (25 f 5) mm apart. The sample and test ribbons shall be weighted, as shown in Figure 1, and the
18、 test assembly adjusted so that the area wrapped by the ribbons is located at the appropriate distance above the burner where the temperature is 1 100 OC. After tensioning with weights, the samples and test ribbons shall be locked at the pulley position to avoid the weights giving high loading under
19、 vibration/resonant conditions. Single core samples shall be connected to a circuit as shown in Figure 2. Multi-core samples shall be connected to a circuit as shown in Figure 3. Screen cables (metal braid) shall be connected to a circuit as shown in Figure 4. 5.2 Procedure 5.2.1 Note the line curre
20、nt (approximately 2 A); 5.2.2 Operate the switch and observe a 25 mA reading; 5.2.3 Leakage current flow shall not exceed 123 mA during the test period. 5.2.4 Sample continuity is shown when a current flow of 2 A is registered with the electrical supply switched on. The insulation degradation detect
21、ion circuit shall be checked by depressing the test switch; an indication of 25 mA flow should be registered. 5.2.5 Each sample shall be simultaneously subjected to the combined flame and vibration test. The test duration shall be: - 5 minutes for fire resistant cables; - 15 minutes for fire proof c
22、ables. Page 5 prEN 3475-408: 2003 Figure 1 - Test fixture Figure 2 - Circuit diagram for single core cables Page 6 prEN 3475-408: 2003 Cable test s?c ien -1ZjV a) Test 1 - Core-to-core Integrlty Figure 3 - Circuit diagram for multi-core cables Oto5A L Cmnec ons ro setal scree-$- -, 125 C h b) Test 2
23、 - Core-to-screen Integrity Figure 4 - Circuit diagram for screened cables 6 Requirements Check electrical continuity and insulation resistance of the conductor before, continuously throughout and after the test. The maximum current value of 123 mA corresponding to an insulation resistance of 1 O O00 SZ shall not be exceeded.
