IEC 62271-106:2011

High-voltage switchgear and controlgear - Part 106: Alternating current contactors, contactor-based controllers and motor-starters

IEC 62271-106:2011 is applicable to a.c. contactors and/or contactor-based controllers and motor-starters designed for indoor installation and operation at frequencies up to and including 60 Hz on systems having voltages above 1 000 V but not exceeding 24 000 V. It is applicable only to three-pole devices for use in three-phase systems, and single-pole devices for use in single-phase systems. Two-pole contactors and starters for use in single-phase systems are subject to agreement between manufacturer and user. This standard cancels and replaces the second edition of IEC 60470 published in 1999. It constitutes a technical revision. This edition includes the following significant technical changes with respect to IEC 60470:1999:
- Scope and object: The voltage range covered by the standard was expanded from 12 kV to 24 kV. Overload relay calibration and testing is not covered by this standard.
- 3 Terms and definitions: Added definitions for capacitor switching classes.
- 4.1 Rated voltage: Added 15, 17,5 and 24 kV as standard voltage values.
- 4.109.2 Starting duty of reduced-voltage starters: Added ratings for autotransformer and reactor starters (was in the testing section).
- 4.112 Rated capacitive switching currents: Added capacitor switching current ratings.
- 5.101 Protective relays: Removed the requirements for overload relays. This section is obsolete since there are only a few MV starters fitted with thermal overload relays and electronic relays have their own standards.
- 6.2.5 Application of the test voltage and test conditions (former 6.2.2 b)): Changed wording of requirement for impulse across the open gap of vacuum contactors.
- 6.4.2 Auxiliary circuits: The requirement for resistance checks of auxiliary circuits was deleted.
- 6.5.5.104 Temperature rise of the auto transformer or reactor for two step auto transformer or reactor starters: Reworded to transfer ratings to subclause 4.109.2.
- 6.102.9 Condition following making and breaking tests: Gave specific direction as to what the tolerance should be based on where the resistance was to be checked.
- 6.104 Short-circuit current making and breaking tests: Clarified test conditions for short-circuit testing.
- 6.109 Capacitive current switching tests: Added capacitive current switching tests.
- Annex B: Added Table B.1 - Tolerances on test quantities for type test. The contents of the corrigendum of February 2014 have been included in this copy.

Appareillage à haute tension - Partie 106: Contacteurs, combinés de démarrage à contacteurs et démarreurs de moteurs, pour courant alternatif

La CEI 62271-106:2011 est applicable aux contacteurs à courant alternatif et/ou aux combinés de démarrage et démarreurs de moteurs à base de contacteurs conçus pour des installations intérieures et pour fonctionner à des fréquences inférieures ou égales à 60 Hz, dans des systèmes de tensions supérieures à 1 000 V mais n'excédant pas 24 000 V. Elle ne s'applique qu'aux dispositifs tripolaires, utilisés dans des systèmes triphasés, et aux dispositifs unipolaires, utilisés dans des systèmes monophasés. Les contacteurs et les démarreurs bipolaires peuvent être utilisés dans des systèmes monophasés, après accord entre le constructeur et l'utilisateur. La présente norme annule et remplace la deuxième édition de la CEI 60470 parue en 1999. Elle constitue une révision technique. La présente édition inclut les modifications techniques importantes suivantes par rapport à la CEI 60470:1999.
- 1.1 Domaine d'application et objet: La plage des tensions couverte par la Norme a été étendue de 12 kV à 24 kV.L'étalonnage et les essais des relais de surcharge ne sont pas couverts par la présente norme.
- 3 Définitions: Définitions supplémentaires pour les classes de commutation de condensateurs.
- 4.1 Tension assignée: Les valeurs normalisées de 15 kV, 17,5 kV et 24 kV ont été ajoutées.
- 4.109.2 Service de démarrage des démarreurs à tension réduite: Des caractéristiques assignées concernant les démarreurs à autotransformateur ou à réactance ont été ajoutées. Elles étaient traitées dans la partie relative aux essais.
- 4.112 Courants capacitifs de man uvre assignés: Des caractéristiques assignées relatives aux courants de commutation des condensateurs ont été ajoutées.
- 5.101 Relais de protection: Les exigences concernant les relais de surcharge ont été retirées. Cette partie n'est plus d'actualité, puisqu'il n'y a plus guère de démarreurs à moyenne tension équipés de relais de surcharge et les relais électroniques ont leurs propres normes.
- 6.2.5 Application de la tension d'essai et conditions d'essai (ancien 6.2.2 b): Le libellé de l'exigence relative à l'impulsion entre l'espace ouvert des contacteurs sous vide a été modifié.
- 6.4.2 Circuits auxiliaires: L'exigence concernant les vérifications de résistance des circuits auxiliaires a été supprimée.
- 6.5.5.104 Échauffement de l'autotransformateur ou de la réactance pour les démarreurs à autotransformateur ou à réactance à deux étapes: Ce paragraphe a été reformulé pour transférer les caractéristiques assignées au paragraphe 4.109.2.
- 6.102.9 État après les essais de fermeture et de coupure: Des indications spécifiques sont données quant à la manière dont il convient de définir la tolérance lors de la vérification de résistance.
- 6.104 Essais d'établissement et de coupure de courants de court-circuit: Les conditions d'essai relatives aux essais de court-circuit ont été explicitées.
- 6.109 Essais d'établissement et de coupure de courants capacitifs: Les essais d'établissement et de coupure des courants capacitifs ont été ajoutés.
- Annexe B: Le Tableau B.1 - Tolérances sur les grandeurs d'essai pour les essais de type - a été ajouté. Le contenu du corrigendum de février 2014 a été pris en considération dans cet exemplaire.

