IEC 63272:2024

IEC 63272 ®
Edition 1.0 2024-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Nuclear facilities – Electrical power systems – AC interruptible power supply
systems
Installations nucléaires – Systèmes d'alimentation électrique – Systèmes
d'alimentation électrique interruptibles en courant alternatif

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IEC 63272 ®
Edition 1.0 2024-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Nuclear facilities – Electrical power systems – AC interruptible power supply

systems
Installations nucléaires – Systèmes d'alimentation électrique – Systèmes

d'alimentation électrique interruptibles en courant alternatif

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 27.120.20  ISBN 978-2-8322-9381-2

– 2 – IEC 63272:2024 © IEC 2024
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
4 Abbreviated terms . 16
5 System requirements . 16
5.1 General requirements . 16
5.2 Electrical system configuration . 23
5.3 Interruptible electrical system architecture . 24
5.4 Off-site power supplies . 25
5.4.1 NPPs . 25
5.4.2 Nuclear facilities other than NPPs . 27
5.5 Safety classified power supply system . 27
5.5.1 NPPs . 27
5.5.2 Nuclear facilities other than NPPs . 29
5.6 Non-safety classified power supply system . 29
5.7 Power supply system operating limits . 29
5.7.1 General . 29
5.7.2 Under-voltages . 30
5.7.3 Over-voltages . 30
5.7.4 System current carrying capacity . 31
5.7.5 Frequency operating limits . 31
5.7.6 Grid operating parameters . 32
5.7.7 Electromagnetic interference . 32
5.7.8 Geomagnetically Induced Currents (GIC) . 33
5.7.9 Harmonics . 33
5.7.10 System operating voltage and limits . 33
5.8 Safety classification . 33
5.9 Equipment qualification . 34
5.10 Separation . 35
5.11 Redundancy and single failure criterion . 36
5.12 Power system capacity . 36
5.13 Load allocation . 37
5.14 Electrical protection . 38
5.14.1 General . 38
5.14.2 Source transfer . 38
5.14.3 Protection of personnel and equipment . 38
5.15 Motor starting. 40
6 Equipment requirements . 40
6.1 Standby power generators . 40
6.2 Operation and starting of standby and alternate generators . 42
6.3 Alternate power generators . 42
6.4 Standby and alternate generator mission times . 42
6.5 Fuel and support systems for standby and alternate generators . 43
6.6 Electrical power generation source transfer . 44

6.7 Programmable devices . 44
6.8 Rating of electrical equipment . 45
6.9 Load sequencing systems . 46
6.10 Nuclear facility control system requirements . 46
6.11 Automatic plant start-up systems . 46
6.12 Generator manual start-up systems . 47
6.13 Power cables . 47
6.14 Power transformers . 47
6.15 Circuit breaker tripping and closing supplies . 48
6.16 Earthing and lightning protection system design. 48
7 Maintenance of electrical equipment . 49
8 Ageing of electrical equipment . 51
9 Status monitoring of electrical power supply system . 51
10 Periodic testing of electrical equipment . 52
11 Commissioning of electrical equipment and systems. 53
Bibliography . 54

Figure 1 – Typical single line diagram of nuclear power plant power supply system . 19
Figure 2 – Typical single line diagram of power supply system for nuclear facilities

other than NPPs . 20
Figure 3 – Typical single line diagram for SMR power supply system . 21

– 4 – IEC 63272:2024 © IEC 2024
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
NUCLEAR FACILITIES – ELECTRICAL POWER SYSTEMS –
AC INTERRUPTIBLE POWER SUPPLY SYSTEMS

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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6) All users should ensure that they have the latest edition of this publication.
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
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shall not be held responsible for identifying any or all such patent rights.
IEC 63272 has been prepared by subcommittee 45A: Instrumentation, control and electrical
power systems of nuclear facilities, of IEC technical committee 45: Nuclear instrumentation. It
is an International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
45A/1528/FDIS 45A/1544/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
This International Standard is to be used in conjunction with IEC 63046.
The language used for the development of this International Standard is English.

