Nuclear power plants - Instrumentation, control and electrical power systems - Requirements for static uninterruptible DC and AC power supply systems (IEC 61225:2019)

This document specifies the performance and the functional characteristics of the low voltage
static uninterruptible power supply (SUPS) systems in a nuclear power plant and, for
applicable parts, in general for nuclear facilities. An uninterruptible power supply is an
electrical equipment which draws electrical energy from a source, stores it and maintains
supply in a specified form by means inside the equipment to output terminals. A static
uninterruptible power supply (SUPS) has no rotating parts to perform its functions.
The specific design requirements for the components of the power supply system are covered
by IEC standards and standards listed in the normative references and are otherwise outside
the scope of this document.

Kernkraftwerke - Leittechnische Systeme und elektrische Stromversorgungssysteme - Anforderungen an statische unterbrechungsfreie Gleich- und Wechselstrom-Energieversorgungssysteme

Centrales nucléaire de puissance - Systèmes d'instrumentation, de contrôle-commande et d'alimentation électrique - Exigences pour les systèmes d'alimentation en courant alternatif et en courant continu statiques sans interruption (IEC 61225:2019)

See the scope of IEC 61225:2019. Adoption of IEC 61225 is to be done without modification.

Nuklearne elektrarne - Merilni, nadzorni in elektroenergetski sistemi - Zahteve za statične neprekinjene enosmerne in izmenične napajalne sisteme (IEC 61225:2019)

General Information

Status
Published
Publication Date
07-Apr-2020
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
02-Apr-2020
Due Date
07-Jun-2020
Completion Date
08-Apr-2020

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SLOVENSKI STANDARD
SIST EN IEC 61225:2020
01-junij-2020
Nuklearne elektrarne - Merilni, nadzorni in elektroenergetski sistemi - Zahteve za
statične neprekinjene enosmerne in izmenične napajalne sisteme (IEC 61225:2019)
Nuclear power plants - Instrumentation, control and electrical power systems -
Requirements for static uninterruptible DC and AC power supply systems (IEC
61225:2019)
Centrales nucléaire de puissance - Systèmes d'instrumentation, de contrôle-commande
et d'alimentation électrique - Exigences pour les systèmes d'alimentation en courant
alternatif et en courant continu statiques sans interruption (IEC 61225:2019)
Ta slovenski standard je istoveten z: EN IEC 61225:2020
ICS:
27.120.20 Jedrske elektrarne. Varnost Nuclear power plants. Safety
SIST EN IEC 61225:2020 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN IEC 61225:2020

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SIST EN IEC 61225:2020


EUROPEAN STANDARD EN IEC 61225

NORME EUROPÉENNE

EUROPÄISCHE NORM
March 2020
ICS 27.120.20

English Version
Nuclear power plants - Instrumentation, control and electrical
power systems - Requirements for static uninterruptible DC and
AC power supply systems
(IEC 61225:2019)
Centrales nucléaire de puissance - Systèmes To be completed
d'instrumentation, de contrôle-commande et d'alimentation (IEC 61225:2019)
électrique - Exigences pour les systèmes d'alimentation en
courant alternatif et en courant continu statiques sans
interruption
(IEC 61225:2019)
This European Standard was approved by CENELEC on 2020-02-17. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.


European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2020 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
 Ref. No. EN IEC 61225:2020 E

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SIST EN IEC 61225:2020
EN IEC 61225:2020 (E)
European foreword
This document (EN IEC 61225:2020) consists of the text of IEC 61225:2019 prepared by IEC/TC 45
"Nuclear instrumentation".
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2020-09-17
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2020-09-17
document have to be withdrawn

Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
As stated in the nuclear safety directive 2009/71/EURATOM, Chapter 1, Article 2, item 2, Member
States are not prevented from taking more stringent safety measures in the subject-matter covered by
the Directive, in compliance with Community law. In a similar manner, this European standard does
not prevent Member States from taking more stringent nuclear safety and security measures in the
subject-matter covered by this standard.
Endorsement notice
The text of the International Standard IEC 61225:2019 was approved by CENELEC as a European
Standard without any modification.

In the official version, for Bibliography, the following notes have to be added for the standards
indicated:
IEC 60964 NOTE Harmonized as EN IEC 60964
IEC 61000-6-2 NOTE Harmonized as EN IEC 61000-6-2
IEC 61000-6-4 NOTE Harmonized as EN IEC 61000-6-4
IEC 61226 NOTE Harmonized as EN 61226
IEC 62040-3 NOTE Harmonized as EN 62040-3
IEC 62340 NOTE Harmonized as EN 62340

2

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SIST EN IEC 61225:2020
EN IEC 61225:2020 (E)
Annex ZA
(normative)

