IEC 62271-110:2017

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

IEC 62271-110:2017 is also available as IEC 62271-110:2017 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.
IEC 62271-110:2017 is applicable to AC switching devices designed for indoor or outdoor installation, for operation at frequencies of 50 Hz and 60 Hz on systems having voltages above 1 000 V and applied for inductive current switching. It is applicable to switching devices (including 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 as covered by IEC 62271-106. This fourth edition cancels and replaces the third edition published in 2012 and constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- all switching devices are now covered, not only circuit-breakers;
- a limited number of T10 tests no longer covers shunt-reactor switching tests below 52 kV;
- evaluation and reporting of a re-ignition-free arcing time window has been added.
The contents of the corrigendum of December 2017 and of February 2018 have been included in this copy.

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

IEC 62271-110:2017 est disponible sous forme de IEC 62271-110:2017 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.
L’IEC 62271-110:2017 est applicable aux appareils de connexion 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. Le présent document est applicable aux appareils de connexion (y compris les disjoncteurs selon l’IEC 62271-100) qui sont utilisés pour l’établissement et la coupure de courants de moteurs à haute tension et de courants de bobines d'inductance shunt, et aussi aux contacteurs à haute tension utilisés pour l’établissement et la coupure de courants de moteurs à haute tension, tels que couverts par l’IEC 62271-106. Cette quatrième édition annule et remplace la troisième édition parue en 2012. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
- tous les appareils de connexion sont dorénavant couverts, et non uniquement les disjoncteurs;
- un nombre limité d’essais T10 ne couvrent plus les essais d’établissement et de coupure de courant de bobine d’inductance shunt en dessous de 52 kV;
- l’évaluation et la consignation d’une plage de coupure sans réallumage ont été ajoutées.
Le contenu des corrigenda de décembre 2017 et février 2018 a été pris en considération dans cet exemplaire.

General Information

• Status: Published
• Publication Date: 04-Oct-2017
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 29.130.10 - High voltage switchgear and controlgear
• Technical Committee: SC 17A - Switching devices
• Current Stage: PPUB - Publication issued
• Start Date: 05-Oct-2017
• Completion Date: 05-Oct-2017

Standards Content (sample)

IEC 62271-110
Edition 4.0 2017-10
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 62271-110:2017-10(en-fr)
---------------------- Page: 1 ----------------------
THIS PUBLICATION IS COPYRIGHT PROTECTED
Copyright © 2017 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 l'IEC ou du Comité national de l'IEC du pays du demandeur. Si vous avez des

questions sur le copyright de l'IEC ou si vous désirez obtenir des droits supplémentaires sur cette publication, utilisez

les coordonnées ci-après ou contactez le Comité national de l'IEC de votre pays de résidence.

IEC Central Office Tel.: [phone]
3, rue de Varembé Fax: [phone]
CH-1211 Geneva 20 [e-mail]
Switzerland 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.
IEC Catalogue - webstore.iec.ch/catalogue Electropedia - www.electropedia.org

The stand-alone application for consulting the entire The world's leading online dictionary of electronic and

bibliographical information on IEC International Standards, electrical terms containing 20 000 terms and definitions in

Technical Specifications, Technical Reports and other English and French, with equivalent terms in 16 additional

documents. Available for PC, Mac OS, Android Tablets and languages. Also known as the International Electrotechnical

iPad. Vocabulary (IEV) online.

IEC publications search - www.iec.ch/searchpub IEC Glossary - std.iec.ch/glossary

The advanced search enables to find IEC publications by a 65 000 electrotechnical terminology entries in English and

variety of criteria (reference number, text, technical French extracted from the Terms and Definitions clause of

committee,…). It also gives information on projects, replaced IEC publications issued since 2002. Some entries have been

and withdrawn publications. collected from earlier publications of IEC TC 37, 77, 86 and

CISPR.
IEC Just Published - webstore.iec.ch/justpublished

Stay up to date on all new IEC publications. Just Published IEC Customer Service Centre - webstore.iec.ch/csc

details all new publications released. Available online and If you wish to give us your feedback on this publication or

also once a month by email. need further assistance, please contact the Customer Service

Centre: [e-mail].
A propos de l'IEC

La Commission Electrotechnique Internationale (IEC) 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 IEC

