EN IEC 62933-5-2:2020

SLOVENSKI STANDARD
01-september-2020
Električne naprave za shranjevanje energije (EES) - 5-2. del: Varnostne zahteve za
sisteme EES, integrirane v omrežje - Elektrokemični sistemi (IEC 62933-5-2:2020)
Electrical energy storage (EES) systems - Part 5-2: Safety requirements for grid
integrated EES systems - Electrochemical based systems (IEC 62933-5-2:2020)
Elektrische Energiespeichersysteme (EES-Systeme) - Teil 5-2:
Sicherheitsanforderungen an netzintegrierte EES-Systeme elektrochemische Systeme
(IEC 62933-5-2:2020)
Systèmes de stockage de l'énergie électrique (EES) - Partie 5-2: Exigences de sécurité
pour les systèmes EES intégrés dans un réseau - Systèmes électrochimiques (IEC
62933-5-2:2020)
Ta slovenski standard je istoveten z: EN IEC 62933-5-2:2020
ICS:
27.010 Prenos energije in toplote na Energy and heat transfer
splošno engineering in general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 62933-5-2

NORME EUROPÉENNE
EUROPÄISCHE NORM
May 2020
ICS 13.020.30
English Version
Electrical energy storage (EES) systems - Part 5-2: Safety
requirements for grid-integrated EES systems - Electrochemical-
based systems
(IEC 62933-5-2:2020)
Systèmes de stockage de l'énergie électrique (EES) - Partie Elektrische Energiespeichersysteme (EES-Systeme) - Teil
5-2: Exigences de sécurité pour les systèmes EES intégrés 5-2: Sicherheitsanforderungen an netzintegrierte EES-
dans un réseau - Systèmes électrochimiques Systeme elektrochemische Systeme
(IEC 62933-5-2:2020) (IEC 62933-5-2:2020)
This European Standard was approved by CENELEC on 2020-05-21. 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 62933-5-2:2020 E

European foreword
The text of document 120/173/FDIS, future edition 1 of IEC 62933-5-2, prepared by IEC/TC 120
"Electrical Energy Storage (EES) Systems" was submitted to the IEC-CENELEC parallel vote and
approved by CENELEC as EN IEC 62933-5-2:2020.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2021-02-21
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2023-05-21
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.

Endorsement notice
The text of the International Standard IEC 62933-5-2:2020 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 60364-4-41 NOTE Harmonized as HD 60364-4-41
IEC 60364-4-42 NOTE Harmonized as HD 60364-4-42
IEC 60364-4-43 NOTE Harmonized as HD 60364-4-43
IEC 60721 (series) NOTE Harmonized as EN 60721 (series)
IEC 60896-21 NOTE Harmonized as EN 60896-21
IEC 60896-22 NOTE Harmonized as EN 60896-22
IEC 61140 NOTE Harmonized as EN 61140
IEC 61427-1 NOTE Harmonized as EN 61427-1
IEC 61427-2 NOTE Harmonized as EN 61427-2
IEC 61508 (series) NOTE Harmonized as EN 61508 (series)
IEC 61511-1:2016 NOTE Harmonized as EN 61511-1:2017 (not modified)
IEC 62040-1 NOTE Harmonized as EN IEC 62040-1
IEC 62040-2 NOTE Harmonized as EN IEC 62040-2
IEC 62116:2014 NOTE Harmonized as EN 62116:2014 (not modified)
IEC 62351 (series) NOTE Harmonized as EN 62351 (series)
IEC 62381:2012 NOTE Harmonized as EN 62381:2012 (not modified)
IEC 62443-2-4 NOTE Harmonized as EN IEC 62443-2-4
IEC 62485-1 NOTE Harmonized as EN IEC 62485-1
IEC 62909-1 NOTE Harmonized as EN IEC 62909-1
IEC 62932-1:2020 NOTE Harmonized as EN IEC 62932-1:2020 (not modified)
ISO 1182 NOTE Harmonized as EN ISO 1182
ISO 9241 (series) NOTE Harmonized as EN ISO 9241 (series)
ISO 13732-1:2006 NOTE Harmonized as EN ISO 13732-1:2008 (not modified)
ISO 13850:2015 NOTE Harmonized as EN ISO 13850:2015 (not modified)

