IEC 62271-110:2009

High-voltage switchgear and controlgear - Part 110: Inductive load switching

IEC 62271-110:2009 is applicable to a.c. circuit-breakers designed for indoor or outdoor installation, for operation at frequencies of 50 Hz and 60 Hz on systems having voltages above 1000 V and applied for inductive current switching with or without additional short-circuit current breaking duties. The standard is applicable to circuit-breakers in accordance with IEC 62271-100 that are used to switch high-voltage motor currents and shunt reactor currents and also to high-voltage contactors used to switch high-voltage motor currents. This second edition cancels and replaces the first edition dated 2005 and constitutes an editorial revision. The main changes from the first edition are that all references to IEC 60694 have been replaced by IEC 62271-1. This standard is to be read in conjunction with IEC 62271-1, first edition, published in 2007, and with IEC 62271-100, second edition, published in 2008.
This publication is to be read in conjunction with IEC 62271-1:2007 and IEC 62271-100:2008.

Appareillage à haute tension - Partie 110: Manoeuvre de charges inductives

La CEI 62271-110:2009 est applicable aux disjoncteurs à courant alternatif conçus pour une installation à l'intérieur ou à l'extérieur, et pour fonctionner à des fréquences de 50 Hz à 60 Hz, sur des réseaux de tensions supérieures à 1 000 V et prévus pour l'établissement et la coupure de courants inductifs avec ou sans pouvoir de coupure de court-circuit additionnel. Cette norme est applicable aux disjoncteurs selon CEI 62271-100 et qui sont utilisés pour l'établissement et la coupure de courants de moteurs à haute tension et de réactances shunt, et aussi aux contacteurs à haute tension utilisés pour l'établissement et la coupure de courants de moteurs à haute tension. Cette deuxième édition annule et remplace la première édition datée 2005, elle constitue en une révision rédactionnelle. Par rapport à la première édition toutes les références à la CEI 60694 ont été remplacées par la celles à la CEI 62271-1. Cette norme doit être lue en conjonction avec la CEI 62271-1, première édition, parue en 2007, et avec la CEI 62271-100, deuxième édition, parue en 2008.
Cette publication doit être lue conjointement avec la CEI 62271-1:2007 et la CEI 62271-100:2008.

General Information

• Status: Published
• Publication Date: 25-Jan-2009
• ICS: 29.130.10 - High voltage switchgear and controlgear
• Technical Committee: SC 17A - Switching devices
• Drafting Committee: MT 32 - TC 17/SC 17A/MT 32
• Current Stage: DELPUB - Deleted Publication
• Completion Date: 27-Sep-2012

Relations

• Revised: IEC 62271-110:2012 - High-voltage switchgear and controlgear - Part 110: Inductive load switching
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 62271-110
Edition 2.0 2009-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE


High-voltage switchgear and controlgear –
Part 110: Inductive load switching

Appareillage à haute tension –
Partie 110: Manœuvre de charges inductives

IEC 62271-110:2009

---------------------- Page: 1 ----------------------
THIS PUBLICATION IS COPYRIGHT PROTECTED
Copyright © 2009 IEC, Geneva, Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by
any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either IEC or
IEC's member National Committee in the country of the requester.
If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,
please contact the address below or your local IEC member National Committee for further information.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite
ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie
et les microfilms, sans l'accord écrit de la CEI ou du Comité national de la CEI du pays du demandeur.
Si vous avez des questions sur le copyright de la CEI ou si vous désirez obtenir des droits supplémentaires sur cette
publication, utilisez les coordonnées ci-après ou contactez le Comité national de la CEI de votre pays de résidence.

IEC Central Office
3, rue de Varembé
CH-1211 Geneva 20
Switzerland
Email: [e-mail]
Web: www.iec.ch

About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.
ƒ Catalogue of IEC publications: www.iec.ch/searchpub
The IEC on-line Catalogue enables you to search by a variety of criteria (reference number, text, technical committee,…).
It also gives information on projects, withdrawn and replaced publications.
ƒ IEC Just Published: www.iec.ch/online_news/justpub
Stay up to date on all new IEC publications. Just Published details twice a month all new publications released. Available
on-line and also by email.
ƒ Electropedia: www.electropedia.org
The world's leading online dictionary of electronic and electrical terms containing more than 20 000 terms and definitions
in English and French, with equivalent terms in additional languages. Also known as the International Electrotechnical
Vocabulary online.
ƒ Customer Service Centre: www.iec.ch/webstore/custserv
If you wish to give us your feedback on this publication or need further assistance, please visit the Customer Service
Centre FAQ or contact us:
Email: [e-mail]
Tel.: [phone]
Fax: [phone]


A propos de la CEI
La Commission Electrotechnique Internationale (CEI) est la première organisation mondiale qui élabore et publie des
normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.

