IEC 62040-3:2011

IEC 62040-3 ®
Edition 2.0 2011-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Uninterruptible power systems (UPS) –
Part 3: Method of specifying the performance and test requirements

Alimentations sans interruption (ASI) –
Partie 3: Méthode de spécification des performances et exigences d’essais

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IEC 62040-3 ®
Edition 2.0 2011-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Uninterruptible power systems (UPS) –
Part 3: Method of specifying the performance and test requirements

Alimentations sans interruption (ASI) –
Partie 3: Méthode de spécification des performances et exigences d’essais

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XE
ICS 29.200 ISBN 978-2-88912-384-1

– 2 – 62040-3  IEC:2011
CONTENTS
FOREWORD . 6
1 Scope . 8
2 Normative references . 9
3 Terms and definitions . 10
3.1 Systems and components . 10
3.2 Performance of systems and components . 14
3.3 Specified values‒ General . 18
3.4 Input values. 22
3.5 Output values . 24
4 Environmental conditions . 26
4.1 Introduction . 26
4.2 Normal conditions . 26
4.2.1 Operation . 26
4.2.2 Storage and transportation . 27
4.3 Unusual conditions . 28
4.3.1 Introduction . 28
4.3.2 Operation . 28
4.3.3 Storage and transportation . 28
5 Electrical conditions, performance and declared values . 28
5.1 General . 28
5.1.1 UPS configuration. 28
5.1.2 Markings and instructions . 29
5.1.3 Safety . 29
5.1.4 Electromagnetic compatibility . 29
5.2 UPS input specification . 29
5.2.1 Conditions for normal mode operation . 29
5.2.2 Characteristics to be declared by the manufacturer . 30
5.2.3 Characteristics and conditions to be identified by the purchaser . 30
5.3 UPS output specification . 31
5.3.1 Conditions for the UPS to supply a load . 31
5.3.2 Characteristics to be declared by the manufacturer . 31
5.3.3 Characteristics and conditions to be identified by the purchaser . 32
5.3.4 Performance classification . 32
5.4 Stored energy specification . 37
5.4.1 General . 37
5.4.2 Battery . 37
5.5 UPS switch specification . 38
5.6 Communication circuits . 38
6 UPS tests . 39
6.1 Summary . 39
6.1.1 Venue, instrumentation and load . 39
6.1.2 Routine test . 40
6.1.3 Site test . 40
6.1.4 Witness test. 40
6.1.5 Type test . 40
6.1.6 Schedule of tests . 40

62040-3  IEC:2011 – 3 –
6.2 Routine test procedure . 42
6.2.1 Environmental . 42
6.2.2 Electrical . 42
6.3 Site test procedure . 44
6.4 Type test procedure (electrical) . 44
6.4.1 Input – a.c. supply compatibility . 44
6.4.2 Output – Linear load . 47
6.4.3 Output – Non-linear load. 52
6.4.4 Stored and restored energy . 54
6.5 Type test procedure (environmental) . 55
6.5.1 Environmental and transportation test methods . 55
6.5.2 Transportation . 55
6.5.3 Storage . 56
6.5.4 Operation . 57
6.5.5 Acoustic noise . 57
6.6 UPS functional unit tests (where not tested as a complete UPS) . 58
6.6.1 UPS rectifier tests . 58
6.6.2 UPS inverter tests . 58
6.6.3 UPS switch tests . 58
6.6.4 Stored energy / battery tests . 58
Annex A (informative) Uninterruptible power system (UPS) configurations . 59
Annex B (informative) Topologies – Uninterruptible power system (UPS) . 65
Annex C (informative) UPS switch applications . 68
Annex D (informative) Purchaser specification guidelines . 74
Annex E (normative) Reference non-linear load . 81
Annex F (informative) Information on backfeed protection . 83
Annex G (normative) Input mains failure – Test method . 84
Annex H (informative) Dynamic output performance – Measurement techniques . 85
Annex I (informative) UPS Efficiency values . 87
Annex J (normative) UPS efficiency – Methods of measurement . 96
Annex K (informative) UPS functional availability . 99
Bibliography . 102

