ETSI TS 102 121 V1.3.1 (2014-07)

Environmental Engineering (EE); Power distribution to telecommunications and datacom (ICT) equipment

RTS/EE-02041

General Information

• Status: Published
• Publication Date: 30-Jun-2014
• Technical Committee: EE 2 - EE Power Supply
• Current Stage: 12 - Completion
• Due Date: 29-Jul-2014
• Completion Date: 01-Jul-2014
• Mandate: M/462

Standards Content (Sample)

ETSI TS 102 121 V1.3.1 (2014-07)






TECHNICAL SPECIFICATION
Environmental Engineering (EE);
Power distribution to telecommunications
and datacom (ICT) equipment

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2 ETSI TS 102 121 V1.3.1 (2014-07)



Reference
RTS/EE-02041
Keywords
distribution, earthing, power, power supply,
system
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3 ETSI TS 102 121 V1.3.1 (2014-07)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
Introduction . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 7
3 Definitions and abbreviations . 8
3.1 Definitions . 8
3.2 Abbreviations . 8
4 Types of power supply systems . 9
4.1 DC supply . 9
4.1.1 Mains operation . 9
4.1.2 Battery operation . 9
4.1.3 Floating/Parallel operation . 9
4.1.3.1 DC switch operation . 10
4.1.3.1.1 Switch operation with interruption . 10
4.1.3.1.2 Switch operation without interruption . 10
4.1.3.2 DC converter operation . 11
4.1.3.3 Redundant DC distribution . 11
4.2 AC supply . 11
4.2.1 Mains operation . 11
4.2.2 Inverter operation . 12
4.2.3 AC switch operation . 12
4.2.3.1 AC switch operation with interruption . 12
4.2.3.2 AC switch operation without interruption (STS) . 12
4.2.3.3 AC uninterruptible power supply systems (UPS) . 13
4.2.4 Reliability and redundancy . 18
5 Power supply interfaces in telecommunication installations . 18
5.1 PSI 1 interface between primary power and telecommunication installations and equipment . 19
5.1.1 Connection conditions . 19
5.1.2 Harmonics and superimposition . 19
5.1.3 Radio interference . 19
5.1.4 Disturbances on the customer installation . 19
5.1.5 Further sources of supply voltage . 19
5.2 PSI 2 interface . 20
5.2.1 Connection conditions . 20
5.2.2 Radio interference . 20
5.2.3 Interference voltage . 20
5.3 PSI 3 interface between telecommunication installations or equipment and the telecommunication
networks . 20
5.3.1 Connection conditions . 21
5.3.2 Operation with remote power feeding of current . 21
5.3.3 Operation with ringing AC voltage . 21
5.3.4 Radio interference . 21
5.3.5 Interference voltage . 21
5.4 Cabling and routing . 21
6 Earthing and equipotential bonding. 21
7 Electrical Safety requirements . 21
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4 ETSI TS 102 121 V1.3.1 (2014-07)
Annex A (normative): Principle of artificial DC mains network for measurement of
disturbance . 22
Annex B (informative): Power supply considerations . 23
History . 24