A propos des publications CEI
Le contenu technique des publications de la CEI est constamment revu. Veuillez vous assurer que vous possédez
l’édition la plus récente, un corrigendum ou amendement peut avoir été publié.
ƒ Catalogue des publications de la CEI: www.iec.ch/searchpub/cur_fut-f.htm
Le Catalogue en-ligne de la CEI vous permet d’effectuer des recherches en utilisant différents critères (numéro de référence,
texte, comité d’études,…). Il donne aussi des informations sur les projets et les publications retirées ou remplacées.
ƒ Just Published CEI: www.iec.ch/online_news/justpub
Restez informé sur les nouvelles publications de la CEI. Just Published détaille deux fois par mois les nouvelles
publications parues. Disponible en-ligne et aussi par email.
ƒ Electropedia: www.electropedia.org
Le premier dictionnaire en ligne au monde de termes électroniques et électriques. Il contient plus de 20 000 termes et
définitions en anglais et en français, ainsi que les termes équivalents dans les langues additionnelles. Egalement appelé
Vocabulaire Electrotechnique International en ligne.
ƒ Service Clients: www.iec.ch/webstore/custserv/custserv_entry-f.htm
Si vous désirez nous donner des commentaires sur cette publication ou si vous avez des questions, visitez le FAQ du
Service clients ou contactez-nous:
Email: [e-mail]
Tél.: [phone]
Fax: [phone]

---------------------- Page: 2 ----------------------
IEC 62271-110
Edition 2.0 2009-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE


High-voltage switchgear and controlgear –
Part 110: Inductive load switching

Appareillage à haute tension –
Partie 110: Manœuvre de charges inductives

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
T
CODE PRIX
ICS 29.130.10 ISBN 978-2-88910-656-1
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

---------------------- Page: 3 ----------------------
– 2 – 62271-110 © IEC:2009
CONTENTS
FOREWORD.4
1 General .6
1.1 Scope.6
1.2 Normative references .6
2 Normal and special service conditions .6
3 Definitions .6
4 Ratings.7
4.1 Rated voltage (U ).7
r
4.2 Rated insulation level .7
4.3 Rated frequency (f ) .7
r
4.4 Rated normal current (I ) and temperature rise.7
r
4.5 Rated short-time withstand current (I ).7
k
4.6 Rated peak withstand current (I ).7
p
4.7 Rated duration of short-circuit (t ) .7
k
4.8 Rated supply voltage of closing and opening devices and of auxiliary and
control circuits (U ) .7
a
4.9 Rated supply frequency of closing and opening devices and auxiliary circuits .7
4.10 Rated pressure of compressed gas supply for insulation, operation and/or
interruption.7
5 Design and construction .8
6 Type tests .8
6.1 General .8
6.2 Dielectric test .8
6.3 Radio interference voltage (r.i.v.) tests .9
6.4 Measurement of the resistance of the main circuit .9
6.5 Temperature-rise tests.9
6.6 Short-time withstand current and peak withstand current tests.9
6.7 Verification of protection .9
6.8 Tightness tests .9
6.9 Electromagnetic compatibility (EMC) tests .9
6.101 Mechanical and environmental tests .9
6.102 Miscellaneous provisions for making and breaking tests .9
6.103 Test circuits for short-circuit making and breaking tests.9
6.104 Short-circuit test quantities.9
6.105 Short-circuit test procedures.9
6.106 Basic short-circuit test duties .10
6.107 Critical current tests .10
6.108 Single-phase and double-earth fault tests .10
6.114 High-voltage motor current switching tests.10
6.115 Shunt reactor current switching tests .14
7 Routine tests .19
8 Guide to selection of circuit-breakers for service .19
9 Information to be given with enquiries, tenders and orders .19
10 Rules for transport, storage, installation, operation and maintenance .20
11 Safety.20

---------------------- Page: 4 ----------------------
62271-110 © IEC:2009 – 3 –
Bibliography.24