Figure 1 – Typical “non-sinusoidal” output voltage waveform . 34
Figure 2 – Curve 1 – Dynamic output performance classification 1 . 35
Figure 3 – Curve 2 – Dynamic output performance classification 2 . 36
Figure 4 – Curve 3 – Dynamic output performance classification 3 . 36
Figure 5 – Linear load test method . 51
Figure 6 – Reference non-linear load test method . 53
Figure A.1 – Single UPS – Basic . 60
Figure A.2 – Single UPS with bypass . 60
Figure A.3 – Parallel UPS with common bypass . 61
Figure A.4 – Parallel UPS with distributed bypass . 62
Figure A.5 – Stand-by redundant UPS . 63
Figure A.6 – Dual bus UPS . 63

– 4 – 62040-3  IEC:2011
Figure A.7 – Stand-by redundant dual bus UPS . 64
Figure B.1 – Double conversion topology . 65
Figure B.2 – Line-interactive topology . 66
Figure B.3 – Stand-by topology . 67
Figure C.1 – UPS interrupter . 68
Figure C.2 – UPS interrupters in parallel UPS application . 68
Figure C.3 – UPS interrupters in split load application . 69
Figure C.4 – Bypass transfer switch . 69
Figure C.5 – Isolation of bypass transfer switch . 70
Figure C.6 – Isolation of interrupters . 70
Figure C.7 – Isolation switches with interrupter function . 71
Figure C.8 – Internal maintenance bypass switch . 71
Figure C.9 – External maintenance bypass switch . 71
Figure C.10 – Tie switch in dual bus application . 72
Figure C.11 – Tie switches in triple bus application . 72
Figure C.12 – Multiple function bypass, interrupter and isolation switch . 73
Figure E.1 – Reference non-linear load . 81
Figure G.1 – Connection of test circuit . 84
Figure H.1 – Example: instantaneous voltage variation in compliance with curve 1 of
Figure 2 . 86
Figure I.1 – Example of VFI-S stand-by allowance . 92
Figure I.2 – Example of VFI-S duty allowance . 93
Figure I.3 – Example of VFI-S stand-by and duty allowance . 94
Figure I.4 – Example of VFD duty allowance calculation . 95
Figure K.1 – Reliability % over time . 100
Figure K.2 – Maintainability % over time . 101

Table 1 – Power derating factors for use at altitudes above 1 000 m . 27
Table 2 – Compatibility levels for individual harmonic voltages in low voltage networks . 30
Table 3 – UPS test schedule . 40
Table 4 – Free fall testing . 56
Table D.1 – UPS technical data – Manufacturer’s declaration . 76
Table I.1 – Efficiency for UPS rated from 0,3 kVA to less than 10,0 kVA with
classification “VFI – S…" . 88
Table I.2 – Efficiency for UPS rated from 0,3 kVA to less than 10,0 kVA with
classification VI and VFI, except "VFI – S…” . 88
Table I.3 – Efficiency for UPS rated from 0,3 kVA to less than 10,0 kVA with
classification VFD . 89
Table I.4 – Efficiency for UPS rated from 10,0 kVA (inclusive) and above with
classification “VFI – S…" . 89
Table I.5 – Efficiency for UPS rated from 10,0 kVA (inclusive) and above with
classification VI and VFI, except "VFI – S…” . 90
Table I.6 – Efficiency for UPS rated from 10,0 kVA (inclusive) and above with
classification VFD . 90
Table I.7 – UPS efficiency allowances for input or output isolation transformer . 91

62040-3  IEC:2011 – 5 –
Table I.8 – UPS efficiency allowances for input harmonic current filtering . 91
Table K.1 – Reliability integrity levels for UPS . 99

