BS IEC IEEE 62582-5-2015 Nuclear power plants Instrumentation and control important to safety Electrical equipment condition monitoring methods Optical time domain reflectometry《核电.pdf

1、BSI Standards PublicationNuclear power plants Instrumentation and controlimportant to safety Electrical equipment conditionmonitoring methodsPart 5: Optical time domain reflectometryBS IEC/IEEE 62582-5:2015National forewordThis British Standard is the UK implementation of IEC/IEEE 62582-5:2015.The U

2、K participation in its preparation was entrusted to TechnicalCommittee NCE/8, Reactor instrumentation.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisions ofa contract. Users are res

3、ponsible for its correct application. The British Standards Institution 2015.Published by BSI Standards Limited 2015ISBN 978 0 580 64474 0ICS 27.120.20Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandar

4、ds Policy and Strategy Committee on 31 July 2015.Amendments/corrigenda issued since publicationDate Text affectedBRITISH STANDARDBS IEC/IEEE 62582-5:2015IEC/IEEE 62582-5 Edition 1.0 2015-06 INTERNATIONAL STANDARD NORME INTERNATIONALE Nuclear power plants Instrumentation and control important to safe

5、ty Electrical equipment condition monitoring methods Part 5: Optical time domain reflectometry Centrales nuclaires de puissance Instrumentation et contrle-commande importants pour la sret Mthodes de surveillance de ltat des matriels lectriques Partie 5: Technique de rtrodiffusion INTERNATIONAL ELECT

6、ROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE ICS 27.120.20 ISBN 978-2-8322-2704-6 Warning! Make sure that you obtained this publication from an authorized distributor. Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agr. Registered tra

7、demark of the International Electrotechnical Commission Marque dpose de la Commission Electrotechnique Internationale colourinside 2 IEC/IEEE 62582-5:2015 IEC/IEEE 2015 CONTENTS FOREWORD . 4 INTRODUCTION . 6 1 Scope and object . 8 2 Normative references 8 3 Terms and definitions 8 4 Abbreviations an

8、d acronyms 10 5 General description . 10 6 Applicability and reproducibility . 10 7 OTDR measurements procedure 11 7.1 General . 11 7.2 Instrumentation . 11 7.3 Measurement wavelengths 12 7.4 Calibration 12 7.5 Precautions for OTDR measurements . 12 7.6 Conditioning 12 7.7 OTDR measurement . 13 7.8

9、Measurement errors 15 7.9 Test report 15 Annex A (informative) Factors affecting the measurement of attenuation in fibre optic systems 16 A.1 General . 16 A.2 Temperature and humidity 16 A.3 Bending 16 A.4 Transmission light power 16 A.5 Connector interface 16 Annex B (informative) Ageing and degrad

10、ation of optical fibres in nuclear power plants . 17 B.1 Factors affecting ageing 17 B.1.1 General . 17 B.1.2 Thermal ageing 17 B.2 Ageing in ionising radiation . 18 B.2.1 General . 18 B.2.2 Increase of attenuation 18 Annex C (informative) Guidance on selection of parameters for the measurement . 22

11、 C.1 Selection of distance range . 22 C.2 Selection of pulse duration and definition of dead zone . 22 C.3 Selection of wavelength 22 C.4 Selection and position of markers . 22 C.5 Selection of method for averaging . 24 C.6 Setting of the vertical and horizontal scale (v-zoom, h-zoom) 24 C.7 Vertica

12、l and horizontal shifts . 24 C.8 Laser on/off 25 C.9 Setting of IOR, group index . 25 C.10 Use of attenuator 25 Bibliography 26 BS IEC/IEEE 62582-5:2015IEC/IEEE 62582-5:2015 3 IEC/IEEE 2015 Figure 1 Block functions of the OTDR 12 Figure 2 A typical OTDR waveform Backscattered power vs distance (km)

13、14 Figure 3 Examples of faults 14 Figure B.1 A typical OTDR-trace 17 Figure B.2 RIA of different fibre types . 19 Figure B.3 Example for RIA and its wavelength dependence of an optical fibre . 20 Figure C.1 Markers for measuring attenuation 23 Figure C.2 Markers for measuring splice loss . 23 Figure

14、 C.3 LSA and 2PA as approximation methods 24 Figure C.4 Fibre signature with the attenuator set at 0 dB and 5 dB, respectively 25 BS IEC/IEEE 62582-5:2015 4 IEC/IEEE 62582-5:2015 IEC/IEEE 2015 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ NUCLEAR POWER PLANTS INSTRUMENTATION AND CONTROL IMPORTANT TO S

15、AFETY ELECTRICAL EQUIPMENT CONDITION MONITORING METHODS Part 5: Optical time domain reflectometry FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organisation for standardisation comprising all national electrotechnical committees (IEC National Committees). The object

