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BRITISH STANDARD BS EN

3745-705:2007

Aerospace series — Fibres and cables, optical, aircraft use — Test methods —

Part 705: Contrast measurement

ICS 49.060

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BS EN 3745-705:2007

This British Standard was

published under the authority

of the Standards Policy and

Strategy Committee

on 31 March 2008

© BSI 2008

ISBN 978 0 580 53160 6

National foreword

This British Standard is the UK implementation of EN 3745-705:2007 The UK participation in its preparation was entrusted by Technical Committee ACE/6, Aerospace avionic electrical and fibre optic technology, to Panel ACE/6/-/10, Aerospace-fibre optic systems and equipment

A list of organizations represented on this committee can be obtained on request to its secretary

This publication does not purport to include all the necessary provisions of a contract Users are responsible for its correct application

Compliance with a British Standard cannot confer immunity from legal obligations.

Amendments/corrigenda issued since publication

EUROPEAN STANDARD

NORME EUROPÉENNE

EUROPÄISCHE NORM

EN 3745-705

December 2007

ICS 49.060

English Version

Aerospace series - Fibres and cables, optical, aircraft use - Test

methods - Part 705: Contrast measurement

Série aérospatiale - Fibres et câbles optiques à usage aéronautique - Méthodes d'essais - Partie 705 : Mesure de

contraste

Luft- und Raumfahrt - Faseroptische Leitungen für Luftfahrzeuge - Prüfverfahren - Teil 705: Kontrastmessung

This European Standard was approved by CEN on 25 July 2007.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German) A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the official versions.

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, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION

C O M I T É E U R O P É E N D E N O R M A L I S A T I O N

E U R O P Ä I S C H E S K O M I T E E F Ü R N O R M U N G

Management Centre: rue de Stassart, 36 B-1050 Brussels

© 2007 CEN All rights of exploitation in any form and by any means reserved

worldwide for CEN national Members.

Ref No EN 3745-705:2007: E

EN 3745-705:2007 (E)

2

Foreword 3

1 Scope 4

2 Normative references 4

3 Terms and definitions 4

4 Preparation of samples 4

5 Test equipment 5

6 Process 6

BS EN 3745-705:2007

EN 3745-705:2007 (E)

3

Foreword

This document (EN 3745-705:2007) 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 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 June 2008, and conflicting national standards shall be withdrawn at the latest by June 2008

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 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, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom

BS EN 3745-705:2007

EN 3745-705:2007 (E)

4

1 Scope

This standard specifies the process to be applied for measuring different colour densities of cable identification markings It is designed to define a reproducible process of contrast value determination

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 of the referenced document (including any amendments) applies

ISO 7724-1, Paints and varnishes — Colorimetry — Part 1: Principles

CIE 15, Colorimetry 1)

3 Terms and definitions

For the purposes of this document, the following terms and definitions apply

3.1

contrast

ratio of reflecting light (here: reflecting light of cable identification marking and cable surface)

3.2

illuminance

reflection of visible light

3.3

measuring range

maximum effective range of measurement

4 Preparation of samples

The cable samples shall be identified in compliance with applicable manufacturing instruction using the power density specified in the technical specification The surfaces of the cable samples shall be clean and without damage

The identification markings to be measured shall even be in colour and shall have sharply defined marking edges i.e marks are correctly focussed

Before starting measurements clean the surfaces with a soft, lint-free cloth to avoid distortion of test results by

a roughened surface or "deposits"

BS EN 3745-705:2007

EN 3745-705:2007 (E)

5

5.1 Components of the measuring device

The measuring device comprises a photometer, lighting equipment and a cable handling device The whole set-up shall be designed to ensure that test results are not falsified by external influences The photometer installation shall be stable and free from vibrations, and influences by external light and reflections from scattered light shall be excluded

5.2 Equipment colour

The device for handling cable samples and accessories shall be designed in matt black colour to absorb scattered light

5.3 Illuminance

Illuminance shall be determined with a calibrated electrical photometer The manufacturer instructions concerning the measuring probe work range and operating instructions shall be observed Measuring sensitivity of the photometer shall be in conformity with CIE-publication 15

5.4 Diameter of measuring spot

The admissible diameter of the measuring spot shall not exceed 75 % of the marking size (X and Y dimension) Measuring tolerance of the photometer shall be < 2 %

5.5 Calibration

The photometer shall be calibrated by the manufacturer The frequency of the calibrate-cycle depends on the guidelines of the equipment manufacturer

5.6 Lighting equipment

The lighting equipment (see Figure 1) consists of two sources of light The lamps illuminate a centred spot on the cable surface under an angle of 45° The photometer is installed above the principal focus at a distance which depends on the objective's focal distance It shall be adjusted before starting measurements and after every change of objective The light cones shall illuminate the cable in longitudinal direction to avoid the formation of shadows

BS EN 3745-705:2007

EN 3745-705:2007 (E)

6

Key

1 Photometer

2 Source of light

Figure 1 — Lighting equipment

Both sources of light shall be of identical power consumption The lamps shall always be exchanged in pairs Radiating light energy and colour temperature of the lamps shall be compatible with the work range of the photometer (see manufacturer instructions) Spectral distribution of light data shall be close to artificial light specifications according to light standard A, ISO 7724-1 Only gas-filled lamps with tungsten filaments shall be used The colour temperature shall be (3 000 ± 500) K

Voltage supply for the lamps shall be insensitive to line fluctuations Stabilized d.c power unit shall be used

6 Process

6.1 Precaution measures

To prevent a heating up of test samples, measurement shall be taken rapidly If necessary, remove the test samples from the handling device for cooling down and repeat measurements

6.2 Picture definition

Adjust the picture definition to the cable identification marking surface Measurement shall be taken vertically

at a centre of the markings to be measured Contrast measurements shall not be performed in areas with manufacturer identification, overlapping tapes, or cable surface irregularities

6.3 Calculation of contrast value

Determination of a cable identification marking contrast value is done by calculating the average value of four contrast measurements taken according to 6.4

BS EN 3745-705:2007

EN 3745-705:2007 (E)

7

6.4 Measuring contrast values

Determination of the contrast value is done by measuring the illuminance on the cable identification marking and the illuminance on the RH or LH side of the marking (distance > diameter of measuring spot) The contrast is calculated as follows:

max.

min.

max.− ×

L

L

(

where

K is the contrast;

L is the light intensity

6.5 Requirement

The contrast value as determined between cable identification marking and cable surface shall conform to the specifications of the corresponding product standard

BS EN

3745-705:2007

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