Environmental Engineering (EE) - Progressive migration of Information and Communication Technology (ICT) site to 400 VDC sources and distribution

DES/EE-0260

Okoljski inženiring (EE) - Postopna migracija informacijske in komunikacijske tehnologije (IKT) na virih in distribuciji 400 VDC

General Information

Status
Published
Publication Date
11-Sep-2022
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
02-Sep-2022
Due Date
07-Nov-2022
Completion Date
12-Sep-2022

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ETSI ES 203 726 V1.1.1 (2022-08)
ETSI STANDARD
Environmental Engineering (EE);
Progressive migration of Information and
Communication Technology (ICT) site to
400 VDC sources and distribution
---------------------- Page: 1 ----------------------
2 ETSI ES 203 726 V1.1.1 (2022-08)
Reference
DES/EE-0260
Keywords
energy efficiency, power supply, site engineering
ETSI
650 Route des Lucioles
F-06921 Sophia Antipolis Cedex - FRANCE
Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16
Siret N° 348 623 562 00017 - APE 7112B
Association à but non lucratif enregistrée à la
Sous-Préfecture de Grasse (06) N° w061004871
Important notice
The present document can be downloaded from:
http://www.etsi.org/standards-search

The present document may be made available in electronic versions and/or in print. The content of any electronic and/or

print versions of the present document shall not be modified without the prior written authorization of ETSI. In case of any

existing or perceived difference in contents between such versions and/or in print, the prevailing version of an ETSI

deliverable is the one made publicly available in PDF format at www.etsi.org/deliver.

Users of the present document should be aware that the document may be subject to revision or change of status.

Information on the current status of this and other ETSI documents is available at

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If you find errors in the present document, please send your comment to one of the following services:

https://portal.etsi.org/People/CommiteeSupportStaff.aspx

If you find a security vulnerability in the present document, please report it through our

Coordinated Vulnerability Disclosure Program:
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Notice of disclaimer & limitation of liability

The information provided in the present deliverable is directed solely to professionals who have the appropriate degree of

experience to understand and interpret its content in accordance with generally accepted engineering or

other professional standard and applicable regulations.

No recommendation as to products and services or vendors is made or should be implied.

No representation or warranty is made that this deliverable is technically accurate or sufficient or conforms to any law

rule and/or regulation and further, no representation or warranty is made of merchantability or fitness

and/or governmental

for any particular purpose or against infringement of intellectual property rights.

In no event shall ETSI be held liable for loss of profits or any other incidental or consequential damages.

Any software contained in this deliverable is provided "AS IS" with no warranties, express or implied, including but not

limited to, the warranties of merchantability, fitness for a particular purpose and non-infringement of intellectual property

rights and ETSI shall not be held liable in any event for any damages whatsoever (including, without limitation, damages

for loss of profits, business interruption, loss of information, or any other pecuniary loss) arising out of or related to the use

of or inability to use the software.
Copyright Notification

No part may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and

microfilm except as authorized by written permission of ETSI.

The content of the PDF version shall not be modified without the written authorization of ETSI.

The copyright and the foregoing restriction extend to reproduction in all media.
© ETSI 2022.
All rights reserved.
ETSI
---------------------- Page: 2 ----------------------
3 ETSI ES 203 726 V1.1.1 (2022-08)
Contents

Intellectual Property Rights ................................................................................................................................ 5

Foreword ............................................................................................................................................................. 5

Modal verbs terminology .................................................................................................................................... 5

Executive summary ............................................................................................................................................ 5

Introduction ........................................................................................................................................................ 6

1 Scope ........................................................................................................................................................ 7

2 References ................................................................................................................................................ 7

2.1 Normative references ......................................................................................................................................... 7

2.2 Informative references ........................................................................................................................................ 9

3 Definition of terms, symbols and abbreviations ..................................................................................... 11

3.1 Terms ................................................................................................................................................................ 11

3.2 Symbols ............................................................................................................................................................ 12

3.3 Abbreviations ................................................................................................................................................... 12

4 Present situation of a telecommunication or data centre powering solution and motivation for

migration to up to 400 VDC ................................................................................................................... 13

5 General evolution cases during migration .............................................................................................. 17

5.1 Present situation ............................................................................................................................................... 17

5.2 DC/DC converter related considerations .......................................................................................................... 20

5.3 400/AC migration inverter consideration ......................................................................................................... 21

5.4 Long distance transport in -48 V/up to 400 VDC/-48 V in centre and multistep migration ............................. 23

5.5 Combined migration cases ............................................................................................................................... 24

5.6 Grid/back-up generator 400 DC switch replacing AC mechanical switch ....................................................... 25

6 Up to 400 VDC batteries ........................................................................................................................ 26

7 Migration of up to 400 VDC remote power to local up to 400 VDC power system .............................. 26

8 Coupling renewable energy to existing buildings distribution with migration to up to 400 VDC ......... 27

9 Up to 400 VDC cabling, earthing and bonding in the migration period ................................................ 27

10 Electrical safety requirements ................................................................................................................ 28

11 Electromagnetic compatibility requirements at the input of telecommunication and datacom (ICT)

equipment ............................................................................................................................................... 28

12 Impacts on energy efficiency and other key performance indicators (environmental impact, life

cycle assessment) ................................................................................................................................... 29

Annex A (normative): Power supply and interface considerations ................................................. 30

Annex B (informative): Information on some papers on up to 400 VDC migration solutions,

advantages and implementation decision and process ............................... 31

Annex C (informative): Details on some saving assessment of migration to up to 400 VDC .......... 32

C.0 Overview ................................................................................................................................................ 32

C.1 Energy efficiency ................................................................................................................................... 32

C.2 Energy cost reduction ............................................................................................................................. 32

C.3 Saving on material, area in ICT room and labour .................................................................................. 33

C.4 Less copper and installation cost, progressive installation by modularity ............................................. 33

C.4.0 Overview .......................................................................................................................................................... 33

ETSI
---------------------- Page: 3 ----------------------
4 ETSI ES 203 726 V1.1.1 (2022-08)

C.4.1 Reliability and dependability improvement (comparative evaluation using Recommendation

ITU-T L.1202) .................................................................................................................................................. 34

C.4.2 Lower life cycle environmental impacts .......................................................................................................... 34

C.4.3 Solar power input to power distribution ........................................................................................................... 34

C.4.4 Open innovation ............................................................................................................................................... 34

History .............................................................................................................................................................. 35

ETSI
---------------------- Page: 4 ----------------------
5 ETSI ES 203 726 V1.1.1 (2022-08)
Intellectual Property Rights
Essential patents

IPRs essential or potentially essential to normative deliverables may have been declared to ETSI. The declarations

pertaining to these essential IPRs, if any, are publicly available for ETSI members and non-members, and can be

found in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to

ETSI in respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the

ETSI Web server (https://ipr.etsi.org/).

Pursuant to the ETSI Directives including the ETSI IPR Policy, no investigation regarding the essentiality of IPRs,

including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not

referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become,

essential to the present document.
Trademarks

The present document may include trademarks and/or tradenames which are asserted and/or registered by their owners.

ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no

right to use or reproduce any trademark and/or tradename. Mention of those trademarks in the present document does

not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks.

DECT™, PLUGTESTS™, UMTS™ and the ETSI logo are trademarks of ETSI registered for the benefit of its

Members. 3GPP™ and LTE™ are trademarks of ETSI registered for the benefit of its Members and of the 3GPP

Organizational Partners. oneM2M™ logo is a trademark of ETSI registered for the benefit of its Members and of the

oneM2M Partners. GSM and the GSM logo are trademarks registered and owned by the GSM Association.

Foreword

This ETSI Standard (ES) has been produced by ETSI Technical Committee Environmental Engineering (EE).

Modal verbs terminology

In the present document "shall", "shall not", "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.

Executive summary

The present document gives explanation, requirements and guidance for increasing the use of up to 400 V Direct

Current (400 VDC) power systems and the distribution to Information and Communication Technology (ICT)

equipment. It includes 400 VDC remote powering up to 400 VDC of distributed ICT equipment, the option of

interconnection of local renewable energy sources and their connection to DC power nanogrids and other users,

extending the resilience capability of the telecommunication network and ICT sites to grid failures and climate change.

