IEC 60947-4-2:2011

IEC 60947-4-2 ®
Edition 3.0 2011-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Low-voltage switchgear and controlgear –
Part 4-2: Contactors and motor-starters – AC semiconductor motor controllers
and starters
Appareillage à basse tension –
Partie 4-2: Contacteurs et démarreurs de moteurs – Gradateurs et démarreurs à
semiconducteurs de moteurs à courant alternatif

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IEC 60947-4-2 ®
Edition 3.0 2011-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Low-voltage switchgear and controlgear –
Part 4-2: Contactors and motor-starters – AC semiconductor motor controllers
and starters
Appareillage à basse tension –
Partie 4-2: Contacteurs et démarreurs de moteurs – Gradateurs et démarreurs à
semiconducteurs de moteurs à courant alternatif

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XD
ICS 29.130.20 ISBN 978-2-88912-505-0

– 2 – 60947-4-2 © IEC:2011
CONTENTS
FOREWORD . 6
INTRODUCTION . 8
1 Scope . 9
2 Normative references . 10
3 Terms, definitions, symbols and abbreviations . 10
3.1 General . 10
3.2 Alphabetical index of terms . 10
3.3 Terms and definitions concerning a.c. semiconductor motor controllers and
starters . 12
3.4 Terms and definitions concerning hybrid motor controllers and starters . 14
3.5 Terms and definitions concerning EMC definitions . 18
3.6 Symbols and abbreviations . 19
4 Classification . 19
5 Characteristics of a.c. semiconductor motor controllers and starters . 20
5.1 Summary of characteristics . 20
5.2 Type of equipment . 20
5.2.1 Form of equipment . 20
5.2.2 Number of poles . 20
5.2.3 Kind of current . 20
5.2.4 Interrupting medium (air, vacuum, etc.) . 20
5.2.5 Operating conditions of the equipment . 20
5.3 Rated and limiting values for main circuits . 21
5.3.1 Rated voltages . 21
5.3.2 Currents . 23
5.3.3 Rated frequency . 23
5.3.4 Rated duty . 23
5.3.5 Normal load and overload characteristics . 24
5.3.6 Rated conditional short-circuit current . 25
5.4 Utilization category . 25
5.4.1 General . 25
5.4.2 Assignment of ratings based on the results of tests . 26
5.5 Control circuits . 27
5.6 Auxiliary circuits . 27
5.7 Characteristics of relays and releases (overload relays) . 27
5.7.1 Summary of characteristics. 28
5.7.2 Types of relay or release . 28
5.7.3 Characteristic values . 28
5.7.4 Designation and current settings of overload relays . 29
5.7.5 Time-current characteristics of overload relays . 29
5.7.6 Influence of ambient air temperature . 30
5.8 Co-ordination with short-circuit protective devices (SCPD) . 30
6 Product information . 30
6.1 Nature of information . 30
6.2 Marking . 31
6.3 Instructions for installation, operation, and maintenance . 31
7 Normal service, mounting and transport conditions . 32

