EN IEC 61280-4-5:2020

SLOVENSKI STANDARD
01-november-2020
Postopki preskušanja optičnega komunikacijskega podsistema - 4-5. del: Vgrajene
žične oblike - Izvedba atenuacije merilne naprave z optičnimi kabli, ki se konča z
MPO, z uporabo preskusne opreme z vmesniki MPO (IEC 61280-4-5:2020)
Fibre-optic communication subsystem test procedures - Part 4-5: Installed cabling plant -
Attenuation measurement of MPO terminated fibre optic cabling plant using test
equipment with MPO interfaces (IEC 61280-4-5:2020)
Prüfverfahren für Lichtwellenleiter-Kommunikationsuntersysteme - Teil 4-5: Installierte
Kabelanlagen - Dämpfungsmessung an Lichtwellenleiter-Kabelanlagen mit MPO-
Abschlüssen mittels Prüfeinrichtungen mit MPO-Steckgesichtern (IEC 61280-4-5:2020)
Procédures d'essai des sous-systèmes de télécommunication fibroniques - Partie 4-5:
Installation câblée - Mesure de l'affaiblissement de l’installation câblée fibronique à
terminaisons MPO utilisant un équipement d’essai avec interfaces MPO (IEC 61280-4-
5:2020)
Ta slovenski standard je istoveten z: EN IEC 61280-4-5:2020
ICS:
33.180.01 Sistemi z optičnimi vlakni na Fibre optic systems in
splošno general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 61280-4-5

NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2020
ICS 33.180.01
English Version
Fibre-optic communication subsystem test procedures - Part 4-5:
Installed cabling plant - Attenuation measurement of MPO
terminated fibre optic cabling plant using test equipment with
MPO interfaces
(IEC 61280-4-5:2020)
Procédures d'essai des sous-systèmes de Prüfverfahren für Lichtwellenleiter-
télécommunication fibroniques - Partie 4-5: Installation Kommunikationsuntersysteme - Teil 4-5: Installierte
câblée - Mesure de l'affaiblissement de l’installation câblée Kabelanlagen - Dämpfungsmessung an Lichtwellenleiter-
fibronique à terminaisons MPO utilisant un équipement Kabelanlagen mit MPO-Abschlüssen mittels
d’essai avec interfaces MPO Prüfeinrichtungen mit MPO-Steckgesichtern
(IEC 61280-4-5:2020) (IEC 61280-4-5:2020)
This European Standard was approved by CENELEC on 2020-08-26. CENELEC 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-CENELEC
Management Centre or to any CENELEC 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 CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2020 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 61280-4-5:2020 E

European foreword
The text of document 86C/1669/FDIS, future edition 1 of IEC 61280-4-5, prepared by SC 86C "Fibre
optic systems and active devices" of IEC/TC 86 "Fibre optics" was submitted to the IEC-CENELEC
parallel vote and approved by CENELEC as EN IEC 61280-4-5:2020.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2021-05-26
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2023-08-26
document have to be withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.

Endorsement notice
The text of the International Standard IEC 61280-4-5:2020 was approved by CENELEC as a
European Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards
indicated:
IEC 60793-1-40 NOTE Harmonized as EN IEC 60793-1-40
IEC 60793-2 NOTE Harmonized as EN 60793-2
IEC 60793-2-10 NOTE Harmonized as EN IEC 60793-2-10
IEC 60793-2-50 NOTE Harmonized as EN IEC 60793-2-50
IEC 60876-1:2014 NOTE Harmonized as EN 60876-1:2014 (not modified)
IEC 61280-4-2 NOTE Harmonized as EN 61280-4-2
IEC 61300-3-6 NOTE Harmonized as EN 61300-3-6
IEC 61300-3-45 NOTE Harmonized as EN 61300-3-45
IEC 61745 NOTE Harmonized as EN 61745
IEC 61754-7 (series) NOTE Harmonized as EN IEC 61754-7 (series)
IEC 61755-3-31 NOTE Harmonized as EN 61755-3-31
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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.
NOTE 1  Where an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2  Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60825 series Safety of laser products EN 60825 series
IEC 61280-1-3 -  Fibre optic communication subsystem test EN 61280-1-3 -
procedures - Part 1-3: General
communication subsystems - Central
wavelength and spectral width
measurement
IEC 61280-4-1 2019 Fibre-optic communication subsystem test EN IEC 61280-4-1 2019
procedures - Part 4-1: Installed cabling
plant - Multimode attenuation
measurement
IEC 61300-3-35 -  Fibre optic interconnecting devices and EN 61300-3-35 -
passive components - Basic test and
measurement procedures - Part 3-35:
Examinations and measurements - Visual
inspection of fibre optic connectors and
fibre-stub transceivers
IEC 61315 -  Calibration of fibre-optic power meters EN IEC 61315 -
IEC 61746-1 -  Calibration of optical time-domain EN 61746-1 -
reflectometers (OTDR) - Part 1: OTDR for
single mode fibres
IEC 61746-2 -  Calibration of optical time-domain EN 61746-2 -
reflectometers (OTDR) - Part 2: OTDR for
multimode fibres
IEC 61280-4-5 ®
Edition 1.0 2020-07
INTERNATIONAL
STANDARD
colour
inside
Fibre-optic communication subsystem test procedures –

