ETSI EN 300 132-2 V2.7.1 (2022-09)

SLOVENSKI STANDARD
SIST EN 300 132-2 V2.7.1:2022
01-november-2022
Okoljski inženiring (EE) - Napajalni vmesnik na vhodu informacijske in
komunikacijske tehnologije (IKT) - 2. del: Enosmerna napetost - 48 V (DC)
Environmental Engineering (EE) - Power supply interface at the input of Information and
Communication Technology (ICT) equipment - Part 2: -48 V Direct Current (DC)
Ta slovenski standard je istoveten z: ETSI EN 300 132-2 V2.7.1 (2022-09)
ICS:
19.040 Preskušanje v zvezi z Environmental testing
okoljem
33.050.01 Telekomunikacijska Telecommunication terminal
terminalska oprema na equipment in general
splošno
SIST EN 300 132-2 V2.7.1:2022 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 300 132-2 V2.7.1:2022

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SIST EN 300 132-2 V2.7.1:2022
ETSI EN 300 132-2 V2.7.1 (2022-09)






EUROPEAN STANDARD
Environmental Engineering (EE);
Power supply interface at the input of
Information and Communication Technology (ICT) equipment;
Part 2: -48 V Direct Current (DC)

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SIST EN 300 132-2 V2.7.1:2022
 2 ETSI EN 300 132-2 V2.7.1 (2022-09)

Reference
REN/EE-02101
Keywords
interface, power supply
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
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print versions of the present document shall not be modified without the prior written authorization of ETSI. In case of any
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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:
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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.
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

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SIST EN 300 132-2 V2.7.1:2022
 3 ETSI EN 300 132-2 V2.7.1 (2022-09)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 6
1 Scope . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 8
3 Definition of terms, symbols and abbreviations . 9
3.1 Terms . 9
3.2 Symbols . 10
3.3 Abbreviations . 10
4 Requirements . 10
4.0 Power interface "A" . 10
4.1 Nominal voltage . 11
4.2 Normal service voltage range at interface "A" . 11
4.3 Abnormal service voltage range at interface "A" . 12
4.3.1 Abnormal service voltage range under steady state conditions . 12
4.3.2 Abnormal conditions: voltage variations, dips and short interruptions . 12
4.3.3 Voltage transients . 13
4.3.3.1 Voltage transient due to short-circuit and protective device clearance . 13
4.3.3.2 Short voltage transient due to switching and lightning . 13
4.3.4 Recovery from voltage transients . 14
4.4 Voltage changes due to the regulation of the power supply . 15
4.5 Power supply protection at interface "A" . 15
4.6 Maximum current drain . 15
4.7 Inrush Current on connection of interface "A" . 16
4.7.1 Limits . 16
4.7.2 Measurements . 17
4.8 Conducted immunity requirements of the ICT equipment at interface "A": narrowband noise . 18
4.9 Conducted emissions requirements of the ICT equipment at interface "A" . 20
5 Earthing and bonding . 21
Annex A (informative): Identification of interface "A" . 22
Annex B (informative): -60 VDC systems . 23
Annex C (informative): Guide for measuring inrush current and for transferring the
recorded pulses onto the limit chart . 24
C.1 Measurement . 24
C.2 Pulse waveform transfor mation . 24
C.3 Measurement of inrush current with filter capacitor current pulses . 27
Annex D (informative): Test arrangements for the injection of electrical noise at interface
"A" . 30
Annex E (informative): Wideband noise . 31
E.0 Wideband noise . 31
E.1 Emission of wideband noise . 31
E.1.0 General . 31
E.1.1 Assessment of wideband noise . 31
ETSI

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SIST EN 300 132-2 V2.7.1:2022
 4 ETSI EN 300 132-2 V2.7.1 (2022-09)
E.2 How to calculate wideband emission . 31
Annex F (informative): Protection dimensioning . 35
Annex G (informative): Effects of protective device operation transients in the power
distribution . 36
Annex H (normative): Verification of measurement network defined in clause 4.9 . 37
Annex I (informative): Bibliography . 38
History . 39

ETSI

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SIST EN 300 132-2 V2.7.1:2022
 5 ETSI EN 300 132-2 V2.7.1 (2022-09)
Intellectual Property Rights
Essential patents
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ETSI in respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the
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Pursuant to the ETSI Directives including the ETSI IPR Policy, no investigation regarding the essentiality of IPRs,
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Foreword
This European Standard (EN) has been produced by ETSI Technical Committee Environmental Engineering (EE).
The present document concerns the requirements for the interface between ICT equipment and its power supply, and
includes requirements relating to its stability and measurement. Various other references and detailed measurement and
test arrangements are contained in informative annexes.
The present document is part 2 of a multi-part deliverable covering Environmental Engineering (EE); Power supply
interface at the input to Information and Communication Technology (ICT) equipment, as identified below:
Part 1: "Alternating Current (AC)";
Part 2: "-48 V Direct Current (DC)";
Part 3: "Up to 400 V Direct Current (DC)".

National transposition dates
Date of adoption of this EN: 12 September 2022
Date of latest announcement of this EN (doa): 31 December 2022
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 30 June 2023
Date of withdrawal of any conflicting National Standard (dow): 30 June 2023

ETSI

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SIST EN 300 132-2 V2.7.1:2022
 6 ETSI EN 300 132-2 V2.7.1 (2022-09)
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.
ETSI

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SIST EN 300 132-2 V2.7.1:2022
 7 ETSI EN 300 132-2 V2.7.1 (2022-09)
1 Scope
The present document contains requirements and measurements methods for the physical interface "A" that is situated
between the power supply system(s) and the power consuming ICT equipment.
The nominal voltage at power interface "A" of ICT equipment defined in the present document is DC voltage -48 V.
The DC power can be supplied by a DC output power system (e.g. based on AC rectifiers on grid or DC/DC converters on
solar system, fuel cell, DC engine or fuel cell generator) and also directly supplied by a battery backup in this DC power
system. The purpose of the present document is to be able to use a power supply system with the same characteristics
for all ICT equipment defined in the area of application:
- to facilitate inter working of different types of load units;
- to facilitate the standardization of ICT equipment;
- to facilitate the installation, operation and maintenance in the same network of ICT equipment and systems
from different origins.
The present document aims at providing electrical compatibility between the power supply equipment and the power
consuming ICT equipment, between different system blocks and loads connected to the same power supply feeding the
interface "A" (e.g. control/monitoring, cooling system, etc.).
The requirements are defined for:
- the power supply input of any type of ICT equipment installed at telecommunication centres that are connected
to interface "A" powered by DC;
- any type of ICT equipment, installed in access networks and customers' premises, the DC interface "A" of
which is also used by equipment requiring a DC supply source;
- any type of ICT equipment powered by DC, used in the fixed and mobile networks installed in different
locations such as buildings, shelters, street cabinets, outdoor installations.
Disturbances on the power supply interface "A" relating to the continuous wave phenomena below 20 kHz are covered
within the present document.
The present document does not cover safety requirements, they are covered by relevant safety standards.
The present document does not cover EMC requirements, they are covered by relevant EMC standards.
NOTE: Annex B gives guidance on -60 VDC supply systems.
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 300 253: "Environmental Engineering (EE); Earthing and bonding of ICT equipment
powered by -48 VDC in telecom and data centres".
ETSI

