EN 62310-1:2005

SLOVENSKI SIST EN 62310-1:2006

STANDARD
marec 2006
Sistemi s statičnim prenosom (STS) – 1. del: Splošne in varnostne zahteve
(IEC 62310-1:2005)
Static transfer systems (STS) - Part 1: General and safety requirements (IEC
62310-1:2005)
ICS 29.240.99 Referenčna številka
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

EUROPEAN STANDARD EN 62310-1
NORME EUROPÉENNE
EUROPÄISCHE NORM April 2005
ICS 29.240.99
English version
Static transfer systems (STS)
Part 1: General and safety requirements
(IEC 62310-1:2005)
Systèmes de transfert statique (STS) Statische Transferschalter (STS)
Partie 1: Exigences générales et règles Teil 1: Allgemeine und
de sécurité Sicherheitsanforderungen
(CEI 62310-1:2005) (IEC 62310-1:2005)

This European Standard was approved by CENELEC on 2005-03-01. 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 Central Secretariat 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 Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden,
Switzerland and United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2005 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 62310-1:2005 E
Foreword
The text of document 22H/66/FDIS, future edition 1 of IEC 62310-1, prepared by SC 22H,
Uninterruptible power systems (UPS), of IEC TC 22, Power electronic systems and equipment, was
submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 62310-1 on
2005-03-01.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2005-12-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2008-03-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 62310-1:2005 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 60947-6-1 NOTE Harmonized as EN 60947-6-1:1991 (not modified).
IEC 61032 NOTE Harmonized as EN 61032:1998 (not modified).
IEC 61140 NOTE Harmonized as EN 61140:2002 (not modified).
IEC 62040 NOTE Harmonized in EN 62040 series (modified).
IEC 62040-1-1 NOTE Harmonized as EN 62040-1-1:2003 (not modified).
IEC 62040-1-2 NOTE Harmonized as EN 62040-1-2:2003 (not modified).
IEC 62040-3 NOTE Harmonized as EN 62040-3:2001 (modified).
__________
- 3 - EN 62310-1:2005
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
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.
NOTE Where an international publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
Publication Year Title EN/HD Year
IEC 60060-1 1989 High-voltage test techniques HD 588.1 S1 1991
+ corr. March 1990 Part 1: General definitions and test
requirements
1) 2)
IEC 60073 - Basic and safety principles for man- EN 60073 2002
machine interface, marking and
identification - Coding principles for
indicators and actuators
1)
IEC/TR 60083 - Plugs and socket-outlets for domestic - -
and similar general use standardized in
member countries of IEC
1) 2)
IEC 60085 - Electrical insulation - Thermal EN 60085 2004
classification
1) 2)
IEC 60112 - Method for the determination of the EN 60112 2003
proof and the comparative tracking
indices of solid insulating materials

1)
IEC 60364-5-54 - Electrical installations of buildings - -
Part 5-54: Selection and erection of
electrical equipment - Earthing
arrangements, protective conductors
and protective bonding conductors

1)
IEC 60364-7-707 - Part 7: Requirements for special - -
installations or locations -- Section 707:
Earthing requirements for the
installations of data processing
equipment
database
IEC 60417 Graphical symbols for use on - -
equipment
IEC 60529 1989 Degrees of protection provided by EN 60529 1991
enclosures (IP Code) + corr. May 1993

1)
Undated reference.
2)
Valid edition at date of issue.

Publication Year Title EN/HD Year
IEC 60664-1 1992 Insulation coordination for equipment
+ A1 2000 within low-voltage systems
+ A2 2002 Part 1: Principles, requirements and EN 60664-1 2003
tests
IEC 60664-3 2003 Part 3: Use of coating, potting or EN 60664-3 2003
moulding for protection against pollution

IEC 60730-1 1999 Automatic electrical controls for EN 60730-1 2000
(mod) household and similar use A11 2002
Part 1: General requirements A12 2003
A1 (mod) 2003 A1 2004
A13 2004
A14 2005
1)
IEC/TR 60755 - General requirements for residual - -
current operated protective devices

