IEC 60947-4-2:2020/AMD1:2024

IEC 60947-4-2 ®
Edition 4.0 2024-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
AMENDMENT 1
AMENDEMENT 1
Low-voltage switchgear and controlgear –
Part 4-2: Contactors and motor-starters – Semiconductor motor controllers,
starters and soft-starters
Appareillage à basse tension –
Partie 4-2: Contacteurs et démarreurs de moteurs – Gradateurs, démarreurs et
démarreurs progressifs à semiconducteurs de moteurs
IEC 60947-4-2:2020-06/AMD1:2024-11(en-fr)

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IEC 60947-4-2 ®
Edition 4.0 2024-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
AMENDMENT 1
AMENDEMENT 1
Low-voltage switchgear and controlgear –
Part 4-2: Contactors and motor-starters – Semiconductor motor controllers,
starters and soft-starters
Appareillage à basse tension –
Partie 4-2: Contacteurs et démarreurs de moteurs – Gradateurs, démarreurs et
démarreurs progressifs à semiconducteurs de moteurs
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.130.20 ISBN 978-2-8322-9820-6
– 2 – IEC 60947-4-2:2020/AMD1:2024
© IEC 2024
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 4-2: Contactors and motor-starters –
Semiconductor motor controllers, starters and soft-starters

AMENDMENT 1
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
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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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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) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
the latest information, which may be obtained from the patent database available at https://patents.iec.ch [and/or]
www.iso.org/patents. IEC shall not be held responsible for identifying any or all such patent rights.
Amendment 1 to IEC 60947-4-2:2020 has been prepared by subcommittee 121A: Low-voltage
switchgear and controlgear, of IEC technical committee 121: Switchgear and controlgear and
their assemblies for low voltage.
This amendment includes the following significant technical changes with respect to the current
edition:
– Requirement for starter intended to be used with high efficiency motors.
– Requirements and tests for abnormal conditions equivalent to Annex DVE of the UL version.
– Alignment to the EMC environments defined in IEC TR 63216 and more detailed emission
limit requirements.
© IEC 2024
– Reference to IEC TS 63058 for environmental information.
– Reference to IEC 63404 for the integration of radio communication.
The text of this Amendment is based on the following documents:
Draft Report on voting
121A/615/FDIS 121A/626/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Amendment is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications/.
A list of all parts in the IEC 60947 series, published 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 document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
___________
1 Scope
Delete footnote 1.
2 Normative references
Replace the existing reference:
IEC 60445, Basic and safety principles for man-machine interface, marking and identification –
Identification of equipment terminals, conductor terminations and conductors
with
IEC 60445:2021, Basic and safety principles for man-machine interface, marking and
identification – Identification of equipment terminals, conductor terminations and conductors

– 4 – IEC 60947-4-2:2020/AMD1:2024
© IEC 2024
Add the following references to the list:
IEC 63404:2024, Switchgear and controlgear and their assemblies for low voltage – Integration
of radiocommunication device above 380 MHz into an equipment
IEC TS 63058, Environmental aspects for low-voltage switchgear and controlgear and their
assemblies
5.3.2.5 Maximum OFF-state current (I )
Lm
Replace the reference to "9.3.3.6.3" with "9.3.3.6.4".

5.3.5.4.1 Starting characteristics of squirrel cage and hermetic refrigeration motors
Replace the third paragraph with the following:
Two directions of rotation are not covered by this document.
Delete the fourth paragraph.
5.4.1 General
Replace the second paragraph with the following:
For semiconductor motor controllers, starters and soft-starters, the utilization categories are
given in Table 1.
5.6 Auxiliary circuits
Delete the second sentence of the third paragraph.

5.7.5 Time-current characteristics of overload relays
Replace in the first paragraph:
"(see 9.3.3.6.5, item c))"
with
"(see 9.3.3.6.6, item c))"
© IEC 2024
6.2 Marking
Replace, in the third paragraph: "k)" with: "j)".
Add, at the end of the existing text, the following new paragraph.
When a radiocommunication device is embedded into the equipment, additional information
according to 6.2 and 6.3 of IEC 63404:2024 shall apply.

