IEC TR 61 282 1 5 Edition 1 0 201 7 05 TECHNICAL REPORT Fibre optic communication system design guides – Part 1 5 Cable plant and l ink – Testing multi fibre optic cable plant terminated with MPO conn[.]
I E C TR 61 -1 ® Edition 201 7-05 TE C H N I C AL RE P ORT F i bre opti c com m u n i cati on s ys tem d e s i g n g u i d e s – P art 5: C abl e pl an t an d l i n k – Te s ti n g m u l ti -fi bre opti c cabl e pl an t term i n ated IEC TR 61 282-1 5:201 7-05(en) wi th M P O n ectors T H I S P U B L I C AT I O N I S C O P YRI G H T P RO T E C T E D C o p yri g h t © I E C , G e n e v a , S wi tz e rl a n d All rights reserved Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either IEC or IEC's member National Committee in the country of the requester If you have any questions about I EC copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or your local I EC member National Committee for further information IEC Central Office 3, rue de Varembé CH-1 21 Geneva 20 Switzerland Tel.: +41 22 91 02 1 Fax: +41 22 91 03 00 info@iec.ch www.iec.ch Ab ou t th e I E C The I nternational Electrotechnical Commission (I EC) is the leading global organization that prepares and publishes I nternational Standards for all electrical, electronic and related technologies Ab o u t I E C p u b l i ca ti o n s The technical content of IEC publications is kept under constant review by the IEC Please make sure that you have the latest edition, a corrigenda or an amendment might have been published I E C Catal og u e - webstore i ec ch /catal og u e The stand-alone application for consulting the entire bibliographical information on IEC International Standards, Technical Specifications, Technical Reports and other documents Available for PC, Mac OS, Android Tablets and iPad I E C pu bl i cati on s s earch - www i ec ch /search pu b The advanced search enables to find IEC publications by a variety of criteria (reference number, text, technical committee,…) It also gives information on projects, replaced and withdrawn publications E l ectroped i a - www el ectroped i a org The world's leading online dictionary of electronic and electrical terms containing 20 000 terms and definitions in English and French, with equivalent terms in additional languages Also known as the International Electrotechnical Vocabulary (IEV) online I E C G l os sary - s td i ec ch /g l oss ary 65 000 electrotechnical terminology entries in English and French extracted from the Terms and Definitions clause of IEC publications issued since 2002 Some entries have been collected from earlier publications of IEC TC 37, 77, 86 and CISPR I E C J u st Pu bl i s h ed - webstore i ec ch /j u stpu bl i sh ed Stay up to date on all new IEC publications Just Published details all new publications released Available online and also once a month by email I E C C u stom er S ervi ce C en tre - webstore i ec ch /csc If you wish to give us your feedback on this publication or need further assistance, please contact the Customer Service Centre: csc@iec.ch I E C TR 61 -1 ® Edition 201 7-05 TE C H N I C AL RE P ORT F i bre opti c com m u n i cati on s ys tem d e s i g n g u i d e s – P art 5: C abl e pl an t an d l i n k – Tes ti n g m u l ti -fi bre opti c cabl e pl an t te rm i n ated wi th M P O n ectors INTERNATIONAL ELECTROTECHNICAL COMMISSION ICS 33.1 80.01 ISBN 978-2-8322-4238-4 Warn i n g ! M ake s u re th a t you ob tai n ed th i s p u b l i cati on from an au th ori zed d i stri b u tor ® Registered trademark of the International Electrotechnical Commission –2– I EC TR 61 282-1 5: 201 I EC 201 CONTENTS FOREWORD I NTRODUCTI ON Scope Norm ative references Terms, definitions and abbreviated term s Terms and definitions Abbreviated terms MPO connectors General Keying and fibre positions Polarity Test methods and measurem ents General Attenuation Polarity Length 5 Optical return loss and reflectance Variations of test m ethods General Optical light source General 2 Source with M PO interface Source with non-MPO interface and fan -out cable Source with non-MPO interface and optical switch Optical power meter General Meter with MPO interface having multiple detectors 3 Meter with MPO interface having large area detector Meter with non-MPO interface and fan-out cable Meter with non-MPO interface and optical switch OTDR General OTDR with MPO interface OTDR with non-M PO interface and fan-out cable 6 4 OTDR with non-M PO interface and optical switch 6 Other adaptations and accessories 6 Adapters 6 Test cords 6 Optical switch Polarity and pinned/unpinned changers 6 Visual inspection 7 Test configurations 7 General 7 LSPM with MPO interface LSPM with non-MPO interface and fan-outs Bibliograph y 21 I EC TR 61 282-1 5: 201 I EC 201 –3– Figure – M PO connector Figure – Polarity for three standard configurations 1 Figure – Polarity for a breakout cord 1 Figure – Reference connections for cabling with unpinned M PO plugs Figure – Connections for m easurem ents on type A cabling with unpinned MPO connectors Figure – Reference connections for tester with non-M PO plugs Figure – Connections for tester with non-MPO plugs 20 –4– I EC TR 61 282-1 5: 201 I EC 201 INTERNATI ONAL ELECTROTECHNI CAL COMMISSI ON F I B RE O P T I C C O M M U N I C AT I O N S YS T E M D E S I G N G U I D E S – P a rt : C a bl e pl a n t an d l i n k – T e s ti n g m u l t i - fi b re o p t i c c a b l e p l a n t te rm i n a te d w i th M P O c o n n e c to rs FOREWORD ) The I nternati on al Electrotechni cal Comm ission (I EC) is a worl d wid e organization for stan dardization com prisin g all n ation al el ectrotechnical comm ittees (I EC National Comm ittees) The object of I EC is to prom ote internati onal co-operation on all q uestions concerni ng stand ardi zati on in the el ectrical an d electronic fi elds To this en d and in additi on to other acti vities, I EC pu blish es I nternational Stan dards, Techn ical Specificati ons, Technical Reports, Publicl y Avail abl e Specificati ons (PAS) an d Gu ides (h ereafter referred to as “I EC Publication(s)”) Th ei r preparation is entrusted to tech nical comm ittees; any I EC N ational Comm ittee interested in the subj ect dealt with m ay partici pate in this preparatory work I nternational, governm ental an d n on governm ental organ izations l iaising with th e I EC also participate i n this preparation I EC collaborates closel y with the I nternational Organi zation for Stand ardization (I SO) in accordance with ditions determ ined by agreem ent between th e two organi zati ons 2) The form al decisions or ag reem ents of I EC on tech nical m atters express, as n early as possible, an i nternati onal consensus of opi nion on the rel evant subjects since each technical com m ittee has representati on from all interested I EC N ational Com m ittees 3) I EC Publications have the form of recom m endations for intern ational use an d are accepted by I EC National Com m ittees in that sense While all reasonable efforts are m ade to ensure that th e tech nical content of I EC Publications is accu rate, I EC cann ot be h eld responsi ble for th e way in which th ey are used or for an y m isinterpretation by an y en d u ser 4) I n order to prom ote intern ational u niform ity, I EC National Com m ittees und ertake to apply I EC Publications transparentl y to the m axim um extent possible i n their national an d regi on al publicati ons Any d ivergence between an y I EC Publication and the correspondi ng national or regi on al publicati on sh all be clearl y in dicated in the latter 5) I EC itself d oes n ot provi de an y attestation of conform ity I n depend ent certificati on bodies provi de conform ity assessm ent services and, in som e areas, access to I EC m arks of conform ity I EC is not responsi ble for an y services carri ed out by ind ependent certification bodi es 6) All users shou ld ensure that th ey h ave the l atest editi on of thi s publicati on 7) No liability shall attach to I EC or its directors, em ployees, servants or ag ents inclu din g in divi du al experts an d m em bers of its tech nical com m ittees and I EC Nati on al Com m ittees for any person al i nju ry, property d am age or other dam age of any n ature whatsoever, wheth er di rect or indirect, or for costs (includ i ng leg al fees) and expenses arisi ng out of the publ ication, use of, or relian ce upon, this I EC Publicati on or any other I EC Publications 8) Attention is drawn to th e N orm ative references cited in th is publ ication Use of the referenced publ ications is indispensable for the correct applicati on of this publication 9) Attention is drawn to the possibility that som e of the elem ents of this I EC Publication m ay be the su bject of patent rig hts I EC shall not be held responsibl e for identifyi ng any or all such patent ri ghts The m ain task of I EC technical com mittees is to prepare I nternational Standards H owever, a technical committee m ay propose the publication of a Technical Report when it has collected data of a different kind from that which is normally published as an I nternational Standard, for exam ple "state of the art" I EC TR 61 282-1 5, which is a Technical Report, has been prepared by subcomm ittee 86C: Fibre optic systems and active devices, of I EC technical comm ittee 86: Fibre optics The text of this Technical Report is based on the following docum ents: Enqui ry draft Report on votin g 86C/1 427/DTR 86C/1 443/RVDTR Full inform ation on the voting for the approval of this Technical Report can be found in the report on voting indicated in the above table I EC TR 61 282-1 5: 201 I EC 201 –5– This document has been drafted