IEC 62040-1:2008

IEC 62040-1
Edition 1.0 2008-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Uninterruptible power systems (UPS) –
Part 1: General and safety requirements for UPS

Alimentations sans interruption (ASI) –
Partie 1: Exigences générales et règles de sécurité pour les ASI

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IEC 62040-1
Edition 1.0 2008-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Uninterruptible power systems (UPS) –
Part 1: General and safety requirements for UPS

Alimentations sans interruption (ASI) –
Partie 1: Exigences générales et règles de sécurité pour les ASI

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
XB
CODE PRIX
ICS 29.200 ISBN 2-8318-9791-2
– 2 – 62040-1 © IEC:2008
CONTENTS
FOREWORD.6

1 Scope and specific applications.8

1.1 Scope.8

1.2 Specific applications.8

2 Normative references .9

3 Terms and definitions .10

3.1 General definitions .10

3.2 UPS electrical ratings.11
3.3 Load types .11
3.4 Connection to the supply .12
3.5 Circuits and circuit characteristics .12
3.6 Insulation .12
3.7 Equipment mobility .12
3.8 Insulation classes of UPS.12
3.9 Earth fault .12
3.10 Enclosures .12
3.11 Accessibility .12
3.12 Components .12
3.13 Power distribution.12
3.14 Flammability.12
3.15 Miscellaneous .12
3.16 Clearances and creepage distances .12
3.17 Telecommunication networks .13
4 General conditions for tests.13
4.1 Introduction .13
4.2 Type test .13
4.3 Operating parameters for tests .13
4.4 UPS loading during tests .14
4.5 Components .14
4.6 Power interfaces .14
4.7 Markings and instructions.15
4.7.1 General .15

4.7.2 Power rating .15
4.7.3 Safety instructions .15
4.7.4 Main voltage adjustment.17
4.7.5 Power outlets .17
4.7.6 Fuses .17
4.7.7 Wiring terminals .17
4.7.8 Battery terminals .17
4.7.9 Controls and indicators.18
4.7.10 Isolation of multiple power sources .18
4.7.11 IT power systems .18
4.7.12 Protection in building installation .18
4.7.13 High leakage current .18
4.7.14 Thermostats and other regulating devices .18
4.7.15 Language .18

62040-1 © IEC:2008 – 3 –
4.7.16 Durability of markings .18

4.7.17 Removable parts .18

4.7.18 Replaceable batteries.19

4.7.19 Operator access with a tool .19

4.7.20 Battery .19

4.7.21 Installation instructions .20

5 Fundamental design requirements.20

5.1 Protection against electric shock and energy hazards .20

5.1.1 Protection for UPS intended to be used in operator access areas .20

5.1.2 Protection for UPS intended to be used in service access areas.21
5.1.3 Protection for UPS intended to be used in restricted access areas .21
5.1.4 Backfeed protection.21
5.1.5 Emergency switching (disconnect) device.22
5.2 Requirements for auxiliary circuits.22
5.2.1 Safety extra low voltage circuits – SELV.22
5.2.2 Telephone network voltage circuits – TNV .22
5.2.3 Limited current circuits .22
5.2.4 External signalling circuits .22
5.2.5 Limited power source .22
5.3 Protective earthing and bonding .22
5.3.1 General .22
5.3.2 Protective earthing .23
5.3.3 Protective bonding.23
5.4 AC and d.c. power isolation.24
5.4.1 General .24
5.4.2 Disconnect devices.24
5.5 Overcurrent and earth fault protection .24
5.5.1 General .24
5.5.2 Basic requirements.24
5.5.3 Battery circuit protection.25
5.6 Protection of personnel – Safety interlocks.25
5.6.1 Operator protection .25
5.6.2 Service person protection .26
5.7 Clearances, creepage distances and distances through insulation.27
6 Wiring, connections and supply .27

6.1 General .27
6.1.1 Introduction .27
6.1.2 Dimensions and ratings of busbars and insulated conductors .28
6.2 Connection to power .28
6.2.1 General provisions for connection to power .28
6.2.2 Means of connection.28
6.3 Wiring terminals for external power conductors .28
7 Physical requirements .29
7.1 Enclosure .29
7.2 Stability .29
7.3 Mechanical strength .29
7.4 Construction details.29
7.4.1 Introduction .29
7.4.2 Openings.30