General Information

• Status: Published
• Publication Date: 18-Aug-2011
• ICS: 19.040 - Environmental testing
• ICS: 29.130.10 - High voltage switchgear and controlgear
• Technical Committee: SC 17A - Switching devices
• Drafting Committee: MT 46 - TC 17/SC 17A/MT 46
• Current Stage: DELPUB - Deleted Publication
• Start Date: 26-Apr-2021
• Completion Date: 01-Jun-2018

Relations

• Replaces: IEC 60470:1999 - High-voltage alternating current contactors and contactor-based motor-starters
• Effective Date: 05-Sep-2023
• Corrected By: IEC 62271-106:2011/COR1:2014 - Corrigendum 1 - High-voltage switchgear and controlgear - Part 106: Alternating current contactors, contactor-based controllers and motor-starters
• Effective Date: 05-Sep-2023
• Revised: IEC 62271-106:2021 - High-voltage switchgear and controlgear - Part 106: Alternating current contactors, contactor-based controllers and motor-starters
• Effective Date: 05-Sep-2023

Overview

IEC 62271-106:2011 is an international standard developed by the International Electrotechnical Commission (IEC) that specifies requirements for high-voltage alternating current (a.c.) contactors, contactor-based controllers, and motor-starters. This standard applies to devices intended for indoor installation and operation on electrical systems with voltages above 1,000 V and up to 24,000 V, operating at frequencies up to and including 60 Hz. It focuses primarily on three-pole devices for three-phase systems and single-pole devices for single-phase systems, including specific guidelines on various types of motor starters and controllers.

This standard replaces the earlier IEC 60470:1999 edition, extending the voltage range and introducing several technical revisions. It serves as a critical reference for manufacturers, users, and professionals involved in the design, testing, and application of high-voltage switchgear and controlgear in industrial, commercial, and utility environments.

Key Topics

• Scope and Application
  IEC 62271-106 covers a.c. contactors, contactor-based controllers, and motor-starters for indoor use on systems with voltages between 1 kV and 24 kV, up to 60 Hz. It includes three-pole devices for three-phase and single-pole devices for single-phase systems. The standard excludes two-pole contactors/starter agreements unless mutually arranged by manufacturers and users.

• Devices Covered

  • Direct-on-line starters
  • Reversing starters
  • Two-direction starters
  • Reduced voltage starters, including autotransformer, rheostatic, and reactor starters
    It excludes circuit-breaker-based starters and some specialized motor starters such as unbalanced rheostatic rotor starters.

• Ratings and Definitions
  The standard adds new rated voltages of 15, 17.5, and 24 kV and introduces definitions related to capacitor switching classes. Ratings for capacitor switching currents and starting duties of reduced voltage starters are detailed.

• Design and Construction
  Requirements for design, construction, and the integration of auxiliary equipment and operating devices are addressed to ensure reliable performance and safety.

• Testing and Performance
  Detailed type tests include making and breaking capacities, short-circuit current tests, capacitive current switching tests, and temperature rise evaluations. Tolerances on test quantities are specified to ensure consistent testing results.

• Safety and Environmental Impact
  The standard outlines safety requirements and the influence of products on the environment, supporting sustainable and safe operational practices.

• Documentation and Maintenance
  IEC 62271-106 provides guidance on the information needed for enquiries, tenders, and orders, as well as recommendations for transport, storage, installation, operation, and maintenance.

Applications

IEC 62271-106:2011 is essential for:

• Manufacturers developing high-voltage a.c. contactors, controlgear, and motor-starting equipment to ensure compliance with international safety, design, and performance requirements.
• Electrical engineers and system designers specifying equipment for medium voltage (1 kV to 24 kV) electrical power distribution, ensuring compatibility with rated voltage, frequency, and system requirements.
• Industrial facilities and utility companies employing reliable motor-starters and controllers to manage heavy electrical loads, enhance operational safety, and maintain system stability.
• Testing and certification bodies performing type and routine tests to verify compliance and product quality according to international standards.