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SIST EN 300 132-2 V2.7.1:2022
 8 ETSI EN 300 132-2 V2.7.1 (2022-09)
[2] Void.
[3] Void.
[4] Void.
[5] EN 61000-4-5: "Electromagnetic compatibility (EMC) - Part 4-5: Testing and measurement
techniques - Surge immunity test" (produced by CENELEC).
[6] Void.
[7] EN 61000-4-29: "Electromagnetic compatibility (EMC) - Part 4-29: Testing and measurement
techniques -Voltage dips, short interruptions and voltage variations on d.c. input power port
immunity tests" (produced by CENELEC).
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] Recommendation ITU-T Q.551: "Transmission characteristics of digital exchanges".
[i.2] Recommendation ITU-T Q.552: "Transmission characteristics at 2-wire analogue interfaces of
digital exchanges".
[i.3] Recommendation ITU-T Q.553: "Transmission characteristics at 4-wire analogue interfaces of
digital exchanges".
[i.4] Recommendation ITU-T Q.554: "Transmission characteristics at digital interfaces of digital
exchanges".
[i.5] ETSI TR 100 283: "Environmental Engineering (EE); Transient voltages at Interface "A" on
telecommunications direct current (dc) power distributions".
[i.6] US Department of Defence MIL-STD-461E: "Requirements for the control of electromagnetic
interference characteristics of subsystems and equipment".
[i.7] Void.
[i.8] Recommendation ITU-T O.41: "Psophometer for use on telephone-type circuits".
[i.9] IEC 60050-601: "International Electrotechnical Vocabulary. Chapter 601: Generation,
transmission and distribution of electricity - General" (Area 826 "Electrical installations",
section 826-11 "Voltages and currents").
[i.10] EN 60269-1: "Low-voltage fuses - Part 1: General requirements" (produced by CENELEC).
[i.11] EN 60934: "Circuit-breakers for equipment (CBE)" (produced by CENELEC).
[i.12] IEC 60050-351: 2013: "International Electrotechnical Vocabulary. Part 351: Control technology".
ETSI

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SIST EN 300 132-2 V2.7.1:2022
 9 ETSI EN 300 132-2 V2.7.1 (2022-09)
3 Definition of terms, symbols and abbreviations
3.1 Terms
For the purposes of the present document, the following terms apply:
abnormal service voltage range: range of steady state voltage over which the equipment will not be expected to
maintain normal service but will survive undamaged
customer premises: location which is the sole responsibility of the customer
DC power return conductor: 0 V power supply conductor
NOTE: Also called "battery return".
fully equipped equipment: configuration that corresponds to the maximum power consumption measured at -48 VDC
with the equipment in operating conditions (e.g. not in standby mode)
NOTE: When there are several fully equipped configurations because of different combinations of possible
boards, the configuration with the boards that gives the highest power consumption should be considered.
ICT equipment: device, in the telecommunication network infrastructure, that provides an ICT service
interface "A": terminals at which the power supply is connected to the system block
NOTE 1: See also figure 1 and annex A.
NOTE 2: This is a functional definition and not an exact depiction of the physical location.
malfunction: termination of the normal service
maximum steady state input current (I ): maximum steady state input current, stated by the manufacturer, for a fully
m
equipped equipment under test connected to interface "A" at nominal voltage
nominal voltage: value of the voltage by which the electrical installation or part of the electrical installation is
designated and identified
NOTE: As defined in IEC 60050-601 [i.9].
normal service: service mode where ICT equipment operates within its specification which includes a defined restart
time after malfunction or full interruption
normal service voltage range: range of steady state voltages over which the equipment will maintain normal service
power supply: power source to which ICT equipment is intended to be connected
service voltage: value of the voltage under normal conditions, at a given instant and a given point of the system
NOTE: As defined in IEC 60050-601 [i.9].
steady-state: state of a system at which all state and output variables remain constant in time while all input variables
are constant
NOTE: This is definition 351-45-10 in IEC 60050-351:2013 [i.12].
system block: functional group of equipment depending for its operation and performance on its connection to the same
power supply
NOTE: A system block may consist of equipment or a functional group of equipment. Different examples of
configurations at interface "A" are given in annex A.
telecommunication centre: location where ICT equipment is installed and which is the sole responsibility of the
operator
ETSI

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SIST EN 300 132-2 V2.7.1:2022
 10 ETSI EN 300 132-2 V2.7.1 (2022-09)
3.2 Symbols
For the purposes of the present document, the following symbols apply:
I instantaneous inrush current
t
maximum steady state input current
I
m
L inductance of inductive element of LISN
R resistance of resistive element of LISN
t time
U
pso,eff effective psophometric voltage
U
rms RMS voltage
Z capacitive impedance of immunity measurement circuit
c
Z resistive impedance of immunity measurement circuit
m
μs microsecond
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AC Alternating Current
DC Direct Current
NOTE: Also when used as a suffix to units of measurement.
EMC ElectroMagnetic Compatibility
ESR Equivalent Series Resistance
EUT Equipment Under Test
HOD High-Ohmic Distributions
ICT Information and Communication Technology
IL Insertion Loss
LISN Line Impedance Stabilization Network
LOD Low-Ohmic Distributions
RF Radio Frequency
rms root mean square
TR Technical Report
VDC Voltage Direct Current
NOTE: Also when used as a suffix to units of measurement.
4 Requirements
4.0 Power interface "A"
The power supply interface, interface "A" of figure 1, is a physical point to which all the requirements are related.
This point is situated between the power supply system(s) and the power consuming ICT equipment.
An example of a configuration in which interface "A" is identified is given in annex A.
ETSI

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SIST EN 300 132-2 V2.7.1:2022
 11 ETSI EN 300 132-2 V2.7.1 (2022-09)
-V
bat
ICT equipment
+V (0 Volt)
bat

Figure 1: Identification of interface "A"
4.1 Nominal voltage
The nominal voltage at interface "A" shall be -48 VDC with positive conductor connected to earth as defined in ETSI
EN 300 253 [1].
NOTE 1: The positive conductor, also called DC return, can be (see ETSI EN 300 253 [1]):
 Isolated DC return: this is a DC power system in which the DC power return conductor has a single
point connection to the bonding network. Equipment intended for this power distribution has a
floating DC power at the power input terminal.
 Common DC return: this is a DC power system in which the return conductor is connected to the
bonding network at many points. Equipment intended for this power distribution can have the DC
return earthed at the power input terminal.
NOTE 2: In most cases the nominal voltage of interface "A" is based on a 24 cells lead-acid battery. Use of other
technologies, such as Lithium-ion batteries, are increasing and are compatible with the requirements of
the present document
4.2 Normal service voltage range at interface "A"
The normal service voltage range for the -48 VDC nominal supply at interface "A" shall be from -40,5 VDC
to -57,0 VDC.
NOTE 1: The maximum voltage is based on a 0,3 V drop in the distribution loop and a battery voltage of
2,35 V/cell plus 0,5 % for regulation.
There shall be no degradation of service performance when ICT equipment is operating at voltages within the normal
service voltage range including voltage variation inside the normal voltage range.
This requirement shall be verified by applying at interface "A" a voltage step test with specification and parameters
defined in table 1. The testing and measurement techniques are described in EN 61000-4-29 [7].
The test shall apply to equipment with single and multiple power supply "A" interface inputs.
ETSI

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SIST EN 300 132-2 V2.7.1:2022
 12 ETSI EN 300 132-2 V2.7.1 (2022-09)
Table 1
Test level of Normal Voltage Basic standard Rise and fall time of Performance criteria
service voltage step step for testing voltage step
variation duration
From -40,5 V to -57,0 VDC 0,1 s EN 61000-4-29 [7] No degradation in the
Between 1 μs and 50 μs on
and 100 Ω resistive load service performance
from -57 VDC to -40,5 VDC during and after the
(see basic standard for test
test
From -57,0 V to -40,5 VDC 0,1 s generator)
and
from -40,5 VDC to -57 VDC

In the case of ICT equipment with power supply input redundancy (e.g. Input 1 and Input 2), this test shall be
performed:
• with Inputs 1 and 2 powered simultaneously and applying the test in table 1 on both inputs simultaneously;
• with Inputs 1 and 2 powered simultaneously and applying the test in table 1 on one input (either Input 1 or 2);
• with either Input 1 or 2 powered and no power on the other power input and applying the test in table 1 on the
powered input.
NOTE 2: The minimum voltage is based on the voltage drop in the distribution network and a battery cell end of
discharge voltage.
NOTE 3: The voltages specified are measured at interface "A". It should be noted that if interface "A" is at any
point other than the ICT equipment interface as presented in annex A, there will be a voltage drop
between interface "A" and the equipment terminals.
4.3 Abnormal service voltage range at interface "A"
4.3.1 Abnormal service voltage range under steady state conditions
ICT equipment designed to work at 48 VDC nominal voltage at the interface "A" shall not suffer any damage when
subjected to the following voltage ranges defined in table 2.
Table 2
0,0 V to -40,5 VDC
-57,0 VDC to -60,0 VDC

Following the restoration of the supply to the normal voltage range, the power conversion and management systems on
the load side of interface "A" shall automatically restore normal service. The ICT equipment
...