– 4 – 62040-1 © IEC:2008
7.4.3 Gas concentration .30

7.4.4 Equipment movement .30

7.5 Resistance to fire .30

7.6 Battery location .30

7.6.1 Battery location and installation .30

7.6.2 Accessibility and maintainability .31

7.6.3 Distance .31

7.6.4 Case insulation.31

7.6.5 Wiring.31

7.6.6 Electrolyte spillage .31

7.6.7 Ventilation .31
7.6.8 Charging voltages.32
7.7 Temperature rise.32
8 Electrical requirements and simulated abnormal conditions .33
8.1 General provisions for earth leakage .33
8.2 Electric strength .33
8.3 Abnormal operating and fault conditions.33
8.3.1 General .33
8.3.2 Simulation of faults.34
8.3.3 Conditions for tests.34
9 Connection to telecommunication networks .35
Annex A (normative) Tests for resistance to heat and fire .36
Annex B (normative) Motor tests under abnormal conditions.37
Annex C (normative) Transformers .38
Annex D (normative) Measuring instruments for touch current tests .39
Annex E (normative) Temperature rise of a winding .40
Annex F (normative) Measurements of clearances and creepage distances .41
Annex G (normative) Alternative method for determining minimum clearances.42
Annex H (informative) Guidance on protection against ingress of water and foreign
objects.43
Annex I (normative) Backfeed protection test .45
Annex J (informative) Table of electrochemical potentials .48
Annex K (normative) Thermal controls .49
Annex L (normative) Reference loads .50
Annex M (normative) Ventilation of battery compartments.54
Annex N (normative) Minimum and maximum cross-sections of copper conductors
suitable for connection (see 6.3) .57
Annex O (informative) Guidance for disconnection of batteries during shipment.58
Bibliography.60

Figure I.1 – Test circuit for load-induced change of reference potential – single-phase
output .46
Figure I.2 – Test circuit for load-induced change of reference potential – three-phase
output .46
Figure O.1 – Precautionary label for products shipped with the battery disconnected.58
Figure O.2 – Precautionary label for products shipped with the battery connected .59

62040-1 © IEC:2008 – 5 –
Table 1 – Temperature limits .32

Table 2 – Permitted temperature limits for magnetic windings at the end of stored

energy mode of operation .33

Table H.1 – Degrees of protection against foreign objects indicated by the first

characteristic numeral.43

Table H.2 – Degrees of protection against water indicated by the second characteristic
numeral .44

Table N.1 – Conductor cross-sections (extract from IEC 60439-1) .57

– 6 – 62040-1 © IEC:2008
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
UNINTERRUPTIBLE POWER SYSTEMS (UPS) –

Part 1: General and safety requirements for UPS

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,
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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 provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
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 62040-1 has been prepared by subcommittee 22H: Uninterruptible
power systems (UPS), of IEC technical committee 22: Power electronic systems and

equipment.
This standard cancels and replaces the first edition of IEC 62040-1-1, published in 2004 and
IEC 62040-1-2, published in 2004 and constitutes a technical revision. This standard merges
all requirements of previous IEC 62040-1-1 and IEC 62040-1-2, with the addition of the
following:
– update of normative references including IEC 60950-1 as Reference Document (RD);
– harmonization and alignment with current world recognized best practices;
– enhancement of backfeed protection, definition of ground-fault, revision of temperature
rise tables and of hydrogen concentration in battery compartments.

62040-1 © IEC:2008 – 7 –
The text of this standard is based on the following documents:

FDIS Report on voting
22H/104/FDIS 22H/106/RVD
Full information on the voting for the approval of this standard can be found in the report on

voting indicated in the above table.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

It is to be used with IEC 60950-1, Edition 2.0, which is referred to in this standard as "RD".

In this standard, the following print types are used:
– requirements proper and normative annexes: in roman type;
– compliance statements and test specifications: in italic type;
– notes and other informative matter: in smaller roman type;
– normative conditions within tables: in smaller roman type;
– terms that are defined in Clause 3: bold.
A list of all parts of the IEC 62040 series, under the general title: Uninterruptible power
systems (UPS), can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
The contents of the corrigendum of September 2008 have been included in this copy.