ETSI
---------------------- Page: 5 ----------------------
6 ETSI ES 203 726 V1.1.1 (2022-08)
Introduction

Telecommunication network energy consumption and cost are increasing at a rate of several percentage points per year

as reported in Trends in worldwide ICT electricity consumption from 2007 to 2012 [i.11]. The use of up to 400 V Direct

Current (400 VDC) architecture (as presented in Table 1, Annex B and Annex C) can result in significant savings.

The use of up to 400 VDC solutions result in energy savings with higher efficiency and reduced distribution losses,

reduction in maintenance cost due to higher reliability and lower unavailability, savings in space for power equipment

in Information and Communication Technology (ICT) rooms (each square metre being of high cost) and, finally, more

simplicity in site installation and development.

Different levels of saving and improvement result from a comparison of up to 400 VDC solutions to -48 V solutions

(copper savings) or to Uninterrupted Power Supply (UPS) solutions (reliability, efficiency, easier installation).

400 VDC remote power can be beneficial.

As for the power system, energy savings in addition to those resulting from efficiency improvements depend on the load

in the telecommunication or data centre. Energy efficiency should be evaluated at the system level, including the

general distribution cabling and voltage conversion stages, as well as the internal power circuits inside the load

downstream of the power interface, i.e. conversion architecture in the system (e.g. dual inputs, local back-up, AC/DC

rectifier losses).

Indirect savings of up to 400 VDC solutions relate to lifecycle in the production and recycling phase as there should be

less passage through copper and electronics as well as less battery usage for given output power and system

dependability. Battery capacity and dependability savings are achieved by removing inverter losses if replacing AC

UPS or by reducing -48 V distribution losses.

The present document specifies requirements for a safe migration of an existing site to a unified up to 400 VDC

powering feeding system, power distribution and the power interface of telecommunication/ICT equipment. It includes

requirements relating to the stability, cabling, earthing, as well as bonding and measurement, for the existing site.

The main significant components of up to 400 VDC equipment and additional progressive migration equipment are

presented in Figures 2 and 3. These are schematic diagrams that do not show all the electrical arrangement details. The

architecture under consideration complies with Recommendation ITU-T L.1204 [14] on electrical architecture,

including energy storage defined in ETSI TS 103 553-1 [i.1] or Recommendation ITU-T L.1220 [i.2], technically

equivalent, and with ETSI ES 203 474 [9] or Recommendation ITU-T L.1205 [15], technically equivalent, for DC

coupling of a local RENewable Energy (REN) system on site or with DC nano/micro grid interconnecting sites with

REN sources and storage or ICT equipment requiring remote powering. Smart DC nanogrids are under study as

reported in Intelligent DC Microgrid Living Lab [i.12].

The migration simplifies the use of up to 400 VDC combined with REN and DC nanogrids and should extend resilience

capability of telecommunication networks sites to grid failures and climate change.

The present document was developed jointly by ETSI TC EE and ITU-T Study Group 5. It is published respectively by

ITU and ETSI as Recommendation ITU-T L.1207 [i.3] and ETSI ES 203 726 (the present document), which are

technically-equivalent.
ETSI
---------------------- Page: 6 ----------------------
7 ETSI ES 203 726 V1.1.1 (2022-08)
1 Scope

The present document defines solutions for progressive migration of Information and Communication Technology

(ICT) sites (telecommunication and data centres) to up to 400 V Direct Current (400 VDC) distribution and direct use of

up to 400 VDC powering ICT equipment from 400 VDC sources. The present document also defines different major

use case options and migration scenarios, such as:
• migration to an up to 400 VDC of telecommunication site power solution;
• migration to an up to 400 VDC of data centre power solution;

• migration with up to 400 VDC power transfer between existing -48 V centralized sources to high power

density -48 V equipment, such as routers;
• integration of up to 400 VDC remote powering;

• combined architecture with up to 400 VDC and AC sources and distributions possibly using hybrid power

interfaces on ICT equipment.

For each of these, the present document describes many possible options and characteristics, such as:

• migration architecture with up to 400 VDC/-48 V conversion to power existing -48 V equipment using

existing -48 V room distribution;

• conditions for tripping overcurrent protection devices without -48 V batteries;

• migration architecture with up to 400 VDC/AC inverter as an alternative to the AC UPS to power existing AC

equipment;
• use of local up to 400 VDC for remote powering of ICT equipment;
• coupling up to 400 VDC systems to a local REN source or to a DC microgrid;

• possibility of conversion between battery and up to 400 VDC distribution, e.g. for long power distribution or

short-circuit current or battery technology (e.g. lithium-ion).

The present document also gives a saving assessment frame reference to define the best migration scenario and its steps

by considering energy, resource, environmental impact and cost savings based on functional aspects such as modularity,

flexibility, reliability, efficiency and distribution losses, as well as maintenance evolution when migrating from -48 V or

Alternating Current (AC) to up to 400 VDC solutions. This also includes consideration of load architecture evolution

dependent on use cases (e.g. telecommunication site, data centres).
2 References
2.1 Normative 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.

Referenced documents which are not found to be publicly available in the expected location might be found at

https://docbox.etsi.org/Reference/.

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 necessary for the application of the present document.

[1] ETSI EN 300 132-1 (V2.1.1) (2019): "Environmental Engineering (EE); Power supply interface at

the input to Information and Communication Technology (ICT) equipment; Part 1: Alternating

Current (AC)".
ETSI
---------------------- Page: 7 ----------------------
8 ETSI ES 203 726 V1.1.1 (2022-08)

[2] ETSI EN 300 132-2 (V2.6.1) (2019): "Environmental Engineering (EE); Power supply interface at

the input of Information and Communication Technology (ICT) equipment; Part 2: -48 V Direct

Current (DC)".

[3] ETSI EN 300 132-3 (V1.2.1) (2003): "Environmental Engineering (EE); Power supply interface at

the input to telecommunications equipment; Part 3: Operated by rectified current source,

alternating current source or direct current source up to 400 V".

[4] ETSI EN 300 253 (V2.2.1) (2015): "Environmental Engineering (EE); Earthing and bonding of

ICT equipment powered by -48 VDC in telecom and data centres".

[5] ETSI EN 301 605 (V1.1.1) (2013): "Environmental Engineering (EE); Earthing and bonding of

400 VDC data and telecom (ICT) equipment".

[6] ETSI ES 202 336-2 (V1.1.1) (2009): "Environmental Engineering (EE); Monitoring and control

interface for infrastructure equipment (Power, Cooling and environment systems used in

telecommunication networks); Part 2: DC power system control and monitoring information

model".

[7] ETSI ES 203 199 (V1.3.1) (2015): "Environmental Engineering (EE); Methodology for

environmental Life Cycle Assessment (LCA) of Information and Communication Technology

(ICT) goods, networks and services".

[8] ETSI ES 203 408 (V1.1.1): "Environmental Engineering (EE); Colour and marking of DC cable

and connecting devices".

[9] ETSI ES 203 474 (V1.1.1): "Environmental Engineering (EE); Interfacing of renewable energy or

distributed power sources to 400 VDC distribution systems powering Information and

Communication Technology (ICT) equipment".

[10] ETSI TS 103 531 (V1.1.1): "Environmental Engineering (EE); Impact on ICT equipment

architecture of multiple AC, -48 VDC or up to 400 VDC power inputs".

[11] Recommendation ITU-T L.1200 (2012): "Direct current power feeding interface up to 400 V at the

input to telecommunication and ICT equipment".

[12] Recommendation ITU-T L.1202 (2015): "Methodologies for evaluating the performance of an up

to 400 VDC power feeding system and its environmental impact".

[13] Recommendation ITU-T L.1203 (2016): "Colour and marking identification of up to 400 VDC

power distribution for information and communication technology systems".

[14] Recommendation ITU-T L.1204 (2016): "Extended architecture of power feeding systems of up to

400 VDC".

[15] Recommendation ITU-T L.1205 (2016): "Interfacing of renewable energy or distributed power

sources to up to 400 VDC power feeding systems".