Normative references to international publications
with their corresponding European publications
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.
NOTE 1  Where an International Publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
NOTE 2  Up-to-date information on the latest versions of the European Standards listed in this annex is available here:
www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60038 (mod) -  IEC standard voltages EN 60038 -
IEC 60146-1-1 -  Semiconductor converters - General EN 60146-1-1 -
requirements and line commutated
converters - Part 1-1: Specification of basic
requirements
IEC 60146-2 -  Semiconductor converters - Part 2: Self-EN 60146-2 -
commutated semiconductor converters
including direct d.c. converters
IEC 60364-4-41 -  Low-voltage electrical installations - Part 4-HD 60364-4-41 -
(mod) 41: Protection for safety - Protection
against electric shock
  +A11 2017
  +A12 2019
IEC 60709 -  EN IEC 60709 -
IEC 60880 -  Nuclear power plants - Instrumentation and EN 60880 -
control systems important to safety -
Software aspects for computer-based
systems performing category A functions
IEC 60980 -  Recommended practices for seismic - -
qualification of electrical equipment of the
safety system for nuclear generating
stations
IEC 61000-1 series Electromagnetic compatibility (EMC) - PartE N 61000-1 series
1-2: General - Methodology for the
achievement of functional safety of
electrical and electronic systems including
equipment with regard to electromagnetic
phenomena
IEC 61508 series Functional safety of EN 61508 series
electrical/electronic/programmable
electronic safety-related systems - Part 1:
General requirements (see href="http://www.iec.ch/functionalsafety">F
unctional Safety and IEC 61508)
IEC 61513 -  Nuclear power plants - Instrumentation and EN 61513 -
control important to safety - General
requirements for systems
IEC 62003 -  Nuclear power plants - Instrumentation and - -
3

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SIST EN IEC 61225:2020
EN IEC 61225:2020 (E)
Publication Year Title EN/HD Year
control important to safety - Requirements
for electromagnetic compatibility testing
IEC 62040 series Uninterruptible power systems (UPS) - PartEN IEC 62040 series
1: Safety requirements
  +prAA
IEC 62138 -  Nuclear power plants - Instrumentation and EN IEC 62138 -
control systems important to safety -
Software aspects for computer-based
systems performing category B or C
functions
IEC 62566 -  Nuclear power plants - Instrumentation and EN 62566 -
control important to safety - Development
of HDL-programmed integrated circuits for
systems performing category A functions
IEC/IEEE 60780--  EN 60780-323 -
323

4

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SIST EN IEC 61225:2020




IEC 61225

®


Edition 3.0 2019-02




INTERNATIONAL



STANDARD




NORME



INTERNATIONALE
colour

inside










Nuclear power plants – Instrumentation, control and electrical power systems –

Requirements for static uninterruptible DC and AC power supply systems




Centrales nucléaires de puissance – Systèmes d'instrumentation, de contrôle-

commande et d'alimentation électrique – Exigences pour les systèmes

d'alimentation en courant alternatif et en courant continu statiques sans


interruption













INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE


INTERNATIONALE




ICS 27.120.20 ISBN 978-2-8322-6382-2



Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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SIST EN IEC 61225:2020
– 2 – IEC 61225:2019 © IEC 2019
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
4 Abbreviated terms . 11
5 System requirements . 11
5.1 General . 11
5.2 Function and description . 12
5.2.1 Preamble . 12
5.2.2 Designations . 14
5.2.3 Direct current systems . 14
5.2.4 Alternating current systems . 14
5.3 System divisions . 15
5.4 System boundaries . 15
6 Functional requirements for static uninterruptible power supplies . 15
6.1 Static uninterruptible power supplies for systems important to safety . 15
6.2 Batteries and battery chargers . 16
6.3 Inverters and bypass switches . 17
6.4 UPS . 18
6.5 Converters used for voltage stabilization . 18
6.6 I&C power supply using DC/DC-converters and AC/DC-converters . 19
7 Requirements for distribution systems . 19
7.1 System aspects . 19
7.2 Load allocation . 19
7.3 Electrical aspects . 21
7.4 Earthing . 22
8 Effects of loads on supply quality. 22
8.1 General . 22
8.2 Electromagnetic interference. 22
8.3 Transients . 22
8.4 Load current . 23
8.5 Power supplies to loads of lower safety classification. 23
9 Monitoring and protection . 23
9.1 General . 23
9.2 Monitoring . 24
9.3 Electrical protection . 24
10 Qualification of equipment . 25
11 Design to cope with ageing . 25
12 Testing . 25
13 Maintenance . 26
Annex A (informative)  Examples of voltage input variations . 27
Annex B (informative) Examples of specifications . 29
B.1 Example 1: Specification for an DC power supply for equipment requiring a
non-interruptible supply. 29

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SIST EN IEC 61225:2020
IEC 61225:2019 © IEC 2019 – 3 –
B.2 Example 2: Specification for AC power supply for equipment requiring a non-
interruptible supply . 30
B.3 Example 3: Specification for DC power supply with DC/DC converter for
equipment . 31
B.4 Human factor engineering programme . 31
Bibliography . 33