IEC 60950-1 2001 Information technology equipment - EN 60950-1 2001
(mod) Safety
Part 1: General requirements
1) 2)
IEC 61008-1 - Residual current operated circuit- EN 61008-1 2004
(mod) breakers without integral overcurrent
protection for household and similar
uses (RCCB's)
Part 1: General rules
1) 2)
IEC 61009-1 - Residual current operated circuit- EN 61009-1 2004
(mod) breakers with integral overcurrent
protection for household and similar
uses (RCBO's)
Part 1: General rules
IEC 62103 2003 Electronic equipment for use in power - -
installations
3)
IEC 62310-2 - Static Transfer Systems (STS) - -
Part 2: Electromagnetic Compatibility
(EMC) requirements
ISO 3864-1 2002 Graphical symbols - Safety colours and - -
safety signs
Part 1: Design principles for safety
signs in workplaces and public areas

ISO 7000 2004 Graphical symbols for use on - -
equipment - Index and synopsis

3)
To be published.
NORME CEI
INTERNATIONALE IEC
62310-1
INTERNATIONAL
Première édition
STANDARD
First edition
2005-03
Systèmes de transfert statique (STS) –
Partie 1:
Exigences générales et règles de sécurité

Static transfer systems (STS) –
Part 1:
General and safety requirements
 IEC 2005 Droits de reproduction réservés  Copyright - all rights reserved
Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in any
utilisée sous quelque forme que ce soit et par aucun procédé, form or by any means, electronic or mechanical, including
électronique ou mécanique, y compris la photocopie et les photocopying and microfilm, without permission in writing from
microfilms, sans l'accord écrit de l'éditeur. the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch Web: www.iec.ch
CODE PRIX
Commission Electrotechnique Internationale PRICE CODE XA
International Electrotechnical Commission
Международная Электротехническая Комиссия
Pour prix, voir catalogue en vigueur
For price, see current catalogue

62310-1  IEC:2005 – 3 –
CONTENTS
FOREWORD.7

1 Scope .11
2 Normative references .13
3 Terms and definitions .15
3.1 General definitions .15
3.2 Specified values .25
3.3 Input values.31
4 Safety requirements .33
4.1 Marking and instructions .33
4.2 Fundamental design requirements .45
4.3 Physical requirements .99
4.4 Thermal requirements, fire protection and fire risks .105
5 Electrical requirements and simulated abnormal conditions .109
5.1 General .109
5.2 Electric strength .111
5.3 Abnormal operating and fault conditions.111

Annex A (normative) Method of calculating the cross-sectional area of protective
conductors with regard to thermal stresses due to currents of short duration (more
detailed information is to be found in IEC 60364-5-54).115
Annex B (normative) Minimum and maximum cross-sections of copper conductors
suitable for connection.117

Bibliography .119

Figure 1 – Test finger (see IEC 60529).47
Figure 2 – Test pin.49
Figure 3 – Test probe.49
Figure 4 – Determination of insulation within a circuit .69
Figure 5 – Determination of insulation between live parts and accessible – surfaces .71
Figure 6 – Determination of insulation a) between circuits and the environment, and b)
between circuits .73
Figure 7 – Determination of functional insulation .75
Figure 8 – Determination of basic insulation .77
Figure 9 – Determination of double or reinforced insulation.79

Table 1 – Distance through insulation of internal wiring .51
Table 2 – Cross-sectional area of protective conductors (PE, PEN).61
Table 3 – Definitions of pollution degrees .81
Table 4 – Clearances between primary circuits and their environment (impulse
withstand voltages according to overvoltage category III).85

62310-1  IEC:2005 – 5 –
b)
Table 5 – Clearances between secondary circuits and their environment (impulse
withstand voltages according to overvoltage category II).87
Table 6 –Clearances within a circuit (impulse withstand voltage according to
overvoltage category I) .89
Table 7 – Minimum creepage distances.93
Table 8 – Limits for inherently limited power sources .95
Table 9 – Limits for power sources not inherently limited (overcurrent protective device
required) .97
Table 10 – Temperature rise limits: Part 1 .107
Table 11 – Temperature rise limits: Part 2 .109
Table A.1 – Values of k for insulated protective conductors not incorporated in cables,
or bare protective conductors in contact with cable covering .115
Table B.1 − Minimum and maximum cross-sections of copper conductors suitable for
connection.117

62310-1  IEC:2005 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
STATIC TRANSFER SYSTEMS (STS) –