Figure 1 – Motor switching test circuit and summary of parameters.20
Figure 2 – Illustration of transient voltages at interruption of inductive current for first
phase clearing in a three-phase non-solidly earthed circuit .21
Figure 3 – Reactor switching test − Basic layout of three-phase test circuit.22
Figure 4 – Reactor switching test − Basic layout of single-phase test circuit .22
Figure 5 – Illustration of transient voltages at interruption of inductive current for a
single-phase test .23

Table 1 – Test duties at motor current switching tests.13
Table 2 – Prospective transient voltage of load circuit including connection to the
circuit-breaker.16
Table 3 – Load circuit 1 test currents .17
Table 4 – Load circuit 2 test currents .17
Table 5 – Test duties for reactor current switching tests .18

---------------------- Page: 5 ----------------------
– 4 – 62271-110 © IEC:2009
INTERNATIONAL ELECTROTECHNICAL COMMISSION
_____________

HIGH-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 110: Inductive load switching


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 62271-110 has been prepared by subcommittee 17A: High-voltage
switchgear and controlgear, of IEC technical committee 17: Switchgear and controlgear.
This second edition cancels and replaces the first edition dated 2005 and constitutes an
editorial revision. The main changes from the first edition are that all references to IEC 60694
have been replaced with IEC 62271-1.

---------------------- Page: 6 ----------------------
62271-110 © IEC:2009 – 5 –
The text of this standard is based on the following documents:
FDIS Report on voting
17A/843/FDIS 17A/856/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.
This standard is to be read in conjunction with IEC 62271-1, first edition, published in 2007,
and with IEC 62271-100, second edition, published in 2008, to which it refers and which are
applicable, unless otherwise specified. In order to simplify the indication of corresponding
requirements, the same numbering of clauses and subclauses is used as in IEC 62271-1 and
IEC 62271-100. Additional subclauses are numbered from 101.
A list of all the parts in the IEC 62271 series, under the general title High-voltage switchgear
and controlgear, 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.

---------------------- Page: 7 ----------------------
– 6 – 62271-110 © IEC:2009
HIGH-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 110: Inductive load switching



1 General
1.1 Scope
This International Standard is applicable to a.c. circuit-breakers designed for indoor or
outdoor installation, for operation at frequencies of 50 Hz and 60 Hz on systems having
voltages above 1000 V and applied for inductive current switching with or without additional
short-circuit current breaking duties. The standard is applicable to circuit-breakers in
accordance with IEC 62271-100 that are used to switch high-voltage motor currents and shunt
reactor currents and also to high-voltage contactors used to switch high-voltage motor
currents [2].
Switching unloaded transformers, i.e. breaking transformer magnetizing current, is not
considered in this standard. The reasons for this are as follows:
a) due to the non-linearity of the transformer core, it is not possible to correctly model the
switching of transformer magnetizing current using linear components in a test laboratory.
Tests conducted using an available transformer, such as a test transformer, will only be
valid for the transformer tested and cannot be representative for other transformers;
b) as detailed in CIGRE Technical Brochure 305 [1], the characteristics of this duty are
usually less severe than any other inductive current switching duty. It should be noted that
such a duty may produce severe overvoltages within the transformer winding(s) depending
on the circuit-breaker re-ignition behaviour and transformer winding resonance
frequencies.
Short-line faults, out-of-phase current making and breaking and capacitive current switching
are not applicable to circuit-breakers applied to switch shunt reactors or motors. These duties
are therefore not included in this standard.
Subclause 1.1 of IEC 62271-100 is otherwise applicable.
1.2 Normative references
Subclause 1.2 of IEC 62271-100 is applicable with the following addition:
IEC 62271-100:2008, High-voltage switchgear and controlgear – Part 100: High-voltage
alternating-current circuit-breakers
2 Normal and special service conditions
Clause 2 of IEC 62271-1 is applicable.
3 Definitions
For the purposes of this document, the definitions of IEC 60050(441) and IEC 62271-1 apply.

