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,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their
preparation
...