[16] Recommendation ITU-T L.1206 (2017): "Impact on ICT equipment architecture of multiple

AC, -48 VDC or up to 400 VDC power inputs".

[17] Recommendation ITU-T L.1320 (2014): "Energy efficiency metrics and measurement for power

and cooling equipment for telecommunications and data centres".

[18] Recommendation ITU-T L.1410 (2014): "Methodology for environmental life cycle assessments

of information and communication technology goods, networks and services".
[19] IEC 60364 (all parts): "Low-voltage electrical installations".
ETSI
---------------------- Page: 8 ----------------------
9 ETSI ES 203 726 V1.1.1 (2022-08)
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 TS 103 553-1 (V1.1.1): "Environmental Engineering (EE); Innovative energy storage

technology for stationary use; Part 1: Overview".

[i.2] Recommendation ITU-T L.1220 (2017): "Innovative energy storage technology for stationary use

- Part 1: Overview of energy storage".
[i.3] Recommendation ITU-T L.1207 (2018-05): "Progressive migration of a

telecommunication/information and communication technology site to 400 VDC sources and

distribution".

[i.4] ETSI EN 302 099 (V2.1.1) (2014): "Environmental Engineering (EE); Powering of equipment in

access network".

[i.5] Recommendation ITU-T K.48 (2017): "EMC requirements for telecommunication equipment -

Product family Recommendation".

[i.6] IEC 60950-1: "Information technology equipment - Safety - Part 1: General requirements".

[i.7] IEC 62368-1: "Audio/video, information and communication technology equipment - Part 1:

Safety requirements".

[i.8] ETSI EN 300 132-3-1 (V2.1.1) (2012): "Environmental Engineering (EE); Power supply interface

at the input to telecommunications and datacom (ICT) equipment; Part 3: Operated by rectified

current source, alternating current source or direct current source up to 400 V; Sub-part 1: Direct

current source up to 400 V".

[i.9] ETSI EN 300 386 (V2.1.1) (2016): "Telecommunication network equipment; ElectroMagnetic

Compatibility (EMC) requirements; Harmonised Standard covering the essential requirements of

the Directive 2014/30/EU".

[i.10] ETSI TR 100 283 (V2.2.1) (2007): "Environmental Engineering (EE); Transient voltages at

Interface "A" on telecommunications direct current (dc) power distributions".

[i.11] Van Heddeghem W., Lambert S., Lannoo B., Colle D., Pickavet M., Demeester P. (2014): "Trends

in worldwide ICT electricity consumption from 2007 to 2012". Computer Communications, 50,

64-76.
NOTE: Available at https://doi.org/10.1016/j.comcom.2014.02.008.
[i.12] Aalborg University: "Intelligent DC Microgrid Living Lab".

[i.13] Tsumura T, Takeda T, Hirose K (2008): "A tool for calculating reliability of power supply for

information and communication technology systems". In Intelec 2008 - IEEE 30 International

Telecommunications Energy Conference, 21.3, 6 pp., San Diego.

[i.14] Marquet D, Tanaka T, Murai K, Tanaka T, Babasaki T (2013): "DC power wide spread in

Telecom/Datacenter and in home/office with renewable energy and energy autonomy". In Intelec

2013 - IEEE 35 International Telecommunications Energy Conference, Smart Power and

Efficiency, pp. 499-504, Hamburg.

[i.15] Caltech Berkeley 2017 Vossos V, Johnson K, Kloss M, Khattar M, Gerber D, Brown R: "Review

of DC power distribution in buildings: A technology and market assessment" pp.71.

ETSI
---------------------- Page: 9 ----------------------
10 ETSI ES 203 726 V1.1.1 (2022-08)

[i.16] Schneider WP 118 Rasmussen N (undated): "High-efficiency AC power distribution for data

centers". White Paper 128. Rueil-Malmaison: Schneider Electric. 19 pp.

[i.17] CE+T Intelec 2016 Frebel F. (eFFiciency research), Bleus P. Bomboir O. (CE+T Power, sa):

"Transformer-less 2 kW non isolated 400 VDC/230 VAC single stage micro inverter". In Intelec

2016 - IEEE International Telecommunications Energy Conference, Austin.
NOTE: Available at https://ieeexplore.ieee.org/document/7749105.

[i.18] CATR Intelec 2012 Qi S, Hou F, Jing H: "Study and application on high voltage DC power

feeding system for telecommunications in China". In Intelec 2012 - IEEE 34 International

Telecommunications Energy Conference, pp. 9.1. 5, Scottsdale.
NOTE: Available at https://ieeexplore.ieee.org/xpl/conhome/6362321/proceeding.

[i.19] CAICT Intelec 2017 Qi S, Sun W, Wu Y: "Comparative analysis on different architectures of

power supply system for data center and telecom center". In Intelec 2017 - IEEE International

Telecommunications Energy Conference, pp. 26-29, Queensland.

[i.20] DCC+G Fraunhofer 2014 Wunde B: "380 VDC in commercial buildings and offices". Presentation

at Vicor Seminar 2014. 71 slides.

NOTE: Available at http://dcgrid.tue.nl/files/2014-02-11%20-%20Webinar%20Vicor.pdf.

[i.21] Fraunhofer Safety Intelec 2017 Kaiser J et al.: "Safety consideration for the operation of bipolar

DC grids". In Intelec 2017 - IEEE International Telecommunications Energy Conference,

pp. 327-334, Queensland.

[i.22] Fraunhofer Droop Intelec 2017 Wunder B et al.: "Droop controlled cognitive power electronics for

DC microgrids". In Intelec 2017 - IEEE International Telecommunications Energy Conference,

pp. 335-342, Queensland.
[i.23] Void.

[i.24] Fujitsu-NTT-Appliance coupler-Intelec 2017 Kiryu K, Tanaka T, Sato K, Seki K, Hirose K:

"Development of appliance coupler for LVDC in Information Communication Technology (ICT)

equipment with having a protection of inrush current and arc". In Intelec 2017 - IEEE International

Telecommunications Energy Conference, pp. 343-346, Queensland.

[i.25] level3-Eltek Intelec 2016 Ambriz A. (Level 3 Communications), Kania M. (Eltek): "A service

provider's decision to move from 48V to 380V powering: The problem statement, technical

assessment, financial analysis and practical implementation plan". In Intelec 2016 - IEEE

International Telecommunications Energy Conference, Austin.
NOTE: Available at https://ieeexplore.ieee.org/document/7749117.

[i.26] NTT Intelec 1999 Yamashita T, Muroyama S, Furubo S, Ohtsu S: "270 VDC System - A highly

efficient and reliable power supply system for both telecom and datacom systems". In Intelec 1999

- IEEE 21 International Telecommunication Ener
...

Final draft ETSI ES 203 726 V1.0.0 (2022-06)
ETSI STANDARD
Environmental Engineering (EE);
Progressive migration of Information and
Communication Technology (ICT) site to
400 VDC sources and distribution
---------------------- Page: 1 ----------------------
2 Final draft ETSI ES 203 726 V1.0.0 (2022-06)
Reference
DES/EE-0260
Keywords
energy efficiency, power supply, site engineering
ETSI
650 Route des Lucioles
F-06921 Sophia Antipolis Cedex - FRANCE
Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16
Siret N° 348 623 562 00017 - APE 7112B
Association à but non lucratif enregistrée à la
Sous-Préfecture de Grasse (06) N° w061004871
Important notice
The present document can be downloaded from:
http://www.etsi.org/standards-search

The present document may be made available in electronic versions and/or in print. The content of any electronic and/or

print versions of the present document shall not be modified without the prior written authorization of ETSI. In case of any

existing or perceived difference in contents between such versions and/or in print, the prevailing version of an ETSI

deliverable is the one made publicly available in PDF format at www.etsi.org/deliver.

Users of the present document should be aware that the document may be subject to revision or change of status.