in accordance with the I SO/I EC Directives, Part A list of all parts in the I EC 61 282 series, published under the general title Fibre optic communication system design guides , can be found on the I EC website The com mittee has decided that the contents of this docum ent will rem ain unchanged until the stability date indicated on the I EC website under "http://webstore iec ch" in the data related to the specific document At this date, the document will be • • • • reconfirmed, withdrawn, replaced by a revised edition, or am ended A bilingual version of this publication m ay be issued at a later date –6– I EC TR 61 282-1 5: 201 I EC 201 INTRODUCTION Cabling testing standards such as I EC 61 280-4-1 for m ultimode attenuation m easurements and I EC 61 280-4-2 for single-mode attenuation and optical return loss measurem ent describe testing simplex or duplex fibre cabling terminated with single-fibre ferrule connectors (e g LC) This docum ent has been written to describe m easurement methods for attenuation and polarity and can be used in the absence of an y m ulti-fibre testing standard This document addresses the testing of installed multim ode and single-m ode cabling term inated with m ulti-fibre connectors of I EC 61 754-7 (all parts) related to multi-fibre push on (MPO) and describes the challenges when testing array connectivity, which parameters are im portant to measure, and wh y the test m ethods of I EC 61 280-4-2 and I EC 61 280-4-1 cannot be used I nstalled optical fibre cabling term inated with MPO interfaces can be tested in different ways, for exam ple, with equipm ent having an MPO connector test port Testing using other types of equipm ent is possible, for exam ple using an optical time domain reflectometer (OTDR) This docum ent focuses on M PO connectors containing fibres in a single row; however, many of the principles can also be applied to testing of cabling term inated with different types of M PO connectors with appropriate changes to test cords and/or test equipm ent interfaces I EC TR 61 282-1 5: 201 I EC 201 –7– F I B RE O P T I C C O M M U N I C AT I O N S YS T E M D E S I G N G U I D E S – P a rt : Cabl e pl an t an d l i n k – T e s ti n g m u l t i - fi b re o p t i c c a b l e p l a n t te rm i n a te d w i th M P O c o n n e c to rs S cop e This part of I EC 61 282 provides guidance for the testing of multi-fibre cable, multim ode or single-m ode, terminated with plugs described in I EC 61 754-7 (all parts) (multiple-fibre push on – MPO) Guidance is provided on the m easurem ent of attenuation , polarity, length and optical return loss The cabling can be installed in a variety of environments, including residential, commercial, industrial, and data centre premises, and possibl y in outside plant environm ents N o rm a t i ve re fe re n c e s The following docum ents are referred to in the text in such a way that som e or all of their content constitutes requirem ents of this document For dated references, only the edition cited applies For undated references, the latest edition of the referenced docum ent (including an y am endm ents) applies I EC 61 280-4-1 , Fibre-optic communication subsystem test procedures – Part 4-1: Installed cable plant – Multimode attenuation measurement I EC 61 280-4-2, Fibre-optic communication subsystem test procedures – Part 4-2: Installed cable plant – Single-mode attenuation and optical return loss measurement T e rm s , d e fi n i t i o n s a n d a b b re vi a t e d t e rm s T e rm s a n d d e fi n i t i o n s For the purposes of this docum ent, the following term s and definitions apply ISO and I EC m aintain terminological databases for use in standardization at the following addresses: • I EC Electropedia: available at http: //www electropedia.org/ • I SO Online browsing platform: available at http://www iso.org/obp ad apter part of a connector in which one or two plugs are inserted and aligned atte n u ati o n reduction of optical power induced by transm ission through a medium such as cabling, given as L = log ( Pin / P out ) where Pin and P out are the power, typicall y measured in mW, into and out of the cabling Note to entry: Atten uati on i s expressed i n dB –8– I EC TR 61 282-1 5: 201 I EC 201 fig u rati on form or arrangements of parts or elem ents such as term inations, connections and splices n ector component consisting of two plugs m ated together in an adapter, for the purpose of providing frequent optical interconnection/disconnection of optical fibres or cables, between two cables, or a cable to an apparatus en ci rcl ed flu x fraction of cum ulative near-field power to total output power as a function of radial distance from the optical centre of the core lau n ch cord test cord used to connect the light source to the cabling under test ligh t sou rce