60947-4-2 © IEC:2011 – 3 –
7.1 Normal service conditions . 32
7.1.1 Ambient air temperature . 32
7.1.2 Altitude . 32
7.1.3 Atmospheric conditions . 32
7.1.4 Shock and vibrations . 32
7.2 Conditions during transport and storage . 32
7.3 Mounting . 32
7.4 Electrical system disturbances and influences . 32
8 Constructional and performance requirements . 33
8.1 Constructional requirements . 33
8.1.1 General . 33
8.1.2 Materials . 33
8.1.3 Current-carrying parts and their connections . 33
8.1.4 Clearances and creepage distances . 33
8.1.5 Actuator . 33
8.1.6 Indication of the contact position . 33
8.1.7 Additional requirements for equipment suitable for isolation . 33
8.1.8 Terminals . 33
8.1.9 Additional requirements for equipment provided with a neutral pole . 34
8.1.10 Provisions for protective earthing . 34
8.1.11 Enclosures for equipment . 34
8.1.12 Degrees of protection of enclosed equipment . 34
8.1.13 Conduit pull-out, torque and bending with metallic conduits . 34
8.2 Performance requirements . 34
8.2.1 Operating conditions . 34
8.2.2 Temperature rise . 38
8.2.3 Dielectric properties. 41
8.2.4 Normal load and overload performance requirements . 42
8.2.5 Co-ordination with short-circuit protective devices . 47
8.3 EMC requirements . 47
8.3.1 General . 47
8.3.2 Emission . 48
8.3.3 Immunity . 48
9 Tests . 50
9.1 Kinds of tests . 50
9.1.1 General . 50
9.1.2 Type tests . 50
9.1.3 Routine tests . 50
9.1.4 Sampling tests . 50
9.1.5 Special tests . 51
9.2 Compliance with constructional requirements . 51
9.3 Compliance with performance requirements . 51
9.3.1 Test sequences . 51
9.3.2 General test conditions . 52
9.3.3 Performance under no load, normal load, and overload conditions . 52
9.3.4 Performance under short-circuit conditions . 62
9.3.5 EMC tests . 65
9.3.6 Routine and sampling tests . 68
Annex A (normative) Marking and identification of terminals . 70

– 4 – 60947-4-2 © IEC:2011
Annex B Vacant . 73
Annex C (normative) Co-ordination at the crossover current between the starter and
associated SCPD . 74
Annex D Vacant . 78
Annex E Vacant . 79
Annex F (informative) Operating capability. 80
Annex G (informative) Examples of control circuit configurations . 83
Annex H Vacant . 85
Annex I (normative) Modified test circuit for short-circuit testing of semiconductor

motor controllers and starters . 86
Annex J (informative) Flowchart for constructing bypassed semiconductor controllers
tests . 88
Annex K (normative) Extended functions within electronic overload relays . 89
Bibliography . 94

Figure 1 – Semiconductor motor control devices . 13
Figure 2 – Connecting methods . 22
Figure 3 – Thermal memory test . 36
Figure 4 – Multiple of current setting limits for ambient air temperature compensated
time-delay overload relays . 62
Figure C.1 – Examples of time-current withstand characteristic . 77
Figure F.1 – Thermal stability test profile . 80
Figure F.2 – Overload capability test profile . 81
Figure F.3 – Blocking and commutating capability test profile . 82
Figure G.1 – Diagrammatic representation of an ECD . 83
Figure G.2 – Single supply and control input . 83
Figure G.3 – Single supply and control input . 84
Figure G.4 – Controllers with an internal control supply and control input only . 84
Figure I.1 − Modified circuit for short-circuit testing of semiconductor devices . 86
Figure I.2 − Time line for the short-circuit test of 9.3.4.1.6 . 87
Figure K.1 – Test circuit for the verification of the operating characteristic of a residual

current electronic overload relay . 93

Table 1 – Functional possibilities of semiconductor motor control devices . 14
Table 2 – Utilization categories . 26
Table 3 – Relative levels of severity . 27
Table 4 – Trip classes of overload relays . 29
Table 5 – Limits of operation of time-delay overload relays when energized on all poles . 35
Table 6 – Limits of operation of three-pole time-delay overload relays when energized
on two poles only . 37
Table 7 – Temperature rise limits for insulated coils in air and in oil . 40
Table 8 – Intermittent duty test cycle data . 40
Table 9 – Minimum overload current withstand time (T ) in relation to overload current
x
ratio (X) and corresponding to overload relay trip class (see Table 19) . 43
a
Table 10 – Minimum requirements for thermal stability test conditions . 43