Part 4-5: Installed cabling plant – Attenuation measurement of MPO terminated

fibre optic cabling plant using test equipment with MPO interfaces

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 33.180.01 ISBN 978-2-8322-8670-8

– 2 – IEC 61280-4-5:2020 © IEC 2020
CONTENTS
FOREWORD . 7
1 Scope . 9
2 Normative references . 9
3 Terms, definitions, graphical symbols and abbreviated terms. 10
3.1 Terms and definitions . 10
3.2 Graphical symbols . 12
3.3 Abbreviated terms . 14
4 Test methods . 14
4.1 General . 14
4.2 Cabling configurations and applicable test methods . 15
5 Overview of uncertainties . 16
5.1 General . 16
5.2 Sources of significant uncertainties . 16
5.3 Consideration of the PM . 17
5.4 Consideration of test cord connector grade . 17
5.5 Typical uncertainty values for multimode testing . 17
5.6 Typical uncertainty values for single-mode testing . 19
6 Apparatus . 20
6.1 General . 20
6.2 Light source . 20
6.2.1 General . 20
6.2.2 Stability . 20
6.2.3 Spectral characteristics (LSPM measurement) . 21
6.3 Launch cord . 21
6.4 Receive or tail cord . 22
6.5 Substitution cord . 22
6.6 Adapter cord . 23
6.7 Power meter – LSPM methods only. 23
6.8 OTDR apparatus . 24
6.9 Connector end face cleaning and inspection equipment . 24
6.10 Adapters . 24
7 Procedures . 24
7.1 General . 24
7.2 Common procedures . 25
7.2.1 Care of the test cords . 25
7.2.2 Take reference measurements. 25
7.2.3 Inspect and clean the ends of the optical fibres in the cabling . 25
7.2.4 Take the measurements . 25
7.2.5 Make the calculations . 25
7.2.6 Multi-fibre and bi-directional testing . 25
7.3 Calibration . 26
7.4 Safety . 26
8 Calculations . 26
9 Documentation . 26
9.1 Information for each test . 26
9.2 Information to be available . 26

IEC 61280-4-5:2020 © IEC 2020 – 3 –
Annex A (normative) One-cord method . 27
A.1 Applicability of the test method . 27
A.2 Apparatus . 27
A.3 Procedure for unpinned to unpinned cabling with unpinned power meter . 27
A.4 Procedure for unpinned to pinned cabling with unpinned power meter . 28
A.5 Procedure for pinned to pinned cabling with pinned power meter . 29
A.6 Procedure for unpinned to unpinned cabling with pinned power meter and
gender-neutral test cord . 30
A.7 Calculation . 31
A.8 Components of reported attenuation . 31
Annex B (normative) Three-cord method . 32
B.1 Applicability of the test method . 32
B.2 Apparatus . 32
B.3 Procedure for unpinned to unpinned cabling . 32
B.4 Procedure for unpinned to pinned cabling . 33
B.5 Procedure for pinned to pinned cabling . 34
B.6 Procedure, channel test (general) . 35
B.7 Calculations . 36
B.8 Components of reported attenuation . 36
Annex C (normative) Adapter-cord method . 37
C.1 Applicability of the test method . 37
C.2 Apparatus . 37
C.3 Procedure for unpinned to unpinned cabling with pinned power meter . 37
C.4 Procedure for unpinned to pinned cabling with pinned power meter . 38
C.5 Procedure for pinned to unpinned cabling with unpinned power meter . 39
C.6 Procedure for pinned to pinned cabling with unpinned power meter . 40
C.7 Calculations . 41
C.8 Components of reported attenuation . 42
Annex D (normative) Equipment cord method . 43
D.1 Applicability of the test method . 43
D.2 Apparatus . 43
D.3 Procedure . 43
D.4 Calculation . 44
D.5 Components of reported attenuation . 44
D.6 Typical uncertainty values . 45
Annex E (normative) Optical time domain reflectometer . 46
E.1 Applicability of the test method . 46
E.2 Apparatus . 46
E.2.1 General . 46
E.2.2 OTDR . 46
E.2.3 Test cords . 47
E.3 Procedure (test method) . 47
E.4 Calculation . 48
E.4.1 General . 48
E.4.2 Connection location . 48
E.4.3 Definition of the power levels F and F . 49
1 2
E.4.4 Alternative calculation. 50
E.5 OTDR uncertainties . 52