This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

– 6 – IEC 63272:2024 © IEC 2024
INTRODUCTION
a) Technical background, main issues and organisation of the standard
The purpose of this document is to provide high level requirements for the design of on-site AC
interruptible power supply systems as part of the overall electrical distribution system in a
nuclear facility.
The on-site AC interruptible electrical power system supports all plant operating functions
including plant safety systems. This includes safety classified electrical distribution systems
which provide interruptible power supplies to support plant safety systems. This document does
not cover requirements for grid connections to the nuclear plant which is the subject of a
separate standard. This document does not cover requirements for uninterruptible power
supplies which are defined in IEC 61225.
b) Situation of the current standard in the structure of the SC 45A standard series
This document is a second level document specifically addressing the particular topic of
requirements for electrical supplies.
For more details on the structure of the SC 45A standard series, see item d) of this introduction.
c) Recommendations and limitations regarding the application of this standard
This document defines the requirements for an electrical designer to establish the design of the
AC interruptible electrical power supply for nuclear facilities. It is used in conjunction with Level
1 standard IEC 63046.
Requirements for uninterruptible power supplies are defined in Level 2 standard IEC 61225.
d) Description of the structure of the IEC SC 45A standard series and relationships with
other IEC documents and other bodies documents (IAEA, ISO)
The IEC SC 45A standard series comprises a hierarchy of four levels. The top-level documents
of the IEC SC 45A standard series are IEC 61513 and IEC 63046.
IEC 61513 provides general requirements for instrumentation and control (I&C) systems and
equipment that are used to perform functions important to safety in nuclear power plants
(NPPs). IEC 63046 provides general requirements for electrical power systems of NPPs; it
covers power supply systems including the supply systems of the I&C systems.
IEC 61513 and IEC 63046 are considered in conjunction and at the same level. IEC 61513 and
IEC 63046 structure the IEC SC 45A standard series and shape a complete framework
establishing general requirements for instrumentation, control and electrical power systems for
nuclear power plants.
IEC 61513 and IEC 63046 refer directly to other IEC SC 45A standards for general
requirements for specific topics, such as categorization of functions and classification of
systems, qualification, separation, defence against common cause failure, control room design,
electromagnetic compatibility, human factors engineering, cybersecurity, software and
hardware aspects for programmable digital systems, coordination of safety and security
requirements and management of ageing. The standards referenced directly at this second level
should be considered together with IEC 61513 and IEC 63046 as a consistent document set.

At a third level, IEC SC 45A standards not directly referenced by IEC 61513 or by IEC 63046
are standards related to specific requirements for specific equipment, technical methods, or
activities. Usually these documents, which make reference to second-level documents for
general requirements, can be used on their own.
A fourth level extending the IEC SC 45 standard series, corresponds to the Technical Reports
which are not normative.
The IEC SC 45A standards series consistently implements and details the safety and security
principles and basic aspects provided in the relevant IAEA safety standards and in the relevant
documents of the IAEA nuclear security series (NSS). In particular this includes the IAEA
requirements SSR-2/1 , establishing safety requirements related to the design of nuclear power
plants (NPPs), the IAEA safety guide SSG-30 dealing with the safety classification of structures,
systems and components in NPPs, the IAEA safety guide SSG-39 dealing with the design of
instrumentation and control systems for NPPs, the IAEA safety guide SSG-34 dealing with the
design of electrical power systems for NPPs, the IAEA safety guide SSG-51 dealing with human
factors engineering in the design of NPPs and the implementing guide NSS42-G for computer
security at nuclear facilities. The safety and security terminology and definitions used by the
SC 45A standards are consistent with those used by the IAEA.
IEC 61513 and IEC 63046 have adopted a presentation format similar to the basic safety
publication IEC 61508 with an overall life-cycle framework and a system life-cycle framework.
Regarding nuclear safety, IEC 61513 and IEC 63046 provide the interpretation of the general
requirements of IEC 61508-1, IEC 61508-2 and IEC 61508-4, for the nuclear application sector.
In this framework, IEC 60880, IEC 62138 and IEC 62566 correspond to IEC 61508-3 for the
nuclear application sector.
IEC 61513 and IEC 63046 refer to ISO 9001 as well as to IAEA GSR part 2 and IAEA GS-G-3.1
and IAEA GS-G-3.5 for topics related to quality assurance (QA).
At level 2, regarding nuclear security, IEC 62645 is the entry document for the IEC/SC 45A
security standards. It builds upon the valid high level principles and main concepts of the
generic security standards, in particular ISO/IEC 27001 and ISO/IEC 27002; it adapts them and
completes them to fit the nuclear context and coordinates with the IEC 62443 series. At level 2,
IEC 60964 is the entry document for the IEC/SC 45A control rooms standards, IEC 63351 is the
entry document for the human factors engineering standards and IEC 62342 is the entry
document for the ageing management standards.
NOTE 1 It is assumed that for the design of I&C systems in NPPs that implements conventional safety functions
(e.g. to address worker safety, asset protection, chemical hazards, process energy hazards) international or national
standards are applied.
NOTE 2 IEC TR 63400 provides a more comprehensive description of the overall structure of the IEC SC 45A
standards series and of its relationship with other standard bodies and standards.