power meter test system consisting of a light source (LS), power m eter (PM) and associated test cords used to m easure the attenuation of installed cable plant M PO n ector multi-fibre component consisting of pi nned or unpinned plug and mating adapter, normall y attached to an optical fibre cable, for the purpose of providing high density term ination capability, and frequent interconnection or disconnection plu g free part of a connector test cord term inated optical fibre cord used to connect the optical source or detector to the cabling, or to provide suitable interfaces to the cabling under test Note to entry There are two types of test cords: – launch cord; – recei ve cord APC LED LSPM MPO OTDR PC VFL OPM OLTS Abbreviated terms angled ph ysical contact (description of plug polish) light emitting diode light source power meter m ultiple-fibre push on optical time dom ain reflectometer ph ysical contact (description of plug polish) visual fault locator optical power meter optical loss test set – 10 – I EC TR 61 282-1 5: 201 I EC 201 The fibre positions in an array plug are referred to as position through N, where N is the number of fibre positions in the plug When viewi ng the plug end-on with the key-way on top, position is the left-m ost fibre position, and N is the right-m ost fibre position M ulti-fibre cabling and connectors can vary in fibre positions An y examples shown in this docum ent are with x 2-position test cords Keying and fibre position also have a specific configuration on angled ph ysical contact (APC) MPO plugs used with single-mode multi-fibre cabling For single-m ode cabling terminated with APC plugs, it is essential to know if key-up/key-up or key-up/key-down adapters and test cords are used NOTE I t is norm al for th e sin gle-m ode ferrules to be "up an gled", i e the hig hest part of th e ferrule is on the sam e side as the key; h owever, it is also possible for the ferrul e to be "down angl ed", with th e slope run nin g the oth er way 4.3 Polarity I EC standards describing M PO connectors can use different polarity nom enclature than other standards bodies Equivalent polarity nom enclatures are shown in parenthesis below: • key-up to key-down (type A) • key-up to key-up (type B) • key-up to key-down, pair-wise flip (type C) For the sake of sim plicity, the type of polarity, A, B, or C is used in the descriptions below The polarity of the connections between the meter and source can have several configurations and can be indicated on the power m eter as "A", "B", and "C" or other comm on polarity types not standardi zed I n some cases, an alternate type is necessary For testers capable of identifying polarity, the polarity is shown on the m eter when the source is selected to scan all fibre positions and all fibres are connected properl y or im properly ) One of three polarity types: The nections use a standard m ethod, key-up to key-down (type A), key-up to key-up (type B), or key-up to key-down pair-wise flip (type C) I n this case, the tester should identify the polarity (see Figure 2) 2) Unknown polarity: The connections not use a standard method, one or m ore fibres are not connected, or the source polarity scanner is off I n this case, something m ay be wrong with the cabling, so the tester cannot determine the polarity H owever, all three cases not necessaril y indicate an error in the cabling 3) Alternate polarity: The connections are m ade to a box wherein a breakout cable, also known as a fan-out cable, is used (see Figure 3) I EC TR 61 282-1 5: 201 7 10 11 12 I EC 201 – 11 – Type A Key-up Source ch ann el: Meter chann el: 10 11 12 1 2 3 4 Key-down 5 6 7 8 9 10 10 10 11 Type C Key-up Source ch ann el: Meter chann el: 2 4 12 12 12 11 10 Key-down Source ch ann el: Meter chann el: 1 4 10 11 12 11 11 Type B Key-up 10 11 12 12 10 12 11 Key-down 6 8 10 10 11 12 12 11 IEC Figure – Polarity for three standard configurations 10 11 12 Key-up Source ch ann el: Meter chann el: 10 11 12 Type A 1 2 3 4 5 6 7 8 9 10 10 11 11 12 12 IEC Figure – Polarity for a breakout cord – 12 – 5.1 I EC TR 61 282-1 5: 201 I EC 201 Test methods and measurements General I nstalled optical fibre term inated with MPO connectors can be tested using three known methods: • a specialized m ulti-fibre tester having an M PO interface (optical loss test set – OLTS or • • optical time domain reflectometer – OTDR); an OLTS (or light source power meter – LSPM) with non-MPO interface; an OTDR with non-MPO interface A red light source or other visual fault locator (VFL) can also be used for continuity and polarity testing but cannot be used for other measurements A visible light source or VFL m ay be used to determine polarity H owever, using a VFL for polarity identification may prove difficult, especiall y when laser safety is considered, because