This standard helps optimize motor control equipment for diverse high-voltage environments, contributing to improved energy efficiency, reduced downtime, and enhanced safety.

Related Standards

IEC 62271-106 references and is intended to be used in conjunction with:

• IEC 62271-1:2007 – General requirements for high-voltage switchgear and controlgear
• Standards governing electronic protective relays that have replaced the obsolete overload relay requirements formerly included in this standard
• Other parts within the IEC 62271 series that cover complementary aspects of high-voltage switchgear and controlgear technologies

For further definition of terms and electrical vocabulary, users are encouraged to consult Electropedia, the IEC’s online dictionary of electronic and electrical terms, ensuring consistency in interpretations and communications.

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Keywords: IEC 62271-106, high-voltage switchgear, a.c. contactors, motor starters, contactor-based controllers, electrical standards, medium voltage equipment, switchgear testing, rated voltage 24 kV, IEC standards, motor controlgear, electrical safety, power distribution equipment.

Standards Content (Sample)

IEC 62271-106 ®
Edition 1.0 2011-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
High-voltage switchgear and controlgear –
Part 106: Alternating current contactors, contactor-based controllers and motor-
starters
Appareillage à haute tension –
Partie 106: Contacteurs, combinés de démarrage à contacteurs et démarreurs de
moteurs, pour courant alternatif

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IEC 62271-106 ®
Edition 1.0 2011-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
High-voltage switchgear and controlgear –
Part 106: Alternating current contactors, contactor-based controllers and motor-
starters
Appareillage à haute tension –
Partie 106: Contacteurs, combinés de démarrage à contacteurs et démarreurs de
moteurs, pour courant alternatif

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XC
ICS 29.130.10 ISBN 978-2-88912-637-8

– 2 – 62271-106  IEC:2011
CONTENTS
FOREWORD. 3
1  General . 5
2  Normal and special service conditions . 7
3  Terms and definitions . 7
4  Ratings . 19
5  Design and construction . 32
6  Type tests . 36
7  Routine tests . 57
8  Guide to the selection of contactors and motor-starters for service . 58
9  Information to be given with enquiries, tenders and orders . 62
10  Transport, storage, installation, operation and maintenance . 63
11  Safety . 63
12  Influence of the product on the environment . 63

Annex A (normative) Records and reports of type tests for making, breaking and
short-time current performance . 70
Annex B (normative) Tolerances . 73
Annex C (informative) List of symbols and abbreviations. 79
Bibliography . . 80

Figure 1 – Examples of speed/time curves . 64
Figure 2 – Test duties A and B – preferred earth point . 65
Figure 3 – Test duties A and B – alternative earth point . 65
Figure 4 – Test duty C – preferred earth point . 66
Figure 5 – Test duty C – alternative earth point . 66
Figure 6 – Representation by two parameters of a prospective TRV of a circuit . 67
Figure 7 – Representation of the specified TRV by a two-parameter reference line and
a delay line . 67
Figure 8 – Determination of power frequency recovery voltage . 68
Figure 9 – Characteristics for determining take-over current . 69

Table 1 – Ratings and characteristics . 20
Table 2 – Utilization categories . 26
Table 3 – Characteristics dependent on starter type . 31
Table 4 – Applicable type tests . 37
Table 5 – Intermittent duty operating cycles . 40
Table 6 – Verification of rated making and breaking capacities – Conditions for making
and breaking corresponding to the several utilization categories at rated voltage U . 44
r
Table 7 – Relationship between current broken I and OFF time . 47
c
Table 8 – Overload current withstand requirements . 48
Table 9 – Transient recovery voltage characteristics . 53
Table 10 – Verification of the number of on-load operating cycles – Conditions for
making and breaking corresponding to the several utilization categories . 55
Table B.1 – Tolerances on test quantities for type test . 73

62271-106  IEC:2011 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
HIGH-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 106: Alternating current contactors,
contactor-based controllers and motor-starters

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
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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
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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 62271-106 has been prepared by subcommittee 17A: High-voltage
switchgear and controlgear, of IEC technical committee 17: Switchgear and controlgear.
This standard cancels and replaces the second edition of IEC 60470 published in 1999. It
constitutes a technical revision.
This edition includes the following significant technical changes with respect to
IEC 60470:1999:
• Scope and object: The voltage range covered by the standard was expanded from 12 kV
to 24 kV. Overload relay calibration and testing is not covered by this standard.
• 3 Terms and definitions: Added definitions for capacitor switching classes.
• 4.1 Rated voltage: Added 15, 17,5 and 24 kV as standard voltage values.
• 4.109.2 Starting duty of reduced-voltage starters: Added ratings for autotransformer and
reactor starters (was in the testing section).