ETSI EN 300 132-2 V2.7.1 (2022-09)






EUROPEAN STANDARD
Environmental Engineering (EE);
Power supply interface at the input of
Information and Communication Technology (ICT) equipment;
Part 2: -48 V Direct Current (DC)

---------------------- Page: 1 ----------------------
2 ETSI EN 300 132-2 V2.7.1 (2022-09)

Reference
REN/EE-02101
Keywords
interface, power supply
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.
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

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3 ETSI EN 300 132-2 V2.7.1 (2022-09)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 6
1 Scope . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 8
3 Definition of terms, symbols and abbreviations . 9
3.1 Terms . 9
3.2 Symbols . 10
3.3 Abbreviations . 10
4 Requirements . 10
4.0 Power interface "A" . 10
4.1 Nominal voltage . 11
4.2 Normal service voltage range at interface "A" . 11
4.3 Abnormal service voltage range at interface "A" . 12
4.3.1 Abnormal service voltage range under steady state conditions . 12
4.3.2 Abnormal conditions: voltage variations, dips and short interruptions . 12
4.3.3 Voltage transients . 13
4.3.3.1 Voltage transient due to short-circuit and protective device clearance . 13
4.3.3.2 Short voltage transient due to switching and lightning . 13
4.3.4 Recovery from voltage transients . 14
4.4 Voltage changes due to the regulation of the power supply . 15
4.5 Power supply protection at interface "A" . 15
4.6 Maximum current drain . 15
4.7 Inrush Current on connection of interface "A" . 16
4.7.1 Limits . 16
4.7.2 Measurements . 17
4.8 Conducted immunity requirements of the ICT equipment at interface "A": narrowband noise . 18
4.9 Conducted emissions requirements of the ICT equipment at interface "A" . 20
5 Earthing and bonding . 21
Annex A (informative): Identification of interface "A" . 22
Annex B (informative): -60 VDC systems . 23
Annex C (informative): Guide for measuring inrush current and for transferring the
recorded pulses onto the limit chart . 24
C.1 Measurement . 24
C.2 Pulse waveform transfor mation . 24
C.3 Measurement of inrush current with filter capacitor current pulses . 27
Annex D (informative): Test arrangements for the injection of electrical noise at interface
"A" . 30
Annex E (informative): Wideband noise . 31
E.0 Wideband noise . 31
E.1 Emission of wideband noise . 31
E.1.0 General . 31
E.1.1 Assessment of wideband noise . 31
ETSI

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4 ETSI EN 300 132-2 V2.7.1 (2022-09)
E.2 How to calculate wideband emission . 31
Annex F (informative): Protection dimensioning . 35
Annex G (informative): Effects of protective device operation transients in the power
distribution . 36
Annex H (normative): Verification of measurement network defined in clause 4.9 . 37
Annex I (informative): Bibliography . 38
History . 39

ETSI

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5 ETSI EN 300 132-2 V2.7.1 (2022-09)
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 European Standard (EN) has been produced by ETSI Technical Committee Environmental Engineering (EE).
The present document concerns the requirements for the interface between ICT equipment and its power supply, and
includes requirements relating to its stability and measurement. Various other references and detailed measurement and
test arrangements are contained in informative annexes.
The present document is part 2 of a multi-part deliverable covering Environmental Engineering (EE); Power supply
interface at the input to Information and Communication Technology (ICT) equipment, as identified below:
Part 1: "Alternating Current (AC)";
Part 2: "-48 V Direct Current (DC)";
Part 3: "Up to 400 V Direct Current (DC)".

National transposition dates
Date of adoption of this EN: 12 September 2022
Date of latest announcement of this EN (doa): 31 December 2022
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 30 June 2023
Date of withdrawal of any conflicting National Standard (dow): 30 June 2023

ETSI

---------------------- Page: 5 ----------------------
6 ETSI EN 300 132-2 V2.7.1 (2022-09)
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.
ETSI

---------------------- Page: 6 ----------------------
7 ETSI EN 300 132-2 V2.7.1 (2022-09)
1 Scope
The present document contains requirements and measurements methods for the physical interface "A" that is situated
between the power supply system(s) and the power consuming ICT equipment.
The nominal voltage at power interface "A" of ICT equipment defined in the present document is DC voltage -48 V.
The DC power can be supplied by a DC output power system (e.g. based on AC rectifiers on grid or DC/DC converters on
solar system, fuel cell, DC engine or fuel cell generator) and also directly supplied by a battery backup in this DC power
system. The purpose of the present document is to be able to use a power supply system with the same characteristics
for all ICT equipment defined in the area of application:
- to facilitate inter working of different types of load units;
- to facilitate the standardization of ICT equipment;
- to facilitate the installation, operation and maintenance in the same network of ICT equipment and systems
from different origins.
The present document aims at providing electrical compatibility between the power supply equipment and the power
consuming ICT equipment, between different system blocks and loads connected to the same power supply feeding the
interface "A" (e.g. control/monitoring, cooling system, etc.).
The requirements are defined for:
- the power supply input of any type of ICT equipment installed at telecommunication centres that are connected
to interface "A" powered by DC;
- any type of ICT equipment, installed in access networks and customers' premises, the DC interface "A" of
which is also used by equipment requiring a DC supply source;
- any type of ICT equipment powered by DC, used in the fixed and mobile networks installed in different
locations such as buildings, shelters, street cabinets, outdoor installations.
Disturbances on the power supply interface "A" relating to the continuous wave phenomena below 20 kHz are covered
within the present document.
The present document does not cover safety requirements, they are covered by relevant safety standards.
The present document does not cover EMC requirements, they are covered by relevant EMC standards.
NOTE: Annex B gives guidance on -60 VDC supply systems.
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 300 253: "Environmental Engineering (EE); Earthing and bonding of ICT equipment
powered by -48 VDC in telecom and data centres".
ETSI

---------------------- Page: 7 ----------------------
8 ETSI EN 300 132-2 V2.7.1 (2022-09)
[2] Void.
[3] Void.
[4] Void.
[5] EN 61000-4-5: "Electromagnetic compatibility (EMC) - Part 4-5: Testing and measurement
techniques - Surge immunity test" (produced by CENELEC).
[6] Void.
[7] EN 61000-4-29: "Electromagnetic compatibility (EMC) - Part 4-29: Testing and measurement
techniques -Voltage dips, short interruptions and voltage variations on d.c. input power port
immunity tests" (produced by CENELEC).
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] Recommendation ITU-T Q.551: "Transmission characteristics of digital exchanges".
[i.2] Recommendation ITU-T Q.552: "Transmission characteristics at 2-wire analogue interfaces of
digital exchanges".
[i.3] Recommendation ITU-T Q.553: "Transmission characteristics at 4-wire analogue interfaces of
digital exchanges".
[i.4] Recommendation ITU-T Q.554: "Transmission characteristics at digital interfaces of digital
exchanges".
[i.5] ETSI TR 100 283: "Environmental Engineering (EE); Transient voltages at Interface "A" on
telecommunications direct current (dc) power distributions".
[i.6] US Department of Defence MIL-STD-461E: "Requirements for the control of electromagnetic
interference characteristics of subsystems and equipment".
[i.7] Void.
[i.8] Recommendation ITU-T O.41: "Psophometer for use on telephone-type circuits".
[i.9] IEC 60050-601: "International Electrotechnical Vocabulary. Chapter 601: Generation,
transmission and distribution of electricity - General" (Area 826 "Electrical installations",
section 826-11 "Voltages and currents").
[i.10] EN 60269-1: "Low-voltage fuses - Part 1: General requirements" (produced by CENELEC).
[i.11] EN 60934: "Circuit-breakers for equipment (CBE)" (produced by CENELEC).
[i.12] IEC 60050-351: 2013: "International Electrotechnical Vocabulary. Part 351: Control technology".
ETSI