– 8 – IEC 63272:2024 © IEC 2024
NUCLEAR FACILITIES – ELECTRICAL POWER SYSTEMS –
AC INTERRUPTIBLE POWER SUPPLY SYSTEMS

1 Scope
This document specifies the performance and functional characteristics of the on-site AC
interruptible power supply systems and applies to new nuclear facilities and newly installed or
upgraded on-site AC interruptible power supply systems.
The specific design requirements for the components of the power supply system are defined
by the IEC standards listed in the normative references and are outside the scope of this
document.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60038, IEC standard voltages
IEC 60076 (all parts), Power transformers
IEC 60076-1, Power transformers – Part 1: General
IEC 60709:2018, Nuclear power plants – Instrumentation, control and electrical power systems
important to safety – Separation
IEC 60909 (all parts), Short-circuit currents in three phase a.c. systems
IEC 61000 (all parts), Electromagnetic compatibility (EMC)
IEC 61000-4 (all parts), Electromagnetic compatibility (EMC) ─ Testing and measurement
techniques
IEC 61226, Nuclear power plants – Instrumentation, control and electrical power systems
important to safety – Categorization of functions and classification of systems
IEC 61439 (all parts), Low-voltage switchgear and controlgear assemblies
IEC 62003, Nuclear power plants – Instrumentation, control and electrical power systems –
Requirements for electromagnetic compatibility testing
IEC 62271 (all parts), High-voltage switchgear and controlgear
IEC 62305 (all parts), Protection against lightning
IEC 62671, Nuclear power plants – Instrumentation and control important to safety – Selection
and use of industrial digital devices of limited functionality

IEC 62855:2016, Nuclear power plants – Electrical power systems– Electrical power systems
analysis
IEC 63046:2020, Nuclear power plants – Electrical power system – General requirements
IEC/IEEE 60780-323, Nuclear facilities – Electrical equipment important to safety – Qualification
IEC/IEEE 60980-344, Nuclear facilities – Equipment important to safety – Seismic qualification
IEC/IEEE 63332-387 , Nuclear facilities – Electrical power systems – Diesel generator units
applied as standby power sources
IAEA Safety Report 91, Impact of Open Phase Conditions on Electrical Power Systems of
Nuclear Power Plants
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
NOTE Other terms not defined below are defined in IAEA Safety Guide SSG-34 and IAEA Safety Guide SSG-39.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
alternate power supply
generator reserved for the power supply to the plant during total loss of all non-battery power
in the safety power systems (station blackout) and other design extension conditions
[SOURCE: IAEA SSG-34:2016, modified – Main term “alternate AC power supply” modified to
read “alternate power supply”.]
3.2
associated circuit
circuit of a lower safety class that is not physically separated or is not electrically isolated from
the circuit(s) of the higher class by acceptable separation distances, safety class structures,
barriers, or electrical isolation devices, but meets suitable criteria for safety
Note 1 to entry: Circuits include the interconnecting cabling and the connected loads.
[SOURCE: IEC 60709:2018, 3.1]
___________
Under preparation. Stage at the time of publication: IEC/IEEE FDIS 63332-387:2024.