60947-4-2 © IEC:2011 – 5 –
Table 11 – Minimum requirements for overload capability test conditions . 44
Table 12 – Minimum requirements and conditions for performance testing with an
induction motor load . 44
Table 13 – Making and breaking capacity test; making and breaking conditions
according to utilization categories for the mechanical switching device of hybrid motor
controllers H1, H2, H3 and for certain forms of bypassed controllers . 46
Table 14 – Conventional operational performance making and breaking conditions
according to utilization categories for the mechanical switching device of hybrid motor
controllers H1B, H2B, H3B and for certain forms of bypassed controllers . 46
Table 15 – Specific acceptance or performance criteria when EM disturbances are
present . 49
Table 16 – Thermal stability test specifications . 57
Table 17 – Initial case temperature requirements . 57
Table 18 – Blocking and commutating capability test specifications . 59
Table 19 – Terminal disturbance voltage limits for conducted radio-frequency emission . 67
Table 20 – Radiated emissions test limits . 67
Table A.1 – Main circuit terminal markings . 70
Table C.1 – Test conditions . 76
Table K.1 – Operating time of residual current electronic overload relays . 90

– 6 – 60947-4-2 © IEC:2011
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 4-2: Contactors and motor-starters –
AC semiconductor motor controllers and 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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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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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
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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 60947-4-2 has been prepared by subcommittee 17B: Low-voltage
switchgear and controlgear, of IEC technical committee 17: Switchgear and controlgear.
This third edition replaces the second edition published in 1999 and its Amendments 1 (2001)
and 2 (2006). It is a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition and its amendments:
• updated EMC normative references and associated requirements,
• new references to IEC 60947-1,
• marking of electronic relays without thermal memory,
• marking of tripping time at 0 °C ambient or below,
• new test requirements for limits of operation of time-delay overload relays,

60947-4-2 © IEC:2011 – 7 –
 new classes of overload current withstand time,
 damp heat, salt mist, vibration and shock tests,
 short-circuit test in the smallest enclosure,
 update of the routine and sampling tests.
This standard shall be read in conjunction with IEC 60947-1:2007, Low-voltage switchgear
and controlgear – Part 1: General rules. The provisions of the general rules are applicable to
this standard, where specifically called for.
The text of this standard is based on the following documents:
FDIS Report on voting
17B/1734/FDIS 17B/1741/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.
A list of all the parts in the IEC 60947 series, under the general title Low-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 July 2012 have been included in this copy.

– 8 – 60947-4-2 © IEC:2011
INTRODUCTION
This standard covers low-voltage a.c. semiconductor motor controllers and starters that have
many capabilities and features beyond the simple starting and stopping of an induction motor,
such as controlled starting and stopping, manoeuvring and controlled running.
The generic term “controller” is used in this standard wherever the unique features of the
power semiconductor switching elements are the most significant points of interest. The
generic term “starter” is used wherever the consequences of operating the power semi-
conductor switching elements, together with suitable overload protective means, are the most
significant points of interest. Specific designations (for example form 1, form HxB, etc.) are
used wherever the unique features of various configurations comprise significant points of
interest.
60947-4-2 © IEC:2011 – 9 –
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 4-2: Contactors and motor-starters –
AC semiconductor motor controllers and starters

1 Scope
This standard applies to a.c. semiconductor motor controllers and starters, which may include
a series mechanical switching device, intended to be connected to circuits, the rated voltage
of which does not exceed 1 000 V a.c.
This standard characterizes a.c. semiconductor motor controllers and starters with and
without bypass means.
AC semiconductor motor controllers and starters dealt with in this standard are not normally
designed to interrupt short-circuit currents. Therefore, suitable short-circuit protection (see
8.2.5) should form part of the installation, but not necessarily of the a.c. semiconductor motor
controller or starter.
In this context, this standard gives requirements for a.c. semiconductor motor controllers and
starters associated with separate short-circuit protective devices.
This standard does not apply to
– continuous operation of a.c. motors at motor speeds other than the normal speed;
– semiconductor equipment, including semiconductor contactors (see 2.2.13 of
IEC 60947-1:2007) controlling non-motor loads;
– electronic a.c. power controllers covered by IEC 60146 series.
Contactors, overload relays and control circuit devices used in a.c. semiconductor motor
controllers and starters should comply with the requirements of their relevant product
standard. Where mechanical switching devices are used, they should meet the requirements
of their own IEC product standard, and the additional requirements of this standard.
The object of this standard is to state as follows:
– the characteristics of a.c. semiconductor motor controllers and starters and associated
equipment;
– the conditions with which a.c. semiconductor motor controllers and starters comply with
reference to
a) their operation and behaviour;
b) their dielectric properties;
c) the degrees of protection provided by their enclosures where applicable;
d) their construction;
– the tests intended for confirming that these conditions have been met, and the methods to
be adopted for these tests;
– the information to be given with the equipment, or in the manufacturer's literature.
NOTE For the purpose of this standard, the term "controller" may be used instead of
"a.c. semiconductor motor controller".