Information on the current status of this and other ETSI documents is available at

https://portal.etsi.org/TB/ETSIDeliverableStatus.aspx

If you find errors in the present document, please send your comment to one of the following services:

https://portal.etsi.org/People/CommiteeSupportStaff.aspx

If you find a security vulnerability in the present document, please report it through our

Coordinated Vulnerability Disclosure Program:
https://www.etsi.org/standards/coordinated-vulnerability-disclosure
Notice of disclaimer & limitation of liability

The information provided in the present deliverable is directed solely to professionals who have the appropriate degree of

experience to understand and interpret its content in accordance with generally accepted engineering or

other professional standard and applicable regulations.

No recommendation as to products and services or vendors is made or should be implied.

No representation or warranty is made that this deliverable is technically accurate or sufficient or conforms to any law

rule and/or regulation and further, no representation or warranty is made of merchantability or fitness

and/or governmental

for any particular purpose or against infringement of intellectual property rights.

In no event shall ETSI be held liable for loss of profits or any other incidental or consequential damages.

Any software contained in this deliverable is provided "AS IS" with no warranties, express or implied, including but not

limited to, the warranties of merchantability, fitness for a particular purpose and non-infringement of intellectual property

rights and ETSI shall not be held liable in any event for any damages whatsoever (including, without limitation, damages

for loss of profits, business interruption, loss of information, or any other pecuniary loss) arising out of or related to the use

of or inability to use the software.
Copyright Notification

No part may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and

microfilm except as authorized by written permission of ETSI.

The content of the PDF version shall not be modified without the written authorization of ETSI.

The copyright and the foregoing restriction extend to reproduction in all media.
© ETSI 2022.
All rights reserved.
ETSI
---------------------- Page: 2 ----------------------
3 Final draft ETSI ES 203 726 V1.0.0 (2022-06)
Contents

Intellectual Property Rights ................................................................................................................................ 5

Foreword ............................................................................................................................................................. 5

Modal verbs terminology .................................................................................................................................... 5

Executive summary ............................................................................................................................................ 5

Introduction ........................................................................................................................................................ 6

1 Scope ........................................................................................................................................................ 7

2 References ................................................................................................................................................ 7

2.1 Normative references ......................................................................................................................................... 7

2.2 Informative references ........................................................................................................................................ 9

3 Definition of terms, symbols and abbreviations ..................................................................................... 11

3.1 Terms ................................................................................................................................................................ 11

3.2 Symbols ............................................................................................................................................................ 12

3.3 Abbreviations ................................................................................................................................................... 12

4 Present situation of a telecommunication or data centre powering solution and motivation for

migration to up to 400 VDC ................................................................................................................... 13

5 General evolution cases during migration .............................................................................................. 17

5.1 Present situation ............................................................................................................................................... 17

5.2 DC/DC converter related considerations .......................................................................................................... 20

5.3 400/AC migration inverter consideration ......................................................................................................... 21

5.4 Long distance transport in -48 V/up to 400 VDC/-48 V in centre and multistep migration ............................. 23

5.5 Combined migration cases ............................................................................................................................... 24

5.6 Grid/back-up generator 400 DC switch replacing AC mechanical switch ....................................................... 25

6 Up to 400 VDC batteries ........................................................................................................................ 26

7 Migration of up to 400 VDC remote power to local up to 400 VDC power system .............................. 26

8 Coupling renewable energy to existing buildings distribution with migration to up to 400 VDC ......... 27

9 Up to 400 VDC cabling, earthing and bonding in the migration period ................................................ 27

10 Electrical safety requirements ................................................................................................................ 28

11 Electromagnetic compatibility requirements at the input of telecommunication and datacom (ICT)

equipment ............................................................................................................................................... 28

12 Impacts on energy efficiency and other key performance indicators (environmental impact, life

cycle assessment) ................................................................................................................................... 29

Annex A (normative): Power supply and interface considerations ................................................. 30

Annex B (informative): information on some papers on up to 400 VDC migration solutions,

advantages and implementation decision and process ............................... 31

Annex C (informative): Details on some saving assessment of migration to up to 400 VDC .......... 32

C.0 Overview ................................................................................................................................................ 32

C.1 Energy efficiency ................................................................................................................................... 32

C.2 Energy cost reduction ............................................................................................................................. 32

C.3 Saving on material, area in ICT room and labour .................................................................................. 33

C.4 Less copper and installation cost, progressive installation by modularity ............................................. 33

C.4.0 Overview .......................................................................................................................................................... 33

ETSI
---------------------- Page: 3 ----------------------
4 Final draft ETSI ES 203 726 V1.0.0 (2022-06)

C.4.1 Reliability and dependability improvement (comparative evaluation using Recommendation

ITU-T L.1202) .................................................................................................................................................. 34

C.4.2 Lower life cycle environmental impacts .......................................................................................................... 34

C.4.3 Solar power input to power distribution ........................................................................................................... 34

C.4.4 Open innovation ............................................................................................................................................... 34

History .............................................................................................................................................................. 35

ETSI
---------------------- Page: 4 ----------------------
5 Final draft ETSI ES 203 726 V1.0.0 (2022-06)
Intellectual Property Rights
Essential patents

IPRs essential or potentially essential to normative deliverables may have been declared to ETSI. The declarations

pertaining to these essential IPRs, if any, are publicly available for ETSI members and non-members, and can be

found in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to

ETSI in respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the

ETSI Web server (https://ipr.etsi.org/).

Pursuant to the ETSI Directives including the ETSI IPR Policy, no investigation regarding the essentiality of IPRs,

including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not

referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become,

essential to the present document.
Trademarks

The present document may include trademarks and/or tradenames which are asserted and/or registered by their owners.

ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no

right to use or reproduce any trademark and/or tradename. Mention of those trademarks in the present document does

not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks.

DECT™, PLUGTESTS™, UMTS™ and the ETSI logo are trademarks of ETSI registered for the benefit of its

Members. 3GPP™ and LTE™ are trademarks of ETSI registered for the benefit of its Members and of the 3GPP

Organizational Partners. oneM2M™ logo is a trademark of ETSI registered for the benefit of its Members and of the

oneM2M Partners. GSM and the GSM logo are trademarks registered and owned by the GSM Association.

Foreword

This final draft ETSI Standard (ES) has been produced by ETSI Technical Committee Environmental Engineering (EE),

and is now submitted for the ETSI standards Membership Approval Procedure.
Modal verbs terminology

In the present document "shall", "shall not", "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.

Executive summary

The present document gives explanation, requirements and guidance for increasing the use of up to 400 V Direct

Current (400 VDC) power systems and the distribution to Information and Communication Technology (ICT)

equipment. It includes 400 VDC remote powering up to 400 VDC of distributed ICT equipment, the option of

interconnection of local renewable energy sources and their connection to DC power nanogrids and other users,

extending the resilience capability of the telecommunication network and ICT sites to grid failures and climate change.

ETSI
---------------------- Page: 5 ----------------------
6 Final draft ETSI ES 203 726 V1.0.0 (2022-06)
Introduction

Telecommunication network energy consumption and cost are increasing at a rate of several percentage points per year

as reported in Trends in worldwide ICT electricity consumption from 2007 to 2012 [i.11]. The use of up to 400 V Direct

Current (400 VDC) architecture (as presented in Table 1, Annex B and Annex C) can result in significant savings.

The use of up to 400 VDC solutions result in energy savings with higher efficiency and reduced distribution losses,

reduction in maintenance cost due to higher reliability and lower unavailability, savings in space for power equipment

in Information and Communication Technology (ICT) rooms (each square metre being of high cost) and, finally, more

simplicity in site installation and development.

Different levels of saving and improvement result from a comparison of up to 400 VDC solutions to -48 V solutions

(copper savings) or to Uninterrupted Power Supply (UPS) solutions (reliability, efficiency, easier installation).

400 VDC remote power can be beneficial.

As for the power system, energy savings in addition to those resulting from efficiency improvements depend on the load

in the telecommunication or data centre. Energy efficiency should be evaluated at the system level, including the

general distribution cabling and voltage conversion stages, as well as the internal power circuits inside the load

downstream of the power interface, i.e. conversion architecture in the system (e.g. dual inputs, local back-up, AC/DC

rectifier losses).