– 10 – IEC 63272:2024 © IEC 2024
3.3
common cause failure
failure of two or more structures, systems or components due to a single event or cause
Note 1 to entry: Common causes may be internal or external to an I&C system.
Note 2 to entry: The definition from IEC differs from the IAEA as follows:
1) The term "specific" was deleted because otherwise the definition of CCF is not consistent with the definition
of CMF "Common mode failure". Furthermore this additional word is not necessary to understand the
definition.
[SOURCE: IAEA Nuclear Safety and Security Glossary:2022, modified – the term “specific” has
been removed]
3.4
defence in depth
hierarchical deployment of different levels of diverse equipment and procedures to prevent the
escalation of anticipated operational occurrences and to maintain the effectiveness of physical
barriers placed between a radiation source or radioactive material and workers, members of the
public or the environment, in operational states and, for some barriers, in accident conditions
[SOURCE: IAEA Nuclear Safety and Security Glossary:2022]
3.5
design basis
range of conditions and events taken explicitly into account in the design of structures, systems
and components and equipment of a facility, according to established criteria, such that the
facility can withstand them without exceeding authorized limits
[SOURCE: IAEA Nuclear Safety and Security Glossary:2022]
3.6
design extension conditions
postulated accident conditions that are not considered for design basis accidents, but that are
considered in the design process of the facility in accordance with best estimate methodology,
and for which releases of radioactive material are kept within acceptable limits
Note 1 to entry: Design extension conditions comprise conditions in events without significant fuel degradation and
conditions in events with melting of the reactor core.
[SOURCE: IAEA Nuclear Safety and Security Glossary:2022]
3.7
diversity
presence of two or more independent (redundant) systems or components to perform an
identified function, where the different systems or components have different attributes so as
to reduce the possibility of common cause failure, including common mode failure
[SOURCE: IAEA Nuclear Safety and Security Glossary:2022]

3.8
division
collection of items, including their interconnections, that form one redundancy of a redundant
system or safety group
Note 1 to entry: Divisions may include multiple channels.
Note 2 to entry: In the context of this document, “division” includes a given system or set of components that
enables the establishment and maintenance of physical, electrical and functional independence from other redundant
sets of components.
[SOURCE: IAEA Nuclear Safety and Security Glossary:2022, modified – Addition of a new
Note 2 to entry.]
3.9
electric grid operator
organisation operating the electric grid, which could be either the transmission system operator
or distribution system operator depending on the relevant part of the electric grid
[SOURCE: IEC 63298:20─, 3.4]
3.10
electrical disturbances
all disturbing phenomena that cause the mains voltage, current or frequency profile to depart
from its nominal characteristics
Note 1 to entry: The electrical disturbances can also generate electromagnetic disturbances that can affect the AC
electrical power supply system.
3.11
electrical isolation
electrical isolation is used to prevent electrical failures in one system from affecting connected
systems
Note 1 to entry: Electrical isolation controls or prevents adverse interactions between equipment and components
caused by factors such as electromagnetic interference, electrostatic pickup, short circuits, open circuits, earthing,
or application of the maximum credible voltage.
[SOURCE: IAEA SSG-34:2016, modified – In Note 1 to entry, “grounding” replaced with
“earthing”, and “(AC or DC)” deleted at the end of Note 1 to entry.]
3.12
electrical power system
system performing electrical power generation, transmission and distribution; performing supply
functions to operate plant equipment (pumps, valves, heaters, etc) and to I&C systems
[SOURCE: IEC 63046:2020, 3.12, modified – Deletion of Note 1 to entry and Note 2 to entry.]
3.13
electrical source transfer
transfer from an initial electrical power source to an alternative supply source when the initial
electrical power source does not provide the performance required by the electrical power
supply system
Note 1 to entry: The transfer can be initiated either manually or automatically.
[SOURCE: IEC 63046:2020, 3.15, modified – Deletion of “(automatically or manually)” in the
definition, and modification of Note 1 to entry.]