– 8 – 62040-1 © IEC:2008
UNINTERRUPTIBLE POWER SYSTEMS (UPS) –

Part 1: General and safety requirements for UPS

1 Scope and specific applications

1.1 Scope
This part of IEC 62040 applies to uninterruptible power systems (UPS) with an electrical
energy storage device in the d.c. link. It is used with IEC 60950-1, which is referred to in this
standard as "RD" (reference document).
NOTE UPS applications generally make use of a chemical battery as the energy storage device. Alternative
devices may be suitable, and as such, where “battery” appears in the text of this standard, where applicable, this
may be understood as “energy storage device”.
When a clause is referred to by the phrase "The definitions or the provisions of item/RD
apply", this phrase is intended to mean that the definitions or provisions in that clause of
IEC 60950-1 apply, except any which are clearly inapplicable to uninterruptible power
systems. National requirements additional to those in IEC 60950-1 apply and are found as
notes under relevant clauses of the RD.
The primary function of the UPS covered by this standard is to ensure continuity of an
alternating power source. The UPS may also serve to improve the quality of the power source
by keeping it within specified characteristics.
This standard is applicable to UPS which are movable, stationary, fixed or for building-in, for
use in low-voltage distribution systems and intended to be installed in any operator
accessible area or in restricted access locations as applicable. It specifies requirements to
ensure safety for the operator and layman who may come into contact with the equipment
and, where specifically stated, for the service person.
This standard is intended to ensure the safety of installed UPS, both as a single UPS unit or
as a system of interconnected UPS units, subject to installing, operating and maintaining the
UPS in the manner prescribed by the manufacturer.
This standard does not cover UPS based on rotating machines.
Electromagnetic compatibility (EMC) requirements and definitions are given in IEC 62040-2.

1.2 Specific applications
Even if this standard does not cover all types of UPS, it may be taken as a guide for such
equipment. Requirements additional to those specified in this standard may be necessary for
specific applications, e.g. related to UPS that operate:
– while exposed to extremes of temperature; to excessive dust, moisture, or vibration; to
flammable gases; to corrosive or to explosive atmospheres;
– where ingress of water and foreign objects are possible;

NOTE 1 Annex H provides guidance on such requirements and on relevant testing.
– in vehicles, on board ships or aircraft, in tropical countries, or at elevations greater
than 1 000 m;
NOTE 2 Guidance for performance of UPS operating at elevations greater than 1 000 m is provided in
4.1.1 of IEC 62040-3.
62040-1 © IEC:2008 – 9 –
– with trapezoidal output waveforms and long run times (greater than 30 min);

NOTE 3 In addition to complying with 5.3.1.2 of IEC 62040-3, voltage distortion tests for the purpose of

load compatibility should also be performed.

– subject to transient overvoltages exceeding those of overvoltage category II according

to IEC 60664;
NOTE 4 Subclause G.2.1/RD provides guidance for additional protection against transient overvoltages

at the mains supply to the UPS. Where such additional protection is an integral part of the equipment

insulation requirements, creepage distances and clearance distances from the mains through to the load
side of the additional protection may be judged as category III or IV as required. All further downstream
insulation requirements, creepage distances, and clearance distances on the load side of the additional

protection may be judged as category I or II as required.

– in electromedical applications with the UPS located within 1,5 m of the patient contact

area;
– in systems classified as emergency power systems by an authority having jurisdiction.
NOTE 5 Additional requirements may also apply in accordance with local regulations.
2 Normative references
The following referenced documents are indispensable for the application 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 60364-4-42, Electrical installations of buildings – Part 4-42: Protection for safety –
Protection against thermal effects
IEC 60417, Graphical symbols for use on equipment
IEC 60529, Degrees of protection provided by enclosures (IP Code)
IEC 60664 (all parts), Insulation coordination for equipment within low-voltage systems
IEC 60755, General requirements for residual current operated protective devices
IEC 60950-1:2005, Information technology equipment – Safety – Part 1: General requirements
IEC 61000-2-2, Electromagnetic compatibility (EMC) – Part 2-2: Environment – Compatibility
levels for low-frequency conducted disturbances and signaling in public low-voltage power
supply systems
IEC 61008-1, Residual current operated circuit-breakers without integral overcurrent
protection for household and similar uses (RCCBs) – Part 1: General rules
IEC 61009-1, Residual current operated circuit-breakers with integral overcurrent protection
for household and similar uses (RCBOs) – Part 1: General rules
IEC 62040-2:2005, Uninterruptible power systems (UPS) – Part 2: Electromagnetic compatibility
(EMC) requirements
IEC 62040-3:1999, Uninterruptible power systems (UPS) – Part 3: Method of specifying the
performance and test requirements