Indirect savings of up to 400 VDC solutions relate to lifecycle in the production and recycling phase as there should be

less passage through copper and electronics as well as less battery usage for given output power and system

dependability. Battery capacity and dependability savings are achieved by removing inverter losses if replacing AC

UPS or by reducing -48 V distribution losses.

The present document specifies requirements for a safe migration of an existing site to a unified up to 400 VDC

powering feeding system, power distribution and the power interface of telecommunication/ICT equipment. It includes

requirements relating to the stability, cabling, earthing, as well as bonding and measurement, for the existing site.

The main significant components of up to 400 VDC equipment and additional progressive migration equipment are

presented in Figures 2 and 3. These are schematic diagrams that do not show all the electrical arrangement details. The

architecture under consideration complies with Recommendation ITU-T L.1204 [14] on electrical architecture,

including energy storage defined in ETSI TS 103 553-1 [i.1] or Recommendation ITU-T L.1220 [i.2], technically

equivalent, and with ETSI ES 203 474 [9] or Recommendation ITU-T L.1205 [15], technically equivalent, for DC

coupling of a local Renewable Energy (REN) system on site or with DC nano/micro grid interconnecting sites with

REN sources and storage or ICT equipment requiring remote powering. Smart DC nanogrids are under study as

reported in Intelligent DC Microgrid Living Lab [i.12].

The migration simplifies the use of up to 400 VDC combined with REN and DC nanogrids and should extend resilience

capability of telecommunication networks sites to grid failures and climate change.

The present document was developed jointly by ETSI TC EE and ITU-T Study Group 5. It is published respectively by

ITU and ETSI as Recommendation ITU-T L.1207 [i.3] and ETSI ES 203 726 (the present document), which are

technically-equivalent.
ETSI
---------------------- Page: 6 ----------------------
7 Final draft ETSI ES 203 726 V1.0.0 (2022-06)
1 Scope

The present document defines solutions for progressive migration of Information and Communication Technology

(ICT) sites (telecommunication and data centres) to up to 400 V Direct Current (400 VDC) distribution and direct use of

up to 400 VDC powering ICT equipment from 400 VDC sources. The present document also defines different major

use case options and migration scenarios, such as:
• migration to an up to 400 VDC of telecommunication site power solution;
• migration to an up to 400 VDC of data centre power solution;

• migration with up to 400 VDC power transfer between existing -48 V centralized sources to high power

density -48 V equipment, such as routers;
• integration of up to 400 VDC remote powering;

• combined architecture with up to 400 VDC and AC sources and distributions possibly using hybrid power

interfaces on ICT equipment.

For each of these, the present document describes many possible options and characteristics, such as:

• migration architecture with up to 400 VDC/-48 V conversion to power existing -48 V equipment using

existing -48 V room distribution;

• conditions for tripping overcurrent protection devices without -48 V batteries;

• migration architecture with up to 400 VDC/AC inverter as an alternative to the AC UPS to power existing AC

equipment;
• use of local up to 400 VDC for remote powering of ICT equipment;
• coupling up to 400 VDC systems to a local REN source or to a DC microgrid;

• possibility of conversion between battery and up to 400 VDC distribution, e.g. for long power distribution or

short-circuit current or battery technology (e.g. lithium-ion).

The present document also gives a saving assessment frame reference to define the best migration scenario and its steps

by considering energy, resource, environmental impact and cost savings based on functional aspects such as modularity,

flexibility, reliability, efficiency and distribution losses, as well as maintenance evolution when migrating from -48 V or

Alternating Current (AC) to up to 400 VDC solutions. This also includes consideration of load architecture evolution

dependent on use cases (e.g. telecommunication site, data centres).
2 References
2.1 Normative 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.

Referenced documents which are not found to be publicly available in the expected location might be found at

https://docbox.etsi.org/Reference/.

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 necessary for the application of the present document.

[1] ETSI EN 300 132-1 (V2.1.1) (2019): "Environmental Engineering (EE); Power supply interface at

the input to Information and Communication Technology (ICT) equipment; Part 1: Alternating

Current (AC)".
ETSI
---------------------- Page: 7 ----------------------
8 Final draft ETSI ES 203 726 V1.0.0 (2022-06)

[2] ETSI EN 300 132-2 (V2.6.1) (2019): "Environmental Engineering (EE); Power supply interface at

the input of Information and Communication Technology (ICT) equipment; Part 2: -48 V Direct

Current (DC)".

[3] ETSI EN 300 132-3 (V1.2.1) (2003): "Environmental Engineering (EE); Power supply interface at

the input to telecommunications equipment; Part 3: Operated by rectified current source,

alternating current source or direct current source up to 400 V".

[4] ETSI EN 300 253 (V2.2.1) (2015): "Environmental Engineering (EE); Earthing and bonding of

ICT equipment powered by -48 VDC in telecom and data centres".

[5] ETSI EN 301 605 (V1.1.1) (2013): "Environmental Engineering (EE); Earthing and bonding of

400 VDC data and telecom (ICT) equipment".

[6] ETSI ES 202 336-2 (V1.1.1) (2009): "Environmental Engineering (EE); Monitoring and control

interface for infrastructure equipment (Power, Cooling and environment systems used in

telecommunication networks); Part 2: DC power system control and monitoring information

model".

[7] ETSI ES 203 199 (V1.3.1) (2015): "Environmental Engineering (EE); Methodology for

environmental Life Cycle Assessment (LCA) of Information and Communication Technology

(ICT) goods, networks and services".

[8] ETSI ES 203 408 (V1.1.1): "Environmental Engineering (EE); Colour and marking of DC cable

and connecting devices".

[9] ETSI ES 203 474 (V1.1.1): "Environmental Engineering (EE); Interfacing of renewable energy or

distributed power sources to 400 VDC distribution systems powering Information and

Communication Technology (ICT) equipment".

[10] ETSI TS 103 531 (V1.1.1): "Environmental Engineering (EE); Impact on ICT equipment

architecture of multiple AC, -48 VDC or up to 400 VDC power inputs".

[11] Recommendation ITU-T L.1200 (2012): "Direct current power feeding interface up to 400 V at the

input to telecommunication and ICT equipment".

[12] Recommendation ITU-T L.1202 (2015): "Methodologies for evaluating the performance of an up

to 400 VDC power feeding system and its environmental impact".

[13] Recommendation ITU-T L.1203 (2016): "Colour and marking identification of up to 400 VDC

power distribution for information and communication technology systems".

[14] Recommendation ITU-T L.1204 (2016): "Extended architecture of power feeding systems of up to

400 VDC".

[15] Recommendation ITU-T L.1205 (2016): "Interfacing of renewable energy or distributed power

sources to up to 400 VDC power feeding systems".

[16] Recommendation ITU-T L.1206 (2017): "Impact on ICT equipment architecture of multiple

AC, -48 VDC or up to 400 VDC power inputs".

[17] Recommendation ITU-T L.1320 (2014): "Energy efficiency metrics and measurement for power

and cooling equipment for telecommunications and data centres".

[18] Recommendation ITU-T L.1410 (2014): "Methodology for environmental life cycle assessments

of information and communication technology goods, networks and services".
[19] IEC 60364 (all parts): "Low-voltage electrical installations".
ETSI
---------------------- Page: 8 ----------------------
9 Final draft ETSI ES 203 726 V1.0.0 (2022-06)
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 TS 103 553-1 (V1.1.1): "Environmental Engineering (EE); Innovative energy storage

technology for stationary use; Part 1: Overview".

[i.2] Recommendation ITU-T L.1220 (2017): "Innovative energy storage technology for stationary use

- Part 1: Overview of energy storage".
[i.3] Recommendation ITU-T L.1207 (2018-05): "Progressive migration of a

telecommunication/information and communication technology site to 400 VDC sources and

distribution".

[i.4] ETSI EN 302 099 (V2.1.1) (2014): "Environmental Engineering (EE); Powering of equipment in

access network".

[i.5] Recommendation ITU-T K.48 (2017): "EMC requirements for telecommunication equipment -

Product family Recommendation".

