1、AECMA STANDARD NORME AECMA AECMA NORM Edition approved for publication Comments should be sent within six months after the date of publication to 31 December 2004 AECMA-STAN prEN 3475-302 Edition P 2 December 2004 Electrical Domain ICs: 49.060 Supersedes issue P 1 of August 1992 and will supersede E
2、N 3475-302:2002 Descriptors: ENGLISH VERSION Aerospace series Cable, electrical, aircraft use Test methods Part 302: Voltage proof test Srie arospatiale Luft- und Raumfahrt Mthodes dessais Prfverfahren Cbles lectriques a usage aronautique Partie 302 : Tenue en tension Elektrische Leitungen fr Luftfa
3、hrtverwendung Teil 302: Spannungsfestigkeit This “Aerospace Series“ Prestandard has been drawn up under the responsibilify 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 app
4、roved by the experts of the concerned Domain following member comments. Subsequent to the publication of this Prestandard, the technical content shall not be changed to an extent that interchangeability is affected, physically or functionally, without re-identification of the standard. After examina
5、tion and review by users 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
6、level by giving the EN the status of a national standard and by withdrawing any national standards conflicting with the EN. Page 2 prEN 3475-302:2004 Foreword This standard was reviewed by the Domain Technical Coordinator of AECMA-STANS Electrical Domain. After inquiries and votes carried out in acc
7、ordance 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 Immersion test . 3 4 Dry spark test (in production) 3 5 Dry impulse test (test in production as an alternativ
8、e to 4) 4 6 Method . 5 7 Voltage test of components (screened cables) . 5 Page 3 prEN 3475-302:2004 1 Scope This standard specifies a method of performing voltage proof tests on finished cables and cables in course of production. It shall be used together with EN 3475-100. 2 Normative references The
9、 following referenced documents are indispensable for the application 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,
10、aircraft use - Test methods - Part 700: General 3 Immersion test The specimens, each 15 m long, shall be immersed in the solution so that their ends are at least 150 mm from the surface of the solution. The composition of the solution, at a temperature of between 15 OC and 25 OC, shall be as follows
11、: - sodium chloride 30 g - distilled water 1 O00 g - wetting agent 2g After immersion for 1 h, the voltage specified by the technical specification with a frequency of 40 Hz to 60 Hz, shall be applied between the conductor of the cable and the screen, if present, or an electrode in contact with the
12、liquid for 5 min. Single and multicore (jacketed) without shield: - between the conductor(s) and an electrode in contact with the liquid Shielded and jacketed cables - between the shield and an electrode in contact with the liquid The voltage rise time shall be between 300 V per second and 500 V per
13、 second. There shall be no perforation of the insulation or jacket. 4 Dry spark test (in production) All the finished cables shall pass, without flash-over, through the electrode of a suitable dry tester, at the voltage stated in the technical specification at a frequency of 40 Hz to 60 Hz. The elec
14、trode consists of an assembly of small chains or other metallic feelers suitable for making close contact with practically the whole surface of the cable. The length of the electrode and speed of the cable shall be such that each portion of the insulation or jacket is subjected to the test voltage f
15、or at least 0,20 s. Page 4 prEN 3475-302:2004 The voltage shall be applied: Single and multicore (jacketed) without shield: - between the conductor(s) and the electrode Shielded and jacketed cables - between the shield and the electrode There shall be no perforation of the insulation or jacket. NOTE
16、 If a defect is found, a minimum length of 30 mrn shall be cut away from each side of the defective point. 5 Dry impulse test (test in production as an alternative to 4) Apparatus The electrode through which the cable passes when subjected to the voltage test shall be formed of beaded chains so that
17、 effectively the whole surface of the cable insulator is in contact with the beads. The characteristics and ancillary apparatus of the impulse test shall be as follows. Impulse test The form of the signal shall be negative pulse with a peak value of the cable test voltage followed by a damped oscill
18、ation. The peak voltage is stated in the technical specification. The rise time of the negative pulse of the signal between O % and 90 % of the peak voltage specified shall not be greater than 75 ps. The peak value of the first positive overshoot of the signal and each of the damped oscillations whi
19、ch flow from it shall be less than the initial negative pulse. The time during which each pulse and its damped oscillation (positive and negative) remain at a voltage equal to 80 % or higher than the specified peak voltage shall be between 20 ps and 100 ps. The pulse rate shall be between 200 pulses
20、 and 500 pulses per second inclusive. Apart from regulation of the peak voltage, conformity with the impulse test parameters shall be defined without capacitance load applied to the electrode. Capacity tolerance As far as the capacitive load is concerned, the suitable tolerance for the apparatus sha
21、ll be such that where there is an increase in the capacitive load between electrode and earth, the peak voltage shall not be reduced by more than 12 % from an initial load of 123 pF/25 mm to 25 pF/25 mm electrode length. Voltmeter A voltmeter allowing continuous reading of the voltage at the electro
22、de terminals is connected. The voltmeter shall be capable of showing a total deviation for a voltage not exceeding 15 kV and shall be accurate to within a minimum of 4 % of the test voltage. Error detection circuit The test apparatus shall consist of an error detection circuit with visual or audible
23、 indication of an insulation fault automatically cutting off the supply to the electrode and stopping the passage of the cable. The detection circuit shall be sensitive enough to show the fault at 75 % of the specified test voltage when an arc occurs between the electrode and earth through a resista
24、nce of 20 k!2; it shall also be capable of detecting a fault with a duration corresponding to that of a pulse. Page 5 prEN 3475-302:2004 Calibration of apparatus The voltmeter shall be calibrated by comparison with another voltmeter capable of detecting the peak voltage of the electrode with or with
25、out auxiliary circuit. During calibration, the calibrated voltmeter shall be directly connected to one of the electrodes or through a calibrated attenuator circuit. The pulse generator shall be switched on and the control voltage of the generator regulated until the voltage reading on the calibrated
26、 voltmeter corresponds to the specified voltage; at this moment the voltage reading on the voltmeter to be calibrated shall be noted. The calibration shall be repeated for each peak voltage at which it is intended to operate the equipment. A calibrated oscilloscope can also be used connected to the
27、electrode through an attenuator. Thus the value of the negative pulse peak can be read directly on the wave form indicator. An oscilloscope connected to the electrode at appropriate different points can also be used to check the conformity of the other waveform parameters specified for the impulse t
28、est. Method The finished cable shall be passed through the electrode and the conductor(s) earthed at one or both ends. The voltage shall be applied: Single and multicore (jacketed) without shield: - between the conductor(s) and the electrode Shielded and jacketed cables - between the shield and the
29、electrode The electrode shall be supplied with the specified voltage and after a final voltage adjustment the cable shall be passed from the pay-off reel to the take-up reel through the electrode. The line speed shall be such that the cable is subjected to no fewer than three pulses and no more than
30、 100 pulses at any given point. During the test, which includes the insertion of new lengths of cable, the cable shall be tested over its total length, including the ends, complying with the procedure. Any ends or other parts of the cable not tested in accordance with this method shall be withdrawn.
31、 There shall be no perforation of the insulation or jacket. NOTE If a defect is found, a minimum length of 50 mrn shall be cut away from each side of the defective point. 6 Voltage test of components (screened cables) The cables shall be subjected to a voltage test at ambient temperature. The r.m.s. value of the voltage shall be specified in the technical specification at a frequency between 40 Hz and 60 Hz. The voltage shall be applied for at least 1 min between one component and the other components and the screen connected together. There shall be no perforation of the insulation.