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5 ETSI TS 102 121 V1.3.1 (2014-07)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is 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 (http://ipr.etsi.org).
Pursuant to the ETSI IPR Policy, no investigation, 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.
Foreword
This Technical Specification (TS) has been produced by ETSI Technical Committee Environmental Engineering (EE).
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "may not", "need", "need not", "will",
"will not", "can" and "cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms
for the expression of provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
Introduction
The present document gives guidance on installation, connection and operation of power supply systems for
telecommunication / datacom (ICT) systems and equipment. Also are considered items of equipment with their own
power supply, which are connected to form a complete system.
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6 ETSI TS 102 121 V1.3.1 (2014-07)
1 Scope
The present document gives guidance on installation, connection and operation of power supply systems for
telecommunication / datacom installations and equipments. Also are considered items of equipment with their own
power supply, which are connected to form a complete system installation.
The present document contains definitions for power supply and distribution systems in complement to power interfaces
standards EN 300 132 series [5], [6], [7], [i.6] and [i.7].
2 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
reference document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://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.
2.1 Normative references
The following referenced documents are necessary for the application of the present document.
[1] IEC EN 60038: "IEC standard voltages".
[2] ETSI EN 300 386: "Electromagnetic compatibility and Radio spectrum Matters (ERM);
Telecommunication network equipment; ElectroMagnetic Compatibility (EMC) requirements".
[3] CENELEC EN 60950-1: "Information technology equipment - Safety - Part 1: General
requirements".
[4] CENELEC EN 60896-21: "Stationary lead-acid batteries - Part 21: Valve regulated types -
Methods of test".
[5] ETSI ETS 300 132-1: "Equipment Engineering (EE); Power supply interface at the input to
telecommunications equipment; Part 1: Operated by alternating current (AC) derived from direct
current (DC) sources".
[6] ETSI EN 300 132-2: "Environmental Engineering (EE); Power supply interface at the input to
telecommunications and datacom (ICT) equipment; Part 2: Operated by -48 V direct current
(DC)".
[7] ETSI EN 300 132-3-1: "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".
[8] ETSI EN 302 099: "Environmental Engineering (EE); Powering of equipment in access network".
[9] ETSI EN 300 253: "Environmental Engineering (EE); Earthing and bonding of telecommunication
equipment in telecommunication centres".
[10] Recommendation ITU-T K.20: "Resistibility of telecommunication equipment installed in a
telecommunications centre to overvoltages and overcurrents".
[11] Recommendation ITU-T K.21: "Resistibility of telecommunication equipment installed in
customer premises to overvoltages and overcurrents".
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7 ETSI TS 102 121 V1.3.1 (2014-07)
[12] Recommendation ITU-T K.45: "Resistibility of telecommunication equipment installed in the
access and trunk networks to overvoltages and overcurrents".
[13] CENELEC HD 384 (all parts)/HD 60364: "Electrical installations of buildings".
[14] ETSI EN 301 489-1: "Electromagnetic compatibility and Radio spectrum Matters (ERM);
ElectroMagnetic Compatibility (EMC) standard for radio equipment and services;
Part 1: Common technical requirements".
[15] CENELEC EN 61000-3-2: "Electromagnetic compatibility (EMC) - Part 3-2: Limits - Limits for
harmonic current emissions (equipment input current ≤ 16 A per phase)".
[16] CENELEC EN 61000-3-3: "Electromagnetic compatibility (EMC) - Part 3-3: Limits - Limitation
of voltage changes, voltage fluctuations and flicker in public low-voltage supply systems, for
equipment with rated current ≤ 16 A per phase and not subject to conditional connection".
[17] Recommendation ITU-T P.53: "Psophometer for use on telephone-type circuits".
[18] CENELEC EN 50310: "Application of equipotential bonding and earthing in buildings with
information technology equipment".
[19] CENELEC EN 61000-4-11: "Electromagnetic compatibility (EMC) - Part 4-11: Testing and
measurement techniques - Voltage dips, short interruptions and voltage variations immunity tests".
[20] CENELEC EN 50174-2: "Information technology - Cabling installation - Part 2: Installation
planning and practices inside buildings".
[21] CENELEC EN 62040-1-1: "Uninterruptible power systems (UPS) - Part 1-1: General and safety
requirements for UPS used in operator access areas".
[22] CENELEC EN 62040-1-2: "Uninterruptible power systems (UPS) - Part 1-2: General and safety
requirements for UPS used in restricted access locations".
[23] CENELEC EN 60896-11: "Stationary lead-acid batteries - Part 11: Vented types - General
requirements and methods of tests".
[24] CENELEC EN 62310-1: "Static transfer systems (STS) - Part 1: General and safety requirements".
[25] CENELEC EN 60896-22: "Stationary lead-acid batteries - Part 22: Valve regulated types -
Requirements".
[26] ETSI EN 301 605: "Environmental Engineering (EE); Earthing and bonding of 400 V DC data and
telecom (ICT) equipment".
2.2 Informative references
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] IEC 60050-601: "International Electrotechnical Vocabulary. Chapter 601: Generation,
transmission and distribution of electricity - General".
[i.2] CENELEC EN 62368-1 Ed. 1.0: "Audio/Video, Information and Communication Technology
Equipment - Part 1: Safety requirements".
[i.3] IEC EN 60445: "Basic and safety principle for man-machine interface, marking and identification-
Identification of equipment terminals, conductor terminations, and conductors".
[i.4] ETSI TR 100 283: "Environmental Engineering (EE); Transient voltages at Interface "A" on
telecommunications direct current (DC) power distributions".
[i.5] 19 Pfl1: "Voltage limits for 60 V consumers in telecommunication installations of the Deutsche
Telekom".
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8 ETSI TS 102 121 V1.3.1 (2014-07)
[i.6] ETSI EN 300 132-3-0: "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 0: Overview".
[i.7] ETSI EN 300 132-3-2: "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 2: Alternating up to 400 V
solution".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
current-using equipment: either a further power supply system or a telecommunication equipment
NOTE: The telecommunication equipment with associated power supply may be considered as
telecommunication installation or telecommunication equipment.
disturbance: electromagnetic disturbance having components in the radio frequency range
immunity: ability of a device, equipment or system to perform without degradation in the presence of an
electromagnetic disturbance
power supply system: electrical equipment, which makes available energy obtained from a primary power source
(e.g. AC distribution) in a form suitable for the current-using equipment
radio interference: degradation of the reception of a wanted signal caused by radio frequency disturbance
supply voltage: voltage preferably obtained from the public distribution system or other primary electric power sources
Transfer Switch (TS): integrated automatic bypass switch used in the UPS, which can be fully static, fully
electromechanical or hybrid
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AC Alternating Current
DC Direct Current
EMC Electro-Magnetic Compatibility
ERM Electromagnetic Radio spectrum Matters
HD Harmonization Document
ICT Information and Communication Technology
MOS Metal Oxide Semiconductor
PSI Power Supply Interface
SBS Systems Bypass Switch
SD Safe Disconnection
STS Static Transfer Switches (for the stand-alone static switches)
TS Transfer Switch
UPS Uninterruptible Power Supply
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9 ETSI TS 102 121 V1.3.1 (2014-07)
4 Types of power supply systems
In telecommunication and datacom installations and equipment the designation of a power supply system refers to its
output.
In this sense there are DC and AC supplies. The operating modes described below are basic forms, which may be
developed into more complex arrangements.
4.1 DC supply
4.1.1 Mains operation
The current-using equipment is supplied with DC voltage obtained by a rectifier from the AC system (see figure 1).
The nominal voltage is a normative definition used to enable differentiating power interfaces as defined in
IEC 60050-601 [i.1].
Current using
equipment