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 60068-2-52 - Environmental testing - Part 2-52: Tests - EN IEC 60068-2-52 -
Test Kb: Salt mist, cyclic (sodium chloride
solution)
IEC 60079-7 2015 Explosive atmospheres - Part 7: Equipment EN 60079-7 2015
protection by increased safety "e"
+ A1 2017 + A1 2018
IEC 60079-13 - Explosive atmospheres - Part 13: EN 60079-13 -
Equipment protection by pressurized room
"p" and artificially ventilated room "v"
IEC 60079-29 series Explosive atmospheres - Gas detectors EN 60079-29 series
IEC 60364 series Low-voltage electrical installations - -
IEC 60364-4-44 - Low-voltage electrical installations - Part 4- HD 60364-4-442 -
44: Protection for safety - Protection
against voltage disturbances and
electromagnetic disturbances
IEC 60364-6 2016 Low voltage electrical installations - Part 6: HD 60364-6 2016
Verification
+ A11 2017
+ A12 2017
IEC 60529 - Degrees of protection provided by - -
enclosures (IP Code)
IEC 60664-1 2007 Insulation coordination for equipment within EN 60664-1 2007
low-voltage systems - Part 1: Principles,
requirements and tests
IEC 60812 - Failure modes and effects analysis (FMEA EN IEC 60812 -
and FMECA)
Publication Year Title EN/HD Year
IEC 61000-1-2 - Electromagnetic compatibility (EMC) - Part EN 61000-1-2 -
1-2: General - Methodology for the
achievement of functional safety of
electrical and electronic systems including
equipment with regard to electromagnetic
phenomena
IEC 61000-6-7 - Electromagnetic compatibility (EMC) - Part EN 61000-6-7 -
6-7: Generic standards - Immunity
requirements for equipment intended to
perform functions in a safety-related
system (functional safety) in industrial
locations
IEC 61025 - Fault tree analysis (FTA) - -
IEC 61660-1 - Short-circuit currents in d.c. auxiliary EN 61660-1 -
installations in power plants and
substations - Part 1: Calculation of short-
circuit currents
IEC 61660-2 - Short-circuit currents in d.c. auxiliary EN 61660-2 -
installations in power plants and
substations - Part 2: Calculation of effects
IEC 61882 - Hazard and operability studies (HAZOP EN 61882 -
studies) - Application guide
IEC 61936-1 (mod) 2010 Power installations exceeding 1 kV a.c. - EN 61936-1 2010
Part 1: Common rules
+ AC 2013
+ A1 2014 + A1 2014
IEC 62305-2 - Protection against lightning - Part 2: Risk - -
management
IEC 62368-1 - Audio/video, information and EN IEC 62368-1 -
communication technology equipment -
Part 1: Safety requirements
IEC 62477-1 2012 Safety requirements for power electronic EN 62477-1 2012
converter systems and equipment - Part 1:
General
+ A11 2014
+ A1 2016 + A1 2017
IEC 62485-2 - Safety requirements for secondary EN IEC 62485-2 -
batteries and battery installations - Part 2:
Stationary batteries
IEC 62619 2017 Secondary cells and batteries containing EN 62619 2017
alkaline or other non-acid electrolytes -
Safety requirements for secondary lithium
cells and batteries, for use in industrial
applications
Publication Year Title EN/HD Year
IEC 62933-1 - Electrical energy storage (EES) systems - EN IEC 62933-1 -
Part 1: Vocabulary
IEC/TS 62933-5-1 2017 Electrical energy storage (EES) systems - - -
Part 5-1: Safety considerations for grid
integrated EES systems - General
specification
ISO/IEC Guide 51 2014 Safety aspects - Guidelines for their - -
inclusion in standards
IEC 62933-5-2 ®
Edition 1.0 2020-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electrical energy storage (EES) systems –

Part 5-2: Safety requirements for grid-integrated EES systems –

Electrochemical-based systems
Systèmes de stockage de l'énergie électrique (EES) –

Partie 5-2: Exigences de sécurité pour les systèmes EES intégrés dans un

réseau – Systèmes électrochimiques

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 13.020.30 ISBN 978-2-8322-8146-8