– 4 – 62271-106  IEC:2011
 4.112 Rated capacitive switching currents: Added capacitor switching current ratings.
 5.101 Protective relays: Removed the requirements for overload relays. This section is
obsolete since there are only a few MV starters fitted with thermal overload relays and
electronic relays have their own standards.
 6.2.5 Application of the test voltage and test conditions (former 6.2.2 b)): Changed
wording of requirement for impulse across the open gap of vacuum contactors.
 6.4.2 Auxiliary circuits: The requirement for resistance checks of auxiliary circuits was
deleted.
 6.5.5.104 Temperature rise of the auto-transformer or reactor for two-step
auto-transformer or reactor starters: Reworded to transfer ratings to subclause 4.109.2.
 6.102.9 Condition following making and breaking tests: Gave specific direction as to
what the tolerance should be based on where the resistance was to be checked.
 6.104 Short-circuit current making and breaking tests: Clarified test conditions for short-
circuit testing.
 6.109 Capacitive current switching tests: Added capacitive current switching tests.
 Annex B: Added Table B.1 – Tolerances on test quantities for type test.
This standard is to be read in conjunction with IEC 62271-1:2007, to which it refers and which
is applicable unless otherwise specified in this standard. In order to simplify the indication of
corresponding requirements, the same numbering of clauses and subclauses is used as in
IEC 62271-1. Amendments to these clauses and subclauses are given under the same
references whilst additional subclauses are numbered from 101.
The text of this standard is based on the following documents:
FDIS Report on voting
17A/971/FDIS 17A/976/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.
The list of all parts of 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 stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
The contents of the corrigendum of February 2014 have been included in this copy.

62271-106  IEC:2011 – 5 –
HIGH-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 106: Alternating current contactors,
contactor-based controllers and motor-starters

1 General
1.1 Scope and object
This part of IEC 62271 is applicable to a.c. contactors and/or contactor-based controllers and
motor-starters designed for indoor installation and operation at frequencies up to and
including 60 Hz on systems having voltages above 1 000 V but not exceeding 24 000 V.
It is applicable only to three-pole devices for use in three-phase systems, and single-pole
devices for use in single-phase systems. Two-pole contactors and starters for use in single-
phase systems are subject to agreement between manufacturer and user.
Contactors and/or starters dealt with in this standard typically do not have adequate
short-circuit interruption capability. In this context, this standard gives requirements for
– motor starters associated with separate short-circuit protective devices;
– controllers - contactors combined with short-circuit protective devices (SCPD).
Contactors intended for closing and opening electric circuits and, if combined with suitable
relays, for protecting these circuits against operating overloads are covered in this standard.
This standard is also applicable to the operating devices of contactors and to their auxiliary
equipment.
Motor-starters intended to start and accelerate motors to normal speed, to ensure continuous
operation of motors, to switch off the supply from the motor and to provide means for the
protection of motors and associated circuits against operating overloads are dealt with.
Motor-starter types included are
– direct-on-line starters;
– reversing starters;
– two-direction starters;
– reduced kVA (voltage) starters;
• auto-transformer starters;
• rheostatic starters;
• reactor starters.
This standard does not apply to
– circuit-breaker-based motor-starters;
– single-pole operation of multi-pole contactors or starters;
– two-step auto-transformer starters designed for continuous operation in the starting
position;
– unbalanced rheostatic rotor starters, i.e. where the resistances do not have the same
value in all phases;
– 6 – 62271-106  IEC:2011
– equipment designed not only for starting, but also for adjustment of speed;
– liquid starters and those of the "liquid-vapour" type;
– semiconductor contactors and starters making use of semiconductor contactors in the
main circuit;
– rheostatic stator starters;
– contactors or starters designed for special applications.
This standard does not deal with components contained in contactors and contactor-based
motor-starters, for which individual specifications exist.
NOTE 1 Thermal electrical relays are covered by IEC 60255-8.
NOTE 2 High-voltage current-limiting fuses are covered by IEC 60282-1 and IEC 60644.
NOTE 3 Metal-enclosed switchgear and controlgear for rated voltages above 1 kV and up to and including 52 kV
are covered by IEC 62271-200.
NOTE 4 Disconnectors and earthing switches are covered by IEC 62271-102.
NOTE 5 High-voltage switches above 1 kV and less than 52 kV are covered by IEC 62271-103 .
The object of this standard is to state
a) the characteristics of contactors and starters and associated equipment;
b) the conditions with which contactors or starters shall comply with reference to:
1) their operation and behaviour,
2) their dielectric properties,
3) the degrees of protection provided by their enclosures, where applicable,
4) their construction,
5) for controllers, interactions between the various components, for example SCPD
co-ordination;
c) the tests intended for confirming that these conditions have been met, and the methods to
be adopted for these tests;
d) the information to be given with the equipment or in the manufacturer's literature.
1.2 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 60282-1, High-voltage fuses – Part 1: Current-limiting fuses
IEC 60417, Graphical symbols for use on equipment
IEC 60644, Specification for high-voltage fuse-links for motor circuit applications
IEC 62271-1:2007, High-voltage switchgear and controlgear – Part 1: Common specifications
IEC 62271-100:2008, High-voltage switchgear and controlgear – Part 100: Alternating-current
circuit-breakers
___________
To be published
62271-106  IEC:2011 – 7 –
IEC 62271-102, High-voltage switchgear and controlgear – Part 102: Alternating current
disconnectors and earthing switches
IEC 62271-200:2003, High-voltage switchgear and controlgear – Part 200: AC metal-enclosed
switchgear and controlgear for rated voltages above 1 kV and up to and including 52 kV
2 Normal and special service conditions
2.1 Normal service conditions
Subclause 2.1 of IEC 62271-1 is applicable with the following addition:
For outdoor installations, refer to 8.102.6.
2.2 Special service conditions
Subclause 2.2 of IEC 62271-1 is applicable with the following exception:
2.2.1 Altitude
Subclause 2.2.1 of IEC 62271-1 is applicable with the following addition:
NOTE Above 1 000 m it is often necessary to make adjustments. See 8.102.7.
3 Terms and definitions
For the purposes of this standard, the terms and definitions given in Clause 3 of IEC 62271-1,
as well as the following, apply.
3.1 General terms and definitions
3.1.101
controlgear
general term covering switching devices and their combination with associated control,
measuring, protective and regulating equipment, also assemblies of such devices and
equipment with associated interconnections, accessories, enclosures and supporting
structures, intended in principle for the control of electric energy consuming equipment
[IEC 60050-441:1984, 441-11-03]
3.1.102
over-current
current exceeding the rated current
[IEC 60050-441:1984, 441-11-06]
3.1.103
short-circuit current
over-current resulting from a short circuit due to a fault or an incorrect connection in an
electric circuit
[IEC 60050-441:1984, 441-11-07]