Part 1: General and safety 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
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 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 62310-1 has been prepared by subcommittee 22H: Uninterruptible
Power Systems (UPS), of IEC technical committee 22: Power electronic systems and
equipment.
The text of this standard is based on the following documents:
FDIS Report on voting
22H/66/FDIS 22H/67/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.
The French version of this standard has not been voted upon.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

62310-1  IEC:2005 – 9 –
IEC 62310 consists of the following parts, under the general title Static transfer systems
(STS):
Part 1: General and safety requirements
Part 2: Electromagnetic Compatibility (EMC) requirements

Part 3: Method of specifying the performance and test requirements
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.
___________
To be published.
Under consideration.
62310-1  IEC:2005 – 11 –
STATIC TRANSFER SYSTEMS (STS) –

Part 1: General and safety requirements

1 Scope
IEC 62310 consists of three parts and applies to free standing a.c. static transfer systems
(STS) intended to ensure the continuity of power to load by automatically or manually
controlled transfer, with or without interruption, from two or several a.c. independent sources.
This part of IEC 62310 concerns general and safety requirements. See future IEC 62310-2 for
electromagnetic compatibility (EMC) and futureIEC 62310-3 for the method of specifying
performance and test requirements.
This part of IEC 62310 is intended to reduce the risk of fire, electric shock, or injury to
persons from installed equipment subject to installing, operating, and maintaining the
equipment in the manner prescribed by the manufacturer.
This part of IEC 62310 includes requirements for the switching elements, their control and
protective elements, where applicable. This part of IEC 62310 also includes information for
the overall integration of the STS and its accessories into the a.c. power distribution system.
Components or devices necessary for the operation/control/protection/isolation (e.g. circuit-
breakers, fuses, transformers, etc.) of a STS should comply with the requirements of the
relevant IEC standards and are not covered by this part of IEC 62310.
This standard applies to systems up to 1 000 V (a.c. value) which are intended to be used in
single phase or phase-phase or three phase applications.
This standard does not apply to:
− devices for d.c. source switching;
− static transfer system using only electromechanical switching devices intended to be used
in emergency power systems with interruption of the supply to the load during transfer.
This equipment is covered by IEC 60947-6-1;
− the automatic switching devices integrated into UPS covered by IEC 62040 series.
NOTE For STS intended to be used in vehicles, onboard ships or aircraft, in tropical countries, for emergency
power systems (such as those used for health care facilities, fire fighting, emergency rescue, etc.), or on elevations
greater than 1 000 m, different requirements may be necessary.

62310-1  IEC:2005 – 13 –
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 60060-1:1989, High-voltage test techniques – Part 1: General definitions and test
requirements
IEC 60073, Basic and safety principles for man-machine interface, marking and identification
– Coding principles for indicators and actuators
IEC 60083, Plugs and socket-outlets for domestic and similar general use, standardised in
member countries of IEC
IEC 60085, Electrical insulation – Thermal classification
IEC 60112, Method for the determination of the proof and the comparative tracking indices of
solid insulating materials
IEC 60364-5-54, Electrical installations of buildings – Part 5-54: Selection and erection of
electrical equipment – Earthing arrangements, protective conductors and protective bonding
conductors
IEC 60364-7-707, Electrical installations of building – Part 7: Requirements for special
installations or locations – Section 707: Earthing requirements for the installation of data
processing equipment
IEC 60417-DB:2002 , Graphical symbols for use on equipment
IEC 60529, Degrees of protection provided by enclosures (IP Code)
IEC 60664-1:1992, Insulation co-ordination for equipment within low-voltage systems – Part 1:
Principles, requirements and tests
Amendment 1 (2000)
Amendment 2 (2002)
IEC 60664-3:2003, Insulation coordination for equipment within low-voltage systems – Part 3:
Use of coating, potting or moulding for protection against pollution
IEC 60730-1:1999, Automatic electrical controls for household and similar use – Part 1:
General requirements
Amendment 1 (2003)
IEC 60755, General requirements for residual current operated protective devices

___________
“DB” refers to the IEC on-line database.
A consolidated edition 1.2 exists including IEC 60664-1:1992 and its Amendments 1 (2000) and 2 (2002).
A consolidated edition 3.1 exists including IEC 60730-1:1999 and its Amendment 1 (2003).