– 2 – IEC 62933-5-2:2020 © IEC 2020
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
4 Basic guidelines for safety of BESS . 11
4.1 General . 11
4.2 Approach to BESS safety . 12
4.3 BESS changes in ownership, control or use . 14
5 Hazard considerations . 14
6 BESS system risk assessment . 15
6.1 BESS structure . 15
6.1.1 General characteristics . 15
6.1.2 Specific characteristics . 16
6.2 Description of BESS conditions . 16
6.3 Risk analysis . 16
6.3.1 General . 16
6.3.2 Hazard identification specific to BESS . 17
6.3.3 Risk consideration . 17
6.3.4 System level risk analysis . 17
6.4 System level risk assessment . 17
7 Requirements necessary to reduce risks . 17
7.1 General measures to reduce risks . 17
7.2 Preventive measures against damage to neighbouring inhabitants . 18
7.3 Preventive measures against physical injury or damage to the health of
workers and residents . 18
7.4 Overcurrent protection design . 18
7.5 BESS disconnection and shutdown . 18
7.6 Operation and maintenance . 18
7.7 Staff training . 18
7.8 Safety design . 19
7.9 General requirements for BESS safety . 19
7.10 Inherently safe design of BESS . 19
7.10.1 Protection from electrical hazards . 19
7.10.2 Protection from mechanical hazards . 20
7.10.3 Protection from explosion . 21
7.10.4 Protection from hazards arising from electric, magnetic, and
electromagnetic fields . 21
7.10.5 Protection from fire hazards . 21
7.10.6 Protection from temperature hazards . 21
7.10.7 Protection from chemical effects . 22
7.10.8 Protection from hazards arising from auxiliary, control and
communication system malfunctions . 22
7.10.9 Protection from hazards arising from environments. 22
7.11 Guards and protective measures. 23
7.11.1 General . 23
7.11.2 BESS disconnection and shutdown . 23

IEC 62933-5-2:2020 © IEC 2020 – 3 –
7.11.3 Other guards and protective functions of BESS . 24
7.12 Information for end users . 28
7.13 Life cycle safety management . 28
7.13.1 Operation and maintenance . 28
7.13.2 Partial system change . 31
7.13.3 Design revision . 32
7.13.4 End of service life management . 33
7.13.5 Measures for validating life cycle safety management . 33
8 System validation and testing . 33
8.1 General . 33
8.2 Validation and testing of BESS . 36
8.2.1 Electrical hazards . 36
8.2.2 Mechanical hazards . 38
8.2.3 Explosion . 38
8.2.4 Hazards arising from electric, magnetic, and electromagnetic fields . 39
8.2.5 Fire hazards (propagation) . 39
8.2.6 Temperature hazards. 40
8.2.7 Chemical effects . 41
8.2.8 Hazards arising from auxiliary, control and communication system
malfunctions . 42
8.2.9 Hazards arising from environments . 42
8.2.10 IP rating of BESS enclosure and protective guards . 43
9 Guidelines and manuals . 43
Annex A (informative) Ownership models of BESS . 44
Annex B (informative) BESS hazards and risks . 45
B.1 General introduction . 45
B.2 Hazard concerns . 51
B.2.1 General . 51
B.2.2 Fire hazards . 51
B.2.3 Chemical hazards . 51
B.2.4 Electrical hazards . 51
B.2.5 Energy hazards . 52
B.2.6 Physical hazards . 52
B.2.7 High-pressure hazards . 52
B.3 Hazard considerations under normal operating conditions . 52
B.3.1 Fire and explosive hazards . 52
B.3.2 Chemical hazards . 52
B.3.3 Electrical hazards . 53
B.3.4 Physical hazards . 53
B.4 Hazard considerations under emergency/abnormal conditions . 54
B.4.1 Fire hazards . 54
B.4.2 Chemical hazards . 54
B.4.3 Electrical hazards . 55
B.4.4 Physical hazards . 56
B.5 Commercially available battery technologies . 56
B.5.1 Lithium ion (Li-ion) batteries (C-A) . 56
B.5.2 Lead-acid batteries (C-B) . 57
B.5.3 Nickel batteries (C-B) . 58
B.5.4 High-temperature sodium batteries (C-C). 60