– 10 – 60947-4-2 © IEC:2011
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 60034-1:2010, Rotating electrical machines – Part 1: Rating and performance
IEC 60085:2007, Electrical insulation – Thermal evaluation and designation
IEC 60269-1:2006, Low-voltage fuses – Part 1: General requirements
Amendment 1 (2009)
IEC 60410:1973, Sampling plans and procedures for inspection by attributes
IEC 60664 (all parts), Insulation coordination for equipment within low-voltage systems
IEC 60947-1:2007, Low-voltage switchgear and controlgear – Part 1: General rules
IEC 61000-4 (all parts), Electromagnetic compatibility (EMC) – Part 4: Testing and
measurement techniques
CISPR 11:2009, Industrial, scientific and medical equipment – Radio-frequency disturbance
characteristics – Limits and methods of measurement
Amendment 1 (2010)
3 Terms, definitions, symbols and abbreviations
3.1 General
For the purposes of this document, the terms and definitions of Clause 2 of IEC 60947-
1:2007, as well as the following terms, definitions, symbol and abbreviations apply.
3.2 Alphabetical index of terms
Reference
A
a.c. semiconductor motor controller . 3.3.2
B
burst (of pulses or oscillations) . 3.5.7
bypassed controller . 3.4.31
C
CO operation . 3.4.32
controlled acceleration . 3.4.6
controlled deceleration . 3.4.7
controlled running . 3.4.8
current-limit function . 3.4.4
E
electromagnetic compatibility [EMC] . 3.5.1
electromagnetic disturbance . 3.5.3
electromagnetic emission . 3.5.2

60947-4-2 © IEC:2011 – 11 –
F
FULL-ON (state of controllers) . 3.4.12
H
hybrid motor controller or starter, form HxA (where x = 1, 2 or 3) . 3.4.1
hybrid motor controller or starter, form HxB . 3.4.2
I
inhibit time . 3.4.28
J
jam sensitive electronic overload relay . 3.4.27
M
manoeuvre . 3.4.5
minimum load current . 3.4.13
O
O operation . 3.4.33
OFF-state . 3.4.14
OFF-state leakage current [I ]. 3.4.15
L
OFF-time . 3.4.30
ON-state . 3.4.11
ON-time . 3.4.29
OPEN position . 3.4.3
operating capability . 3.4.18
operating cycle (of a controller) . 3.4.17
operation (of a controller). 3.4.16
overload current profile . 3.4.19
P
phase loss sensitive overload relay or release . 3.4.23
prospective current (of a circuit and with respect to a switching device or a fuse) . 3.4.9
prospective locked rotor current [I ] . 3.4.10
LRP
R
radio (frequency) disturbance . 3.5.4
radio frequency interference [RFI] . 3.5.5
rating index . 3.4.20
S
semiconductor direct on line (DOL) motor controller (form 3) . 3.3.5
semiconductor motor controller (form 1) . 3.3.3
semiconductor motor starter (form 1, form 2, form 3) . 3.3.6
semiconductor soft-start motor controller (form 2) . 3.3.4
semiconductor switching device . 3.3.1
stall sensitive electronic overload relay . 3.4.26
T
transient (adjective and noun) . 3.5.6
trip-free controller or starter . 3.4.22
tripping operation (of a controller or starter) . 3.4.21
U
under-current relay or release . 3.4.24
under-voltage relay or release . 3.4.25