Figure 1: Principle of mains operation
4.1.2 Battery operation
The current-using equipment is supplied from a battery. Both primary and secondary cells (Accumulators) can be used
as batteries. The Accumulator is disconnected from the current-using equipment for charging (see figure 2).
current
using
equipment


Figure 2: Principle of battery operation
4.1.3 Floating/Parallel operation
The current-using equipment is connected continuously to a rectifier and battery (see figure 3).
Current using
equipment

Figure 3: Principle of parallel operation
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10 ETSI TS 102 121 V1.3.1 (2014-07)
The current-using equipment is supplied in parallel operation; the rectifier being dimensioned in such a way that it can
cover the total power consumption of the current-using equipment and in addition supply an appropriate charging
current for the battery (see figure 3).
With this configuration the battery is continuously ready for operation in a fully charged condition. If the mains AC
voltage is outside of the specification (e.g. fails, reduction of voltage, high harmonics), the current-using equipment
continues to be supplied without interruption.
Parallel operation includes a very common charging mode known as floating mode and other charging modes such as
intermittent charge.
Floating charge is a charging mode where the self-discharge of the battery is compensated by maintaining a sufficient
voltage to the battery. The charging voltage can be varied due to temperature compensation.
Intermittent charge is a charging mode where the self-discharge of the battery is compensated by periodically raising the
voltage of rectifiers for short periods. Between these periods the rectifier voltage is left lower than it should be in
floating mode. The aim is to reduce plate corrosion and loss of water, as well as to reduce the risk of thermal runaway.
This may help to prolong the life span of batteries used in outdoor equipments or areas with high ambient temperature.
4.1.3.1 DC switch operation
The power requirement of the current using equipment is normally provided by a rectifier. A disconnected battery is
maintained in a charged condition by a separate charger. If the rectifier fails, the current-using equipment is switched to
the battery and supplied by the latter (see figure 4).
F
Current using
equipment
F Monitoring of the supply circuit