– 4 – IEC 62933-5-2:2020 © IEC 2020
B.5.5 Flow batteries (C-D) . 61
B.5.6 Lithium metal solid state batteries (C-Z) . 63
B.6 Other technologies . 63
Annex C (informative) Large-scale fire testing on BESS . 64
Annex D (informative) Test methods for protection from hazards arising from
environments . 65
D.1 General . 65
D.2 Outdoor installations subject to moisture exposure . 65
D.3 Outdoor installation near marine environments . 65
Annex E (informative)  Information for validation of BESS life cycle safety
management . 66
E.1 Overview . 66
E.2 General introduction . 66
E.3 Operation and maintenance process . 66
E.4 Preventive maintenance . 66
E.5 Measuring and monitoring of system soundness . 67
E.6 Staff training . 67
E.7 Partial system change . 67
E.8 Design revision . 67
Annex F (informative) BESS safety signage . 68
Annex G (informative) Example of testing for verification of thermal control operation . 69
Bibliography . 70

Figure 1 – General description for risk assessment and reduction of BESS . 11
Figure 2 – An example of BESS architecture. 15
Figure 3 – Example of isolated condition (whole isolation of BESS) . 24
Figure 4 – Incompatibility of capacity and/or usage in a BESS . 32

Table 1 – BESS categories . 13
Table 2 – Examples of BESS use. 14
Table 3 – Examples of components within subsystems of a BESS . 16
Table 4 – Examples of incompatibilities that can arise from system changes . 32
Table 5 – Overview of validation and testing for BESS . 35
Table B.1 – Hazards of BESS in common . 47
Table B.2 – Hazards of BESS using non-aqueous electrolyte battery (category "C-A") . 48
Table B.3 – Hazards of BESS using aqueous electrolyte battery (category "C-B") . 49
Table B.4 – Hazards of BESS using high temperature battery (category "C-C") . 50
Table B.5 – Hazards of BESS using flow battery (category "C-D") . 51

IEC 62933-5-2:2020 © IEC 2020 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL ENERGY STORAGE (EES) SYSTEMS –

Part 5-2: Safety requirements for grid-integrated EES systems –
Electrochemical-based 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 62933-5-2 has been prepared by IEC technical committee 120:
Electrical Energy Storage (EES) Systems.
This International Standard is to be used in conjunction with IEC TS 62933-5-1:2017.
The text of this International Standard is based on the following documents:
FDIS Report on voting
120/173/FDIS 120/182/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.

– 6 – IEC 62933-5-2:2020 © IEC 2020
A list of all parts in the IEC 62933 series, published under the general title Electrical energy
storage (EES) systems, can be found on the IEC website.
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.

IEC 62933-5-2:2020 © IEC 2020 – 7 –
INTRODUCTION
All the electrical energy storage systems (EESS) follow the general safety requirements as
described in IEC TS 62933-5-1, which is based on a systems approach. IEC 62933-5-2 follows
the same structure as IEC TS 62933-5-1 and provides additional requirements for battery
energy storage systems (BESS). The additional requirements are provided for the following
reasons:
a) BESS can be integrated into a significant range of electrical grids.
b) The level of safety requirements awareness can vary between utilities, system integrators,
operators and end-users.
c) Although the safety of individual subsystems is generally covered by international standards
at ISO and IEC levels, the safety matters that arise due to the combination of
electrochemical accumulation subsystems and any electrical subsystems are not always
considered. BESS are complex at the systems level due to the variety of potential battery
options and configurations, including the combination of subsystems (e.g. control systems
for electrochemical accumulation subsystems, electrochemical accumulation subsystems,
power conversion subsystems and auxiliary subsystems). Compliance with standards and
related material produced specifically for the safety of subsystems cannot be sufficient to
reach an acceptable level of safety for the overall system.
d) BESS can have additional safety hazards, due, for example, to the presence of chemicals,
the emission of toxic gases, chemicals spilt around the electrochemical accumulation
subsystems and to events critical for safety from electrochemical accumulation subsystems
that cause safety issues for the entire BESS. They can cause loss of power at any part of
the systems and buildings that can result in additional threats to safety. From a systems
perspective, these individual hazards can have a system wide impact.