[i.6] IEC 60950-1: "Information technology equipment - Safety - Part 1: General requirements".

[i.7] IEC 62368-1: "Audio/video, information and communication technology equipment - Part 1:

Safety requirements".

[i.8] ETSI EN 300 132-3-1 (V2.1.1) (2012): "Environmental Engineering (EE); Power supply interface

at the input to telecommunications and datacom (ICT) equipment; Part 3: Operated by rectified

current source, alternating current source or direct current source up to 400 V; Sub-part 1: Direct

current source up to 400 V".

[i.9] ETSI EN 300 386 (V2.1.1) (2016): "Telecommunication network equipment; ElectroMagnetic

Compatibility (EMC) requirements; Harmonised Standard covering the essential requirements of

the Directive 2014/30/EU".

[i.10] ETSI TR 100 283 (V2.2.1) (2007): "Environmental Engineering (EE); Transient voltages at

Interface "A" on telecommunications direct current (dc) power distributions".

[i.11] Van Heddeghem W., Lambert S., Lannoo B., Colle D., Pickavet M., Demeester P. (2014): "Trends

in worldwide ICT electricity consumption from 2007 to 2012". Computer Communications, 50,

64-76.
NOTE: Available at https://doi.org/10.1016/j.comcom.2014.02.008.
[i.12] Aalborg University: "Intelligent DC Microgrid Living Lab".

[i.13] Tsumura T, Takeda T, Hirose K (2008): "A tool for calculating reliability of power supply for

information and communication technology systems". In Intelec 2008 - IEEE 30th International

Telecommunications Energy Conference, 21.3, 6 pp., San Diego.

[i.14] Marquet D, Tanaka T, Murai K, Tanaka T, Babasaki T (2013): "DC power wide spread in

Telecom/Datacenter and in home/office with renewable energy and energy autonomy". In Intelec

2013 - IEEE 35th International Telecommunications Energy Conference, Smart Power and

Efficiency, pp. 499-504, Hamburg.

[i.15] Caltech Berkeley 2017 Vossos V, Johnson K, Kloss M, Khattar M, Gerber D, Brown R: "Review

of DC power distribution in buildings: A technology and market assessment" pp.71.

ETSI
---------------------- Page: 9 ----------------------
10 Final draft ETSI ES 203 726 V1.0.0 (2022-06)

[i.16] Schneider WP 118 Rasmussen N (undated): "High-efficiency AC power distribution for data

centers". White Paper 128. Rueil-Malmaison: Schneider Electric. 19 pp.

[i.17] CE+T Intelec 2016 Frebel F. (eFFiciency research), Bleus P. Bomboir O. (CE+T Power, sa):

"Transformer-less 2 kW non isolated 400 VDC/230 VAC single stage micro inverter". In Intelec

2016 - IEEE International Telecommunications Energy Conference, Austin.
NOTE: Available at https://ieeexplore.ieee.org/document/7749105.

[i.18] CATR Intelec 2012 Qi S, Hou F, Jing H: "Study and application on high voltage DC power

feeding system for telecommunications in China". In Intelec 2012 - IEEE 34th International

Telecommunications Energy Conference, pp. 9.1. 5, Scottsdale.
NOTE: Available at https://ieeexplore.ieee.org/xpl/conhome/6362321/proceeding.

[i.19] CAICT Intelec 2017 Qi S, Sun W, Wu Y: "Comparative analysis on different architectures of

power supply system for data center and telecom center". In Intelec 2017 - IEEE International

Telecommunications Energy Conference, pp. 26-29, Queensland.

[i.20] DCC+G Fraunhofer 2014 Wunde B: "380VDC in commercial buildings and offices". Presentation

at Vicor Seminar 2014. 71 slides.

NOTE: Available at http://dcgrid.tue.nl/files/2014-02-11%20-%20Webinar%20Vicor.pdf.

[i.21] Fraunhofer Safety Intelec 2017 Kaiser J et al.: "Safety consideration for the operation of bipolar

DC grids". In Intelec 2017 - IEEE International Telecommunications Energy Conference, pp. 327-

334, Queensland.

[i.22] Fraunhofer Droop Intelec 2017 Wunder B et al.: "Droop controlled cognitive power electronics for

DC microgrids". In Intelec 2017 - IEEE International Telecommunications Energy Conference, pp.

335-342, Queensland.
[i.23] Void.

[i.24] Fujitsu-NTT-Appliance coupler-Intelec 2017 Kiryu K, Tanaka T, Sato K, Seki K, Hirose K:

"Development of appliance coupler for LVDC in information communication technology (ICT)

equipment with having a protection of inrush current and arc". In Intelec 2017 - IEEE International

Telecommunications Energy Conference, pp. 343-346, Queensland.

[i.25] level3-Eltek Intelec 2016 Ambriz A. (Level 3 Communications), Kania M. (Eltek): "A service

provider's decision to move from 48V to 380V powering: The problem statement, technical

assessment, financial analysis and practical implementation plan". In Intelec 2016 - IEEE

International Telecommunications Energy Conference, Austin.
NOTE: Available at https://ieeexplore.ieee.org/document/7749117.
[i.26] NTT Intelec 1999 Yamashita T, Muroyama S,
...

SLOVENSKI STANDARD
SIST ES 203 726 V1.1.1:2022
01-oktober-2022
Okoljski inženiring (EE) - Postopna migracija informacijske in komunikacijske
tehnologije (IKT) na virih in distribuciji 400 VDC
Environmental Engineering (EE) - Progressive migration of Information and
Communication Technology (ICT) site to 400 VDC sources and distribution
Ta slovenski standard je istoveten z: ETSI ES 203 726 V1.1.1 (2022-08)
ICS:
19.040 Preskušanje v zvezi z Environmental testing
okoljem
35.020 Informacijska tehnika in Information technology (IT) in
tehnologija na splošno general
SIST ES 203 726 V1.1.1:2022 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST ES 203 726 V1.1.1:2022
---------------------- Page: 2 ----------------------
SIST ES 203 726 V1.1.1:2022
ETSI ES 203 726 V1.1.1 (2022-08)
ETSI STANDARD
Environmental Engineering (EE);
Progressive migration of Information and
Communication Technology (ICT) site to
400 VDC sources and distribution
---------------------- Page: 3 ----------------------
SIST ES 203 726 V1.1.1:2022
2 ETSI ES 203 726 V1.1.1 (2022-08)
Reference
DES/EE-0260
Keywords
energy efficiency, power supply, site engineering
ETSI
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All rights reserved.
ETSI
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SIST ES 203 726 V1.1.1:2022
3 ETSI ES 203 726 V1.1.1 (2022-08)
Contents

Intellectual Property Rights ................................................................................................................................ 5

Foreword ............................................................................................................................................................. 5

Modal verbs terminology .................................................................................................................................... 5

Executive summary ............................................................................................................................................ 5

Introduction ........................................................................................................................................................ 6

1 Scope ........................................................................................................................................................ 7

2 References ................................................................................................................................................ 7

2.1 Normative references ......................................................................................................................................... 7

2.2 Informative references ........................................................................................................................................ 9

3 Definition of terms, symbols and abbreviations ..................................................................................... 11

3.1 Terms ................................................................................................................................................................ 11

3.2 Symbols ............................................................................................................................................................ 12

3.3 Abbreviations ................................................................................................................................................... 12

4 Present situation of a telecommunication or data centre powering solution and motivation for

migration to up to 400 VDC ................................................................................................................... 13

5 General evolution cases during migration .............................................................................................. 17

5.1 Present situation ............................................................................................................................................... 17

5.2 DC/DC converter related considerations .......................................................................................................... 20

5.3 400/AC migration inverter consideration ......................................................................................................... 21

5.4 Long distance transport in -48 V/up to 400 VDC/-48 V in centre and multistep migration ............................. 23

5.5 Combined migration cases ............................................................................................................................... 24

5.6 Grid/back-up generator 400 DC switch replacing AC mechanical switch ....................................................... 25

6 Up to 400 VDC batteries ........................................................................................................................ 26