seeing which fibre is lit in an MPO plug involves looking directl y into the plug Each of these m ethods can test fibre installations term inated with M PO plugs The im plem entation of the first m ethod can have different form s, while the second and third methods utilize equipm ent typicall y used to make m easurem ents described in I EC 61 280-4-2 and I EC 61 280-4-1 5.2 Attenu ation The attenuation measurem ent indicates how m uch optical power is lost in the fibre, connectors and other passive devices in a link (see 2) Polarity Optical fibre trunk cabling can be configured in different ways Deployment mistakes are common because these different configurations require a com bination of patch cords with different polarity types A polarity test is perform ed to verify that connectivity will be established between the transm itters at one end of th e cabling and the receivers at the other end and vice versa Length Fibre length verification can be obtained from several methods, including cable sheath markings, installed cabling documentation, job bill of m aterials, propagation delay, or with an OTDR Cabling and trunk lines term inated with M PO plugs are typicall y of a known length and are labelled accordingly Due to the com plexity of testing, som e testers use simplex measurem ents, so length is determ ined from labelling or other docum entation For duplex installations where an OLTS can be used, propagation delay m ay som etim es be used for length measurem ents H owever, this requires a round trip m easurement where the far-end tester loops the propagation pulse back to the source Since m ultiple fibres term inated with MPO plugs are bundled together within cabling, and their lengths are equal or within % of each other due to the helical nature of some cabling, it m ay be adequate to measure the length of just one fibre 5.5 Opti cal retu rn loss and reflectan ce Optical components such as fibre, connectors, and splices exhibit various am ounts of return loss and reflectance Overall optical return loss includes the contributions from all of the optical com ponents in a link Som e cabling standards and transmission system standards define a lim it for the reflectance of individual com ponents (e g connectors) and som e standards (e.g I EEE) also define a limit on the overall return loss I EC TR 61 282-1 5: 201 I EC 201 – 13 – Optical return loss m ay be im portant for installed single-m ode cabling This is because singlemode transm ission systems m ay be m ore sensitive to back-reflections H owever, all singlemode MPO plugs have APC end faces specified with a typicall y low return loss (e.g > 50 dB) Multimode MPO plugs terminated with ph ysical contact (PC) end faces typicall y have high return loss (e g 20 dB) However, m ultimode transm ission systems are less sensitive to back reflections I f needed, an OTDR is capable of measuring overall cabling return loss and the discrete return loss of individual components also known as reflectance Vari ati on s of test methods G en eral The equipment used to test installed fibre optical cabling can have either an MPO interface or a non-MPO interface For these two types of testers, the apparatus can be a light source/power meter or an OTDR For either the MPO interface or non-MPO interface type, optical swi tching and fan-out assem blies (e g M PO to LC plug test cord) can be used to expand testing to a higher fibre count Testers with an MPO interface specificall y designed for M PO testing can be designed in different ways and are described herein; there may be other im plementations Testers with a non-M PO interface can also be used for testing cabling with M PO term inations; they are also described herein 6 Opti cal l i gh t sou rce Gen eral The light source used during LSPM testing can be a simplex version (one fibre port) or an MPO version (multi-fibre port) I n general, since source optical ports are coupled to a fibre, either m ultimode or single-m ode, different light sources are used for testing multim ode or single-mode cabling Another consideration when testing with the MPO ported version is that multimode uses a flat MPO plug while the single-m ode version uses an angled M PO plug Caution is advised not to mix flat and angled M PO plugs, unless the light source is designed to so Determ ine whether the light source MPO port is pinned or unpinned before connecting a launch cord The wavelengths used for the m easurem ents can be the sam e as the wavelengths used in the installed cabling, such as 850 nm and 300 nm for m ultim ode and 31 nm and 550 nm for single-m ode The characteristics of the light sources, such as centre wavelength, spectral width, and stability, are found in I EC 61 280-4-1 , using an LED, and I EC 61 280-4-2 The m ultimode source shall m eet the encircled flux requirem