---------------------- Page: 8 ----------------------
9 ETSI EN 300 132-2 V2.7.1 (2022-09)
3 Definition of terms, symbols and abbreviations
3.1 Terms
For the purposes of the present document, the following terms apply:
abnormal service voltage range: range of steady state voltage over which the equipment will not be expected to
maintain normal service but will survive undamaged
customer premises: location which is the sole responsibility of the customer
DC power return conductor: 0 V power supply conductor
NOTE: Also called "battery return".
fully equipped equipment: configuration that corresponds to the maximum power consumption measured at -48 VDC
with the equipment in operating conditions (e.g. not in standby mode)
NOTE: When there are several fully equipped configurations because of different combinations of possible
boards, the configuration with the boards that gives the highest power consumption should be considered.
ICT equipment: device, in the telecommunication network infrastructure, that provides an ICT service
interface "A": terminals at which the power supply is connected to the system block
NOTE 1: See also figure 1 and annex A.
NOTE 2: This is a functional definition and not an exact depiction of the physical location.
malfunction: termination of the normal service
maximum steady state input current (I ): maximum steady state input current, stated by the manufacturer, for a fully
m
equipped equipment under test connected to interface "A" at nominal voltage
nominal voltage: value of the voltage by which the electrical installation or part of the electrical installation is
designated and identified
NOTE: As defined in IEC 60050-601 [i.9].
normal service: service mode where ICT equipment operates within its specification which includes a defined restart
time after malfunction or full interruption
normal service voltage range: range of steady state voltages over which the equipment will maintain normal service
power supply: power source to which ICT equipment is intended to be connected
service voltage: value of the voltage under normal conditions, at a given instant and a given point of the system
NOTE: As defined in IEC 60050-601 [i.9].
steady-state: state of a system at which all state and output variables remain constant in time while all input variables
are constant
NOTE: This is definition 351-45-10 in IEC 60050-351:2013 [i.12].
system block: functional group of equipment depending for its operation and performance on its connection to the same
power supply
NOTE: A system block may consist of equipment or a functional group of equipment. Different examples of
configurations at interface "A" are given in annex A.
telecommunication centre: location where ICT equipment is installed and which is the sole responsibility of the
operator
ETSI

---------------------- Page: 9 ----------------------
10 ETSI EN 300 132-2 V2.7.1 (2022-09)
3.2 Symbols
For the purposes of the present document, the following symbols apply:
I instantaneous inrush current
t
maximum steady state input current
I
m
L inductance of inductive element of LISN
R resistance of resistive element of LISN
t time
U
pso,eff effective psophometric voltage
U
rms RMS voltage
Z capacitive impedance of immunity measurement circuit
c
Z resistive impedance of immunity measurement circuit
m
μs microsecond
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AC Alternating Current
DC Direct Current
NOTE: Also when used as a suffix to units of measurement.
EMC ElectroMagnetic Compatibility
ESR Equivalent Series Resistance
EUT Equipment Under Test
HOD High-Ohmic Distributions
ICT Information and Communication Technology
IL Insertion Loss
LISN Line Impedance Stabilization Network
LOD Low-Ohmic Distributions
RF Radio Frequency
rms root mean square
TR Technical Report
VDC Voltage Direct Current
NOTE: Also when used as a suffix to units of measurement.
4 Requirements
4.0 Power interface "A"
The power supply interface, interface "A" of figure 1, is a physical point to which all the requirements are related.
This point is situated between the power supply system(s) and the power consuming ICT equipment.
An example of a configuration in which interface "A" is identified is given in annex A.
ETSI

---------------------- Page: 10 ----------------------
11 ETSI EN 300 132-2 V2.7.1 (2022-09)
-V
bat
ICT equipment
+V (0 Volt)
bat

Figure 1: Identification of interface "A"
4.1 Nominal voltage
The nominal voltage at interface "A" shall be -48 VDC with positive conductor connected to earth as defined in ETSI
EN 300 253 [1].
NOTE 1: The positive conductor, also called DC return, can be (see ETSI EN 300 253 [1]):
 Isolated DC return: this is a DC power system in which the DC power return conductor has a single
point connection to the bonding network. Equipment intended for this power distribution has a
floating DC power at the power input terminal.
 Common DC return: this is a DC power system in which the return conductor is connected to the
bonding network at many points. Equipment intended for this power distribution can have the DC
return earthed at the power input terminal.
NOTE 2: In most cases the nominal voltage of interface "A" is based on a 24 cells lead-acid battery. Use of other
technologies, such as Lithium-ion batteries, are increasing and are compatible with the requirements of
the present document
4.2 Normal service voltage range at interface "A"
The normal service voltage range for the -48 VDC nominal supply at interface "A" shall be from -40,5 VDC
to -57,0 VDC.
NOTE 1: The maximum voltage is based on a 0,3 V drop in the distribution loop and a battery voltage of
2,35 V/cell plus 0,5 % for regulation.
There shall be no degradation of service performance when ICT equipment is operating at voltages within the normal
service voltage range including voltage variation inside the normal voltage range.
This requirement shall be verified by applying at interface "A" a voltage step test with specification and parameters
defined in table 1. The testing and measurement techniques are described in EN 61000-4-29 [7].
The test shall apply to equipment with single and multiple power supply "A" interface inputs.
ETSI

---------------------- Page: 11 ----------------------
12 ETSI EN 300 132-2 V2.7.1 (2022-09)
Table 1
Test level of Normal Voltage Basic standard Rise and fall time of Performance criteria
service voltage step step for testing voltage step
variation duration
From -40,5 V to -57,0 VDC 0,1 s EN 61000-4-29 [7] No degradation in the
Between 1 μs and 50 μs on
and 100 Ω resistive load service performance
from -57 VDC to -40,5 VDC during and after the
(see basic standard for test
test
From -57,0 V to -40,5 VDC 0,1 s generator)
and
from -40,5 VDC to -57 VDC

In the case of ICT equipment with power supply input redundancy (e.g. Input 1 and Input 2), this test shall be
performed:
• with Inputs 1 and 2 powered simultaneously and applying the test in table 1 on both inputs simultaneously;
• with Inputs 1 and 2 powered simultaneously and applying the test in table 1 on one input (either Input 1 or 2);
• with either Input 1 or 2 powered and no power on the other power input and applying the test in table 1 on the
powered input.
NOTE 2: The minimum voltage is based on the voltage drop in the distribution network and a battery cell end of
discharge voltage.
NOTE 3: The voltages specified are measured at interface "A". It should be noted that if interface "A" is at any
point other than the ICT equipment interface as presented in annex A, there will be a voltage drop
between interface "A" and the equipment terminals.
4.3 Abnormal service voltage range at interface "A"
4.3.1 Abnormal service voltage range under steady state conditions
ICT equipment designed to work at 48 VDC nominal voltage at the interface "A" shall not suffer any damage when
subjected to the following voltage ranges defined in table 2.
Table 2
0,0 V to -40,5 VDC
-57,0 VDC to -60,0 VDC

Following the restoration of the supply to the normal voltage range, the power conversion and management systems on
the load side of interface "A" shall automatically restore normal service. The ICT equipment shall then resume
operation according to its specifications. The abnormal service voltage shall not lead to the disconnection of the power
supply e.g. by causing circuit breakers, fuses or other such devices to operate.
NOTE: It is acceptable that the system may restart when the voltage is -40,5 VDC or anywhere within the
nominal service voltage range and/or after a time delay.
4.3.2 Abnormal conditions: voltage variations, dips and short interruptions
ICT equipment shall comply with the requirements defined in this clause when subject to the abnormal voltage range
defined in table 3 that can be present at the interface "A".
This requirement shall be verified by applying at interface "A" a voltage step test with specification and parameters
defined in table 3. The testing and measurement techniques are described in EN 61000-4-29 [7].
The test shall apply to equipment with single and multiple power supply inputs.
ETSI

---------------------- Page: 12 ----------------------
13 ETSI EN 300 132-2 V2.7.1 (2022-09)
Table 3
Test level of abnormal Voltage step Basic standard Rise and fall time of Performance criteria
voltage step variation duration for testing voltage step
From -40,5 VDC to -60,0 VDC 0,1 s EN 61000-4-29 [7] Self restart to a normal
Between 1 μs an
...