Le contenu technique des publications IEC est constamment revu. Veuillez vous assurer que vous possédez l’édition la

plus récente, un corrigendum ou amendement peut avoir été publié.
Catalogue IEC - webstore.iec.ch/catalogue Electropedia - www.electropedia.org
Application autonome pour consulter tous les renseignements
Le premier dictionnaire en ligne de termes électroniques et
bibliographiques sur les Normes internationales,
électriques. Il contient 20 000 termes et définitions en anglais
Spécifications techniques, Rapports techniques et autres
et en français, ainsi que les termes équivalents dans 16
documents de l'IEC. Disponible pour PC, Mac OS, tablettes
langues additionnelles. Egalement appelé Vocabulaire
Android et iPad.
Electrotechnique International (IEV) en ligne.
Recherche de publications IEC - www.iec.ch/searchpub
Glossaire IEC - std.iec.ch/glossary
65 000 entrées terminologiques électrotechniques, en anglais
La recherche avancée permet de trouver des publications IEC

en utilisant différents critères (numéro de référence, texte, et en français, extraites des articles Termes et Définitions des

comité d’études,…). Elle donne aussi des informations sur les publications IEC parues depuis 2002. Plus certaines entrées

projets et les publications remplacées ou retirées. antérieures extraites des publications des CE 37, 77, 86 et

CISPR de l'IEC.
IEC Just Published - webstore.iec.ch/justpublished
Service Clients - webstore.iec.ch/csc
Restez informé sur les nouvelles publications IEC. Just

Published détaille les nouvelles publications parues. Si vous désirez nous donner des commentaires sur cette

Disponible en ligne et aussi une fois par mois par email. publication ou si vous avez des questions contactez-nous:

[e-mail].
---------------------- Page: 2 ----------------------
IEC 62271-110
Edition 4.0 2017-10
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
INTERNATIONALE
ICS 29.130.10 ISBN 978-2-8322-4866-9

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – IEC 62271-110:2017 © IEC 2017
CONTENTS

FOREWORD ........................................................................................................................... 4

1 Scope .............................................................................................................................. 6

2 Normative references ...................................................................................................... 6

3 Terms and definitions ...................................................................................................... 7

4 Type tests ....................................................................................................................... 8

4.1 General ................................................................................................................... 8

4.2 Miscellaneous provisions for inductive load switching tests ..................................... 8

4.3 High-voltage motor current switching tests .............................................................. 9

4.3.1 Applicability ..................................................................................................... 9

4.3.2 General ........................................................................................................... 9

4.3.3 Characteristics of the supply circuits .............................................................. 10

4.3.4 Characteristics of the load circuit ................................................................... 11

4.3.5 Test voltage ................................................................................................... 11

4.3.6 Test-duties .................................................................................................... 12

4.3.7 Test measurements ....................................................................................... 12

4.3.8 Behaviour and condition of switching device .................................................. 12

4.3.9 Test report ..................................................................................................... 13

4.4 Shunt reactor current switching tests .................................................................... 14

4.4.1 Applicability ................................................................................................... 14

4.4.2 General ......................................................................................................... 15

4.4.3 Test circuits ................................................................................................... 15

4.4.4 Characteristics of the supply circuit ............................................................... 18

4.4.5 Characteristics of the connecting leads .......................................................... 18

4.4.6 Characteristics of the load circuits ................................................................. 18

4.4.7 Earthing of the test circuit .............................................................................. 23

4.4.8 Test voltage ................................................................................................... 23

4.4.9 Test-duties .................................................................................................... 23

Annex A (normative) Calculation of t values ....................................................................... 27

Bibliography .......................................................................................................................... 29

Figure 1 – Motor switching test circuit and summary of parameters ....................................... 10

Figure 2 – Illustration of voltage transients at interruption of inductive current for first

phase clearing in a three-phase non-effectively earthed circuit ............................................. 14

Figure 3 – Reactor switching test circuit – Three-phase test circuit for in-service load

circuit configurations 1 and 2 (Table 2) ................................................................................. 16

Figure 4 – Reactor switching test circuit – Single-phase test circuit for in-service load

circuit configurations 1, 2 and 4 (Table 2) ............................................................................. 17

Figure 5 – Reactor switching test circuit − Three-phase test circuit for in-service load

circuit configuration 3 (Table 2) ............................................................................................. 18

Figure 6 – Illustration of voltage transients at interruption of inductive current for a

single-phase test .................................................................................................................. 26

Table 1 – Test-duties at motor current switching tests ........................................................... 12

Table 2 – In-service load circuit configurations ..................................................................... 15

---------------------- Page: 4 ----------------------
– 3 – IEC 62271-110:2017 © IEC 2017

Table 3 –Values of prospective transient recovery voltages – Rated voltages 12 kV to

170 kV for effectively and non-effectively earthed systems – Switching shunt reactors

with isolated neutrals (Table 2: In-service load circuit configuration 1) .................................. 19