– 12 – IEC 63272:2024 © IEC 2024
3.14
equipment qualification
generation and maintenance of evidence to ensure that equipment will operate on demand,
under specified service conditions, to meet system performance requirements
[SOURCE: IAEA Nuclear Safety and Security Glossary:2022]
3.15
house load operation
operation of a nuclear power plant to supply power only to its own electrical loads
[SOURCE: IEC 62855:2016, 3.2]
3.16
I&C system
system, based on electrical and/or electronic and/or programmable electronic technology,
performing I&C functions as well as service and monitoring functions related to the operation
of the system itself
Note 1 to entry: The term is used as a general term which encompasses all elements of the system such as internal
power supplies, sensors and other input devices, data highways and other communication paths, interfaces to
actuators and other output devices. The different functions within a system may use dedicated or shared resources.
[SOURCE: IEC 61513:2011, 3.29, modified – deletion of Notes 1 to 3 to entry.]
3.17
independence
condition that exists when successful completion of a system’s required functions is not
dependent upon any behaviour including failures and normal operation of another system, or
upon any signals, data or information derived from the other system
[SOURCE: IEC 60709:2018, 3.13, modified – Deletion of Note 1 to entry.]
3.18
interruptible power supply system
power supply of loads for which a defined power supply interruption time does not impair the
mission of the safety objective
[SOURCE: IEC 63046:2020, 3.22]
3.19
item important to safety
item that is part of a safety group and/or whose malfunction or failure could lead to radiation
exposure of the site personnel or members of the public
Note 1 to entry: Items important to safety include:
– those structures, systems and components whose malfunction or failure could lead to undue radiation exposure
of site personnel or members of the public;
– those structures, systems and components that prevent anticipated operational occurrences from leading to
accident conditions;
– safety features (for design extension conditions);
– those features that are provided to mitigate the consequences of malfunction or failures of structures, systems
and components
[SOURCE: IAEA Nuclear Safety and Security Glossary:2022]

3.20
IT earthing system
earthing system with the transformer neutral not earthed or with high impedance earth
connection
3.21
loss of electrical power
plant condition corresponding to a station black-out condition and also the loss of alternate AC
power supplies
[SOURCE: IEC 63046:2020, 3.24, modified – Deletion of Note 1 to entry.]
3.22
loss of off-site power
simultaneous loss of electrical power to all unit safety buses, requiring the standby AC power
sources to start and supply power to the safety buses
[SOURCE: IEC 62855:2016, 3.4, modified – Deletion of Note 1 to entry.]
3.23
mission time
operational period required for electrical loads or sources after the initiation of accidental
conditions during which equipment shall be capable of operating within the limits of its
acceptability criteria for the specified operating conditions
[SOURCE: IEC 63046:2020, 3.26]
3.24
nuclear facility
facility (including associated buildings and equipment) in which nuclear material is produced,
processed, used, handled, stored or disposed of
[SOURCE: IAEA Nuclear Safety and Security Glossary:2022]
3.25
preferred power supply
power supply from the transmission system to the safety classified electrical power system
[SOURCE: IAEA Nuclear Safety and Security Glossary:2022]
3.26
protective conductor
conductor provided for purposes of electrical safety, for example protection against electric
shock
Note 1 to entry: In an electrical installation, the conductor identified PE is normally also considered as protective
earthing conductor
3.27
probabilistic safety assessment
PSA
comprehensive structured approach to identifying failure scenarios, constituting a conceptual
and mathematical toll for deriving numerical estimates of risk
[SOURCE: IAEA Nuclear Safety and Security Glossary:2022]