– 8 – 62271-106  IEC:2011
3.1.104
overload
operating conditions in an electrically undamaged circuit, which cause an over-current
[IEC 60050-441:1984, 441-11-08]
3.1.105
conductive part
part which is capable of conducting current although it may not necessarily be used for
carrying service current
[IEC 60050-441:1984, 441-11-09]
3.1.106
ambient air temperature
temperature, determined under prescribed conditions, of the air surrounding the complete
switching device or fuse
NOTE For switching devices or fuses installed inside an enclosure, it is the temperature of the air outside the
enclosure.
[IEC 60050-441:1984, 441-11-13]
3.2 Assemblies of switchgear and controlgear
Clause 3.2 of IEC 62271-1 applies
3.3 Parts of assemblies
Clause 3.3 of IEC 62271-1 applies.
3.4 Switching devices
3.4.101
switching device
device designed to make or break the current in one or more electric circuits
[IEC 60050-441:1984, 441-14-01]
3.4.102
mechanical switching device
switching device (such as a contactor or a disconnector) designed to close and open one or
more electric circuits by means of separable contacts
[IEC 60050-441:1984, 441-14-02, modified]
3.4.103
disconnector
mechanical switching device which provides, in the open position, an isolating distance in
accordance with specified requirements
NOTE 1 A disconnector is capable of opening and closing a circuit either when negligible current is broken or
made, or when no significant change in the voltage across the terminals of each of the poles of the disconnector
occurs. It is also capable of carrying currents under normal circuit conditions and carrying for a specified time
currents under abnormal conditions such as those of short circuit.
NOTE 2 A withdrawable contactor assembly may be used as a disconnector.
NOTE 3 In North America, this device is also called an isolating means or an isolating switch.
[IEC 60050-441:1984, 441-14-05, modified]

62271-106  IEC:2011 – 9 –
3.4.104
earthing switch
mechanical switching device for earthing parts of a circuit, capable of withstanding for a
specified time currents under abnormal conditions such as those of short circuit, but not
required to carry current under normal conditions of the circuit
NOTE An earthing switch may have a short-circuit making capacity.
[IEC 60050-441:1984, 441-14-11]
3.4.105
contactor (mechanical)
mechanical switching device having only one position of rest, operated otherwise than by
hand, capable of making, carrying and breaking currents under normal circuit conditions
including operating overload conditions
NOTE Contactors may be designated according to the method by which the force for closing the main contacts is
provided.
[IEC 60050-441:1984, 441-14-33]
3.4.106
electromagnetic contactor
contactor in which the force for closing or opening the main contacts is provided by an
electromagnet
3.4.107
vacuum contactor
contactor in which the main contacts open and close within a highly evacuated envelope
3.4.108
SF contactor
contactor in which the main contacts open and close within an SF gas-filled compartment
3.4.109
latched contactor
contactor, the moving elements of which are prevented by means of a latching arrangement
from returning to the position of rest when the operating means are de-energized
NOTE The latching, and the release of the latching, may be mechanical, electromagnetic, pneumatic, etc.
[IEC 60050-441:1984, 441-14-34, modified]
3.4.110
starter
combination of all the switching means necessary to start and stop a motor in combination
with suitable overload protection
[IEC 60050-441:1984, 441-14-38, modified]
3.4.110.1
direct-on-line starter
starter which connects the line voltage across the motor terminals in one step
[IEC 60050-441:1984, 441-14-40]
3.4.110.2
reversing starter
starter intended to cause the motor to reverse the direction of rotation by reversing the motor
primary connections even when the motor is running