Table 4 – Values of prospective transient recovery voltages – Rated voltages 100 kV to

1 200 kV for effectively earthed systems – Switching shunt reactors with earthed

neutrals (See Table 2: In-service load circuit configuration 2) ............................................... 20

Table 5 – Values of prospective transient recovery voltages – Rated voltages 12 kV to

52 kV for effectively and non-effectively earthed systems – Switching shunt reactors

with isolated neutrals (See Table 2: In-service load circuit configuration 3) ........................... 21

Table 6 – Values of prospective transient recovery voltages – Rated voltages 12 kV to

52 kV for effectively and non-effectively earthed systems – Switching shunt reactors

with earthed neutrals (See Table 2: In-service load circuit configuration 4) ........................... 22

Table 7 – Load circuit 1 test currents .................................................................................... 22

Table 8 – Load circuit 2 test currents .................................................................................... 23

Table 9 – Test-duties for reactor current switching tests ....................................................... 24

---------------------- Page: 5 ----------------------
– 4 – IEC 62271-110:2017 © IEC 2017
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 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 62271-110 has been prepared by subcommittee 17A: Switching

devices, of IEC technical committee 17: High-voltage switchgear and controlgear.

This fourth edition cancels and replaces the third edition published in 2012 and constitutes a

technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:
– all switching devices are now covered, not only circuit-breakers;

– a limited number of T10 tests no longer covers shunt-reactor switching tests below 52 kV;

– evaluation and reporting of a re-ignition-free arcing time window has been added.

---------------------- Page: 6 ----------------------
– 5 – IEC 62271-110:2017 © IEC 2017
The text of this International Standard is based on the following documents:
FDIS Report on voting
17A/1151/FDIS 17A/1155/RVD

Full information on the voting for the approval of this International Standard can be found in

the report on voting indicated in the above table.

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

A list of all parts of the IEC 62271 series can be found, under the general title High-voltage

switchgear and controlgear, on the IEC website.

The committee has decided that the contents of this document will remain unchanged until the

stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to

the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

The contents of the corrigenda of December 2017 and February 2018 have been included in

this copy.
---------------------- Page: 7 ----------------------
– 6 – IEC 62271-110:2017 © IEC 2017
HIGH-VOLTAGE SWITCHGEAR AND CONTROLGEAR –
Part 110: Inductive load switching
1 Scope

This part of IEC 62271 is applicable to AC switching devices designed for indoor or outdoor

installation, for operation at frequencies of 50 Hz and 60 Hz on systems having voltages

above 1 000 V and applied for inductive current switching. It is applicable to switching devices

(including 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 as covered by IEC 62271-106.

Switching unloaded transformers, i.e. breaking transformer magnetizing current, is not

considered in this document. The reasons for this are as follows:

a) Owing 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 IEC TR 62271-306, the characteristics of this duty are usually less severe

than any other inductive current switching duty. Such a duty may produce severe

overvoltages within the transformer winding(s) depending on the re-ignition behaviour of

the switching device and transformer winding resonance frequencies.

NOTE 1 The switching of tertiary reactors from the high-voltage side of the transformer is not covered by this

document.

NOTE 2 The switching of shunt reactors earthed through neutral reactors is not covered by this document.

However, the application of test results according to this document, on the switching of neutral reactor earthed

reactors (4-leg reactor scheme), is discussed in IEC TR 62271-306.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their

content constitutes requirements of this document. For dated references, only the edition

cited applies. For undated references, the latest edition of the referenced document (including

any amendments) applies.

IEC 60050-441, International Electrotechnical Vocabulary – Chapter 441: Switchgear,

controlgear and fuses (available at www.electropedia.org)

IEC 62271-1:2017, High-voltage switchgear and controlgear – Part 1: Common specifications

for alternating current switchgear and controlgear

IEC 62271-100:2008, High-voltage switchgear and controlgear – Part 100: Alternating current

circuit-breakers
IEC 62271-100:2008/AMD1:2012

IEC 62271-106:2011, High-voltage switchgear and controlgear – Part 106: Alternating current

contactors, contactor-based controllers and motor-starters
---------------------- Page: 8 ----------------------
– 7 – IEC 62271-110:2017 © IEC 2017
3 Terms and definitions

For the purposes of this document, the terms and definitions given in IEC 60050-441,

IEC 62271-1 and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
inductive current

power-frequency current drawn by an inductive circuit having a power factor 0,5 or less

3.2
current chopping

abrupt current interruption in a switching device at a point-on-wave other than the natural

power-frequency current zero
3.3
virtual current chopping

current chopping in one of the three phases in a three-phase circuit originated by transients in

another phase of the circuit
3.4
suppression peak

first peak of the transient voltage to earth on the load side of the switching device following

current interruption

Note 1 to entry: Suppression peak is not necessarily the absolute maximum of the transient recovery voltage.