– 6 – 62040-3  IEC:2011
INTERNATIONAL ELECTROTECHNICAL COMMISSION
_____________
UNINTERRUPTIBLE POWER SYSTEMS (UPS) –

Part 3: Method of specifying the performance and test requirements

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
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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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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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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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 62040-3 has been prepared by subcommittee 22H: Uninterruptible
power systems (UPS), of IEC technical committee 22: Power electronic systems and
equipment.
This second edition cancels and replaces first edition published in 1999 and constitutes a
technical revision. The significant technical changes are:
– reference test load – definition and application revised (3.3.5 and 6.1.1.3);
– test schedule – presented as a single table grouped by revised type and routine tests (see
6.1.6, Table 3);
– dynamic output voltage performance characteristics – guidance to measure – addition
(Annex H);
– UPS efficiency – requirements and methods of measure – addition (Annexes I and J);
– functional availability – guidance for UPS reliability integrity level classification – addition
(Annex K).
62040-3  IEC:2011 – 7 –
The text of this standard is based on the following documents:
FDIS Report on voting
22H/129/FDIS 22H/133A/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.
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 stability 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 2011 have been included in this copy.

– 8 – 62040-3  IEC:2011
UNINTERRUPTIBLE POWER SYSTEMS (UPS) –

Part 3: Method of specifying the performance and test requirements

1 Scope
This International Standard applies to movable, stationary and fixed electronic
uninterruptible power systems (UPS) that deliver single or three-phase fixed frequency a.c.
output voltage not exceeding 1 000 V a.c. and that incorporate an energy storage system,
generally connected through a d.c. link.
This standard is intended to specify performance and test requirements of a complete UPS
and not of individual UPS functional units. The individual UPS functional units are dealt with
in IEC publications referred to in the bibliography that apply so far that they are not in
contradiction with this standard.
The primary function of the UPS covered by this standard is to ensure continuity of an a.c.
power source. The UPS may also serve to improve the quality of the power source by keeping
it within specified characteristics. UPS have been developed over a wide range of power, from
less than hundred watts to several megawatts, to meet requirements for availability and
quality of power to a variety of loads. Refer to Annexes A and B for information on typical
UPS configurations and topologies.
This standard also covers UPS test and performance when power switches form integral part
of a UPS and are associated with its output. Included are interrupters, bypass switches,
isolating switches, and tie switches. These switches interact with other functional units of the
UPS to maintain continuity of load power.
This standard does not cover
– conventional a.c. input and output distribution boards or d.c. boards and their
associated switches (e.g. switches for batteries, rectifier output or inverter input);
– stand-alone static transfer systems covered by IEC 62310-3;
– systems wherein the output voltage is derived from a rotating machine.
NOTE 1 This standard recognises that power availability to information technology (IT) equipment represents a
major UPS application. The UPS output characteristics specified in this standard are therefore also aimed at
ensuring compatibility with the requirements of IT equipment. This, subject any limitation stated in the
manufacturer’s declaration, includes requirements for steady state and transient voltage variation as well as for the
supply of both linear and non-linear load characteristics of IT equipment.
NOTE 2 Test loads specified in this standard simulate both linear and non-linear load characteristics. Their use is
prescribed with the objective of verifying design and performance, as declared by the manufacturer, and also of
minimising any complexity and energy consumption during the tests.
NOTE 3 This standard is aimed at 50 Hz and 60 Hz applications but does not exclude other frequency