62310-1  IEC:2005 – 15 –
IEC 60950-1:2001, Information technology equipment – Safety – Part 1: General requirements
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 without integral overcurrent
protection for household and similar uses (RCBOs) – Part 1: General rules
IEC 62103:2003, Electronic equipment for use in power installations
IEC 62310-2, ___ Static transfer systems (STS) – Part 2: Electromagnetic Compatibility
(EMC) requirements
ISO 3864-1:2002, Graphical symbols – Safety colours and safety signs – Part 1: Design
principles for safety signs in workplaces and public areas
ISO 7000:2004, Graphical symbols for use on equipment – Index and synopsis
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 General definitions
3.1.1
transfer switch
switching equipment consisting of one or more switches used to transfer power from one
source to another
3.1.2
static transfer system
STS
system that transfers a load, by static means, between a preferred source and an alternate
source
NOTE 1 The transfer may be automatic and/or manual.
NOTE 2 The transfer may be with or without interruption.
3.1.3
electronic (power) switch
operative unit for electronic power switching comprising at least one controllable valve device
[IEV 551-13-01]
3.1.4
line commutated electronic switch
electronic switch where the commutating voltage is supplied by the line
___________
To be published.
62310-1  IEC:2005 – 17 –
3.1.5
maintenance by-pass
power path designed to allow isolation of an appropriate section or sections of a STS for
safety during maintenance and/or to maintain continuity of load power
3.1.6
redundant system
addition of functional units or groups of functional units in a system to enhance the continuity
of power to the load
3.1.7
STS input power
power supplied to STS and bypass, if any, which can be either the preferred source or the
alternate source
3.1.8
alternate source
source used as alternate power supply of the load when the preferred source fails or is out of
tolerance or is switched off for maintenance
3.1.9
preferred source
source used as normal power supply to the load, usually set by the operator
3.1.10
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.
3.1.11
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
3.1.12
power failure
any variation in power source deemed to cause unacceptable performance of the load
equipment
3.1.13
normal mode of STS operation
when the load is supplied by the preferred source or the alternate source via the electronic
(power) switches
3.1.14
by-pass mode
when the load is supplied via the maintenance by-pass isolation switch

62310-1  IEC:2005 – 19 –
3.1.15
manual control
control of an operation by human intervention
[IEV 441-16-04]
3.1.16
manual transfer
transfer operation initiated by human intervention
3.1.17
automatic control
control of an operation without human intervention, in response to the occurrence of
predetermined conditions
[IEV 441-16-05]
3.1.18
automatic transfer
transfer initiated without human intervention, in response to the occurrence of predetermined
conditions
3.1.19
STS synchronous transfer
transfer of load power between two sources which are synchronised within specified limits of
frequency, voltage phase and magnitude
3.1.20
STS asynchronous transfer
transfer of load power between two sources which are not synchronised within specified limits
3.1.21
operator access area
area to which, under normal operating conditions, one of the following applies:
– access can be gained without the use of a tool, or
– the means of access is deliberately provided to the operator, or
– the OPERATOR is instructed to enter regardless of whether or not a tool is needed to gain
access
NOTE The terms "access" and "accessible", unless qualified, relate to operator access area as defined above.
3.1.22
service access area
area, other than an operator access area, where it is necessary for service personnel to have
access even with the equipment switched on
3.1.23
restricted access location
location for equipment where both of the following paragraphs apply:
– access can only be gained by service personnel or by users who have been instructed
about the reasons for the restrictions applied to the location and about any precautions
that shall be taken; and
62310-1  IEC:2005 – 21 –
– access is through the use of a tool or lock and key, or other means of security, and is
controlled by the authority responsible for the location
NOTE The requirements for equipment intended for installation in restricted access locations are the same as for
operator access areas, except as given in 1.7.17, 2.1.3 and 4.5.1 of IEC 60950-1.
3.1.24
STS primary circuit
internal circuit which is directly connected to the external supply source which supplies the
electric power to the load, including the primary windings of transformers, motors, other
loading devices and the means of connection to the supply source
3.1.25
STS secondary circuit
circuit which has no direct connection to STS primary circuit
3.1.26
decisive voltage
voltage, taking into account non-sinusoidal waveforms (see 5.2.13 of IEC 62103), defining the
borderlines to be used between extra-low-voltage, low voltage and high voltage
NOTE These borderlines are used to determine the requirements of protective earthing when designing
clearances and creepage distances for the arrangement of protective measures.
3.1.27
hazardous voltage
voltage exceeding 42,4 V (peak value), or 60 V (d.c. value), existing in a circuit which does
not meet the requirements of either:
− a limited current circuit, or
− a TNV circuit that is in compliance with the requirements of 3.1.31
3.1.28
extra-low voltage
ELV
secondary circuit with voltages between conductors, and between any conductor and earth,
not exceeding 42,4 V (peak value), or 60 V (d.c. value) under normal operating conditions,
which is separated from hazardous voltage by at least basic insulation, and which meets
neither all of the requirements for an SELV circuit nor all of the requirements for a limited
current circuit
3.1.29
SELV-system (safety extra-low voltage)
electrical system
− in which the voltage cannot exceed ELV, and
− with protective separation from systems other than SELV, and
− with no provision for earthing the SELV-system, or its exposed conductive parts, and
− with simple separation from earth
NOTE Under normal conditions this limit is either 42,4 V (peak value), or 60 V (d.c. value).