Draft ETSI EN 300 132-2 V2.6.6 (2022-06)






EUROPEAN STANDARD
Environmental Engineering (EE);
Power supply interface at the input of
Information and Communication Technology (ICT) equipment;
Part 2: -48 V Direct Current (DC)

---------------------- Page: 1 ----------------------
2 Draft ETSI EN 300 132-2 V2.6.6 (2022-06)

Reference
REN/EE-02101
Keywords
interface, power supply
ETSI
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Tel.: +33 4 92 94 42 00  Fax: +33 4 93 65 47 16

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Sous-Préfecture de Grasse (06) N° w061004871

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© ETSI 2022.
All rights reserved.

ETSI

---------------------- Page: 2 ----------------------
3 Draft ETSI EN 300 132-2 V2.6.6 (2022-06)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 6
1 Scope . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 8
3 Definition of terms, symbols and abbreviations . 9
3.1 Terms . 9
3.2 Symbols . 10
3.3 Abbreviations . 10
4 Requirements . 11
4.0 Power interface "A" . 11
4.1 Nominal voltage . 11
4.2 Normal service voltage range at interface "A" . 11
4.3 Abnormal service voltage range at interface "A" . 12
4.3.1 Abnormal service voltage range under steady state conditions . 12
4.3.2 Abnormal conditions: voltage variations, dips and short interruptions . 12
4.3.3 Voltage transients . 13
4.3.3.1 Voltage transient due to short-circuit and protective device clearance . 13
4.3.3.2 Short voltage transient due to switching and lightning . 14
4.3.4 Recovery from voltage transients . 14
4.4 Voltage changes due to the regulation of the power supply . 15
4.5 Power supply protection at interface "A" . 15
4.6 Maximum current drain . 15
4.7 Inrush Current on connection of interface "A" . 16
4.7.1 Limits . 16
4.7.2 Measurements . 17
4.8 Conducted immunity requirements of the ICT equipment at interface "A": narrowband noise . 18
4.9 Conducted emissions requirements of the ICT equipment at interface "A" . 20
5 Earthing and bonding . 21
Annex A (informative): Identification of interface "A" . 22
Annex B (informative): -60 VDC systems . 23
Annex C (informative): Guide for measuring inrush current and for transferring the
recorded pulses onto the limit chart . 24
C.1 Measurement . 24
C.2 Pulse waveform transfor mation . 24
C.3 Measurement of inrush current with filter capacitor current pulses . 27
Annex D (informative): Test arrangements for the injection of electrical noise at interface
"A" . 30
Annex E (informative): Wideband noise . 31
E.0 Wideband noise . 31
E.1 Emission of wideband noise . 31
E.1.0 General . 31
E.1.1 Assessment of wideband noise . 31
ETSI

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4 Draft ETSI EN 300 132-2 V2.6.6 (2022-06)
E.2 How to calculate wideband emission . 31
Annex F (informative): Protection dimensioning . 35
Annex G (informative): Effects of protective device operation transients in the power
distribution . 36
Annex H (normative): Verification of measurement network defined in clause 4.9 . 37
Annex I (informative): Bibliography . 38
History . 39

ETSI

---------------------- Page: 4 ----------------------
5 Draft ETSI EN 300 132-2 V2.6.6 (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 draft European Standard (EN) has been produced by ETSI Technical Committee Environmental Engineering (EE),
and is now submitted for the combined Public Enquiry and Vote phase of the ETSI standards EN Approval Procedure.
The present document concerns the requirements for the interface between ICT equipment and its power supply, and
includes requirements relating to its stability and measurement. Various other references and detailed measurement and
test arrangements are contained in informative annexes.
The present document is part 2 of a multi-part deliverable covering Environmental Engineering (EE); Power supply
interface at the input to Information and Communication Technology (ICT) equipment, as identified below:
Part 1: "Alternating Current (AC)";
Part 2: "-48 V Direct Current (DC)";
Part 3: "Up to 400 V Direct Current (DC)".

Proposed national transposition dates
Date of latest announcement of this EN (doa): 3 months after ETSI publication
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 6 months after doa
Date of withdrawal of any conflicting National Standard (dow): 6 months after doa

ETSI

---------------------- Page: 5 ----------------------
6 Draft ETSI EN 300 132-2 V2.6.6 (2022-06)
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.
ETSI

---------------------- Page: 6 ----------------------
7 Draft ETSI EN 300 132-2 V2.6.6 (2022-06)
1 Scope
The present document contains requirements and measurements methods for the physical interface "A" that is situated
between the power supply system(s) and the power consuming ICT equipment.
The nominal voltage at power interface "A" of ICT equipment defined in the present document is DC voltage -48 V.
The DC power can be supplied by a DC output power system (e.g. based on AC rectifiers on grid or DC/DC converters on
solar system, fuel cell, DC engine or fuel cell generator) and also directly supplied by a battery backup in this DC power
system. The purpose of the present document is to be able to use a power supply system with the same characteristics
for all ICT equipment defined in the area of application:
- to facilitate inter working of different types of load units;
- to facilitate the standardization of ICT equipment;
- to facilitate the installation, operation and maintenance in the same network of ICT equipment and systems
from different origins.
The present document aims at providing electrical compatibility between the power supply equipment and the power
consuming ICT equipment, between different system blocks and loads connected to the same power supply feeding the
interface "A" (e.g. control/monitoring, cooling system, etc.).
The requirements are defined for:
- the power supply input of any type of ICT equipment installed at telecommunication centres that are connected
to interface "A" powered by DC;
- any type of ICT equipment, installed in access networks and customers' premises, the DC interface "A" of
which is also used by equipment requiring a DC supply source;
- any type of ICT equipment powered by DC, used in the fixed and mobile networks installed in different
locations such as buildings, shelters, street cabinets, outdoor installations.
Disturbances on the power supply interface "A" relating to the continuous wave phenomena below 20 kHz are covered
within the present document.
The present document does not cover safety requirements, they are covered by relevant safety standards.
The present document does not cover EMC requirements, they are covered by relevant EMC standards.
NOTE: Annex B gives guidance on -60 VDC supply systems.
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 300 253: "Environmental Engineering (EE); Earthing and bonding of ICT equipment
powered by -48 VDC in telecom and data centres".
ETSI

---------------------- Page: 7 ----------------------
8 Draft ETSI EN 300 132-2 V2.6.6 (2022-06)
[2] Void.
[3] Void.
[4] Void.
[5] EN 61000-4-5: "Electromagnetic compatibility (EMC) - Part 4-5: Testing and measurement
techniques - Surge immunity test" (produced by CENELEC).
[6] Void.
[7] EN 61000-4-29: "Electromagnetic compatibility (EMC) - Part 4-29: Testing and measurement
techniques -Voltage dips, short interruptions and voltage variations on d.c. input power port
immunity tests" (produced by CENELEC).
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] Recommendation ITU-T Q.551: "Transmission characteristics of digital exchanges".
[i.2] Recommendation ITU-T Q.552: "Transmission characteristics at 2-wire analogue interfaces of
digital exchanges".
[i.3] Recommendation ITU-T Q.553: "Transmission characteristics at 4-wire analogue interfaces of
digital exchanges".
[i.4] Recommendation ITU-T Q.554: "Transmission characteristics at digital interfaces of digital
exchanges".
[i.5] ETSI TR 100 283: "Environmental Engineering (EE); Transient voltages at Interface "A" on
telecommunications direct current (dc) power distributions".
[i.6] US Department of Defence MIL-STD-461E: "Requirements for the control of electromagnetic
interference characteristics of subsystems and equipment".
[i.7] Void.
[i.8] Recommendation ITU-T O.41: "Psophometer for use on telephone-type circuits".
[i.9] IEC 60050-601: "International Electrotechnical Vocabulary. Chapter 601: Generation,
transmission and distribution of electricity - General" (Area 826 "Electrical installations",
section 826-11 "Voltages and currents").
[i.10] EN 60269-1: "Low-voltage fuses - Part 1: General requirements" (produced by CENELEC).
[i.11] EN 60934: "Circuit-breakers for equipment (CBE)" (produced by CENELEC).
[i.12] IEC 60050-351: 2013: "International Electrotechnical Vocabulary. Part 351: Control technology.
ETSI