applications within the domain of IEC 60196. This is subject to an agreement between manufacturer and purchase
in respect to any particular requirements arising.
NOTE 4 Single phase and three-phase voltage UPS covered by this standard include without limitation UPS
supplying single-phase, two-wire; single-phase, three-wire; two-phase, three-wire, three-phase, three-wire and
three-phase, four-wire loads.
62040-3  IEC:2011 – 9 –
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 60038, IEC standard voltages
IEC 60068-2-1, Environmental testing - Part 2-1: Tests – Test A: Cold
IEC 60068-2-2, Environmental testing – Part 2-2: Tests – Test B: Dry heat
IEC 60068-2-27, Environmental testing – Part 2-27: Tests – Test Ea and guidance: Shock
IEC 60068-2-31:2008, Environmental testing – Part 2-31: Tests – Test Ec: Rough handling
shocks, primarily for equipment-type specimens
IEC 60068-2-78, Environmental testing – Part 2-78: Tests – Test Cab: Damp heat, steady
state
IEC 60146-1-1:2009, Semiconductor converters – General requirements and line commutated
converters – Part 1-1: Specification of basic requirements
IEC 60146-2:1999, Semiconductor converters – Part 2: Self-commutated semiconductor
converters including direct d.c. converters
IEC 60196, IEC standard frequencies
IEC 60364-1, Low-voltage electrical installations – Part 1: Fundamental principles,
assessment of general characteristics, definitions
IEC 60364-5-52, Low-voltage electrical installations – Part 5-52: Selection and erection of
electrical equipment – Wiring systems
IEC 60947-3, Low-voltage switchgear and controlgear – Part 3: Switches, disconnectors,
switch-disconnectors and fuse-combination units
IEC 60947-6-1, Low-voltage switchgear and controlgear – Part 6-1: Multiple function
equipment – Transfer switching equipment
IEC 60950-1, Information technology equipment – Safety – Part 1: General requirements
IEC 60990, Methods of measurement of touch current and protective conductor current
IEC 61000-2-2:2002, Electromagnetic compatibility (EMC) – Part 2-2: Environment –
Compatibility levels for low-frequency conducted disturbances and signalling in public low-
voltage power supply systems
IEC 61000-3-2, Electromagnetic compatibility (EMC) – Part 3-2: Limits – Limits for harmonic
current emissions (equipment input current ≤ 16 A per phase)
IEC/TS 61000-3-4, Electromagnetic compatibility (EMC) – Part 3-4: Limits – Limitation of
emission of harmonic currents in low-voltage power supply systems for equipment with rated
current greater than 16 A
– 10 – 62040-3  IEC:2011
IEC 61000-3-12, Electromagnetic compatibility (EMC) – Part 3-12: Limits – Limits for
harmonic currents produced by equipment connected to public low-voltage systems with input
current > 16 A and ≤ 75 A per phase
IEC 61000-4-30, Electromagnetic compatibility (EMC) – Part 4-30: Testing and measurement
techniques – Power quality measurement methods
IEC 61672-1, Electroacoustics ‒ Sound level meters – Part 2: Pattern evaluation tests
IEC 62040-1:2008, Uninterruptible power systems (UPS) – Part 1: General and safety
requirements for UPS
IEC 62040-2, Uninterruptible power systems (UPS) – Part 2: Electromagnetic compatibility
(EMC) requirements
IEC 62310-3:2008, Static transfer systems (STS) – Part 3: Method for specifying performance
and test requirements
ISO 7779:2010, Acoustics – Measurement of airborne noise emitted by information technology
and telecommunications equipment
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
NOTE In this standard, IEC 60050 definitions are referenced wherever possible, particularly those of
IEC 60050(551).
When an existing IEC 60050 definition needs amplification or additional information, this is indicated by adding the
word “modified” after the IEC 60050 reference.
3.1 Systems and components
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 Input power failure occurs when voltage and frequency are outside rated steady-state and transient
tolerance bands or when distortion or interruptions are outside the limits specified for the UPS.
3.1.2
(electronic) (power) converter or convertor
an operative unit for electronic power conversion, comprising one or more electronic valve
devices, transformers and filters if necessary and auxiliaries if any
NOTE In English, the two spellings "converter" and "convertor" are in use, and both are correct.
[IEC 60050-551:1998, 551-12-01]
3.1.3
UPS functional unit
functional unit, for example, a UPS rectifier, a UPS inverter or a UPS switch