– 10 – 62271-106  IEC:2011
3.4.110.3
two-direction starter
starter intended to cause the motor to reverse the direction of rotation by reversing the motor
primary connections only when the motor is not running
3.4.110.4
reduced kVA (voltage) starter
starter which reduces the starting kVA of the motor
NOTE Reduced kVA starters may include auto-transformer, reactor, rheostatic starters.
3.4.110.5
auto-transformer starter
starter which uses one or more reduced voltages derived from an auto-transformer
3.4.110.6
rheostatic starter
starter utilizing one or several resistors for obtaining, during starting, stated motor torque
characteristics and for limiting the current
NOTE A rheostatic starter generally consists of three basic parts, which may be supplied either as a composite
unit or as separate units to be connected at the place of utilization:
– the mechanical switching devices for supplying the stator (generally associated with an overload protective device);
– the resistor(s) inserted in the rotor circuit;
– the mechanical switching devices for cutting out the resistor(s) successively.
[IEC 60050-441:1984, 441-14-42, modified]
3.4.110.7
rheostatic rotor starter
rheostatic starter for an asynchronous wound-rotor motor which, during the starting period,
cuts out successively one or several resistors previously provided in the rotor circuit
[IEC 60050-441:1984, 441-14-43]
3.4.110.8
reactor starter
primary reactor starter
starter that includes a reactor connected in series with the stator winding of an alternating
current motor to furnish reduced voltage for starting
3.4.110.9
electromagnetic starter
starter in which the force for closing the main contacts is provided by an electromagnet
3.4.110.10
n-step starter
starter in which there are (n – 1) intermediate accelerating positions between the off and full
on positions
NOTE 1 A starter in which there is no intermediate accelerating position between the OFF and ON positions is a
single step or direct-on-line starter (see 3.4.110.1).
NOTE 2 A starter in which there is only one intermediate accelerating position between the OFF and ON positions
is known as a two-step starter.
NOTE 3 A three-step rheostatic starter has two sections of resistors used for starting.
[IEC 60050-441:1984, 441-14-41, modified]

62271-106  IEC:2011 – 11 –
3.4.111
controller
combination starter
equipment consisting of a contactor, overload protection, a manual externally operated
disconnector and a short-circuit protective device (SCPD), mounted and wired in a dedicated
enclosure
NOTE 1 A dedicated enclosure is an enclosure specifically designed and dimensioned for its application, in which
all tests are conducted, and which may also include an earthing function.
NOTE 2 A controller may be used for functions other than motor starting, for example transformer control and
protection.
3.4.111.1
transformer controller
combination of all the switching means necessary to energize and de-energize a transformer
in combination with suitable overload protection
3.4.111.2
capacitor controller
combination of all the switching means necessary to energize and de-energize a capacitor or
capacitor bank in combination with suitable protection
3.4.112
short-circuit protective device
SCPD
device intended to protect a circuit or parts of a circuit against short-circuit currents by
interrupting them
NOTE Usually this function is provided by fuses.
3.4.113
contactor class C1
contactor with a low probability of restrike during capacitive current breaking as demonstrated
by the type tests (see 4.112)
3.4.114
contactor class C2
contactor with a very low probability of restrike during capacitive current breaking as
demonstrated by type tests (see 4.112)
3.5 Parts of contactors and motor starters
3.5.101
pole of a switching device
portion of a switching device associated exclusively with one electrically separated conducting
path of its main circuit and excluding those portions which provide a means for mounting and
operating all poles together
NOTE A switching device is called single-pole if it has only one pole. If it has more than one pole, it may be called
multipole (two-pole, three-pole, etc.) provided the poles are or can be coupled in such a manner as to operate
together.
[IEC 60050-441:1984, 441-15-01]
3.5.102
main circuit (of a switching device)
all the conductive parts of a switching device included in the circuit which it is designed to
close or open
– 12 – 62271-106  IEC:2011
[IEC 60050-441:1984, 441-15-02]
3.5.103
control circuit (of a switching device)
all the conductive parts (other than the main circuit) of a switching device which are included
in a circuit used for the closing operation or opening operation, or both, of the device
[IEC 60050-441:1984, 441-15-03]
3.5.104
auxiliary circuit (of a switching device)
all the conductive parts of a switching device which are intended to be included in a circuit
other than the main circuit and the control circuits of the device
NOTE Some auxiliary circuits fulfil supplementary functions such as signalling, interlocking, etc., and, as such,
they may be part of the control circuit of another switching device.
[IEC 60050-441:1984, 441-15-04]
3.5.105
main contact
contact included in the main circuit of a mechanical switching device, intended to carry, in the
closed position, the current of the main circuit
[IEC 60050-441:1984, 441-15-07]
3.5.106
control contact
contact included in a control circuit of a mechanical switching device and mechanically
operated by this device
[IEC 60050-441:1984, 441-15-09]
3.5.107
auxiliary contact
contact included in an auxiliary circuit and mechanically operated by the switching device
[IEC 60050-441:1984, 441-15-10]
3.5.108
"a" contact
make contact
control or auxiliary contact which is closed when the main contacts of the mechanical
switching device are closed and open when they are open
[IEC 60050-441:1984, 441-15-12]
3.5.109
"b" contact
break contact
control or auxiliary contact which is open when the main contacts of a mechanical switching
device are closed and closed when they are open
[IEC 60050-441:1984, 441-15-13]
3.6 Operation
3.6.101
operation (of a mechanical switching device)
transfer of the moving contact(s) from one position to an adjacent position