62310-1  IEC:2005 – 23 –
3.1.30
SELV circuit
secondary circuit which is so designed and protected that under normal operating conditions
and single fault conditions, its voltages do not exceed a safe value
NOTE 1 The limit values of voltages under normal operating conditions and single fault conditions (see
IEC 60950-1, 1.4.14) are specified in 2.2 of IEC 60950-1. See also Table 1A of IEC 60950-1.
NOTE 2 This definition of an SELV circuit differs from the term “SELV system” as used in IEC 61140.
3.1.31
TNV circuit
circuit which is in the equipment and to which the accessible area of contact is limited and
that is so designed and protected that, under normal operating conditions and single fault
conditions, the voltages do not exceed specified limit values
NOTE TNV circuits are classified as TNV-1, TNV-2 and TNV-3 circuits as defined in 3.1.32, 3.1.33 and 3.1.34.
3.1.32
TNV-1 circuit
TNV circuit
– whose normal operating voltages do not exceed the limits for an SELV circuit under
normal operating conditions, and
– on which overvoltages from telecommunication networks are possible
3.1.33
TNV-2 circuit
TNV circuit
– whose normal operating voltages exceed the limits for an SELV circuit under normal
operating conditions, and
– which is not subject to overvoltages from telecommunication networks
3.1.34
TNV-3 circuit
TNV circuit
– whose normal operating voltages exceed the limits for an SELV circuit under normal
operating conditions, and
– on which overvoltages from telecommunication networks are possible
3.1.35
safety interlock
means either of preventing access to a hazardous area until the hazard is removed, or of
automatically removing the hazardous condition when access is gained
3.1.36
make-time
interval of time between the initiation of the closing operation and the instant when the current
begins to flow in the main circuit
[IEV 441-17-40]
NOTE In the case of an electronic switch, the initiation is the instant when a control signal is applied to the
control terminal of the switch.

