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BSI PD ISO/IEC TS 29125:2017+A1:2020

BSI PD ISO/IEC TS 29125:2017+A1:2020

$167.15

Information technology. Telecommunications cabling requirements for remote powering of terminal equipment

Published By Publication Date Number of Pages
BSI 2020 42
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This document

  1. addresses the support of safety extra low voltage (SELV) and limited power source (LPS) applications that provide remote power over:

    • 4-pair balanced cabling in accordance with the reference implementations of ISO/IEC 11801 series standards using currents per conductor of up to 500 mA;

    • 1-pair balanced cabling using currents per conductor of up to 1 000 mA;

    and targets the support of applications that provide remote power over balanced cabling to terminal equipment,

    1. covers the transmission and electrical p arameters needed to support r emote power o ver balanced cabling,

    2. covers various installation scenarios and how these may impact the capability of balanced cabling to support remote powering,

    3. specifies design and configuration of cabling as specified in ISO/IEC 11801-1.

NOTE SELV requirements specify a maximum voltage of 60 V DC and LPS is understood in the applications referenced to be up to 100 W supplied within 4-pair cabling.

This document includes a mathematical model to predict the behaviour of different bundle sizes, various cabling constructions, and installation conditions for different current capacities.

Safety (e.g. electrical safety and protection and fire) and electromagnetic compatibility (EMC) requirements are outside the scope of this document, and are covered by other standards and regulations. However, information given by this document can be of assistance.

PDF Catalog

PDF Pages PDF Title
2 undefined
4 CONTENTS
6 FOREWORD
8 INTRODUCTION
9 1 Scope
2 Normative references
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
10 3.2 Abbreviated terms
4 Conformance
11 5 Cabling selection and performance
6 Installation conditions
6.1 General
6.2 Ambient temperature
6.3 Temperature rise and current capacity
12 Tables
Table 1 – Maximum current per conductor versus temperature rise in a 37-cable bundlein air and conduit (all 4 pairs energized)
13 6.4 Factors affecting temperature increase
6.4.1 General
6.4.2 Installation near equipment
6.4.3 Cable count within a bundle
Table 2 – Calculated worst case current per conductor versus temperature rise in a bundle of 37 4-pair cables (all pairs energized)
14 Blank Page
15 Blank Page
16 6.4.4 Reducing temperature increase
Table 3 – Temperature rise versus cable bundle size (500 mA per conductor)
17 6.4.5 Cable bundle suspended in air
Table 4 – Temperature rise for a type of cable versus the numberof energized pairs in a 37-cable bundle (500 mA per conductor)
18 Blank Page
19 Blank Page
20 6.4.6 Administration
7 Remote power delivery over balanced cabling
Figures
Figure 1 – Examples of end point powering systems using signal pairs (top) and spare pairs (bottom)
21 8 Connecting hardware
Figure 2 – Examples of mid-span powering systems
23 Annex A (informative) Mitigation considerations for installed cabling
A.1 General
A.2 Minimum cabling class
A.3 Bundle size and location
A.4 Mitigation options
24 Annex B (informative) Modelling temperature rise for cable types, bundle sizes and installation conditions
B.1 Model basics
B.2 Power dissipated (P)
Figure B.1 – Temperature rise profile
25 B.3 Temperature difference from ambient temperature to bundle surface (∆Tu)
B.3.1 Model equations
B.3.2 Typical values for constant (u
B.4 Temperature difference from bundle surface to bundle centre (∆Tth)
B.4.1 Model equations
B.4.2 Typical values for constant (th
26 B.5 Temperature variation within the bundle (∆T(x))
B.6 Alternative presentation of the model
B.7 Adaptation model used to derive temperature rise vs. cables in a bundle
27 B.8 Calculations
B.9 Example
28 B.10 Coefficients for air and conduit
Table B.1 – Bundling coefficients for different types of cables and cords (all 4 pairs energized)
29 Annex C (informative) Transmission parameters related to remote powering
C.1 DC loop resistance
C.2 DC resistance unbalance (within pair)
Table C.1 – Maximum DC loop resistance of channels
30 C.3 DC resistance unbalance (pair to pair)
Table C.2 – DC resistance unbalance of cables, connecting hardware and channels
31 Table C.3 – DC resistance unbalance (pair to pair)
32 Annex D (informative) Illustrations of heating of various bundle sizes and configurations
D.1 Limiting cable bundle size
Figure D.1 – 91-cable bundle
Figure D.2 – Three bundles of 37 cables
33 D.2 Separating into smaller bundles
Figure D.3 – Three bundles of 37 cables with separation
34 Annex E (informative) Test protocol
E.1 Background
E.2 Test set-up
Figure E.1 – 37-cable bundle and temperature location
35 Figure E.2 – “Perfect bundle” and thermocouple configuration
Figure E.3 – Conductor configuration
36 Blank Page
37 Blank Page
38 Annex F (informative) Detailed test procedure
F.1 General
F.2 Test set-up
F.2.1 Thermocouple placement
Figure F.1 – Placement of thermocouple
39 F.2.2 Measurement of cable bundle in air
Figure F.2 – Securing of the thermocouple
40 F.2.3 Measurement of cable bundle in conduit
Figure F.3 – Test set-up for cable bundles in air
41 Figure F.4 – Test set-up for cable bundles in conduit

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BSI PD ISO/IEC TS 29125:2017+A1:2020
$167.15