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9 Draft ETSI EN 300 132-2 V2.6.6 (2022-06)
3 Definition of terms, symbols and abbreviations
3.1 Terms
For the purposes of the present document, the following terms apply:
abnormal service voltage range: range of steady state voltage over which the equipment will not be expected to
maintain normal service but will survive undamaged
customer premises: location which is the sole responsibility of the customer
DC power return conductor: 0 V power supply conductor
NOTE: Also called "battery return".
fully equipped equipment: configuration that corresponds to the maximum power consumption measured at -48 VDC
with the equipment in operating conditions (e.g. not in standby mode)
NOTE: When there are several fully equipped configurations because of different combinations of possible
boards, the configuration with the boards that gives the highest power consumption should be considered.
ICT equipment: device, in the telecommunication network infrastructure, that provides an ICT service
interface "A": terminals at which the power supply is connected to the system block
NOTE 1: See also figure 1 and annex A.
NOTE 2: This is a functional definition and not an exact depiction of the physical location.
malfunction: termination of the normal service
maximum steady state input current (I ): maximum steady state input current, stated by the manufacturer, for a fully
m
equipped equipment under test connected to interface "A" at nominal voltage
nominal voltage: value of the voltage by which the electrical installation or part of the electrical installation is
designated and identified [i.9]
normal service: service mode where ICT equipment operates within its specification which includes a defined restart
time after malfunction or full interruption
normal service voltage range: range of steady state voltages over which the equipment will maintain normal service
power supply: power source to which ICT equipment is intended to be connected
service voltage: value of the voltage under normal conditions, at a given instant and a given point of the system [i.9]
system block: functional group of equipment depending for its operation and performance on its connection to the same
power supply
NOTE: A system block may consist of equipment or a functional group of equipment. Different examples of
configurations at interface "A" are given in annex A.
steady-state: state of a system at which all state and output variables remain constant in time while all input variables
are constant
NOTE: This is definition 351-45-10 in IEC 60050-351:2013 [i.12]
telecommunication centre: location where ICT equipment is installed and which is the sole responsibility of the
operator
ETSI

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10 Draft ETSI EN 300 132-2 V2.6.6 (2022-06)
3.2 Symbols
For the purposes of the present document, the following symbols apply:
I instantaneous inrush current
t
maximum steady state input current
I
m
L inductance of inductive element of LISN
R resistance of resistive element of LISN
t time
U
pso,eff effective psophometric voltage
U
rms RMS voltage
Z capacitive impedance of immunity measurement circuit
c
Z resistive impedance of immunity measurement circuit
m
μs microsecond
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AC Alternating Current
DC Direct Current
NOTE: Also when used as a suffix to units of measurement.
EMC ElectroMagnetic Compatibility
ESR Equivalent Series Resistance
EUT Equipment Under Test
HOD High-Ohmic Distributions
ICT Information and Communication Technology
IL Insertion Loss
LISN Line Impedance Stabilization Network
LOD Low-Ohmic Distributions
RF Radio Frequency
rms root mean square
TR Technical Report
VDC Voltage Direct Current
NOTE: Also when used as a suffix to units of measurement.
4 Requirements
4.0 Power interface "A"
The power supply interface, interface "A" of figure 1, is a physical point to which all the requirements are related.
This point is situated between the power supply system(s) and the power consuming ICT equipment.
An example of a configuration in which interface "A" is identified is given in annex A.
ETSI

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11 Draft ETSI EN 300 132-2 V2.6.6 (2022-06)
-V
bat
ICT equipment
+V (0 Volt)
bat

Figure 1: Identification of interface "A"
4.1 Nominal voltage
The nominal voltage at interface "A" shall be -48 VDC with positive conductor connected to earth as defined in ETSI
EN 300 253 [1].
NOTE 1: The positive conductor, also called DC return, can be (see ETSI EN 300 253 [1]):
 Isolated DC return: this is a DC power system in which the DC power return conductor has a single
point connection to the bonding network. Equipment intended for this power distribution has a
floating DC power at the power input terminal.
 Common DC return: this is a DC power system in which the return conductor is connected to the
bonding network at many points. Equipment intended for this power distribution can have the DC
return earthed at the power input terminal.
NOTE 2: In most cases the nominal voltage of interface "A" is based on a 24 cells lead-acid battery. Use of other
technologies, such as Lithium-ion batteries, are increasing and are compatible with the requirements of
the present document
4.2 Normal service voltage range at interface "A"
The normal service voltage range for the -48 VDC nominal supply at interface "A" shall be from -40,5 VDC
to -57,0 VDC.
NOTE 1: The maximum voltage is based on a 0,3 V drop in the distribution loop and a battery voltage of
2,35 V/cell plus 0,5 % for regulation.
There shall be no degradation of service performance when ICT equipment is operating at voltages within the normal
service voltage range including voltage variation inside the normal voltage range.
This requirement shall be verified by applying at interface "A" a voltage step test with specification and parameters
defined in table 1. The testing and measurement techniques are described in EN 61000-4-29 [7].
The test shall apply to equipment with single and multiple power supply "A" interface inputs.
ETSI

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12 Draft ETSI EN 300 132-2 V2.6.6 (2022-06)
Table 1
Test level of Normal Voltage Basic standard Rise and fall time of Performance criteria
service voltage step step for testing voltage step
variation duration
From -40,5 V to -57,0 VDC 0,1 s EN 61000-4-29 [7] No degradation in the
Between 1 μs and 50 μs on
and from -57 VDC 100 Ω resistive load service performance
to -40,5 VDC during and after the
(see basic standard for test
test
From -57,0 V to -40,5 VDC 0,1 s generator)
and from -40,5 VDC to -57
VDC

In the case of ICT equipment with power supply input redundancy (e.g. Input 1 and Input 2), this test shall be
performed:
• with Inputs 1 and 2 powered simultaneously and applying the test in table 1 on both inputs simultaneously;
• with Inputs 1 and 2 powered simultaneously and applying the test in table 1 on one input (either Input 1 or 2);
• with either Input 1 or 2 powered and no power on the other power input and applying the test in table 1 on the
powered input.
NOTE 2: The minimum voltage is based on the voltage drop in the distribution network and a battery cell end of
discharge voltage.
NOTE 3: The voltages specified are measured at interface "A". It should be noted that if interface "A" is at any
point other than the ICT equipment interface as presented in annex A, there will be a voltage drop
between interface "A" and the equipment terminals.
4.3 Abnormal service voltage range at interface "A"
4.3.1 Abnormal service voltage range under steady state conditions
ICT equipment designed to work at 48 VDC nominal voltage at the interface "A" shall not suffer any damage when
subjected to the following voltage ranges defined in table 2.
Table 2
0,0 V to -40,5 VDC
-57,0 VDC to -60,0 VDC

Following the restoration of the supply to the normal voltage range, the power conversion and management systems on
the load side of interface "A" shall automatically restore normal service. The ICT equipment shall then resume
operation according to its specifications. The abnormal service voltage shall not lead to the disconnection of the power
supply e.g. by causing circuit breakers, fuses or other such devices to operate.
NOTE: It is acceptable that the system may restart when the voltage is -40,5 VDC or anywhere within the
nominal service voltage range and/or after a time delay.
4.3.2 Abnormal conditions: voltage variations, dips and short interruptions
ICT equipment shall comply with the requirements defined in this clause when subject to the abnormal voltage range
defined in table 3 that can be present at the interface "A".
This requirement shall be verified by applying at interface "A" a voltage step test with specification and parameters
defined in table 3. The testing and measurement techniques are described in EN 61000-4-29 [7].
The test shall apply to equipment with single and multiple power supply inputs.
ETSI

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13 Draft ETSI EN 300 132-2 V2.6.6 (2022-06)
Table 3
Test level of abnormal Voltage step Basic standard Rise and fall time of Performance criteria
voltage step variation duration for testing volta
...