– 4 – IEC 61280-4-5:2020 © IEC 2020
Annex F (normative) Requirements for the multimode source characteristics . 53
Annex G (informative) OTDR configuration information . 54
G.1 General . 54
G.2 Other measurement configurations . 54
G.2.1 General . 54
G.2.2 Measurement with low return loss connectors or short length cabling . 54
G.2.3 Measurement with APC connectors . 56
Annex H (informative) Test cord, breakout cord, and cassette attenuation verification . 58
H.1 General . 58
H.2 Apparatus . 58
H.3 General procedure . 58
H.3.1 Overview . 58
H.3.2 Test cord verification . 59
H.3.3 Cassette and breakout cord verification . 60
H.4 Test cord verification prior to cabling measurement . 61
H.4.1 General . 61
H.4.2 Procedure for unpinned to unpinned cabling measurement . 61
H.4.3 Procedure for unpinned to pinned cabling measurement . 62
H.4.4 Procedure for pinned to pinned cabling measurement . 63
Annex I (normative) On the use of low attenuation grade test cords . 66
I.1 General . 66
I.2 Practical configurations and assumptions. 66
I.2.1 Component specifications . 66
I.2.2 Conventions . 67
I.2.3 Reference planes . 67
I.3 Impact of using low attenuation grade test cords for recommended LSPM
methods . 68
I.4 Examples for LSPM measurements . 68
I.4.1 Example 1: Configuration Au-u, 1-C method (Annex A) . 68
I.4.2 Example 2: Configuration Du-u, EC method (Annex D) . 69
I.5 Impact of using reference grade test cords for different configurations using
the OTDR test method . 69
I.5.1 Cabling configurations Au-u, Ap-u and Ap-p . 69
I.5.2 Cabling configuration Du-u . 70
Bibliography . 72

Figure 1 – Connector and apparatus symbols . 13
Figure 2 – Symbol for cabling under test . 14
Figure 3 – OTDR schematic with external optical switch . 24
Figure A.1 – Reference measurement for unpinned to unpinned cabling using unpinned
power meter . 28
Figure A.2 – Test measurement for unpinned to unpinned cabling using unpinned
power meter . 28
Figure A.3 – Reference measurement for unpinned to pinned cabling using unpinned
power meter . 29
Figure A.4 – Test measurement for unpinned to pinned cabling using unpinned power
meter . 29
Figure A.5 – Reference measurement for pinned to pinned cabling using pinned power
meter . 30