62271-106  IEC:2011 – 13 –
NOTE 1 For a circuit-breaker, this may be a closing operation or an opening operation.
NOTE 2 If distinction is necessary, an operation in the electrical sense, e.g. make or break, is referred to as a
switching operation, and an operation in the mechanical sense, e.g. close or open, is referred to as a mechanical
operation.
[IEC 60050-441:1984, 441-16-01]
3.6.102
operating cycle (of a mechanical switching device)
succession of operations from one position to another and back to the first position through all
other positions, if any
NOTE 1 This may be a closing operation followed by an opening operation.
NOTE 2 A succession of operations not forming an operating cycle is referred to as an operating series.
[IEC 60050-441:1984, 441-16-02, modified]
3.6.103
closing operation (of a mechanical switching device)
operation by which the device is brought from the open position to the closed position
[IEC 60050-441:1984, 441-16-08]
3.6.104
opening operation (of a mechanical switching device)
operation by which the device is brought from the closed position to the open position
[IEC 60050-441:1984, 441-16-09]
3.6.105
closed position (of a mechanical switching device)
position in which the predetermined continuity of the main circuit of the device is secured
[IEC 60050-441:1984, 441-16-22]
3.6.106
open position (of a mechanical switching device)
position in which the predetermined clearance between open contacts in the main circuit of
the device is secured
[IEC 60050-441:1984, 441-16-23]
3.6.107
position of rest (of a contactor)
position which the moving elements of the contactor take up when its electromagnet or its
compressed-air device is not energized
[IEC 60050-441:1984, 441-16-24]
3.6.108
overload relay or release
over-current relay or release intended for protection against overloads (including, where
applicable, operating transformer(s) and interconnections)
3.6.109
thermal overload relay or release
inverse time-delay overload relay or release depending for its operation (including its time
delay) on the thermal action of the current flowing in the relay or release