ents of I EC 61 280-4-1 at the output of the test cord that is coupled to the light source This can be met with com merciall y available equipm ent for single fibre port sources 2 Sou rce with M PO i n terface The light source contains one or more em itters attached, typicall y fibre coupled, to an MPO plug at the light source interface (bulkhead connector) The M PO plug at the bulkhead can be pinned or unpinned For determining polarity, the light source emits power sequentiall y at each fibre position from position to position to position 3, etc – 14 – I EC TR 61 282-1 5: 201 I EC 201 Sou rce with n on -M PO i n terface an d fan -ou t cabl e The light source contains one or two emitters attached to a , 25 m m or 2, mm circular ferruled plug placed at the light source bulkhead ; there is no M PO interface The non-MPO side of the breakout cable is connected to the bulkhead The MPO end of the breakout cable is connected to the cabling under test At the completion of each m easurement, the non-MPO side of the breakout cable is moved to the next position, from position to position 2, etc Sou rce wi th n on -M PO i n terface an d opti cal swi tch The light source contains one or two emitters attached to a , 25 mm or 2, mm circular ferruled plug The ferruled plug is placed at the light source bulkhead An optical switch is connected to the light source via a non-MPO connectorized test cord The other port on the optical switch has an MPO interface An MPO to MPO test cord is attached between the optical switch and the cabling under test 6 Opti cal power m eter G en eral An optical power m eter (OPM) without an MPO com patible port shall meet the requirements for the power meter (LSPM methods onl y) defined in I EC 61 280-4-1 and I EC 61 280-4-2 This type of power meter uses a single detector An optical power meter with an MPO com patible port shall meet the requirem ents of the nonMPO com patible meter defined in I EC 61 280-4-1 and I EC 61 280-4-2 The M PO ported meter should interface with either a m ultim ode MPO plug that has PC end faces or a single-mode MPO plug that has APC end faces Although not as easy to use, it is acceptable to have separate m eters for PC and APC The MPO end face (i e the actual fibre) may not be in contact with the detector The MPO type power meter should be able to determine the position (polarity) of each fibre during testing, in addition to m easuring attenuation Caution is advised: note if the power m eter MPO port is pinned or unpinned M eter wi th M PO in terface h avi n g m u lti pl e detectors This m eter should be able to determ ine installed cabling polarity regardless of the polarity of the test cord connected to the m eter The power meter contains m ultiple detectors attached to an MPO plug, via optical fibres for exam ple, at the power m eter interface (bulkhead) The power m eter measures the emitted power or attenuation in a sequence and also indicates the polarity of the cabling under test The M PO type power meter should be able to determine if there are absent fibres I n one example, a 2-fibre M PO plug m ay have the m iddle four fibres absent I n another example, a 2-position MPO plug m ay have positions and absent This type of tester uses the -cord or 2-cord reference method and can automaticall y measure attenuation and polarity by rel ying on the sequence of a specific light source Testing is fast and setup is minimal Length measurements can be supplemented wi th a single-ended measurem ent such as with an OTDR An OTDR can also be used to m easure reflectance of individual connectors and optical return loss of the entire cabling system I EC TR 61 282-1 5: 201 6.3 I EC 201 – 15 – M eter with M PO interface h aving l arge area detector The power meter contains one large area detector, used in typical power meters, wide enough (greater than mm ) to capture received light at the MPO interface Alternativel y, an integrating sphere can be used in conj unction with a sm aller detector The power meter m easures attenuation (optical power) from an y fibre position but cannot differentiate between adj acent fibre positions The sequence of emitted light from the source cannot be determ ined This type of tester uses the -cord reference method and can m easure onl y attenuation Length, reflectance, and optical return loss can be measured with an OTDR as a secondary test Since this is a sim plex tester, propagation delay cannot be used to m easure fibre length 6.3 M eter with non-M PO interface and fan-out cable The power meter contains one large area detector comm onl y used in typical power m eters A breakout cord with a non-MPO plug is attached to the power meter port The other end of the breakout cord is term inated with an MPO plug that is attached to the cabling under test The power meter can then measure the