IEC 61280-4-5:2020 © IEC 2020 – 5 –
Figure A.6 – Test measurement for pinned to pinned cabling using pinned power meter . 30
Figure A.7 – Reference measurement for unpinned to unpinned cabling using pinned
power meter . 31
Figure A.8 – Test measurement for unpinned to unpinned cabling (gender-neutral TC1)
using pinned power meter . 31
Figure B.1 – Reference measurement for unpinned to unpinned cabling using pinned
power meter . 33
Figure B.2 – Test measurement for unpinned to unpinned cabling using pinned power
meter . 33
Figure B.3 – Reference measurement for unpinned to pinned cabling using pinned
power meter . 34
Figure B.4 – Test measurement for unpinned to pinned cabling using pinned power
meter . 34
Figure B.5 – Reference measurement for pinned to pinned cabling using unpinned
power meter . 35
Figure B.6 – Test measurement for pinned to pinned cabling using unpinned power
meter . 35
Figure B.7 – Reference measurement for channel test using unpinned power meter . 36
Figure B.8 – Test measurement for channel test using unpinned power meter . 36
Figure C.1 – Reference measurement for unpinned to unpinned cabling using pinned
power meter . 38
Figure C.2 – Test measurement for unpinned to unpinned cabling using pinned power
meter . 38
Figure C.3 – Reference measurement for unpinned to pinned cabling using pinned
power meter . 39
Figure C.4 – Test measurement for unpinned to pinned cabling using pinned power
meter . 39
Figure C.5 – Reference measurement for unpinned to pinned cabling using unpinned
power meter . 40
Figure C.6 – Test measurement for unpinned to pinned cabling using unpinned power
meter . 40
Figure C.7 – Reference measurement for unpinned to pinned cabling using unpinned
power meter . 41
Figure C.8 – Test measurement for unpinned to pinned cabling using unpinned power
meter . 41
Figure D.1 – Reference measurement using pinned power meter . 44
Figure D.2 – Test measurement using pinned power meter . 44
Figure E.1 – OTDR method . 48
Figure E.2 – Location of the ports of the cabling under test . 49
Figure E.3 – Graphic construction of F and F . 50
1 2
Figure E.4 – Graphic construction of F , F , F and F . 51
1 11 12 2
Figure G.1 – Attenuation measurement with low return loss connectors . 55
Figure G.2 – Attenuation measurement of a short length cabling. 56
Figure G.3 – Attenuation measurement with APC MPO connections . 57
Figure H.1 – Obtaining reference power level P . 59
Figure H.2 – Obtaining power level P . 59
Figure H.3 – Obtaining reference power level P . 60
– 6 – IEC 61280-4-5:2020 © IEC 2020
Figure H.4 – Obtaining power level P . 60
Figure H.5 – Test measurement for unpinned to unpinned cabling . 61
Figure H.6 – Step 1: obtaining reference power level P . 61
Figure H.7 – Step 2: verification cords, obtaining power level P . 62
Figure H.8 – Test measurement for unpinned to pinned cabling . 62
Figure H.9 – Step 1: obtaining reference power level P . 63
Figure H.10 – Step 2: obtaining power level P . 63
Figure H.11 – Test measurement for pinned to pinned cabling . 63
Figure H.12 – Step 1: obtaining reference power level P . 64
Figure H.13 – Step 2: verification of cords, obtaining power level P . 64
Figure H.14 – Step 3: verification of receive cord, obtaining power level P . 65
Figure I.1 – Cabling configurations Au-u, Ap-u and Ap-p tested with OTDR method . 70
Figure I.2 – Cabling configuration Du-u tested with OTDR method . 71

Table 1 – Cabling configurations . 16
Table 2 – Test methods and configurations . 16
Table 3 – Measurements bias related to test cord connector grade . 17
Table 4 – Uncertainty for a given attenuation at 850 nm using same photodetector . 18
Table 5 – Uncertainty for a given attenuation at 850 nm using different photodetectors . 19
Table 6 – Uncertainty for a given attenuation at 1 310 nm using same photodetector . 19
Table 7 – Uncertainty for a given attenuation at 1 310 nm using different
photodetectors . 20
Table 8 – Spectral requirements . 21
Table D.1 – Uncertainty for a given attenuation when equipment cord method is used . 45
Table I.1 – Measurement bias adjustment when using low attenuation grade test cords . 68
Table I.2 – Acceptance figure adjustment using low attenuation grade test cords –
OTDR method . 70

IEC 61280-4-5:2020 © IEC 2020 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIBRE-OPTIC COMMUNICATION SUBSYSTEM TEST PROCEDURES –

Part 4-5: Installed cabling plant –
Attenuation measurement of MPO terminated fibre
optic cabling plant using test equipment with MPO interfaces

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
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preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
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Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
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members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) 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 some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61280-4-5 has been prepared by subcommittee 86C: Fibre optic
systems and active devices, of IEC technical committee 86: Fibre optics.
The text of this International Standard is based on the following documents:
FDIS Report on voting
86C/1669/FDIS 86C/1679/RVD
Full information on the voting for the approval of this International Standard can be found in the
report on voting indicated in the above table.
A list of all the parts in the IEC 61280 series, under the general title Fibre-optic communication
subsystem test procedures, can be found on the IEC website.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 8 – IEC 61280-4-5:2020 © IEC 2020
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC 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
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

IEC 61280-4-5:2020 © IEC 2020 – 9 –
FIBRE-OPTIC COMMUNICATION SUBSYSTEM TEST PROCEDURES –

Part 4-5: Installed cabling plant –
Attenuation measurement of MPO terminated fibre
optic cabling plant using test equipment with MPO interfaces