– 8 – IEC 62933-5-2:2020 © IEC 2020
ELECTRICAL ENERGY STORAGE (EES) SYSTEMS –

Part 5-2: Safety requirements for grid-integrated EES systems –
Electrochemical-based systems
1 Scope
This part of IEC 62933 primarily describes safety aspects for people and, where appropriate,
safety matters related to the surroundings and living beings for grid-connected energy storage
systems where an electrochemical storage subsystem is used.
This safety standard is applicable to the entire life cycle of BESS (from design to end of service
life management).
This document provides further safety provisions that arise due to the use of an electrochemical
storage subsystem (e.g. battery system) in energy storage systems that are beyond the general
safety considerations described in IEC TS 62933-5-1.
This document specifies the safety requirements of an “electrochemical” energy storage system
as a "system" to reduce the risk of harm or damage caused by the hazards of an electrochemical
energy storage system due to interactions between the subsystems as presently understood.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitute 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 60068-2-52, Environmental testing – Part 2-52: Tests – Test Kb: Salt mist, cyclic (sodium
chloride solution)
IEC 60079-7:2015, Explosive atmospheres – Part 7: Equipment protection by increased safety
"e"
IEC 60079-7:2015/AMD1:2017
IEC 60079-13, Explosive atmospheres – Part 13: Equipment protection by pressurized room "p"
and artificially ventilated room "v"
IEC 60079-29 (all parts), Explosive atmospheres – Gas detectors
IEC 60364 (all parts), Low-voltage electrical installations
IEC 60364-4-44, Low-voltage electrical installations – Part 4-44: Protection for safety –
Protection against voltage disturbances and electromagnetic disturbances
IEC 60364-6:2016, Low voltage electrical installations – Part 6: Verification
IEC 60529, Degrees of protection provided by enclosures (IP Code)
IEC 60664-1:2007, Insulation coordination for equipment within low-voltage systems – Part 1:
Principles, requirements and tests

IEC 62933-5-2:2020 © IEC 2020 – 9 –
IEC 60812, Failure modes and effects analysis (FMEA and FMECA)
IEC 61000-1-2, Electromagnetic compatibility (EMC) – Part 1-2: General – Methodology for the
achievement of functional safety of electrical and electronic systems including equipment with
regard to electromagnetic phenomena
IEC 61000-6-7, Electromagnetic compatibility (EMC) – Part 6-7: Generic standards – Immunity
requirements for equipment intended to perform functions in a safety-related system (functional
safety) in industrial locations
IEC 61025, Fault tree analysis (FTA)
IEC 61660-1, Short-circuit currents in d.c. auxiliary installations in power plants and substations
– Part 1: Calculation of short-circuit currents
IEC 61660-2, Short-circuit currents in d.c. auxiliary installations in power plants and substations
– Part 2: Calculation of effects
IEC 61882, Hazard and operability studies (HAZOP studies) – Application guide
IEC 61936-1:2010, Power installations exceeding 1 kV a.c. – Part 1: Common rules
IEC 61936-1:2010/AMD1:2014
IEC 62305-2, Protection against lightning – Part 2: Risk management
IEC 62368-1, Audio/video, information and communication technology equipment – Part 1:
Safety requirements
IEC 62477-1:2012, Safety requirements for power electronic converter systems and equipment
– Part 1: General
IEC 62477-1:2012/AMD1:2016
IEC 62485-2, Safety requirements for secondary batteries and battery installations – Part 2:
Stationary batteries
IEC 62619:2017, Secondary cells and batteries containing alkaline or other non-acid
electrolytes – Safety requirements for secondary lithium cells and batteries, for use in industrial
applications
IEC 62933-1, Electrical energy storage (EES) systems – Part 1: Vocabulary
IEC TS 62933-5-1:2017, Electrical energy storage (EES) systems – Part 5-1: Safety
considerations for grid integrated EES systems – General specification
ISO/IEC Guide 51:2014, Safety aspects – Guidelines for their inclusion in standards
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 62933-1,
IEC TS 62933-5-1 and the following apply.