– 12 – 60947-4-2 © IEC:2011
V
voltage surge . 3.5.8

3.3 Terms and definitions concerning a.c. semiconductor motor controllers and
starters
3.3.1
semiconductor switching device
switching device designed to make and/or break the current in an electric circuit by means of
the controlled conductivity of a semiconductor
NOTE This definition differs from IEC 60050-441:1984, 441-14-03 since a semiconductor switching device is also
designed for breaking the current.
[IEC 60947-1:2007, 2.2.3]
3.3.2
a.c. semiconductor motor controller
semiconductor switching device that provides the starting function for an a.c. motor and an
OFF-state
NOTE 1 Because dangerous levels of leakage currents can exist in a semiconductor motor controller in the OFF-
state, the load terminals should be considered as live parts at all times.
NOTE 2 In a circuit where the current passes through zero (alternately or otherwise), the effect of "not making"
the current following such a zero value is equivalent to breaking the current.
3.3.3
semiconductor motor controller (form 1)
a.c. semiconductor motor controller, in which the starting function may comprise any starting
method specified by the manufacturer, and that provides control functions which may include
any combination of manoeuvring, controlled acceleration, running or controlled deceleration of
an a.c. motor. A FULL-ON state may also be provided
NOTE See Figure 1 and Table 1.
3.3.4
semiconductor soft-start motor controller (form 2)
special form of a.c. semiconductor motor controller, in which the starting function is limited to
a voltage and/or current ramp which may include controlled acceleration, and where the
additional control function is limited to providing FULL-ON
NOTE See Figure 1 and Table 1.
3.3.5
semiconductor direct on line (DOL) motor controller (form 3)
special form of a.c. semiconductor motor controller, in which the starting function is limited to
a full-voltage, unramped starting method only, and where the additional control function is
limited to providing FULL-ON
NOTE See Figure 1 and Table 1.
3.3.6
semiconductor motor starter (form 1, form 2, form 3)
a.c. semiconductor motor controller with suitable overload protection, rated as a unit
NOTE See Figure 1 and Table 1.

60947-4-2 © IEC:2011 – 13 –
Device
Semiconductor
motor controller
(forms 1, 2, 3)
IEC  1731/99
Semiconductor
motor starter
(forms 1, 2, 3)
IEC  1732/99
Hybrid motor
controller
a
HxA
where x = 1, 2 or 3
IEC  1733/99
Hybrid motor
controller
b
HxB
IEC  1734/99
Parallel mechanical
contact
Bypassed controller
Semiconductor controller
L T
(Forms 1, 2, 3)
IEC  2344/01
Parallel mechanical
contact
Hybrid motor controller
Bypassed hybrid motor
c
controller
Series Semiconductor
L
T
mechanical controller
contact
(Forms HxA, HxB)
IEC  2345/01
Form H1A or H1B Form H2A or H2B Form H3A or H3B
Hybrid motor
with motor overload with motor overload with motor overload
starter
protection protection protection
a
Two separate controls for the controller and the series mechanical switching device.
b
One control only for the series mechanical switching device.
c
For other configurations, tests may be suitably adapted by agreement between the user and the
manufacturer.
Figure 1 – Semiconductor motor control devices

– 14 – 60947-4-2 © IEC:2011
Table 1 – Functional possibilities of semiconductor motor control devices
Device Form 1 Form 2 Form 3
Semiconductor – OFF – OFF state Not available
motor controller
– Starting function – Starting function
– Manoeuvring – Controlled acceleration
– Controlled acceleration – FULL ON
– Running
– FULL ON
– Controlled deceleration
Semiconductor DOL Not available Not available – OFF state
motor controller
– Starting function
– FULL ON
Semiconductor Form 1 controller with motor Form 2 controller with Not available
motor starter overload protection motor overload protection
Semiconductor DOL Not available Not available Form 3 DOL motor
motor starter controller with motor
overload
protection
Hybrid motor H1A: H2A: H3A:
a
controller HxA
– Open – Open – Open
where x = 1, 2 or 3
– OFF state – OFF state – OFF state
– Starting function – Starting function – Starting function
– Manoeuvring – Controlled acceleration – FULL ON
– Controlled acceleration – FULL ON
– Ru
...