7 Migration of up to 400 VDC remote power to local up to 400 VDC power system .............................. 26

8 Coupling renewable energy to existing buildings distribution with migration to up to 400 VDC ......... 27

9 Up to 400 VDC cabling, earthing and bonding in the migration period ................................................ 27

10 Electrical safety requirements ................................................................................................................ 28

11 Electromagnetic compatibility requirements at the input of telecommunication and datacom (ICT)

equipment ............................................................................................................................................... 28

12 Impacts on energy efficiency and other key performance indicators (environmental impact, life

cycle assessment) ................................................................................................................................... 29

Annex A (normative): Power supply and interface considerations ................................................. 30

Annex B (informative): Information on some papers on up to 400 VDC migration solutions,

advantages and implementation decision and process ............................... 31

Annex C (informative): Details on some saving assessment of migration to up to 400 VDC .......... 32

C.0 Overview ................................................................................................................................................ 32

C.1 Energy efficiency ................................................................................................................................... 32

C.2 Energy cost reduction ............................................................................................................................. 32

C.3 Saving on material, area in ICT room and labour .................................................................................. 33

C.4 Less copper and installation cost, progressive installation by modularity ............................................. 33

C.4.0 Overview .......................................................................................................................................................... 33

ETSI
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SIST ES 203 726 V1.1.1:2022
4 ETSI ES 203 726 V1.1.1 (2022-08)

C.4.1 Reliability and dependability improvement (comparative evaluation using Recommendation

ITU-T L.1202) .................................................................................................................................................. 34

C.4.2 Lower life cycle environmental impacts .......................................................................................................... 34

C.4.3 Solar power input to power distribution ........................................................................................................... 34

C.4.4 Open innovation ............................................................................................................................................... 34

History .............................................................................................................................................................. 35

ETSI
---------------------- Page: 6 ----------------------
SIST ES 203 726 V1.1.1:2022
5 ETSI ES 203 726 V1.1.1 (2022-08)
Intellectual Property Rights
Essential patents

IPRs essential or potentially essential to normative deliverables may have been declared to ETSI. The declarations

pertaining to these essential IPRs, if any, are publicly available for ETSI members and non-members, and can be

found in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to

ETSI in respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the

ETSI Web server (https://ipr.etsi.org/).

Pursuant to the ETSI Directives including the ETSI IPR Policy, no investigation regarding the essentiality of IPRs,

including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not

referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become,

essential to the present document.
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Foreword

This ETSI Standard (ES) has been produced by ETSI Technical Committee Environmental Engineering (EE).

Modal verbs terminology

In the present document "shall", "shall not", "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.

Executive summary

The present document gives explanation, requirements and guidance for increasing the use of up to 400 V Direct

Current (400 VDC) power systems and the distribution to Information and Communication Technology (ICT)

equipment. It includes 400 VDC remote powering up to 400 VDC of distributed ICT equipment, the option of

interconnection of local renewable energy sources and their connection to DC power nanogrids and other users,

extending the resilience capability of the telecommunication network and ICT sites to grid failures and climate change.

ETSI
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Introduction

Telecommunication network energy consumption and cost are increasing at a rate of several percentage points per year

as reported in Trends in worldwide ICT electricity consumption from 2007 to 2012 [i.11]. The use of up to 400 V Direct

Current (400 VDC) architecture (as presented in Table 1, Annex B and Annex C) can result in significant savings.

The use of up to 400 VDC solutions result in energy savings with higher efficiency and reduced distribution losses,

reduction in maintenance cost due to higher reliability and lower unavailability, savings in space for power equipment

in Information and Communication Technology (ICT) rooms (each square metre being of high cost) and, finally, more

simplicity in site installation and development.

Different levels of saving and improvement result from a comparison of up to 400 VDC solutions to -48 V solutions

(copper savings) or to Uninterrupted Power Supply (UPS) solutions (reliability, efficiency, easier installation).

400 VDC remote power can be beneficial.

As for the power system, energy savings in addition to those resulting from efficiency improvements depend on the load

in the telecommunication or data centre. Energy efficiency should be evaluated at the system level, including the

general distribution cabling and voltage conversion stages, as well as the internal power circuits inside the load

downstream of the power interface, i.e. conversion architecture in the system (e.g. dual inputs, local back-up, AC/DC

rectifier losses).

Indirect savings of up to 400 VDC solutions relate to lifecycle in the production and recycling phase as there should be

less passage through copper and electronics as well as less battery usage for given output power and system

dependability. Battery capacity and dependability savings are achieved by removing inverter losses if replacing AC

UPS or by reducing -48 V distribution losses.

The present document specifies requirements for a safe migration of an existing site to a unified up to 400 VDC

powering feeding system, power distribution and the power interface of telecommunication/ICT equipment. It includes

requirements relating to the stability, cabling, earthing, as well as bonding and measurement, for the existing site.

The main significant components of up to 400 VDC equipment and additional progressive migration equipment are

presented in Figures 2 and 3. These are schematic diagrams that do not show all the electrical arrangement details. The

architecture under consideration complies with Recommendation ITU-T L.1204 [14] on electrical architecture,

including energy storage defined in ETSI TS 103 553-1 [i.1] or Recommendation ITU-T L.1220 [i.2], technically

equivalent, and with ETSI ES 203 474 [9] or Recommendation ITU-T L.1205 [15], technically equivalent, for DC

coupling of a local RENewable Energy (REN) system on site or with DC nano/micro grid interconnecting sites with

REN sources and storage or ICT equipment requiring remote powering. Smart DC nanogrids are under study as

reported in Intelligent DC Microgrid Living Lab [i.12].

The migration simplifies the use of up to 400 VDC combined with REN and DC nanogrids and should extend resilience

capability of telecommunication networks sites to grid failures and climate change.

The present document was developed jointly by ETSI TC EE and ITU-T Study Group 5. It is published respectively by

ITU and ETSI as Recommendation ITU-T L.1207 [i.3] and ETSI ES 203 726 (the present document), which are

technically-equivalent.
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7 ETSI ES 203 726 V1.1.1 (2022-08)
1 Scope

The present document defines solutions for progressive migration of Information and Communication Technology

(ICT) sites (telecommunication and data centres) to up to 400 V Direct Current (400 VDC) distribution and direct use of

up to 400 VDC powering ICT equipment from 400 VDC sources. The present document also defines different major

use case options and migration scenarios, such as:
• migration to an up to 400 VDC of telecommunication site power solution;
• migration to an up to 400 VDC of data centre power solution;

• migration with up to 400 VDC power transfer between existing -48 V centralized sources to high power

density -48 V equipment, such as routers;
• integration of up to 400 VDC remote powering;

• combined architecture with up to 400 VDC and AC sources and distributions possibly using hybrid power

interfaces on ICT equipment.

For each of these, the present document describes many possible options and characteristics, such as:

• migration architecture with up to 400 VDC/-48 V conversion to power existing -48 V equipment using

existing -48 V room distribution;

• conditions for tripping overcurrent protection devices without -48 V batteries;

• migration architecture with up to 400 VDC/AC inverter as an alternative to the AC UPS to power existing AC

equipment;
• use of local up to 400 VDC for remote powering of ICT equipment;
• coupling up to 400 VDC systems to a local REN source or to a DC microgrid;

• possibility of conversion between battery and up to 400 VDC distribution, e.g. for long power distribution or

short-circuit current or battery technology (e.g. lithium-ion).

The present document also gives a saving assessment frame reference to define the best migration scenario and its steps

by considering energy, resource, environmental impact and cost savings based on functional aspects such as modularity,

flexibility, reliability, efficiency and distribution losses, as well as maintenance evolution when migrating from -48 V or

Alternating Current (AC) to up to 400 VDC solutions. This also includes consideration of load architecture evolution

dependent on use cases (e.g. telecommunication site, data centres).
2 References
2.1 Normative 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.

Referenced documents which are not found to be publicly available in the expected location might be found at

https://docbox.etsi.org/Reference/.

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 necessary for the application of the present document.