SLOVENSKI STANDARD
oSIST prEN 300 132-2 V2.6.6:2022
01-september-2022
Okoljski inženiring (EE) - Napajalni vmesnik na vhodu informacijske in
komunikacijske tehnologije (IKT) - 2. del: Enosmerna napetost - 48 V (DC)
Environmental Engineering (EE) - Power supply interface at the input of Information and
Communication Technology (ICT) equipment - Part 2: -48 V Direct Current (DC)
Ta slovenski standard je istoveten z: ETSI EN 300 132-2 V2.6.6 (2022-06)
ICS:
19.040 Preskušanje v zvezi z Environmental testing
okoljem
33.050.01 Telekomunikacijska Telecommunication terminal
terminalska oprema na equipment in general
splošno
oSIST prEN 300 132-2 V2.6.6:2022 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN 300 132-2 V2.6.6:2022

---------------------- Page: 2 ----------------------
oSIST prEN 300 132-2 V2.6.6:2022
Draft ETSI EN 300 132-2 V2.6.6 (2022-06)






EUROPEAN STANDARD
Environmental Engineering (EE);
Power supply interface at the input of
Information and Communication Technology (ICT) equipment;
Part 2: -48 V Direct Current (DC)

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oSIST prEN 300 132-2 V2.6.6:2022
 2 Draft ETSI EN 300 132-2 V2.6.6 (2022-06)

Reference
REN/EE-02101
Keywords
interface, power supply
ETSI
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All rights reserved.

ETSI

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oSIST prEN 300 132-2 V2.6.6:2022
 3 Draft ETSI EN 300 132-2 V2.6.6 (2022-06)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 6
1 Scope . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 8
3 Definition of terms, symbols and abbreviations . 9
3.1 Terms . 9
3.2 Symbols . 10
3.3 Abbreviations . 10
4 Requirements . 11
4.0 Power interface "A" . 11
4.1 Nominal voltage . 11
4.2 Normal service voltage range at interface "A" . 11
4.3 Abnormal service voltage range at interface "A" . 12
4.3.1 Abnormal service voltage range under steady state conditions . 12
4.3.2 Abnormal conditions: voltage variations, dips and short interruptions . 12
4.3.3 Voltage transients . 13
4.3.3.1 Voltage transient due to short-circuit and protective device clearance . 13
4.3.3.2 Short voltage transient due to switching and lightning . 14
4.3.4 Recovery from voltage transients . 14
4.4 Voltage changes due to the regulation of the power supply . 15
4.5 Power supply protection at interface "A" . 15
4.6 Maximum current drain . 15
4.7 Inrush Current on connection of interface "A" . 16
4.7.1 Limits . 16
4.7.2 Measurements . 17
4.8 Conducted immunity requirements of the ICT equipment at interface "A": narrowband noise . 18
4.9 Conducted emissions requirements of the ICT equipment at interface "A" . 20
5 Earthing and bonding . 21
Annex A (informative): Identification of interface "A" . 22
Annex B (informative): -60 VDC systems . 23
Annex C (informative): Guide for measuring inrush current and for transferring the
recorded pulses onto the limit chart . 24
C.1 Measurement . 24
C.2 Pulse waveform transfor mation . 24
C.3 Measurement of inrush current with filter capacitor current pulses . 27
Annex D (informative): Test arrangements for the injection of electrical noise at interface
"A" . 30
Annex E (informative): Wideband noise . 31
E.0 Wideband noise . 31
E.1 Emission of wideband noise . 31
E.1.0 General . 31
E.1.1 Assessment of wideband noise . 31
ETSI

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oSIST prEN 300 132-2 V2.6.6:2022
 4 Draft ETSI EN 300 132-2 V2.6.6 (2022-06)
E.2 How to calculate wideband emission . 31
Annex F (informative): Protection dimensioning . 35
Annex G (informative): Effects of protective device operation transients in the power
distribution . 36
Annex H (normative): Verification of measurement network defined in clause 4.9 . 37
Annex I (informative): Bibliography . 38
History . 39

ETSI

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oSIST prEN 300 132-2 V2.6.6:2022
 5 Draft ETSI EN 300 132-2 V2.6.6 (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
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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 draft European Standard (EN) has been produced by ETSI Technical Committee Environmental Engineering (EE),
and is now submitted for the combined Public Enquiry and Vote phase of the ETSI standards EN Approval Procedure.
The present document concerns the requirements for the interface between ICT equipment and its power supply, and
includes requirements relating to its stability and measurement. Various other references and detailed measurement and
test arrangements are contained in informative annexes.
The present document is part 2 of a multi-part deliverable covering Environmental Engineering (EE); Power supply
interface at the input to Information and Communication Technology (ICT) equipment, as identified below:
Part 1: "Alternating Current (AC)";
Part 2: "-48 V Direct Current (DC)";
Part 3: "Up to 400 V Direct Current (DC)".

Proposed national transposition dates
Date of latest announcement of this EN (doa): 3 months after ETSI publication
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 6 months after doa
Date of withdrawal of any conflicting National Standard (dow): 6 months after doa

ETSI

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oSIST prEN 300 132-2 V2.6.6:2022
 6 Draft ETSI EN 300 132-2 V2.6.6 (2022-06)
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.
ETSI

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oSIST prEN 300 132-2 V2.6.6:2022
 7 Draft ETSI EN 300 132-2 V2.6.6 (2022-06)
1 Scope
The present document contains requirements and measurements methods for the physical interface "A" that is situated
between the power supply system(s) and the power consuming ICT equipment.
The nominal voltage at power interface "A" of ICT equipment defined in the present document is DC voltage -48 V.
The DC power can be supplied by a DC output power system (e.g. based on AC rectifiers on grid or DC/DC converters on
solar system, fuel cell, DC engine or fuel cell generator) and also directly supplied by a battery backup in this DC power
system. The purpose of the present document is to be able to use a power supply system with the same characteristics
for all ICT equipment defined in the area of application:
- to facilitate inter working of different types of load units;
- to facilitate the standardization of ICT equipment;
- to facilitate the installation, operation and maintenance in the same network of ICT equipment and systems
from different origins.
The present document aims at providing electrical compatibility between the power supply equipment and the power
consuming ICT equipment, between different system blocks and loads connected to the same power supply feeding the
interface "A" (e.g. control/monitoring, cooling system, etc.).
The requirements are defined for:
- the power supply input of any type of ICT equipment installed at telecommunication centres that are connected
to interface "A" powered by DC;
- any type of ICT equipment, installed in access networks and customers' premises, the DC interface "A" of
which is also used by equipment requiring a DC supply source;
- any type of ICT equipment powered by DC, used in the fixed and mobile networks installed in different
locations such as buildings, shelters, street cabinets, outdoor installations.
Disturbances on the power supply interface "A" relating to the continuous wave phenomena below 20 kHz are covered
within the present document.
The present document does not cover safety requirements, they are covered by relevant safety standards.
The present document does not cover EMC requirements, they are covered by relevant EMC standards.
NOTE: Annex B gives guidance on -60 VDC supply systems.
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 300 253: "Environmental Engineering (EE); Earthing and bonding of ICT equipment
powered by -48 VDC in telecom and data centres".
ETSI