62040-3  IEC:2011 – 11 –
3.1.4
UPS rectifier
electronic converter for rectification
[IEC 60050-551:1998, 551-12-07, modified]
3.1.5
UPS inverter
electronic converter for inversion
[IEC 60050-551:1998, 551-12-10, modified]
3.1.6
energy storage system
system consisting of single or multiple devices and designed to provide power to the UPS
inverter for the required stored energy time
NOTE Notwithstanding challenges with respect to recharge, examples of energy storage systems include but are
not limited to battery, double-layer capacitor (“super” or “ultra” capacitor), flywheel and fuel-cell systems.
3.1.7
d.c. link
direct current power interconnection between the rectifier or rectifier/charger and the inverter
functional unit
NOTE 1 The voltage of the energy storage system may differ from that of the d.c. link.
NOTE 2 The d.c. link may include converters.
3.1.8
battery
set of electrochemical cells of the same type so connected as to act together
[IEC 60050-151:2001, 151-12-11, modified]
3.1.9
secondary battery (of electrochemical cells)
composite system in which electric energy produces chemical reactions or, conversely, in
which the energy produced by chemical reactions is mainly delivered as electric energy
[IEC 60050-111:1996, 111-15-10]
NOTE 1 A valve regulated secondary battery consists of cells which are closed but have a valve which allows the
escape of gas if the internal pressure exceeds a predetermined value. Valve regulated lead-acid cells are
abbreviated as VRLA cells [IEC 60050-482:2004, 482-05-15, modified].
NOTE 2 A vented secondary battery consists of cells having a cover provided with an opening through which
products of electrolysis and evaporation are allowed to escape freely, or through a venting system, from the cell to
the atmosphere [IEC 60050-482:2004, 482-05-14, modified].
3.1.10
flywheel storage system
mechanical energy storage system wherein stored kinetic energy can be converted to d.c.
power during stored energy mode of operation
3.1.11
battery charger
device for changing alternating current power to direct current power for the purpose of
charging a battery
– 12 – 62040-3  IEC:2011
3.1.12
UPS switch
controllable switch used in accordance with applicable requirements for load power continuity
to interconnect or isolate power ports of UPS units, bypass or load
NOTE 1 Annex C details UPS switch applications.
NOTE 2 Examples of ports include a group of terminals and sockets.
3.1.13
transfer switch
UPS switch used to transfer power from one source to another
NOTE Transfer represents the act of switching the supply path to the load from one source to another.
3.1.14
electronic (power) switch
UPS switch comprising at least one controllable valve device
[IEC 60050-551:1998, 551-13-01, modified]
NOTE A static bypass switch is an example of an electronic (power) switch.
3.1.15
mechanical (power) switch
UPS switch with mechanically separable contacts
3.1.16
hybrid (power) switch
UPS switch with mechanically separable contacts in combination with at least one controlled
electronic valve device
3.1.17
self-commutated electronic switch
electronic switch where the commutating voltage is supplied by components within the
electronic switch
3.1.18
line-commutated electronic switch
electronic switch where the commutating voltage is supplied by the line
3.1.19
interrupter
UPS switch which is capable of making, carrying and breaking currents under normal circuit
conditions, making and carrying currents for a specified time and breaking currents under
specified unusual circuit conditions
3.1.20
isolation switch
mechanical UPS switch that provides in the open position an isolating distance and that may
be capable of making, carrying and breaking currents in accordance with UPS operational
requirements
NOTE Resettable circuit-breakers and manual disconnectors are examples of isolation switches.
3.1.21
tie switch
UPS switch which can connect two or more a.c. busbars together