1 Scope
This part of IEC 61280 is applicable to the measurement of attenuation and determination of
polarity and length of installed multimode and single-mode optical fibre cabling plant, terminated
with MPO connectors, using test equipment having an MPO interface. This cabling plant can
include multimode or single-mode optical fibres, connectors, adapters, splices, and other
passive devices. The cabling can be installed in a variety of environments including residential,
commercial, industrial, and data centre premises, as well as outside plant environments.
In this document, the optical fibres that are addressed include sub-categories A1-OMx, where
x = 2, 3, 4 and 5 (50/125 μm) multimode optical fibres, as specified in IEC 60793-2-10, and
category B-652 and B-657 (9/125 μm) single-mode optical fibres, as specified in
IEC 60793-2-50. The attenuation measurements of the other multimode and single-mode
categories can also be made using a light source and power meter (LSPM) or optical time
domain reflectometer (OTDR) utilising an internal or external optical switch having one MPO
interface. Multimode measurements are made with an 850 nm source because transceivers
used for parallel optics applications having an MPO interface only operate at 850 nm; 1 300 nm
measurements are optional. Single-mode measurements are made with a 1 310 nm and/or
1 550 nm source because transceivers used for parallel optics applications having an MPO
interface operate at these wavelengths. This document does not include descriptions of cabling
that is not exclusively MPO to MPO.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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.
IEC 60825 (all parts), Safety of laser products
IEC 61280-1-3, Fibre optic communication subsystem test procedures – Part 1-3: General
communication subsystems – Central wavelength and spectral width measurement
IEC 61280-4-1:2019, Fibre-optic communication subsystem test procedures – Part 4-1:
Installed cabling plant – Multimode attenuation measurement
IEC 61300-3-35, Fibre optic interconnecting devices and passive components – Basic test and
measurement procedures – Part 3-35: Examinations and measurements – Visual inspection of
fibre optic connectors and fibre-stub transceivers
IEC 61315, Calibration of fibre-optic power meters
IEC 61746-1, Calibration of optical time-domain reflectometers (OTDR) – Part 1: OTDR for
single mode fibres
– 10 – IEC 61280-4-5:2020 © IEC 2020
IEC 61746-2, Calibration of optical time-domain reflectometers (OTDR) – Part 2: OTDR for
multimode fibres
3 Terms, definitions, graphical symbols and abbreviated terms
For the purposes of this document, the following terms, definitions, graphical symbols and
abbreviated terms apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1 Terms and definitions
3.1.1
adapter
female-part of a connector in which one or two plugs are inserted and aligned
[SOURCE: IEC TR 61931:1998, 2.6.4]
3.1.2
alternative test method
ATM
test method for measuring a given characteristic in a manner consistent with the definition of
this characteristic, and giving results which are reproducible and relatable to the reference test
method and to practical use
[SOURCE: IEC TR 61931:1998, 2,8.2, modified – The alternative term "practical test method
(for optical fibres)" has been removed.]
3.1.3
attenuation
A
reduction of optical power induced by transmission through a medium such as cabling, given
as A:
A = 10 log (P /P )
10 in out
where
P and P are the power, typically measured in mW, into and out of the cabling
in out
Note 1 to entry: Attenuation is expressed in dB.
3.1.4
bi-directional measurement
two measurements of the same optical fibre made by launching light into opposite ends of that
fibre
3.1.5
channel
end-to-end transmission path connecting any two pieces of application-specific equipment
[SOURCE: ISO/IEC 11801-1:2017, 3.1.26]

IEC 61280-4-5:2020 © IEC 2020 – 11 –
3.1.6
configuration
form or arrangements of parts or elements such as terminations, connections and splices
3.1.7
connector
component normally attached to an optical cable or piece of apparatus for the purpose of
providing frequent optical interconnection/disconnection of optical fibres or cables
[SOURCE: IEC TR 61931:1998, 2.6.1, modified – The words in brackets "optical" and "fibre"
have been omitted from the term.]
3.1.8
encircled flux
EF
fraction of cumulative near-field power to total output power as a function of radial distance
from the optical centre of the core
[SOURCE: IEC TR 62614-2:2015, 3.3, modified – The words "radial-weighted" have been
deleted from the definition.]
3.1.9
light source power meter
LSPM
test system consisting of a light source (LS) and power meter (PM) used to measure the
attenuation of installed cabling plant
3.1.10
low attenuation grade
connector and plug whose attenuation of a connection formed by mating two such assemblies
is lower and more repeatable than a "standard grade" termination (grade B in this document)
Note 1 to entry: An adapter required to assure the reduced attenuation can be considered to be part of the low
attenuation grade where required by the test configuration.
3.1.11
measurement bias
estimate of a systematic measurement error
Note 1 to entry: A systematic e
...