---------------------- Page: 8 ----------------------
62271-110 © IEC:2009 – 7 –
4 Ratings
Clause 4 of IEC 62271-100 is applicable except for the references to short-line faults, out-of-
phase making and breaking, capacitive current switching and as noted in specific subclauses
below.
4.1 Rated voltage (U )
r
Subclause 4.1 of IEC 62271-1 is applicable.
4.2 Rated insulation level
Subclause 4.2 of IEC 62271-1 is applicable with the following addition:
The rated values stated in Tables 1a and 1b and Tables 2a and 2b of IEC 62271-1 are
applicable with the exception of column (8) in the latter two tables.
NOTE 1 The reason for this exception is the passive nature of the shunt reactor load circuit.
NOTE 2 In some cases (high chopping overvoltage levels, or where a neutral reactor is present or in cases of
shunt reactors with isolated neutral), it may be necessary to specify an appropriate insulation level which is higher
than the rated values given in Tables 1a, 1b, 2a and 2b.
4.3 Rated frequency (f )
r
Subclause 4.3 of IEC 62271-1 is applicable with the following addition:
The standard values for the rated frequency of high voltage circuit-breakers are 50 Hz and
60 Hz.
4.4 Rated normal current (I ) and temperature rise
r
Subclause 4.4 of IEC 62271-1 is applicable.
4.5 Rated short-time withstand current (I )
k
Subclause 4.5 of IEC 62271-100 is applicable.
4.6 Rated peak withstand current (I )
p
Subclause 4.6 of IEC 62271-100 is applicable.
4.7 Rated duration of short-circuit (t )
k
Subclause 4.7 of IEC 62271-100 is applicable.
4.8 Rated supply voltage of closing and opening devices and of auxiliary and control
circuits (U )
a
Subclause 4.8 of IEC 62271-1 is applicable.
4.9 Rated supply frequency of closing and opening devices and auxiliary circuits
Subclause 4.9 of IEC 62271-1 is applicable.
4.10 Rated pressure of compressed gas supply for insulation, operation and/or
interruption
Subclause 4.10 of IEC 62271-1 is applicable.

---------------------- Page: 9 ----------------------
– 8 – 62271-110 © IEC:2009
4.101 Rated short-circuit breaking current (I )
sc
Subclause 4.101 of IEC 62271-100 is applicable.
4.102 Transient recovery voltage related to the rated short-circuit breaking current
Subclause 4.102 of IEC 62271-100 is applicable.
4.103 Rated short-circuit making current
Subclause 4.103 of IEC 62271-100 is applicable.
4.104 Rated operating sequence
Subclause 4.104 of IEC 62271-100 is applicable.
4.108 Inductive load switching
This standard is applicable.
4.109 Rated time quantities
Subclause 4.109 of IEC 62271-100 is applicable.
4.110 Number of mechanical operations
Subclause 4.110 of IEC 62271-100 is applicable.
5 Design and construction
Clause 5 of IEC 62271-100 is applicable.
6 Type tests
6.1 General
Subclause 6.1 of IEC 62271-100 is applicable with the following addition:
Inductive current switching tests performed for a given current rating and type of application
may be considered valid for another current rating and same type of application as detailed
below:
a) for high-voltage shunt reactor switching at rated voltage 52 kV and above, tests at a
particular current rating are to be considered valid for applications up to the tested current
value +20 %;
b) for shunt reactor switching at rated voltage below 52 kV, no type testing is required and
reference should be made to the guide [1];
c) for high-voltage motor switching, no further type testing is considered necessary for
stalled motor currents between 100 A and 300 A or for stalled motor currents between
300 A and the current associated with the short-circuit current of test duty T10 according
to 6.106.1 of IEC 62271-100.
6.2 Dielectric test
Subclause 6.2 of IEC 62271-100 is applicable with the following addition:

---------------------- Page: 10 ----------------------
62271-110 © IEC:2009 – 9 –
Refer to 4.2 of this standard.
6.3 Radio interference voltage (r.i.v.) tests
Subclause 6.3 of IEC 62271-1 is applicable.
6.4 Measurement of the resistance of the main circuit
Subclause 6.4 of IEC 62271-1 is applicable.
6.5 Temperature-rise tests
Subclause 6.5 of IEC 62271-1 is applicable.
6.6 Short-time withstand current and peak withstand current tests
Subclause 6.6 of IEC 62271-1 is applicable.
6.7 Verification of protection
Subclause 6.7 of IEC 62271-1 is applicable.
6.8 Tightness tests
Subclause 6.8 of IEC 62271-1 is applicable.
6.9 Electromagnetic compatibility (EMC) tests
Subclause 6.9 of IEC 62271-1 is applicable.
6.101 Mechanical and environmental tests
Subclause 6.101 of IEC 62271-100 is applicable.
6.102 Miscellaneous provisions for making and breaking tests
Subclause 6.102 of IEC 62271-100 is applicable with the following addition:
High-voltage motor current and shunt reactor switching tests shall be performed at rated
auxiliary and control voltage or, where necessary, at maximum auxiliary and control voltage to
facilitate consistent control of the opening and closing operation according to 6.102.3.1 of
IEC 62271-100 and at rated functional pressure for interruption and insulation. For gas circuit-
breakers shunt reactor switching tests shall also be performed at the minimum functional
pressure for interruption and insulation.
6.103 Test circuits for short-circuit making and breaking tests
Subclause 6.103 of IEC 62271-100 is applicable.
6.104 Short-circuit test quantities
Subclause 6.104 of IEC 62271-100 is applicable.
6.105 Short-circuit test procedures
Subclause 6.105 of IEC 62271-100 is applicable.

