1、BRITISH STANDARD AEROSPACE SERIESBS EN 3475-705:2005Cables, electrical, aircraft use Test methods Part 705: Contrast measurementThe European Standard EN 3475-705:2005 has the status of a British StandardICS 49.060g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g
2、44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN 3475-705:2005This British Standard was published under the authority of the Standards Policy and Strategy Committee on 10 February 2006 BSI 10 February 2006ISBN 0 580 47796 7Nationa
3、l forewordThis British Standard is the official English language version of EN 3475-705:2005. It supersedes BS EN 3475-705:2002 which is withdrawn.The UK participation in its preparation was entrusted by Technical Committee ACE/6, Aerospace avionic electrical and fibre optic technology, to Subcommit
4、tee ACE/6/-/2, Aerospace Cables, which has the responsibility to: A list of organizations represented on this subcommittee can be obtained on request to its secretary.Cross-referencesThe British Standards which implement international or European publications referred to in this document may be foun
5、d in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online.This publication does not purport to include all the necessary provisions of a contract. Users are respon
6、sible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep UK
7、 interests informed; monitor related international and European developments and promulgate them in the UK.Summary of pagesThis document comprises a front cover, an inside front cover, the EN title page, pages 2 to 10, an inside back cover and a back cover.The BSI copyright notice displayed in this
8、document indicates when the document was last issued.Amendments issued since publicationAmd. No. Date CommentsEUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 3475-705October 2005ICS 49.060 Supersedes EN 3475-705:2002 English VersionAerospace series - Cables, electrical, aircraft use - Testmethods
9、- Part 705: Contrast measurementSrie arospatiale - Cbles lectriques usagearonautique - Mthodes dessais - Partie 705 : Mesure decontrasteLuft- und Raumfahrt - Elektrische Leitungen frLuftfahrtverwendung - Prfverfahren - Teil 705:KontrastmessungThis European Standard was approved by CEN on 12 Septembe
10、r 2005.CEN members are bound to comply with the CEN/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
11、 on application to the Central Secretariat or to 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 Central Secretaria
12、t has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, S
13、lovakia,Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2005 CEN All rights of exploitation in any form and by any means reservedworldwide
14、for CEN national Members.Ref. No. EN 3475-705:2005: E2 Contents Page Foreword 3 Introduction4 1 Scope .4 2 Normative references .4 3 Terms and definitions.5 4 Preparation of samples 5 5 Apparatus, measurement and process .6 5.1 Apparatus 6 5.2 Measurement.7 5.3 Process8 6 Requirements 10 EN 3475-705
15、:20053 Foreword This European Standard (EN 3475-705:2005) has been prepared by the European Association of Aerospace Manufacturers - Standardization (AECMA-STAN). After enquiries and votes carried out in accordance with the rules of this Association, this Standard has received the approval of the Na
16、tional Associations and the Official Services of the member countries of AECMA, 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 April 2006, and conflicting nation
17、al standards shall be withdrawn at the latest by April 2006. 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 rights. This European Standard su
18、persedes EN 3475-705:2002. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
19、 Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. EN 3475-705:20054 Introduction It is a requirement within the aerospace industry that all wires and cables within an aircraft electrica
20、l system are identified with a circuit identification code at regular intervals down the length of the wire. Various marking methods are used for marking these identification codes on to the surface of electrical wires or cables including ink based and laser based processes. The legibility of the ma
21、rkings is dependent upon the process used and the insulation medium. Minimum standards of contrast are required to facilitate reading back of the identity codes. 1 Scope This standard specifies the process to be applied for measuring the contrast of wire and cable identification markings against the
22、 background of the unmarked wire insulation. It has been developed primarily to define a reproducible process of contrast value determination for use both to determine the intrinsic laser markability of wires at the time of manufacture or later, and to enable electrical wiring systems manufacturers
23、to ensure that the whole process of wire marking is carried out to the required standard. 2 Normative references The 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
24、 of the referenced document (including any amendments) applies. ISO 7724-1, Paints and varnishes Colorimetry Part 1: Principles. EN 3475-706, Aerospace series Cables, electrical, aircraft use Test methods Part 706: Laser markability. IEC 15-2, Colorimetry. TR 4543, UV laser wire marking systems for
25、aircraft wire and cable identification.1)1) In preparation at the date of publication of this standard. EN 3475-705:20055 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 contrast the ratio of the difference in luminance between the marked and
26、 unmarked areas of the insulation divided by the luminance of the unmarked insulation 3.2 luminance the quantitative measurement of the visible light reflected from a surface, in this case the wire or cable insulation 3.3 laser laser is an acronym for Light Amplification by the Stimulated Emission o
27、f Radiation. Lasers are a source of intense monochromatic light in the ultraviolet, visible or infrared region of the spectrum. 3.4 ultraviolet (abbreviation UV) electromagnetic radiation in a wavelength range from approximately 200 nm to 400 nm 3.5 UV laser a laser that produces a beam of UV radiat
28、ion 3.6 fluence the energy density, measured in J cm-2(Joules per square cm) of a single pulse of the laser beam, which, for the purposes of this document, is taken at the surface of the wire insulation or cable jacket 3.7 wavelength wavelength () is measured in nanometres, nm. 1 nm = 10-9m. = c/f w