Previous breakdowns may have appeared at higher voltage values.
3.5
recovery peak

maximum value of the voltage across the switching device occurring when the polarity of the

recovery voltage is equal to the polarity of the power-frequency voltage

Note 1 to entry: Recovery peak is not necessarily the absolute maximum of the transient recovery voltage.

Previous breakdowns may have appeared at higher voltage values.
3.6
re-ignition

resumption of current between the contacts of a mechanical switching device during a

breaking operation with an interval of zero current of less than a quarter cycle of power

frequency

Note 1 to entry: In the case of inductive load switching the initiation of the re-ignition is a high-frequency event,

which can be of a single or multiple nature and may in some cases be interrupted without power-frequency follow

current.
3.7
re-ignition-free arcing time window

period of arc duration during a breaking operation during which the contacts of a mechanical

switching device reach sufficient distance to exclude re-ignition
---------------------- Page: 9 ----------------------
– 8 – IEC 62271-110:2017 © IEC 2017
4 Type tests
4.1 General

Circuit-breakers according to IEC 62271-100 and contactors according to IEC 62271-106 do

not have dedicated inductive switching ratings. However, switching devices applied for this

purpose shall meet the requirements of this document.

For shunt reactor switching test of circuit-breakers, the rated insulation level values stated in

Tables 1a, 1b, 3 and 4 of IEC 62271-1:2017 are applicable with the exception of combined

voltage tests across the isolating distance (columns (6) and (8) in Table 3 and column (7) in

Table 4).

The type tests are in addition to those specified in the relevant product standard, with the

exception of short-line faults, out-of-phase switching and capacitive current switching.

NOTE 1 The reason for this exception is the source-less 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 can be necessary to specify an appropriate insulation level which is higher

than the rated values stated above.

Inductive current switching tests performed for a given current level and type of application

may be considered valid for another current rating and same type of application as detailed

below:

a) for shunt reactor switching at rated voltages of 52 kV and above, tests at a particular

current level are to be considered valid for applications with a higher current level up to

150 % of the tested current value;

b) for shunt reactor switching at rated voltages below 52 kV, type testing is required;

c) for high-voltage motor switching, type testing for stalled motor currents at 100 A and 300 A

is considered to cover stalled motor currents in the range 100 A to 300 A and up to the

current associated with the short-circuit current of test-duty T10 according to 6.106.1 of

IEC 62271-100:2008 for circuit-breakers and up to the rated operational current for

contactors.

With respect to a) the purpose of type testing is also to determine a re-ignition-free arcing

time window for controlled switching purposes (refer to IEC TR 62271-302) and caution

should be exercised when considering applications at higher currents than the tested values

since the re-ignition-free arcing window can increase at higher current.

Annex B of IEC 62271-100:2008 can be used with respect to tolerances on test quantities.

4.2 Miscellaneous provisions for inductive load switching tests

Subclause 6.102 of IEC 62271-100:2008+IEC 62271-100:2008/AMD1:2012 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 62271-100:2008.

For gas filled switching devices (including vacuum switching devices using gaseous media for

insulation), tests shall be performed at the rated functional pressure for interruption and

insulation, except for test-duty 4, where the pressure shall be the minimum functional

pressure for interruption and insulation.
---------------------- Page: 10 ----------------------
– 9 – IEC 62271-110:2017 © IEC 2017
4.3 High-voltage motor current switching tests
4.3.1 Applicability

Subclause 4.3 is applicable to three-phase alternating current switching devices 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 switching devices 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 switching device may be of a higher rated

voltage than the motor when connected to the motor through a stepdown transformer.

However, the usual application is a direct cable connection between switching device and

motor. When tests are required, they shall be made in accordance with 4.3.2 to 4.3.9.

When overvoltage limitation devices are mandatory for the tested equipment, the voltage

limiting devices may be included in the test circuit provided that the devices are an intrinsic

part of the equipment under test.

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.
4.3.2 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 switching device 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 switching device’s

performance in other motor circuits. Tests performed with the test currents defined in 4.3.3

and 4.3.4 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 switching device and

motor. However, the results of such field tests are only valid for switching devices working in

circuits similar to those during the tests.
The apparatus under test includ
...