---------------------- Page: 11 ----------------------
– 10 – 62271-110 © IEC:2009
6.106 Basic short-circuit test duties
Subclause 6.106 of IEC 62271-100 is applicable.
6.107 Critical current tests
Subclause 6.107 of IEC 62271-100 is applicable.
6.108 Single-phase and double-earth fault tests
Subclause 6.108 of IEC 62271-100 is applicable.
NOTE Subclauses 6.109 to 6.112 of IEC 62271-100 are not applicable to this standard.
6.114 High-voltage motor current switching tests
6.114.1 Applicability
This subclause is applicable to three-phase alternating current circuit-breakers having rated
voltages above 1 kV and up to 17,5 kV, which are used for switching high-voltage motors.
Tests may be carried out at 50 Hz with a relative tolerance of ±10 % or 60 Hz with a relative
tolerance of ±10 %, both frequencies being considered equivalent.
Motor switching tests are applicable to all three-pole circuit-breakers having rated voltages
equal to or less than 17,5 kV, which may be used for the switching of three-phase
asynchronous squirrel-cage or slip-ring motors. The circuit-breaker may be of a higher rated
voltage than the motor when connected to the motor through a stepdown transformer.
However, the more usual application is a direct cable connection between circuit-breaker and
motor. When tests are required, they shall be made in accordance with 6.114.2 to 6.114.9.
No limits to the overvoltages are given as the overvoltages are only relevant to the specific
application. Overvoltages between phases may be as significant as phase-to-earth
overvoltages.
6.114.2 General
The switching tests can be either field tests or laboratory tests. As regards overvoltages, the
switching of the current of a starting or stalled motor is usually the more severe operation.
Due to the non-linear behaviour of the motor iron core, it is not possible to exactly model the
switching of motor current using linear components in a test station. Tests using linear
components to simulate the motors can be considered to be more conservative than switching
actual motors.
For laboratory tests a standardized circuit simulating the stalled condition of a motor is
specified (refer to Figure 1). The parameters of this test circuit have been chosen to represent
a relatively severe case with respect to overvoltages and will cover the majority of service
applications.
The laboratory tests are performed to prove the ability of a circuit-breaker to switch motors
and to establish its behaviour with respect to switching overvoltages, re-ignitions and current
chopping. These characteristics may serve as a basis for estimates of the circuit-breaker
performance in other motor circuits. Tests performed with the test currents defined in 6.114.3
and 6.114.4 demonstrate the capability of the switching device to switch high-voltage motors
up to its rated interrupting current.
For field tests, actual circuits are used with a supply system on the source side and a cable
and motor on the load side. There may be a transformer between the circuit-breaker and

---------------------- Page: 12 ----------------------
62271-110 © IEC:2009 – 11 –
motor. However, the results of such field tests are only valid for circuit-breakers working in
circuits similar to those during the tests.
The apparatus under test includes the circuit-breaker with overvoltage protection devices if
they are normally fitted.
NOTE 1 Overvoltages may be produced when switching running motors. This condition is not represented by the
substitute circuit, but is regarded as less severe.
NOTE 2 The starting period switching of a slip-ring motor is generally less severe due to the effect of the starting
resistor.
NOTE 3 The rated voltage of the circuit-breaker may differ from that of the motor.
6.114.3 Characteristics of the supply circuits
6.114.3.1 General
A three-phase supply circuit shall be used. The tests shall be performed using two different
supply circuits A and B as specified in 6.114.3.2 and 6.114.3.3, respectively. Supply circuit A
represents the case of a motor connected directly to a transformer. Supply circuit B
represents the case where parallel cables are applied on the supply side.
6.114.3.2 Supply circuit A
The three-phase supply may be earthed through a high ohmic impedance so that the supply
voltage is defined with respect to earth. The impedance value shall be high enough to limit a
prospective line-to-earth fault current to a value below the test current
...