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30、 Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is indispensable for the correct application of this publication. 9) Attention is drawn to the possibility that implementation of this IEC/IEEE Publication may require use of material covere

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33、that determination of the validity of any patent rights, and the risk of infringement of such rights, is entirely their own responsibility. BS IEC/IEEE 62582-5:2015IEC/IEEE 62582-5:2015 5 IEC/IEEE 2015 International Standard IEC/IEEE 62582-5 has been prepared by subcommittee 45A: Instrumentation, co

34、ntrol and electrical systems of nuclear facilities, of IEC technical committee 45: Nuclear instrumentation, in cooperation with the Nuclear Power Engineering Committee of the IEEE Power c is the velocity of light in vacuum (299 792 458 m/s); cfibreis the velocity of light in the fibre. IOR determine

35、s the length of the cable over which the OTDR measurements are made. 3.5 optical attenuation A() measure of the decreasing transmission light power in a fibre at a given wavelength. The definition is: A() = 10 lg (P1()/P2() (2) where A() is the attenuation, in dB, at wavelength ; P1() is the transmi

36、ssion light power traversing one cross-section (marker 1); P2() is the transmission light power traversing a second cross-section (marker 2). Note 1 to entry: It depends on the nature and length and condition of the fibre and is also affected by measurement conditions. Note 2 to entry: The term loss

37、 is used synonymous with attenuation in this International Standard. 3.6 optical attenuation coefficient a() attenuation per unit length, defined as: a() = A()/L (3) where L is the unit length in km. 3.7 optical time domain reflectometer device for characterizing an optical fibre whereby an optical

38、pulse is transmitted through the optical fibre and the optical power of resulting light scattered and reflected back to the input is measured as a function of time SOURCE: IEC 60050-731:1991, 731-07-08, modified BS IEC/IEEE 62582-5:2015 10 IEC/IEEE 62582-5:2015 IEC/IEEE 2015 3.8 step index fibre fib

39、re having a uniform IOR within the core Note 1 to entry: The step is the shift between the core and the cladding, which has a lower IOR. 4 Abbreviations and acronyms Al Aluminum A/D Analog/digital F Fluorine FUT Fibre under test Ge Germanium GI Graded index IOR Index of refraction (Group index) LSA

40、Least square approximation OH Hydroxide ion OTDR Optical time domain reflectometer P Phosphorus RIA Radiation induced attenuation Si Silicon SI Step index SNR Signal to noise ratio UV Ultra-violet 2PA Two point approximation 5 General description Optical time domain reflectometry is a measurement te

41、chnique for characterising an optical fibre whereby an optical pulse is transmitted through the optical fibre and the transmission light power of the resulting light scattered and reflected back to the input is measured as a function of time. The result is reported as the attenuation coefficient (in

42、 dB/km). OTDR measurements are useful in estimating the attenuation coefficient for fibres with uniform attenuation and for identifying and localizing defects and localized losses. The method gives results that are accurate, reproducible and related to practical use. Details about attenuation unifor

43、mity of optical fibres can be found in IEC TR 62033. 6 Applicability and reproducibility This International Standard is limited to the use of an OTDR as an instrument for monitoring the attenuation of optical fibres and optical cables as part of management of ageing. The method is not suitable for m

44、onitoring the condition of fibre with respect to mechanical integrity. In general optical fibres are sensitive to ageing, e.g., due to exposure to ionising radiation, which manifests itself mainly through the increase of the optical attenuation, see also Annexes A and B. The attenuation (in dB/km) i

45、s used as an indicator of ageing for both optical and hybrid (electrical-optical) cables, with in-situ access, whilst these cables are being operated in nuclear environments. BS IEC/IEEE 62582-5:2015IEC/IEEE 62582-5:2015 11 IEC/IEEE 2015 OTDR measurements allow analysis of the condition of the entir

46、e fibre, particularly of longitudinal subsections of the fibre, or even identification of discrete points such as splices. It also permits calculation of the fibre length, although this is outside the scope of this international standard. Optical cables in safety related applications in nuclear powe

47、r plants may be shorter than in general applications. Measurement of short optical cables ( 500 m) requires OTDR instruments with high resolution. The OTDR measurement is affected by the propagation speed and the backscattering behaviour of the fibre. Best accuracy is obtained by measuring the atten

48、uation from both ends of the fibre and averaging the two backscatter traces. Therefore, measurements shall normally be repeated from both ends. This is especially useful in case of unexpected discontinuities. However, the improvement to the accuracy from measurements on both ends is limited and meas

49、urements from one end are acceptable in cases where two ends are not accessible. 7 OTDR measurements procedure 7.1 General For condition monitoring one supervisory channel over all cable segments shall be accessible for OTDR measurements. This could be one spare fibre in each cable segment, one multiplexer channel or the use of an OTDR wavelength not disturbing the data transmission in a fibre (or vice versa) using splitters. 7.2 Instrumentation An OTDR may conta