29、here c is the velocity of light and f is the frequency 4 Preparation of samples The wire or cable samples shall be identified in accordance with the applicable manufacturing instructions for the marking equipment. Where samples are to be UV laser marked this shall be done using the fluence specified
30、 in TR 4543 or the relevant wire or aircraft manufacturers process specification if different. When determining the laser markability of wires, this shall be in accordance with EN 3475-706. Take a sample of the wire for marking. Before marking the wire ensure that the wire surface is clean and dry a
31、nd free from dust and dirt; if necessary wipe it clean using propan-2-ol (isopropyl alcohol). The surfaces of the samples shall be clean and without damage. The identification markings to be measured shall be even in colour and characters shall have well defined edges. Before starting measurements c
32、lean the surfaces with a soft, lint-free cloth, if required, to avoid distortion of test results by a roughened surface or “deposits”. EN 3475-705:20056 5 Apparatus, measurement and process 5.1 Apparatus 5.1.1 Components of the measuring device The measuring device shall comprise, at a minimum, a ph
33、otometer, an illumination system and a purpose designed sample holder suitable for wire and cable. The whole system shall be designed to ensure that test results are not falsified by external influences. The photometer shall be designed to be stable and free from vibrations and to exclude the influe
34、nces of external light and reflections from scattered light. 5.1.2 Equipment colour The device for holding samples and any accessories and the equipment in the vicinity of the measurement area shall be matt black in colour to absorb scattered light. 5.1.3 Photometer The luminance shall be determined
35、 with a calibrated electrical photometer, which shall incorporate a photopic filter to simulate the response of the human eye. The manufacturers instructions concerning the photometer working range and operating instructions shall be observed. The measurement sensitivity of the photometer shall be i
36、n conformity with IEC publication 15-2. 5.1.4 Illumination and viewing system The illumination system shall consist of two light sources of equal intensity (see Figure 1). The two sources may be two separate lamps or, preferably, two fibre light guides fed from a single lamp. The light from the sour
37、ces shall overlap to illuminate a central spot on the sample at an angle of 45oto the surface. The light cones shall illuminate the wire sample longitudinally along its length and in a manner to avoid the formation of shadows. The photometer must be installed to view the sample along the normal to t
38、he surface, i.e. at 90o, and above the principal focus at a distance that depends on the objectives focal distance. It shall be adjusted during calibration and after every change of objective. If two separate lamps are used they shall be of identical power consumption and shall always be exchanged i
39、n pairs. The radiating light energy and colour temperature of the lamps shall be compatible with the working range of the photometer, according to the manufacturers instructions. The spectral distribution of the light shall be close to artificial light specifications according to light standard A, I
40、SO 7724-1. Only gas filled lamps with tungsten filaments shall be used. The colour temperature shall be (3 000 500) K. The voltage supply for the lamps shall be insensitive to line fluctuations. A stabilised d.c. power unit shall be used. EN 3475-705:20057 Key 1 Photometer 2 Source of light 3 Marked
41、 cable Figure 1 Lighting equipment 5.2 Measurement 5.2.1 Equipment design and measurement methodology To determine the contrast, measurements must be taken of the luminance from both marked and unmarked areas of the insulation. Depending upon the contrast measurement equipment design, the photometer
42、 may be used either to take a series of individual point measurements sequentially or it may determine the contrast instantaneously by the simultaneous measurement of the luminance of all the sample points of an area of the sample. If a point measurement system is used, sufficient points shall be sa
43、mpled on both the marked and unmarked portion of the wire to ensure that a good average value of the reflectance of each is obtained. 5.2.2 Measurement spot size The maximum admissible diameter of the photometer measurement spot shall be not in excess of 75 % of the character stroke width. This is p
44、articularly important if using a point measurement system where spot sizes are typically relatively large. 5.2.3 Measurement area The contrast shall be measured over a finite area to include a significant portion of the marked and the unmarked surface of the wire. EN 3475-705:20058 It is important t
45、hat spot measurements should not be made immediately adjacent to the edge of a character, either on the mark or the unmarked insulation, to avoid scattered light from the adjacent area from interfering with the measurement. Area measurement systems should discriminate against such scattered light by
46、 suitable means. 5.2.4 Calibration The photometer shall be calibrated by use of a reference sample, e.g. ceramic tiles, of known reflectance, certified and traceable to National Standards. The frequency of calibration shall be in accordance with the equipment manufacturers guidelines. 5.2.5 Measurem
47、ent tolerance The measuring tolerance of the photometer shall be not more than 2 %. 5.3 Process 5.3.1 Precautionary measures There may be a danger from some illumination systems that they may cause the samples to heat up significantly. If this is the case then measurements should be taken without de
48、lay and the sample removed from the test area after the measurements have been taken. Contrast measurements shall not be taken in areas of the sample a) incorporating the wire manufacturers markings, b) for tape wrapped wires, in areas where the tapes overlap, or c) where there are visible inclusion
49、s, deformities or other surface irregularities, as these can all cause errors in the determination of the contrast value. NOTE If checking for repeatability it is of the utmost importance to ensure that the same character of the same mark and the same position within the character are measured each time. Significant variations in contrast may occur otherwise. WARNING The contrast formula in 5.3.5 is limited in its application to white and light coloured wires. Care must be taken when interpreting the contrast results of some dark colour