– 10 – 62040-1 © IEC:2008
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

3.1 General definitions
NOTE 1 Where the terms "voltage" and "current" are used, they imply the r.m.s. values, unless otherwise
specified.
NOTE 2 Care should be taken that measuring instruments give a true r.m.s. reading in the presence of non-

sinusoidal signals.
3.1.1
uninterruptible power system
UPS
combination of convertors, switches and energy storage devices (such as batteries),
constituting a power system for maintaining continuity of load power in case of input power
failure
NOTE Continuity of load power occurs when voltage and frequency are within rated steady-state and transient
tolerance bands and with distortion and interruptions within the limits specified for the load. Input power failure
occurs when voltage and frequency are outside rated steady-state and transient tolerance bands or with distortion
or interruptions outside the limits specified for the UPS.
3.1.2
bypass
alternative power path, either internal or external to the UPS
3.1.3
primary power
power supplied by an electrical utility company or by a user’s generator
3.1.4
active power
under periodic conditions, mean value, taken over one period T, of the instantaneous power p:

NOTE 1 Under sinusoidal conditions, the active power is the real part of the complex power.
NOTE 2 The SI unit for active power is the watt.
[IEV 131-11-42]
NOTE 3 DC, fundamental and harmonic voltages contribute directly to the magnitude of the active power. Where
applicable, instruments used to measure active power should therefore present sufficient bandwidth and be
capable of measuring any significant non-symmetrical and harmonic power components.
3.1.5
apparent power
product of the r.m.s. voltage and r.m.s. current
3.1.6
backfeed
condition in which a voltage or energy available within the UPS is fed back to any of the input
terminals, either directly or by a leakage path while operating in the stored energy mode and
with primary power not available
3.1.7
backfeed protection
control scheme that reduces the risk of electric shock due to backfeed

62040-1 © IEC:2008 – 11 –
3.1.8
stored energy mode
operation of the UPS when supplied by the following conditions:

– primary power is disconnected or is out of a given tolerance;

– battery is being discharged;

– load is within the given range;

– output voltage is within the given tolerance

3.2 UPS electrical ratings
3.2.1
rated voltage
input or output voltage (for three-phase supply, the phase-to-phase voltage) as declared by
the manufacturer
3.2.2
rated voltage range
input or output voltage range as declared by the manufacturer, expressed by its lower and
upper rated voltages
3.2.3
rated current
input or output current of the UPS as declared by the manufacturer
NOTE See 4.7.2.
3.3 Load types
3.3.1
normal load
mode of operation which approximates as closely as possible the most severe conditions of
normal use in accordance with the manufacturer’s operating instructions
NOTE 1 However, when the conditions of actual use can obviously be more severe than the maximum load
conditions recommended by the manufacturer, a load should be used that is representative of the maximum that
can be applied
NOTE 2 For examples of reference normal load conditions for UPS, see Annex L.
3.3.2
linear load
load where the current drawn from the supply is defined by the relationship:

I = U/Z
where
I is the load current;
U is the supply voltage;
Z is the load impedance
3.3.3
non-linear load
load where the parameter Z (load impedance) is no longer a constant but is a variable
dependent on other parameters, such as voltage or time (see Annex L)

– 12 – 62040-1 © IEC:2008
3.4 Connection to the supply
The definitions of 1.2.5/RD apply together with the following.

3.4.1
power cord
flexible cord or cable for interconnection purposes

3.5 Circuits and circuit characteristics

The definitions of 1.2.8/RD (e.g. hazardous voltage 1.2.8.6/RD) apply.

3.6 Insulation
The definitions of 1.2.9/RD apply.
3.7 Equipment mobility
The definitions of 1.2.3/RD apply.
3.8 Insulation classes of UPS
The definitions of 1.2.4/RD apply.
3.9 Earth fault
Occurrence of an accidental conductive path between a live conductor and the earth
[IEV 195-04-14]
3.10 Enclosures
The definitions of 1.2.6/RD apply.
3.11 Accessibility
The definitions of 1.2.7/RD apply.
3.12 Components
The definitions of 1.2.11/RD apply.

3.13 Power distribution
The definitions of 1.2.8.1/RD and 1.2.8.2/RD apply.
3.14 Flammability
The definitions of 1.2.12/RD apply.
3.15 Miscellaneous
The definitions of 1.2.13/RD (e.g. type test definition 1.2.13.1/RD) apply.
3.16 Clearances and creepage distances
The definitions of 1.2.10/RD apply.

62040-1 © IEC:2008 – 13 –
3.17 Telecommunication networks

The following definitions apply: 1.2.8.11/RD, 1.2.8.12/RD, 1.2.8.13/RD, 1.2.8.14/RD.