62040-3  IEC:2011 – 13 –
3.1.22
maintenance bypass switch
UPS switch designed to isolate a UPS, or part thereof, from the load and to maintain
continuity of load power via an alternative path during maintenance activities
3.1.23
a.c. input power
primary or stand-by power supplied to UPS and bypass circuits (maintenance bypass
included)
3.1.24
bypass
power path alternative to the a.c. converter
3.1.25
maintenance bypass (path)
alternative power path provided to maintain continuity of load power during maintenance
activities
3.1.26
static bypass (electronic bypass)
power path (primary or stand-by) alternative to the indirect a.c. converter where control is via
an electronic power switch, for example transistors, thyristors, triacs or other semiconductor
device or devices
3.1.27
UPS unit
complete UPS consisting of at least one of each of the following functional units: UPS
inverter, UPS rectifier and battery or other energy storage means
NOTE A UPS unit may operate with other UPS units to form a parallel or redundant UPS.
3.1.28
single UPS
UPS comprising only one UPS unit
3.1.29
parallel UPS
UPS comprising two or more UPS units operating in parallel
3.1.30
redundant system
addition of functional units or groups of functional units in a system to enhance the continuity
of load power
3.1.31
stand-by redundant UPS
UPS in which one or more UPS are held in reserve until the operating UPS unit fails
3.1.32
parallel redundant UPS
UPS with a number of paralleled load sharing UPS units which, upon failure of one or more
UPS units, can take over full load with the remainders

– 14 – 62040-3  IEC:2011
3.2 Performance of systems and components
3.2.1
primary power
external electrical power source usually the public mains supply or other equivalent source
such as user’s own generation
3.2.2
stand-by power
external electrical power source intended to replace primary power in the event of primary
power failure
3.2.3
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
while a.c. input power is not available
3.2.4
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 constant load impedance
NOTE Application of a linear load to a sinusoidal voltage results in a sinusoidal current.
3.2.5
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
3.2.6
power failure
any variation in power supply which can cause unacceptable performance of the load
equipment
3.2.7
continuity of load power
voltage and frequency within rated steady-state and transient tolerance bands and with
distortion and power interruptions within the limits specified for the load
3.2.8
battery ripple current
superimposed effective (r.m.s.) alternating component of the battery current
3.2.9
normal mode of UPS operation
stable mode of operation that the UPS attains under the following conditions:
a) a.c. input supply is within required tolerances and supplies the UPS;
b) the energy storage system remains charged or is under recharge;

62040-3  IEC:2011 – 15 –
c) the load is within the specified rating of the UPS;
d) the bypass is available and within specified tolerances (if applicable)
3.2.10
stored energy mode of UPS operation
stable mode of operation that the UPS attains under the following conditions:
a) a.c. input power is disconnected or is out of required tolerance;
b) all power is derived from the energy storage system;
c) the load is within the specified rating of the UPS
3.2.11
bypass mode of UPS operation
mode of operation that the UPS attains when the load is supplied via the bypass only
3.2.12
UPS double conversion
any UPS operation, where continuity of load power is maintained by a UPS inverter, with
energy supplied from the d.c. link in normal mode of operation or from the energy storage
system in stored energy mode of operation
NOTE 1 The output voltage and frequency are independent of input voltage and frequency conditions.
NOTE 2 See Clause B.2.
3.2.13
UPS double conversion with bypass
UPS double conversion with the addition of an alternative bypass path for load supply
3.2.14
UPS line interactive operation
any UPS operation where, in normal mode of operation, the load is supplied with conditioned
a.c. input power at the input supply frequency and where, in stored energy mode of operation,
the load is supplied from the output of an inverter
NOTE See Clause B.3.
3.2.15
UPS line interactive operation with bypass
UPS line interactive with the addition of an alternative bypass path for load supply.
3.2.16
UPS passive stand-by operation
any UPS operation where the normal mode of operation consists of supplying the load from
the primary power source, except when the latter is outside stated limits in which case the
load is supplied from the UPS inverter operating in
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