ETSI TR 101 147 V1.2.1 (2025-02)

Environmental Engineering (EE); Interworking between Direct Current/Isolated (DC/I) and Direct Current/Common (DC/C) electrical power systems

RTR/EE-02100

General Information

• Status: Not Published
• Technical Committee: EE 2 - EE Power Supply
• Current Stage: 12 - Completion
• Due Date: 15-Feb-2025
• Completion Date: 06-Feb-2025

Standards Content (Sample)

TECHNICAL REPORT
Environmental Engineering (EE);
Interworking between Direct Current/Isolated (DC/I) and
Direct Current/Common (DC/C) electrical power systems

2 ETSI TR 101 147 V1.2.1 (2025-02)

Reference
RTR/EE-02100
Keywords
earthing, power supply
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ETSI
3 ETSI TR 101 147 V1.2.1 (2025-02)
Contents
Intellectual Property Rights . 4
Foreword . 4
Modal verbs terminology . 4
Introduction . 4
1 Scope . 5
2 References . 5
2.1 Normative references . 5
2.2 Informative references . 5
3 Definition of terms, symbols and abbreviations . 5
3.1 Terms . 5
3.2 Symbols . 6
3.3 Abbreviations . 6
4 Description of the DC/C and DC/I systems . 7
4.1 Global view of the systems. 7
4.2 Identification of the connections . 7
4.3 Definition of the connections . 8
4.3.1 Ground connections (G connections) . 8
4.3.2 DC Power supply return links (B connection) . 9
4.3.3 DC return conductor connections (C connections) . 9
4.3.4 Signal screen connections (S connections) . 10
4.3.5 AC Mains Protective Conductor (D1 connection) . 10
5 Modelling of the systems . 10
5.1 DC/C power supply model . 10
5.2 DC/I power supply model . 11
6 Interworking . 11
6.1 Interworking between 2 systems . 11
6.1.0 Introduction. 11
6.1.1 Interconnection between DC/C and DC/I models . 12
6.1.2 Interconnection between 2 DC/C models . 13
6.1.3 Interconnection between 2 DC/I models . 14
Annex A (informative): Bibliography . 15
History . 16

ETSI
4 ETSI TR 101 147 V1.2.1 (2025-02)
Intellectual Property Rights
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Foreword
This Technical Report (TR) has been produced by ETSI Technical Committee Environmental Engineering (EE).
Modal verbs terminology
In the present document "should", "should not", "may", "need not", "will", "will not", "can" and "cannot" are to be
interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
Introduction
ETSI EN 300 253 [i.1] recognizes the Direct Current/Common (DC/C) and Direct Current /Isolated (DC/I) electrical
power systems usable in telecommunication equipments.
The aim of the present document is to show the effective interconnecting possibility of the two systems and to list some
engineering precautions ensuring good interworking.
ETSI
5 ETSI TR 101 147 V1.2.1 (2025-02)
1 Scope
The present document describes and establishes simplified models of the different sections of the ground distribution
network constituting the DC/I and the DC/C electrical power systems.
These models are interworked to identify the common impedance where DC power supply currents can circulate
(interconnection between DC/C and DC/I, DC/C and DC/C, DC/I and DC/I).
These results allow the establishment of some basic engineering advice that should be applied to guarantee the good
behaviour when interconnecting two systems. These precautions are given for functionality reasons:
• the noise immunity of the pre-existing system and of the links between the system and the MDF should be
conserved;
and safety aspects:
• the screens of signal cables between the pre-existing system and the Main Distribution Frame (MDF), the
conductors and the connections of the pre-existing system have to withstand additional currents.
2 References
2.1 Normative references
Normative references are not applicable in the present document.
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ETSI EN 300 253 "Environmental Engineering (EE); Earthing and bonding of ICT equipment
powered by -48 VDC in telecom and data centres".
3 Definition of terms, symbols and abbreviations
3.1 Terms
For the purposes of the present document, the following terms apply:
DC power return conductor: name given to the 0V power supply conductor
NOTE: It is also called "battery return".
DC/C system: system where the DC power return conductors are connected to the Common Bonding Network (CBN),
ensuring simultaneously the supply and protection functions
NOTE: The DC/C system is also called a "2 wire system".
ETSI
6 ETSI TR 101 147 V1.2.1 (2025-02)
DC/I system: system where the current return function and the grounding of t
...