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oSIST prEN 300 132-2 V2.6.6:2022
 8 Draft ETSI EN 300 132-2 V2.6.6 (2022-06)
[2] Void.
[3] Void.
[4] Void.
[5] EN 61000-4-5: "Electromagnetic compatibility (EMC) - Part 4-5: Testing and measurement
techniques - Surge immunity test" (produced by CENELEC).
[6] Void.
[7] EN 61000-4-29: "Electromagnetic compatibility (EMC) - Part 4-29: Testing and measurement
techniques -Voltage dips, short interruptions and voltage variations on d.c. input power port
immunity tests" (produced by CENELEC).
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] Recommendation ITU-T Q.551: "Transmission characteristics of digital exchanges".
[i.2] Recommendation ITU-T Q.552: "Transmission characteristics at 2-wire analogue interfaces of
digital exchanges".
[i.3] Recommendation ITU-T Q.553: "Transmission characteristics at 4-wire analogue interfaces of
digital exchanges".
[i.4] Recommendation ITU-T Q.554: "Transmission characteristics at digital interfaces of digital
exchanges".
[i.5] ETSI TR 100 283: "Environmental Engineering (EE); Transient voltages at Interface "A" on
telecommunications direct current (dc) power distributions".
[i.6] US Department of Defence MIL-STD-461E: "Requirements for the control of electromagnetic
interference characteristics of subsystems and equipment".
[i.7] Void.
[i.8] Recommendation ITU-T O.41: "Psophometer for use on telephone-type circuits".
[i.9] IEC 60050-601: "International Electrotechnical Vocabulary. Chapter 601: Generation,
transmission and distribution of electricity - General" (Area 826 "Electrical installations",
section 826-11 "Voltages and currents").
[i.10] EN 60269-1: "Low-voltage fuses - Part 1: General requirements" (produced by CENELEC).
[i.11] EN 60934: "Circuit-breakers for equipment (CBE)" (produced by CENELEC).
[i.12] IEC 60050-351: 2013: "International Electrotechnical Vocabulary. Part 351: Control technology.
ETSI

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oSIST prEN 300 132-2 V2.6.6:2022
 9 Draft ETSI EN 300 132-2 V2.6.6 (2022-06)
3 Definition of terms, symbols and abbreviations
3.1 Terms
For the purposes of the present document, the following terms apply:
abnormal service voltage range: range of steady state voltage over which the equipment will not be expected to
maintain normal service but will survive undamaged
customer premises: location which is the sole responsibility of the customer
DC power return conductor: 0 V power supply conductor
NOTE: Also called "battery return".
fully equipped equipment: configuration that corresponds to the maximum power consumption measured at -48 VDC
with the equipment in operating conditions (e.g. not in standby mode)
NOTE: When there are several fully equipped configurations because of different combinations of possible
boards, the configuration with the boards that gives the highest power consumption should be considered.
ICT equipment: device, in the telecommunication network infrastructure, that provides an ICT service
interface "A": terminals at which the power supply is connected to the system block
NOTE 1: See also figure 1 and annex A.
NOTE 2: This is a functional definition and not an exact depiction of the physical location.
malfunction: termination of the normal service
maximum steady state input current (I ): maximum steady state input current, stated by the manufacturer, for a fully
m
equipped equipment under test connected to interface "A" at nominal voltage
nominal voltage: value of the voltage by which the electrical installation or part of the electrical installation is
designated and identified [i.9]
normal service: service mode where ICT equipment operates within its specification which includes a defined restart
time after malfunction or full interruption
normal service voltage range: range of steady state voltages over which the equipment will maintain normal service
power supply: power source to which ICT equipment is intended to be connected
service voltage: value of the voltage under normal conditions, at a given instant and a given point of the system [i.9]
system block: functional group of equipment depending for its operation and performance on its connection to the same
power supply
NOTE: A system block may consist of equipment or a functional group of equipment. Different examples of
configurations at interface "A" are given in annex A.
steady-state: state of a system at which all state and output variables remain constant in time while all input variables
are constant
NOTE: This is definition 351-45-10 in IEC 60050-351:2013 [i.12]
telecommunication centre: location where ICT equipment is installed and which is the sole responsibility of the
operator
ETSI

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oSIST prEN 300 132-2 V2.6.6:2022
 10 Draft ETSI EN 300 132-2 V2.6.6 (2022-06)
3.2 Symbols
For the purposes of the present document, the following symbols apply:
I instantaneous inrush current
t
maximum steady state input current
I
m
L inductance of inductive element of LISN
R resistance of resistive element of LISN
t time
U
pso,eff effective psophometric voltage
U
rms RMS voltage
Z capacitive impedance of immunity measurement circuit
c
Z resistive impedance of immunity measurement circuit
m
μs microsecond
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AC Alternating Current
DC Direct Current
NOTE: Also when used as a suffix to units of measurement.
EMC ElectroMagnetic Compatibility
ESR Equivalent Series Resistance
EUT Equipment Under Test
HOD High-Ohmic Distributions
ICT Information and Communication Technology
IL Insertion Loss
LISN Line Impedance Stabilization Network
LOD Low-Ohmic Distributions
RF Radio Frequency
rms root mean square
TR Technical Report
VDC Voltage Direct Current
NOTE: Also when used as a suffix to units of measurement.
4 Requirements
4.0 Power interface "A"
The power supply interface, interface "A" of figure 1, is a physical point to which all the requirements are related.
This point is situated between the power supply system(s) and the power consuming ICT equipment.
An example of a configuration in which interface "A" is identified is given in annex A.
ETSI

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oSIST prEN 300 132-2 V2.6.6:2022
 11 Draft ETSI EN 300 132-2 V2.6.6 (2022-06)
-V
bat
ICT equipment
+V (0 Volt)
bat

Figure 1: Identification of interface "A"
4.1 Nominal voltage
The nominal voltage at interface "A" shall be -48 VDC with positive conductor connected to earth as defined in ETSI
EN 300 253 [1].
NOTE 1: The positive conductor, also called DC return, can be (see ETSI EN 300 253 [1]):
 Isolated DC return: this is a DC power system in which the DC power return conductor has a single
point connection to the bonding network. Equipment intended for this power distribution has a
floating DC power at the power input terminal.
 Common DC return: this is a DC power system in which the return conductor is connected to the
bonding network at many points. Equipment intended for this power distribution can have the DC
return earthed at the power input terminal.
NOTE 2: In most cases the nominal voltage of interface "A" is based on a 24 cells lead-acid battery. Use of other
technologies, such as Lithium-ion batteries, are increasing and are compatible with the requirements of
the present document
4.2 Normal service voltage range at interface "A"
The normal service voltage range for the -48 VDC nominal supply at interface "A" shall be from -40,5 VDC
to -57,0 VDC.
NOTE 1: The maximum voltage is based on a 0,3 V drop in the distribution loop and a battery voltage of
2,35 V/cell plus 0,5 % for regulation.
There shall be no degradation of service performance when ICT equipment is operating at voltages within the normal
service voltage range including voltage variation inside the normal voltage range.
This requirement shall be verified by applying at interface "A" a voltage step test with specification and parameters
defined in table 1. The testing and measurement techniques are described in EN 61000-4-29 [7].
The test shall apply to equipment with single and multiple power supply "A" interface inputs.
ETSI

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oSIST prEN 300 132-2 V2.6.6:2022
 12 Draft ETSI EN 300 132-2 V2.6.6 (2022-06)
Table 1
Test level of Normal Voltage Basic standard Rise and fall time of Performance criteria
service voltage step step for testing voltage step
variation duration
From -40,5 V to -57,0 VDC 0,1 s EN 61000-4-29 [7] No degradation in the
Between 1 μs and 50 μs on
and from -57 VDC 100 Ω resistive load service performance
to -40,5 VDC during and after the
(see basic standard for test
test
From -57,0 V to -40,5 VDC 0,1 s generator)
and from -40,5 VDC to -57
VDC

In the case of ICT equipment with power supply input redundancy (e.g. Input 1 and Input 2), this test shall be
performed:
• with Inputs 1 and 2 powered simultaneously and applying the test in table 1 on both inputs simultaneously;
• with Inputs 1 and 2 powered simultaneously and applying the test in table 1 on one input (either Input 1 or 2);
• with either Input 1 or 2 powered and no power on the other power input and applying the test in table 1 on the
powered input.
NOTE 2: The minimum voltage is based on the voltage drop in the distribution network and a battery cell end of
discharge voltage.
NOTE 3: The voltages specified are measured at interface "A". It should be noted that if interface "A" is at any
point other than the ICT equipment interface as presented in annex A, there will be a voltage drop
between interface "A" and the equipment terminals.
4.3 Abnormal service voltage range at interface "A"
4.3.1 Abnormal service voltage range under steady state conditions
ICT equipment designed to work at 48 VDC nominal voltage at the interface "A" shall not suffer any damage when
subjected to the following voltage ranges defined in table 2.
Table 2
0,0 V to -40,5 VDC
-57,0 VDC to -60,0 VDC

Following the restoration of the supply to the normal voltage range
...