attenuation (optical power) of each channel as described in 6.3 M eter with non-M PO interface and optical switch The power m eter is connected to an optical switch via a non-M PO connectorized test cord The other port on the optical switch has an M PO interface An MPO to MPO test cord is attached between the optical switch and the cabling under test This method may improve test tim e compared to using fan-outs However, setting a reference with an optical switch on the source side and power m eter side m ay be difficult or m ay have high uncertainty 6 4.1 OTDR Gen eral The OTDR should meet the requirem ents defined in I EC 61 280-4-1 for m ultimode and IEC 61 280-4-2 for single-m ode as described for a single connector port When using an OTDR, and to compl y with some testing standards, it is required to add a launch and tail cord to the cabling under test The OTDR can make total attenuation measurem ents, provided that a long enough launch cord and tail cord are used The OTDR test can m easure polarity if, for exam ple, a single fibre tail cord is used to identify fibre connectivity Another possible way to identify polarity is to use a m ulti-fibre tail cord where each fibre is of a known different length, for exam ple fibre = m, fibre = m , fibre = 20 m 6.4.2 OTDR with M PO interface An OTDR utilizing an MPO interface would need to em it optical power sequentiall y at the MPO interface (bulkhead) I n addition, a launch cord com prising m ultiple optical fibres would need to interface between the OTDR and the cabling under test This implem entation may be possible by using an optical switch inside the OTDR – 16 – 6.4 I EC TR 61 282-1 5: 201 I EC 201 OTDR with non-M PO interface and fan-out cabl e To make m easurem ents with an OTDR, attach the MPO end of a fan-out to the cabling under test The other end of the fan-out, typicall y a plug with a , 25 mm or 2, mm ferrule, is attached to the OTDR The OTDR executes a test with fibre position of the fan-out Next, fibre position on the fan-out replaces fibre position on the OTDR port The sequence is repeated for the rem aining fibre positions Note that the fan out assembl y in this scenario becom es the OTDR launch cord, and therefore every fibre in it shall meet the requirements of an OTDR launch cord, i e it shall be long enough to get past the dead zone of the OTDR and give a reliable straight line fit to the trace of the fibre in the launch cord 6.4.4 OTDR with non-M PO interface and optical switch An OTDR, without an MPO interface, using an optical switch m ay be an im provement over the use of a fan-out cable One test cord is attached from the OTDR to the optical switch using a non-M PO test cord The other port of the optical switch is the MPO interface that couples an MPO to MPO launch cord from the switch to the cabling under test Other adaptations and accessories 5.1 Ad apters Devices that couple two MPO plugs are required during testing There are two types of array adapters: opposed key or key-up to key-down (type A) and aligned key or key-up to key-up (type B) I n the key-up to key-up type, both ends of the adapter have the key on the same side For the key-up to key-down adapter, the keys are on opposite sides IEC 61 754-7 (all parts) provides information on adapters and keying differences 6.5 Test cord s Testing an installed multi-fibre network using MPO connectors m ay require several types of test cords to accommodate various test configurations The cabling under test could be pinned or unpinned and of various polarity types The M PO end of the test cord should have low attenuation (i e 0, 35 dB) and for testing single-m ode, it should have a high return loss (i e 60 dB) when mated to another MPO plug The single-fibre ferrule end of fan-out plugs should be com patible with perform ance described in I EC 61 280-4-1 and I EC 61 280-4-2 for reference grade connectors The following test cords are typicall y used with com patible test equipm ent such as light sources, power meters, OTDRs, and optical switches The LSPM with M PO interface are assum ed to be unpinned for these exam ples • Fan-out (e g breakout) cord with an MPO plug on one end and or m ore individual • • • single fibre ferrule plugs (e.g LC or SC plugs) on the other end – used when testing breakout cassettes (i e box with MPO and non-MPO) or when using a sim plex or duplex LSPM Test reference cord, with MPO unpinned on both ends, key-up to key-up – used as the launch cord conversion when using MPO interfaced testers on type A, B, or C cabling that are pinned on each end Test reference cord, with MPO unpin ned on one end and MPO pinned on the other end, key-up to key-up – used as the launch and receive cords when using MPO interfaced testers on type A, B, or C cabling that are pinned on one end and unpinned on the other Test