62310-1  IEC:2005 – 25 –
3.1.37
break-time
interval of time between the initiation of the opening operation of a STS switch and the end of
current flow in the circuit considered
[IEV 441-17-39, modified]
NOTE In the case of an electronic switch, the initiation is the instant when a control signal is applied to the
control terminal of the switch.
3.1.38
interruption time
time interval during which the output voltage is below the lower limit of the tolerance band
3.1.39
transfer time
time interval between initiation of transfer and the instant when the output quantities have
been transferred
3.1.40
total STS transfer time
time interval between the occurrence of an abnormality or out-of tolerance condition and the
instant when the output quantities have been transferred
3.1.41
return transfer time (for performance part)
the time from the instant when the preferred source is fully restored to the instant when the
set of semiconductor switches is closed on the preferred source
3.1.42
emergency power systems
those power systems that are classed by legal authorities as having jurisdiction as essential
power systems, that when interrupted could create hazard to life, hamper rescue or fire-
fighting operations, or jeopardise any such emergency operations
3.1.43
optional standby power systems
those power systems where life safety does not depend on the performance of the power
system, however, power interruption could cause discomfort, interruption of data processing
or communication, serious malfunction/interruption of industrial processes, damage to the
product or the like
3.2 Specified values
3.2.1
rating
set of rated values and operating conditions of a machine or a device or equipment
[IEV 151-16-11, modified]
3.2.2
rated value
quantity value assigned, generally by a manufacturer, for a specified operating condition of a
component, device or equipment
[IEV 151-16-08, modified]
62310-1  IEC:2005 – 27 –
3.2.3
nominal value
suitable approximate quantity value used to designate or identify a component, device or
equipment
[IEV 151-16-09, modified]
3.2.4
limiting value
in a specification, greatest or smallest admissible value of one of the quantities
[IEV 151-16-10, modified]
3.2.5
tolerance band
range of values of a quantity within specified limits
3.2.6
deviation
difference between the desired value and the actual value of a variable at a given instant
[IEV 351-12-15]
3.2.7
rated voltage
input or output voltage (for three-phase supply, the phase-to-phase voltage) as declared by
the manufacturer
3.2.8
rated voltage range
input or output voltage range as declared by the manufacturer expressed by its lower and
upper rated voltages
3.2.9
r.m.s voltage variation
difference between the r.m.s voltage and the corresponding previously undisturbed r.m.s
voltage
NOTE For the purposes of this part of IEC 62310, the term "variation" has the following meaning: the difference of
the value of a quantity before and after a change of an influence quantity.
3.2.10
voltage time integral variation
difference between the voltage time integral over one half-cycle and the corresponding values
of the previously undisturbed waveform
3.2.11
peak voltage variation
difference between the peak voltage and the corresponding value of the previously
undisturbed waveform
3.2.12
phase angle
angle (usually expressed in electrical degrees or radians) between reference points on one or
more a.c. waveforms
3.2.13
rated current
input or output current of the equipment as declared by the manufacturer

62310-1  IEC:2005 – 29 –
3.2.14
active power
P
sum of the electrical power at the fundamental frequency and the powers of each harmonic
component
[IEV 131-11-42, modified]
3.2.15
power factor
λ
ratio of the active power to the apparent power
[IEV 131-11-46, modified]
P
λ =
S
3.2.16
apparent power
S
product of the r.m.s values of voltage and current at a port
[IEV 131-11-41, modified]
S=UI
3.2.17
displacement factor
displacement component of the power factor; ratio of the active power of the fundamental
wave to the apparent power of the fundamental wave
3.2.18
STS efficiency
ratio of output active power to input active power under specified conditions
3.2.19
rated frequency
operating frequency as declared by the manufacturer
3.2.20
rated frequency range
input or output frequency range as declared by the manufacturer, expressed by its lower and
upper rated frequencies
3.2.21
frequency variation (performance part)
variation of the input or output frequency
3.2.22
form factor
ratio of r.m.s. value to the average value of a periodic quantity rectified
[IEV 101-14-56, modified]
62310-1  IEC:2005 – 31 –
3.2.23
peak factor
ratio of its peak value to the r.m.s. value of a periodic quantity
NOTE The term «crest factor» has the same meaning.
3.2.24
transient
behaviour of a variable during transition between two steady states
[IEV 351-14-04]
3.2.25
ambient temperature
average temperature of air or other medium in the vicinity of the equipment

NOTE During the measurement of the ambient temperature, the measuring instrument/probe should be shielded
from draughts and radiant heating.
[IEV 826-10-03]
3.2.26
operating temperature
temperature at which an STS operates
NOTE The maximum ambient temperature of the air or other medium for operation of the STS is 40 °C unless
otherwise specified by manufacturer.
3.3 Input values
3.3.1
input voltage tolerance
maximum variation of steady-state input voltage acceptable by the STS
3.3.2
input voltage distortion
input voltage harmonic distortion acceptable by the STS
3.3.3
input frequency tolerance
maximum variation of steady-state input frequency acceptable by the STS
3.3.4
source impedance
power source impedance at the input terminals to the STS with the STS disconnected
3.3.5
low impedance source failure
failure where the source impedance is negligible (for example upstream short circuit)