Figure 1 – System boundary . 13
Figure 2 – Example of one division of an uninterruptible power supply system . 20
Figure 3 – Example of I&C uninterruptible AC power supply system . 21
Figure A.1 – Example of voltage variations on the on-site AC power system during
clearing of a transmission system fault . 27
Figure A.2 – Example of on-site voltage profile after loss of load (transfer to house
load operation). 27
Figure A.3 – Example of simulated safety bus voltages, double open phase condition

in the 400 kV line to the unit transformer . 28


Table B.1 – Example 1 . 29
Table B.2 – Example 2 . 30
Table B.3 – Example 3 . 31

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SIST EN IEC 61225:2020
– 4 – IEC 61225:2019 © IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

NUCLEAR POWER PLANTS – INSTRUMENTATION, CONTROL AND
ELECTRICAL POWER SYSTEMS – REQUIREMENTS FOR STATIC
UNINTERRUPTIBLE DC AND AC 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, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61225 has been prepared by subcommittee 45A: Instrumentation,
control and electrical power systems of nuclear facilities, of IEC technical committee 45:
Nuclear instrumentation.
This third edition cancels and replaces the second edition published in 2005. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) the principal objective of this edition is to address the requirements on the static
uninterruptible power supplies in nuclear power plants;
b) in addition to Instrumentation and Control (I&C) power supplies include all static
uninterruptible power supplies;

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SIST EN IEC 61225:2020
IEC 61225:2019 © IEC 2019 – 5 –
c) emphasize that the static uninterruptible power supplies shall protect the connected
equipment (loads) from transients on the on-site AC distribution system (the immunity
concept);
d) in accordance with the defence-in-depth concept, this standard applies to static
uninterruptible power supplies for all equipment, not only for equipment important to
safety, with a graded approach to verification and validation;
e) addition of the requirement that, when batteries are connected in parallel under abnormal
operating conditions, they shall be properly protected with isolation devices to avoid any
failure that may impair more than one division of the uninterruptible power supply.
The text of this International Standard is based on the following documents:
FDIS Report on voting
45A/1235/FDIS 45A/1250/RVD

Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

IMPORTANT – The 'colour inside' logo on the cover page of this publication 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.

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SIST EN IEC 61225:2020
– 6 – IEC 61225:2019 © IEC 2019
INTRODUCTION
a) Technical background, main issues and organization of the standard
The 1993 issue of IEC 61225 was developed for specifying the requirements relevant to
the design of electrical supplies for I&C systems in nuclear power plants. Considering the
experience gathered worldwide on this subject, in 2003 working group A2 recommended a
revision to this standard so that a new revision, IEC 61225 Ed. 2 (2005), could be
consistently integrated into the SC 45A standard series. In 2015, working group A11
recommended a revision to this standard following the publication of the revision of IAEA
SSG-34 and that the scope of the standard should cover static uninterruptible power
supplies for all types of connected equipment.
International operating experience with electrical supply systems in nuclear power plants
has highlighted a number of supply voltage variations and malfunctions, such as:
– voltage perturbations due to disturbances on the internal AC distribution system (with
origin off-site or on-site);
– voltage overshoot on loss of grid;
– open phase conditions (one or two phases);
– asymmetrical faults.
These types of perturbations can degrade the performance of static uninterruptible power
supplies and ultimately result in failure of connected equipment.
One of the objectives of the uninterruptible power supplies is to protect the connected
equipment from voltage variations on the on-site AC distribution system (the immunity
concept). The power supplies shall also guarantee an output voltage with specified
magnitude and waveform (in case of AC) to connected loads. The power supplies shall
have the capacity to supply the relevant loads during a specified time regardless of any
voltage variations on the on-site AC distribution system.
Examples of voltage and frequency variations in the incoming feeder to the supplies can
be found in informative Annex A. Examples of specifications for static uninterruptible
power supplies can be found in informative Annex B.
This standard is applicable to the design of static uninterruptible electrical power supplies
in new nuclear power plants, when design work is initiated after the publication of this
standard. It also serves as a reference for upgrading and modernizing existing nuclear
power plants.
b) Situation of the current standard in the structure of the SC 45A standard series
IEC 61225 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 standard is to be applied in conjunction with IEC 61513, IEC 60709, IEC 60880,
IEC 62138, IEC 62855 and IEC 63046 (to be published).
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 top-level documents of the IEC SC 45A standard series are IEC 61513 and
IEC 63046. IEC 61513 provides general requirements for I&C systems and equipment that
are used to perform functions important to safety in 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 to be
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 systems for nuclear power plants.
IEC 61513 and IEC 63046 refer directly to other IEC SC 45A standards for general topics
related to categorization of functions and classification of systems, qualification,
separation, defence against common cause failure, control room design, electromagnetic

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SIST EN IEC 61225:2020
IEC 61225:2019 © IEC 2019 – 7 –
compatibility, 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 equipment, technical methods, or specific
activities. Usually these documents, which make reference to second-level documents for
general topics, 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 and the implementing guide NSS17 for computer security at nuclear facilities. The
safety and security terminology and definitions used by 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 as well as to IAEA GS-R 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 6096
...

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