– 14 – 62271-106  IEC:2011
3.6.110
current setting of an overload relay or release
value of current for which the relay or release is adjusted and in accordance with which its
operating conditions are defined
3.6.111
current setting range of an overload relay or release
range between the minimum and maximum values over which the current setting of the relay
or release can be adjusted
3.6.112
phase failure sensitive overload relay or release
multi-pole overload relay or release which, in accordance with specified requirements,
operates at a current value lower than its current setting in the case of current unbalance
3.6.113
under-current (under-voltage) relay or release
measuring relay or release which operates automatically when the current through it (or the
voltage applied to it) is reduced below a pre-determined value
3.6.114
starting time (of a rheostatic starter)
period of time during which the starting resistors or parts of them carry current
NOTE The starting time of a starter is shorter than the total starting time of the motor, which takes into account
the last period of acceleration following the switching operation ON position.
3.6.115
starting time (of an auto-transformer starter)
period of time during which the auto-transformer carries current
NOTE The starting time of a starter is shorter than the total starting time of the motor, which takes into account
the last period of acceleration following the switching operation ON position.
3.6.116
open transition (with an auto-transformer starter)
circuit arrangement so that the supply to the motor is interrupted and reconnected when
changing over from one step to another
NOTE The transition stage is not considered an additional step.
3.6.117
closed transition (with an auto-transformer starter)
circuit arrangement so that the supply to the motor is not interrupted (even momentarily) when
changing over from one step to another
NOTE The transition stage is not considered an additional step.
3.6.118
inching
jogging
energizing a motor or solenoid repeatedly for short periods to obtain small movements of the
driven mechanism
3.6.119
plugging
stopping or reversing a motor rapidly by reversing the motor primary connections while the
motor is running
62271-106  IEC:2011 – 15 –
3.7 Characteristic quantities
3.7.101
breaking current (of a switching device or a fuse)
current in a pole of a switching device or in a fuse at the instant of initiation of the arc during a
breaking process
[IEC 60050-441:1984, 441-17-07]
3.7.102
breaking capacity (of a switching device or a fuse)
value of prospective current that a switching device or a fuse is capable of breaking at a
stated voltage under prescribed conditions of use and behaviour
NOTE 1 The voltage to be stated and the conditions to be prescribed are dealt with in the relevant publications.
NOTE 2 For switching devices, the breaking capacity may be termed according to the kind of current included in
the prescribed conditions, e.g. line charging breaking capacity, cable charging breaking capacity, single capacitor
bank breaking capacity, etc.
[IEC 60050-441:1984, 441-17-08]
3.7.103
making capacity (of a switching device)
value of prospective making current that a switching device is capable of making at a stated
voltage under prescribed conditions of use and behaviour
NOTE The voltage to be stated and the conditions to be prescribed are dealt with in the relevant specifications.
[IEC 60050-441:1984, 441-17-09]
3.7.104
short-time withstand current
current that a circuit or a switching device in the closed position can carry during a specified
short time under prescribed conditions of use and behaviour
[IEC 60050-441:1984, 441-17-17]
3.7.105
recovery voltage
voltage which appears across the terminals of a pole of a switching device or a fuse after the
breaking of the current
NOTE This voltage may be considered in two successive intervals of time, one during which a transient voltage exists,
followed by a second one during which the power frequency or the steady-state recovery voltage alone exists.
[IEC 60050-441:1984, 441-17-25]
3.7.106
transient recovery voltage
TRV
recovery voltage during the time in which it has a significant transient character
NOTE 1 The transient recovery voltage may be oscillatory or non-oscillatory, or a combination of these, depending on
the characteristics of the circuit and the switching device. It includes the voltage shift of the neutral of a polyphase
circuit.
NOTE 2 The transient recovery voltage in three-phase circuits is, unless otherwise stated, that across the first
pole to clear, because this voltage is generally higher than that which appears across each of the other two poles.
[IEC 60050-441:1984, 441-17-26]

– 16 – 62271-106  IEC:2011
3.7.107
prospective transient recovery voltage (of a circuit)
transient recovery voltage following the breaking of the prospective symmetrical current by an
ideal switching device
NOTE The definition assumes that the switching device or the fuse, for which the prospective transient recovery
voltage is sought, is replaced by an ideal switching device, i.e. having instantaneous transition from zero to infinite
impedance at the very instant of zero current, i.e. at the "natural" zero. For circuits where the current can follow
several different paths, e.g. a polyphase circuit, the definition further assumes that the breaking of the current by
the ideal switching device takes place only in the pole considered.
[IEC 60050-441:1984, 441-17-29]
3.7.108
power frequency recovery voltage
recovery voltage after the transient voltage phenomena have subsided
[IEC 60050-441:1984, 441-17-27]
3.7.109
prospective current (of a circuit and with respect to a controller situated therein)
current that would flow in the circuit if each pole of the controller were replaced by a
conductor of negligible impedance
[IEC 60050-441:1984, 441-17-01, modified]
3.7.110
prospective peak current
peak value of a prospective current during the transient period following initiation
NOTE The definition assumes that the current is made by an ideal switching device, i.e. with instantaneous
transition from infinite to zero impedance. For circuits where the current can follow several different paths, e.g. polyphase
circuits, it further assumes that the current is made simultaneously in all poles, even if only the current in one pole
is considered.
[IEC 60050-441:1984, 441-17-02]
3.7.111
maximum prospective peak current (of an a.c. circuit)
prospective peak current when initiation of the current takes place at the instant which leads
to the highest possible value
NOTE For a multiple device in a polyphase circuit, the maximum prospective peak current refers to a single pole
only.
[IEC 60050-441:1984, 441-17-04]
3.7.112
prospective breaking current (for a pole of a switching device or a fuse)
prospective current evaluated at a time corresponding to the instant of the initiation of the
breaking process
NOTE Specifications concerning the instant of the initiation of the breaking process are to be found in the
relevant publications. For mechanical switching devices or fuses, it is usually defined as the moment of initiation of
the arc during the breaking process.
[IEC 60050-441:1984, 441-17-06]
3.7.113
minimum breaking current
minimum value of prospective current that a fuse-link is capable of breaking at a stated
voltage under prescribed conditions of use and behaviour
[IEC 60050-441:1984, 441-18-29]

62271-106  IEC:2011 – 17 –
3.7.114
cut-off current
let-through current
maximum instantaneous value of current attained during the breaking operation of a switching
device or a fuse
[IEC 60050-441:1984, 441-17-12]
NOTE Th
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