62310-1  IEC:2005 – 33 –
4 Safety requirements
4.1 Marking and instructions
4.1.1 General
The STS shall be provided with a marking as detailed below, provision shall be allowed for
equivalent wording. For equipment intended to be installed by anyone other than a service
person, the marking shall be readily visible either in an operator access area or shall be located
on an outside surface of the equipment. If located on an outside surface of fixed equipment, the
marking shall be visible after the equipment has been installed as in normal use.
Markings that are not visible from the outside of the equipment are considered to be in
compliance if they are directly visible when opening a door or cover.
4.1.2 Equipment ratings
The markings shall include:
– rated operational voltage(s);or rated voltage range(s), in volts;
– rated frequency or rated frequency range, in hertz;
– rated current, in amperes;
– number of output phases (1φ–3φ) with or without neutral;
– number of poles switched;
– maximum ambient operating temperature range (optional).
When multiple ratings apply, ratings shall be separated by solidus (/).
For units designed with additional separate maintenance bypass(s) or additional input a.c.
supply, it shall be allowed for relevant supply ratings to be specified in the accompanying
installation instructions. Where this is done, the following instruction shall appear on or near
the points of connection.
SEE INSTALLATION INSTRUCTIONS BEFORE
CONNECTING TO THE SUPPLY
Additional markings are permitted, provided that they do not lead to misunderstanding.
Where symbols are used, they shall conform to ISO 7000 or IEC 60417-DB:2002 where
appropriate symbols exist.
4.1.3 Safety instructions
The manufacturer shall provide instructions to safely transport, store, install, operate and
maintain STS. The manufacturer shall also provide relevant guidance on the level of
competency needed to perform above tasks and to whom they apply e.g. operator, service
personnel, etc.
62310-1  IEC:2005 – 35 –
When disconnect devices for isolation of input power supplies are not incorporated in the
equipment, the installation instructions shall state that:
– for permanently connected equipment, an appropriate and readily accessible disconnect
device shall be incorporated in the fixed wiring;
– for pluggable STS, the socket outlet that supplies the STS shall be installed near the STS
and shall be easily accessible.
For permanently connected STS without internal automatic backfeed isolation, the installation
instructions shall require fitting by the installer of a warning label on each dedicated and
immediately upstream power isolator feeding the STS, to warn electrical maintenance
personnel.
The warning label shall carry the following wording or equivalent.
ISOLATE STATIC TRANSFER SYSTEM (STS)
BEFORE WORKING ON THIS CIRCUIT
For STS provided with or designed to work with external separate bypass/maintenance
bypass, relevant supply ratings shall be specified in the accompanying installation
instructions. Where this is done, the following instruction shall appear on or near the point of
connection:
SEE INSTALLATION INSTRUCTIONS BEFORE
CONNECTING TO THE SUPPLY
Compliance is determined by inspection.
4.1.4 Supply voltage adjustment
For equipment intended for connection to multiple rated voltages or frequencies, the method
of adjustment shall be fully described in the servicing or installation instructions.
Unless the means of adjustment is a simple control near the power rating marking, and the
setting is obvious by inspection, the following instruction or a similar one shall appear in or
near the power rating marking:
SEE INSTALLATION INSTRUCTIONS
BEFORE CONNECTING INPUT SUPPLIES
4.1.5 Power outlets on the equipment
If any standard power supply outlet in the equipment is accessible to the operator, a marking
shall be placed in the vicinity of the outlet to show the maximum load that is permitted to be
connected to it.
Socket-outlets conforming to IEC 60083 are examples of standard power supply outlets.
4.1.6 Fuses identification
Marking shall be located adjacent to each fuse or fuseholder, or on the fuseholder, or in
another location provided that it is obvious to which fuse the marking applies, giving the fuse
current rating and, where fuses of different voltage rating value could be fitted, the fuse
voltage rating.
62310-1  IEC:2005 – 37 –
Where fuses with special fusing characteristics such as time delay or breaking capacity are
necessary, the type shall also be indicated.
For fuses not located in operator access areas and for soldered-in fuses located in operator
access areas, it is permitted to provide an unambiguous cross-reference (e.g. F1, F2, etc.) to
the servicing instructions which shall contain the relevant information.
4.1.7 Wiring terminals
4.1.7.1 Protective earthing and bonding terminals
A wiring terminal intended for connection of a protective earthing conductor shal
...