4 General conditions for tests

4.1 Introduction
The provisions of 1.4.1/RD, 1.4.3/RD, 1.4.6/RD, 1.4.7/RD, 1.4.8/RD, 1.4.10/RD, 1.4.11/RD,

1.4.12/RD, 1.4.13/RD, 1.4.14/RD apply together with the following.

Only the leakage current and heating tests shall be performed at input voltage tolerances (see
1.4.5/RD). All tests shall be run at nominal input voltages, unless specifically prescribed
otherwise.
4.2 Type test
The provisions of 1.4.2/RD apply together with the following addition.
Where in this standard compliance of materials, components or subassemblies is checked by
inspection or by testing of properties, it is permitted to confirm compliance by reviewing any
relevant data or previous test results that are available instead of carrying out the specified
type tests.
NOTE For physically large units and/or power ratings, adequate test facilities to demonstrate some of the type
tests may not exist.
This situation also applies to some electrical tests for which no commercial test simulation
equipment is available or requires specialized test facilities beyond the scope of the
manufacturer's premises.
4.3 Operating parameters for tests
Except where specific test conditions are stated elsewhere in the standard, and where it
is clear that there is a significant impact on the results of the test, the tests shall be carried
out at rated voltage and under the most unfavorable combination of the following parameters,
within the manufacturer's operating specifications:
– absence of supply voltage;
– supply frequency;
– charge condition of the battery;
– physical location of UPS and position of movable parts;

– operating mode.
The following does not apply to UPS installed in restricted access locations:
– adjustments of thermostats, regulating devices or similar controls in operator access
areas, which are
a) adjustable without the use of a tool, or
b) adjustable using a means, such as a key or a tool, deliberately provided for the
operator.
– 14 – 62040-1 © IEC:2008
4.4 UPS loading during tests
Where test results could reasonably be expected to vary upon UPS loading, adjustments shall

be made to provide the most unfavorable results. This is achieved by considering loading

– that could be connected to any standard supply outlet or terminal on the equipment, up to

the value indicated in the marking required by 4.7.2;

– due to recharge of the stored energy source (batteries or similar);

– due to optional features, offered or provided for by the manufacturer for inclusion in or

with the equipment under test;

– due to other units of equipment intended by the manufacturer to draw power from the
equipment under test.
NOTE 1 Artificial loads may be used to simulate such loading while testing.
NOTE 2 See also 4.6.
4.5 Components
Where safety is involved, components shall comply either with the requirements of this
standard or with the safety aspects of the relevant IEC component standards.

NOTE 1 An IEC component standard is considered relevant only if the component in question clearly falls within
its scope.
Further, the provisions of 1.5.2/RD, 1.5.3/RD, 1.5.4/RD, 1.5.5/RD, 1.5.6/RD, 1.5.7/RD and
1.5.8/RD apply.
NOTE 2 The requirements of this standard include abnormal tests to ensure safe failure mode of components;
see 8.3.
4.6 Power interfaces
The provisions of 1.6.1/RD, 1.6.2/RD, 1.6.4/RD apply together with the following.
NOTE While supplying rated output under each of the conditions described in a) to d) below, the relevant a.c. or
d.c. steady state input current should not exceed 110 % of the rated current.
a) Recharging mode – Applicable to the primary power received by the UPS while also charging the battery.
b) Stored energy mode – Applicable to the d.c. current from, for example, a remote battery while simulating
primary power outage. The inverter portion of the UPS should receive power from either a fully charged battery
bank or an external d.c. source of supply.
c) Bypass mode – The transfer switch should be positioned to allow the primary power for the output load to
bypass the rectifier/charger and inverter sections of the UPS and be delivered directly to the load.

d) Normal mode – With a fully charged battery, the UPS should receive power from the primary power source.
The neutral conductors, if any, shall be insulated from earth and the body throughout the
equipment, as if they were phase conductors. Components connected between neutral and
earth shall be rated for a working voltage equal to the phase-to-neutral voltage. In the case
of the output neutral conductor being isolated from the input neutral conductor, the service
person responsible for the installation shall connect this output neutral conductor as required
by local wiring rules and as detailed in the installation instructions.
Compliance is checked by inspection.

62040-1 © IEC:2008 – 15 –
4.7 Markings and instructions
4.7.1 General
Where a marking is required as detailed below, provision shall be allowed for equivalent

wording. The marking
...