– 14 – IEC 63272:2024 © IEC 2024
3.28
redundancy
provision of alternative (identical or diverse) structures, systems, and components, so that any
single structure, system or component can perform the required function regardless of the state
of operation or failure of any other
[SOURCE: IAEA Nuclear Safety and Security Glossary:2022]
3.29
resilience
the capability of a power system to withstand, respond to, and recover from major power system
disruptions
3.30
robustness of the Electrical Power System
ability of the Electrical Power Supply System to perform its safety functions whilst withstanding
failures and electrical disturbances
[SOURCE: IEC 63046:2020, 3.39, modified – Addition of “Supply” and replacement of
“missions” with “functions whilst” in the definition.]
3.31
safety case
collection of arguments and evidence in support of the safety of a facility or activity
[SOURCE: IAEA Nuclear Safety and Security Glossary:2022]
3.32
safety classification
for nuclear power plants, the assignment to a limited number of safety classes of systems and
components and other items of equipment on the basis of their functions and their safety
significance
[SOURCE: IAEA Nuclear Safety and Security Glossary:2022]
3.33
safety system
system important to safety, provided to ensure the safe shutdown of the
reactor or residual heat removal from the core, or to limit the consequences of anticipated
operational occurrences and design basis accidents
[SOURCE: IAEA Nuclear Safety and Security Glossary:2022, modified ─ “Reactor core”
replaced with “core”.]
3.34
safety system
system important to safety, provided to limit the
consequences of anticipated operational occurrences and design basis accidents
[SOURCE: IAEA Nuclear Safety and Security Glossary:2022, modified ─ “to ensure the safe
shutdown of the reactor or residual heat removal from the core”.]

3.35
segregation
physical separation of structures, systems and components by distance or by means of some
form of barrier to reduce the likelihood of common cause failures
[SOURCE: IAEA Nuclear Safety and Security Glossary:2022]
3.36
separation
set of measures that minimize the influence of one entity onto the other entity to improve the
independence of the entities
[SOURCE: IEC 60709:2018, 3.20]
3.37
single failure criterion
SFC
criterion (or requirement) applied to a system such that it must be capable of performing its task
in the presence of any single failure
[SOURCE: IAEA Nuclear Safety and Security Glossary:2022]
3.38
standby AC power source
power source, capable of supplying the necessary power in anticipated operational occurrences
and accident conditions, in the event of the loss of off-site power and main generator
[SOURCE: IEC 63046:2020, 3.48]
3.39
station blackout
plant condition with complete loss of all AC power from off-site sources, from the main generator
and from safety classified standby AC power sources to the essential and non-essential
switchgear buses
[SOURCE: IAEA Nuclear Safety and Security Glossary:2022, modified – Addition of “safety
classified”.]
3.40
transmission system operator
party responsible for providing and operating networks for long distance transmission of
electricity as well as regional distribution and responsible to ensure the system security with a
high level of reliability and quality
[SOURCE: IEC 63046:2020, 3.51]
3.41
uninterruptible power supply system
power supply for loads required to ensure functional availability during the unavailability of the
interruptible power supply
Note 1 to entry: Specific loads requiring high voltage stability can also be supplied power by the uninterruptible
power supply system.
Note 2 to entry: Typical loads of the uninterruptible power supply systems are: isolation valves, dampers, I&C and
monitoring systems.
[SOURCE: IEC 63046:2020, 3.52]

– 16 – IEC 63272:2024 © IEC 2024
4 Abbreviated terms
AC alternating current
AOO anticipated operational occurrences
CB circuit breaker
CCF common cause failure
DBC design basis conditions
DC direct current
DEC design extension conditions
DSO distribution system operator
EGO electric grid operator (a collective name for TSO and DSO)
EMI electromagnetic interference
GIC geomagnetically induced current
HV high voltage
I&C instrumentation and control
IAEA international atomic energy agency
IEC international electrotechnical commission
IEEE institute of electrical and electronics engineers
LEP loss of electrical power
LOOP loss of off-site power
LV low voltage
NPP nuclear power plant
PSA probabilistic safety assessment
SBO station black out
SFC single failure criterion
SMR small modular reactor
THD total harmonic distortion
TSO transmission system operator
UPS uninterruptible power supply
5 System requirements
5.1 General requirements
This document is one of a series of standards covering the design of electrical power supply
systems for nuclear facilities. This is a Level 2 standard and should be used in conjunction with
the Level 1 standard IEC 63046 which defines general requirements for electrical power
systems. Other Level 2 standard
...