[1] ETSI EN 300 132-1 (V2.1.1) (2019): "Environmental Engineering (EE); Power supply interface at

the input to Information and Communication Technology (ICT) equipment; Part 1: Alternating

Current (AC)".
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8 ETSI ES 203 726 V1.1.1 (2022-08)

[2] ETSI EN 300 132-2 (V2.6.1) (2019): "Environmental Engineering (EE); Power supply interface at

the input of Information and Communication Technology (ICT) equipment; Part 2: -48 V Direct

Current (DC)".

[3] ETSI EN 300 132-3 (V1.2.1) (2003): "Environmental Engineering (EE); Power supply interface at

the input to telecommunications equipment; Part 3: Operated by rectified current source,

alternating current source or direct current source up to 400 V".

[4] ETSI EN 300 253 (V2.2.1) (2015): "Environmental Engineering (EE); Earthing and bonding of

ICT equipment powered by -48 VDC in telecom and data centres".

[5] ETSI EN 301 605 (V1.1.1) (2013): "Environmental Engineering (EE); Earthing and bonding of

400 VDC data and telecom (ICT) equipment".

[6] ETSI ES 202 336-2 (V1.1.1) (2009): "Environmental Engineering (EE); Monitoring and control

interface for infrastructure equipment (Power, Cooling and environment systems used in

telecommunication networks); Part 2: DC power system control and monitoring information

model".

[7] ETSI ES 203 199 (V1.3.1) (2015): "Environmental Engineering (EE); Methodology for

environmental Life Cycle Assessment (LCA) of Information and Communication Technology

(ICT) goods, networks and services".

[8] ETSI ES 203 408 (V1.1.1): "Environmental Engineering (EE); Colour and marking of DC cable

and connecting devices".

[9] ETSI ES 203 474 (V1.1.1): "Environmental Engineering (EE); Interfacing of renewable energy or

distributed power sources to 400 VDC distribution systems powering Information and

Communication Technology (ICT) equipment".

[10] ETSI TS 103 531 (V1.1.1): "Environmental Engineering (EE); Impact on ICT equipment

architecture of multiple AC, -48 VDC or up to 400 VDC power inputs".

[11] Recommendation ITU-T L.1200 (2012): "Direct current power feeding interface up to 400 V at the

input to telecommunication and ICT equipment".

[12] Recommendation ITU-T L.1202 (2015): "Methodologies for evaluating the performance of an up

to 400 VDC power feeding system and its environmental impact".

[13] Recommendation ITU-T L.1203 (2016): "Colour and marking identification of up to 400 VDC

power distribution for information and communication technology systems".

[14] Recommendation ITU-T L.1204 (2016): "Extended architecture of power feeding systems of up to

400 VDC".

[15] Recommendation ITU-T L.1205 (2016): "Interfacing of renewable energy or distributed power

sources to up to 400 VDC power feeding systems".

[16] Recommendation ITU-T L.1206 (2017): "Impact on ICT equipment architecture of multiple

AC, -48 VDC or up to 400 VDC power inputs".

[17] Recommendation ITU-T L.1320 (2014): "Energy efficiency metrics and measurement for power

and cooling equipment for telecommunications and data centres".

[18] Recommendation ITU-T L.1410 (2014): "Methodology for environmental life cycle assessments

of information and communication technology goods, networks and services".
[19] IEC 60364 (all parts): "Low-voltage electrical installations".
ETSI
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9 ETSI ES 203 726 V1.1.1 (2022-08)
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 TS 103 553-1 (V1.1.1): "Environmental Engineering (EE); Innovative energy storage

technology for stationary use; Part 1: Overview".

[i.2] Recommendation ITU-T L.1220 (2017): "Innovative energy storage technology for stationary use

- Part 1: Overview of energy storage".
[i.3] Recommendation ITU-T L.1207 (2018-05): "Progressive migration of a

telecommunication/information and communication technology site to 400 VDC sources and

distribution".

[i.4] ETSI EN 302 099 (V2.1.1) (2014): "Environmental Engineering (EE); Powering of equipment in

access network".

[i.5] Recommendation ITU-T K.48 (2017): "EMC requirements for telecommunication equipment -

Product family Recommendation".

[i.6] IEC 60950-1: "Information technology equipment - Safety - Part 1: General requirements".

[i.7] IEC 62368-1: "Audio/video, information and communication technology equipment - Part 1:

Safety requirements".

[i.8] ETSI EN 300 132-3-1 (V2.1.1) (2012): "Environmental Engineering (EE); Power supply interface

at the input to telecommunications and datacom (ICT) equipment; Part 3: Operated by rectified

current source, alternating current source or direct current source up to 400 V; Sub-part 1: Direct

current source up to 400 V".

[i.9] ETSI EN 300 386 (V2.1.1) (2016): "Telecommunication network equipment; ElectroMagnetic

Compatibility (EMC) requirements; Harmonised Standard covering the essential requirements of

the Directive 2014/30/EU".

[i.10] ETSI TR 100 283 (V2.2.1) (2007): "Environmental Engineering (EE); Transient voltages at

Interface "A" on telecommunications direct current (dc) power distributions".

[i.11] Van Heddeghem W., Lambert S., Lannoo B., Colle D., Pickavet M., Demeester P. (2014): "Trends

in worldwide ICT electricity consumption from 2007 to 2012". Computer Communications, 50,

64-76.
NOTE: Available at https://doi.org/10.1016/j.comcom.2014.02.008.
[i.12] Aalborg University: "Intelligent DC Microgrid Living Lab".

[i.13] Tsumura T, Takeda T, Hirose K (2008): "A tool for calculating reliability of power supply for

information and communication technology systems". In Intelec 2008 - IEEE 30 International

Telecommunications Energy Conference, 21.3, 6 pp., San Diego.

[i.14] Marquet D, Tanaka T, Murai K, Tanaka T, Babasaki T (2013): "DC power wide spread in

Telecom/Datacenter and in home/office with renewable energy and energy autonomy". In Intelec

2013 - IEEE 35 International Telecommunications Energy Conference, Smart Power and

Efficiency, pp. 499-504, Hamburg.

[i.15] Caltech Berkeley 2017 Vossos V, Johnson K, Kloss M, Khattar M, Gerber D, Brown R: "Review

of DC power distribution in buildings: A technology and market assessment" pp.71.

ETSI
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[i.16] Schneider WP 118 Rasmussen N (undated): "High-efficiency AC power distribution for data

centers". White Paper 128. Rueil-Malmaison: Schneider Electric. 19 pp.

[i.17] CE+T Intelec 2016 Frebel F. (eFFiciency research), Bleus P. Bomboir O. (CE+T Power, sa):

"Transformer-less 2 kW non isolated 400 VDC/230 VAC single stage micro inverter". In Intelec

2016 - IEEE International Telecommunications Energy Conference, Austin.
NOTE: Available at https://ieeexplore.ieee.org/document/7749105.

[i.18] CATR Intelec 2012 Qi S, Hou F, Jing H: "Study and application on high voltage DC power

feeding system for telecommunications in China". In Intelec 2012 - IEEE 34 International

Telecommunications Energy Conference, pp. 9.1. 5, Scottsdale.
NOTE: Available at https://ieeexplore.ieee.org/xpl/conhome/6362321/proceeding.

[i.19] CAICT Intelec 2017 Qi S, Sun W, Wu Y: "Comparative analysis on different architectures of

power supply system for data center and telecom center". In Intelec 2017 - IEEE International

Telecommunications Energy Conference, pp. 26-29, Queensland.

[i.20] DCC+G Fraunhofer 2014 Wunde B: "380 VDC in commercial buildings and offices". Presentation

at Vicor Seminar 2014. 71 slides.

NOTE: Available at http://dcgrid.tue.nl/files/2014-02-11%20-%20Webinar%20Vicor.pdf.

[i.21] Fraunhofer Safety Intelec 2017 Kaiser J et al.: "Safety consideration for the operation of bipolar

DC grids". In Intelec 2017 - IEEE International Telecommunications Energy Conference,

pp. 327-334, Queensland.
[i.22] Fraunhofer Droop Intelec 2017 Wunder B et al.: "Droop controlled cog
...

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