– 10 – IEC 62933-5-2:2020 © IEC 2020
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
NOTE Where differences in definitions appearing in IEC 62933-1 and IEC TS 62933-5-1 exist, the definition given
in IEC 62933-1 prevails, unless otherwise specified here.
3.1
battery energy storage system
BESS
electrical energy storage system with accumulation subsystem based on batteries with
secondary cells
Note 1 to entry: The battery energy storage system includes a flow battery energy system (IEC 62932-1:2020,
3.1.15).
Note 2 to entry: Batteries are defined in IEC 60050-482:2004, 482-01-04, and secondary cells are defined in
IEC 60050-482:2004, 482-01-03.
3.2
occupied site
location that is within or adjacent to a building or structure with an overhead cover, where
people live or work
Note 1 to entry: A location that is not an occupied site is called “unoccupied site”.
3.3
type test
conformity test made on one or more items representative of the production
[SOURCE: IEC 60050-151:2001, 151-16-16]
3.4
routine test
conformity test made on each individual item during or after manufacture
[SOURCE: IEC 60050-151:2001, 151-16-17]
3.5
factory acceptance test
FAT
factory activity to demonstrate that the EES system, subsystems, components and additionally
supplied systems/devices are in accordance with the specifications
[SOURCE: IEC 62381:2012, 3.1.3, modified – Original definition has been particularized for the
ESS system.]
3.6
site acceptance test
SAT
on site activity to demonstrate that the EES system can operate in accordance with the
applicable system specifications and installation instructions
[SOURCE: IEC 62381:2012, 3.1.4, modified – Original definition has been particularized for the
ESS system .]
IEC 62933-5-2:2020 © IEC 2020 – 11 –
4 Basic guidelines for safety of BESS
4.1 General
An assessment and reduction of the risk associated with the BESS as manufactured and as
intended to be installed shall be conducted according to the sequence shown in Figure 1.

Figure 1 – General description for risk assessment and reduction of BESS

– 12 – IEC 62933-5-2:2020 © IEC 2020
Risks can depend on many factors including location, chemistry and the size/scale (e.g. power)
of the BESS and will need to be assessed accordingly. The location of BESS can range from
single domestic situations, commercial and industrial applications, to utility scale systems; risks
need to be assessed accordingly. Selection of chemistry for the electrochemical accumulation
subsystem of the BESS can depend on their environment, performance characteristics and any
associated costs and benefits.
As described in ISO/IEC Guide 51, risk reduction measures taken during design are "inherently
safe design", "guards and protective devices", and "information for end users". Additional
measures at the use phase (life cycle safety management) are also described in ISO/IEC Guide
51.
4.2 Approach to BESS safety
The design of the BESS and its intended installation and integration with the built environment
shall accommodate the specific risks that arise during each phase of the BESS life cycle. These
life cycle phases typically include, but are not limited to:
• manufacturing/final assembly and factory acceptance testing (see 7.10, 7.11, and 8.2);
• transport (see 7.10, 7.11, and 8.2);
• installation, commissioning and site acceptance testing (see 7.10, 7.11, 7.12 and 8.2);
• operation (see 7.13);
• maintenance and repair (see 7.13);
• repurposing or decommissioning (see 7.13).
During the installation process, soundness of communication among subsystems which are
critical to minimizing risk and facilitating incident response shall be ensured to avoid any
malfunctions of the protection subsystems. After the installation of the BESS, these subsystems
shall be verified by inspection or other suitable means so that their proper functions are assured
before the BESS is placed into service.
All health, safety and environment (HSE) requirements applicable to the BESS as installed shall
be satisfied during system maintenance and repair.
The safety design considerations and risk analyses for each identified life cycle phase shall be
documented and supplied in accordance with Clause 6 and 7.13.
A BESS that is designed and constructed to provide a specified level of reliability and durability
shall include not only the levels of safety as a design feature of the overall system but also the
subsystem safety level which is necessary to achieve the specified level. At the subsystem level,
all integrated electrochemical energy storage subsystems shall comply with appropriate safety
standards (e.g. IEC 62477-1, IEC 62619).
Safety measures for interactions between subsystems shall be consistent with the result of the
system level safety risk assessment.
Commonly used electrochemical-based BESS POC (point of connection) voltages, energy
capacity, site occupancy and chemistry of electrochemical accumulation subsystems are
distinguished as listed in Table 1.
Detailed implementation of safety measures required in Clauses 7 and 8 can be optimized in
accordance with the result of the system risk assessment of BESS (see Clause 6) using the
basic conditions in Table 1.
NOTE 1 Chemistries that are not in common widespread use for stationary applications are not considered in this
document but can be considered in future editions

IEC 62933-5-2:2020 © IEC 2020 – 13 –
NOTE 2 "Energy capacity" of BESS" means the total energy capacity of electrochemical accumulation subsystems
which are equipped behind one POC.
Table 1 – BESS categories
Features for Category
Explanation
categorizatio
...