Figure 4: Principle of DC switch operation
4.1.3.1.1 Switch operation with interruption
The power supply of the equipment is briefly interrupted when the current-using equipment is switched between the
rectifier and the battery.
The battery is not charged in this case by the main power supply but can be recharged in any mode (floating,
intermittent) as previously described by a separate charger. Sizing of the primary AC power source and associated
protection systems shall take into account the maximum load of the telecom equipment and battery charging power.
Battery charging power depends on the battery capacity and required charging-time. Generally, the charging power is
from 10 % to 100 % of the power supply of telecom equipment. This solution separates the functions of charging and
supplying power to the current-using equipment and allows both to be optimized separately.
4.1.3.1.2 Switch operation without interruption
The current-using equipment is switched by switching equipment without interruption between the rectifier and the
battery. The distance from the power source to the switching equipment as well as the input circuit of the current-using
equipment should be considered.
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11 ETSI TS 102 121 V1.3.1 (2014-07)
4.1.3.2 DC converter operation
The current-using equipment is supplied with a DC voltage obtained by a DC converter from a DC voltage system
(see figure 5).
If the DC/DC converter is isolated in accordance with EN 60950-1 [3], different earth connections at input and output
are requested. These connections shall comply with EN 300 253 [9] and EN 50310 [18].

current
using
equipment

Figure 5: Principle of DC converter operation
4.1.3.3 Redundant DC distribution
For high availability services or hot operation and maintenance on installation, power supply distribution redundancy
may be required. It is commonly achieved by independent inputs de-coupled at the input of the current-using equipment
in the distribution frame. Another solution is to couple several converters in a minimum of n+1 redundancy at the
output.
It should be noted that the cabling and protection device of each feed of redundant distribution systems shall be sized to
allow for the maximum load of the current-using equipment.
It should be noted that redundancy is easier to achieve in DC systems than it is in AC systems as there is no phase
difference. However, differences in voltage levels have to be considered for load-sharing purposes.
The design of redundant power distribution systems should consider the use of independent power sources.
The input current of DC/DC converters in redundant distribution systems will increase as a result of a fault condition
e.g. short circuit on the output of any one DC/DC converter. Protection against internal short circuits in a DC/DC
converter may be achieved by an active circuit at the input (MOS switch for example).
Protection against overvoltage caused by short circuits release may be achieved by active circuits at the output of the
DC/DC converter (MOS switch for example).
4.2 AC supply
4.2.1 Mains operation
The current-using equipment is supplied with AC voltage directly from an AC supply circuit, e.g. a consumer
installation or a distribution system (see figure 6).
Current using
equipment

Figure 6: Principle of mains operation
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12 ETSI TS 102 121 V1.3.1 (2014-07)
4.2.2 Inverter operation
The current-using equipment is supplied with AC voltage obtained from an inverter fed by a DC supply system (see
figure 7). The telecommunication equipment connected to interface "A", powered by AC derived from DC sources as
specified in EN 300 132-2 [6] shall comply with ETS 300 132-1 [5].
Current using
equipment

Figure 7: Principle of inverter operation
4.2.3 AC switch operation
4.2.3.1 AC switch operation with interruption
If the mains AC voltage fails, the current-using equipment is transferred to another AC supply after a time delay i.e. due
to an interruption or phase failure (see figure 8).
F
Current using
equipment
F Monitoring of the supply circuit

Figure 8: Principle of AC switch operation WITH interruption
4.2.3.2 AC switch operation without interruption (STS)
The current-using equipment usually operates with very fast switch-over of AC sources without an adverse effect
(see figure 9).
Zero-time switching requires phase and amplitude synchronization of inputs. Generally, a circuit controls this before
switch-over. If synchronization is lost it is possible to achieve switch-over after an introduced time delay that shall
comply with EN 61000-4-11 [19]. This allows inverter or UPS redundancy.
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13 ETSI TS 102 121 V1.3.1 (2014-07)

Static switch
Current using
equipment
Standby supply (phase-controlled)


Figure 9: Principle of AC switch operation WITHOUT interruption
In some cases, the static switch can be shunted by mechanical contactors that operate slowly but are more robust to
power disturbances. They can withstand the very high short-circuit current available from the AC mains.
A general description and safety requirements of STS shall follow EN 62310-1 [24].
4.2.3.3 AC uninterruptible power supply systems (UPS)
The current-using equipment is supplied with AC voltage from an UPS.
Several configurations
...