reference cord, with MPO pinned on both ends, key-up to key-up – used as the launch and receive cords when using MPO interfaced testers on unpinned type A, B, or C cabling I EC TR 61 282-1 5: 201 I EC 201 – 17 – The following applies to the preparation of the test cords • The cords should be term inated at one end with a plug suitable for attachment to the light • source and m eter – MPO plug for a tester with an MPO interface or single fibre ferruled plug for a tester with a non-MPO interface The fibre used in the cord should be protected This m ay be done by enclosing most of the length of the cord in a container or by using test cords that have a thick j acket The single-fibre ferruled end of the fan-out cords and MPO plugs m ay be inspected using I EC 61 300-3-35 Optical switch An optical switch can be used with existing equipm ent that does not have an M PO port The optical switch (MPO switch) may have a circular, single-fibre, ferrule input test port and an MPO output port The tester is coupled to the input port of the switch using a test cord The MPO output port is coupled to the cabling under test using an MPO to MPO test cord and an appropriate adapter The tester can com municate with an external optical switch to select fibre positions autom atically The advantage of the M PO switch is that fan-outs, which typicall y require re-m ating and unmating connectors, are not needed The MPO switch is used to advance from one fibre position to the next position along the MPO cabling under test 5.4 Polarity and pinned/u npinned chan gers Som e brands of MPO plugs are available with a mechanism to change the polarity from a “type A” to a “type B” or vice versa The polarity can be changed by removing the outer housing from the plug, rotating the housing 80°, and re-installing the housing onto the plug Som e brands of MPO plugs are also available with a m echanism to change from pinned to unpinned The pins can be changed by rem oving the outer housing from the plug, using a special tool in the inner housing to slide the guide pins out/in, and re-installing the housing onto the plug This changes the plug from pinned to unpinned or vice versa This type of plug simplifies testing and reduces the conversions and re-mating with test cords 6 Visu al inspection Testing fibre optic cabling term inated with MPO plugs requires the same level of care as other fibre optic plugs, specificall y inspecting and cleaning I EC 61 300-3-35 describes methods for evaluating the end face of a polished fibre optic plug The entire ferrule surface of the MPO plug should be inspected for contam ination I f contam ination is found, proper cleaning m ethods should be used to rem ove the contam ination Attention should be given to cleaning the m ale M PO plug since unclean pins m ay cause m echanical interference 7.1 Test configurations General Clause describes two comm on practices for m easuring attenuation and polarity on installed cabling terminated with M PO plugs – 18 – 7.2 I EC TR 61 282-1 5: 201 I EC 201 LSPM with MPO interface When using test equipment having an MPO interface, for exam ple, an LSPM, the light source or power m eter can have a pinned or unpinned MPO bulkhead interface I n order for the test cords to function with the cabling under test, while still using a low-uncertainty reference method, the light source and power m eter shall have com patible pinning For example, if testing cabling is term inated with unpinned MPO plugs on each end, the launch and receive cords shall be pinned on the cabling interface side Furthermore, for the -cord reference method, the meter shall be unpinned to accept the pinned launch cord (see Figure and Figure 5) I n the exam ples of Figure and Figure 5, the light source and power m eter bulkhead ports are unpinned I n this example, one test cord is used to set the reference (test cord ) Then, test cord is disconnected from the meter and a second test cord is connected to the meter Type B Source Meter Test cord pinn ed/pinned STEP Type B Source Type B Meter Test cord pinn ed/pinn ed Test cord pinn ed/pinn ed STEP IEC Figure – Reference connections for cabling with unpinned MPO plugs Type A fibre l ink Source Type B Unpi nn ed/pinn ed Pinned/un pin ned Test cord pinn ed/pinned Type B Test cord pinned/pinned Type A adapter key-down/key-up Type A adapter key-down/key-up Meter shows POLARI TY A STEP Source ch ann el: Meter chann el: 1 2 3 Meter 4 5 6 7 8 9 10 10 11 11 12 12 IEC Figure – Connections for measurements on type A cabling with unpinned MPO connectors While there are various methods of testing cabling term inated with MPO plugs, the method that can automaticall y determ ine polarity may be easier to use than other methods The mul tifibre optical power meter and source can be used to measure the polarity of MPO cords and