6.3 Instructions for installation, operation, maintenance, decommissioning and
dismantling
Add, after the fourth paragraph, the following new text:
The instructions shall also cover other specific application limitations, when applicable, such as
altitude above 1 000 m and two direction starters.
When the embedded radiocommunication device can be upgraded, additional information
according to 6.4 of IEC 63404:2024 shall apply.
Delete in the sixth paragraph the word "relevant" and add after "potential hazard", "according
to 8.1.1, 8.1.15, 8.1.17 and 8.2.2."

6.4 Environmental information
Replace the existing text, including the note, with the following new text:
Hazardous substances used by design in the equipment shall be declared in the product
documentation.
When declared, the material declarations shall be provided according to IEC TS 63058.
IEC TS 63058 should also be considered carefully for providing measures to prevent emission
of or contact with hazardous substances.
NOTE IEC TS 63058 provides methods for assessing the environmental impact of switchgear and controlgear,
guidance on environmentally conscious design and on information needed for end-of-life treatments.

7.1.2 Altitude
Add, in the first sentence, after "maximum altitude", the following:
"in 6.1 t)".
Replace the existing second paragraph with the following new text:
For the use of the equipment above 1 000 m, specific instruction can be necessary for the
additional cooling means of the power semiconductor or the derating of rated values of 5.3.

– 6 – IEC 60947-4-2:2020/AMD1:2024
© IEC 2024
7.1.3.2 Degrees of pollution
Replace, in the first sentence,
"by the manufacturer"
with: "in the product documentation".

8.1.1 General
Add, at the end of the first sentence of the fourth paragraph, the following:
"if tested under the conditions given in this document."
Replace, in the last sentence of the fourth paragraph:
"should"
with
"shall".
Add, at the end of the fourth paragraph, the following new text:
When a radiocommunication device is embedded into the equipment, C.4.2 of IEC 63404:2024
applies. The interruption of the radiocommunication link shall not affect the current operation of
the equipment.
Delete the existing seventh paragraph.
Delete the existing last paragraph.

8.1.8.2 Terminal identification and marking
Replace in the second paragraph:
"in accordance with IEC 60445"
with
"in accordance with Clause 5 of IEC 60445:2021".

© IEC 2024
8.1.16 Fault and abnormal conditions
Add at the end of the fourth paragraph the following new sentence:
The analysis shall be included in the test report.
Add after the existing fourth paragraph the following new note:
NOTE 1 FMEA (Failure Mode and Effects Analysis) is generally used for this circuit analysis method.
Add, at the end of the subclause, the following new text:
In case of an operating condition with a loss of phase, polyphase products shall not present a
hazard. Compliance shall be checked by the test of 9.2.7.2.
NOTE 2 A loss of phase can be the result of an external phase supply interruption from the mains or an internal
phase interruption.
8.1.17 Short-circuit and overload protection of ports
Replace in the second paragraph:
"inspection"
with
"review of the product documentation"

8.2.1.3 Limits of operation of under-voltage relays and releases
Replace in the first paragraph:
"9.3.3.6.5"
with
"9.3.3.6.6"
8.2.1.5.1.1.1 General tripping requirements of overload relays
Delete:
NOTE 1
and renumber subsequent notes accordingly.

– 8 – IEC 60947-4-2:2020/AMD1:2024
© IEC 2024
8.2.1.5.1.2 Limits of operation of three-pole time-delay overload relays energized on two
poles
Replace, in the third paragraph:
"Moreover, when …"
With:
"Then, one pole shall be disconnected. When …".
Delete, in the third paragraph "and the third pole de-energized".

8.2.1.6 Mechanical switching devices used in semiconductor motor controllers and
starters
Add, after the existing text, the following new paragraph:
The effectiveness of the interlocking shall be demonstrated during the thermal stability test or
overload capability test in 9.3.3.6.1 or be verified by any other test covering the interlocking
function for example by oscillographic means.

8.2.4.1 Operating capability requirements
Delete the sixth paragraph and the NOTE.
Replace the existing seventh paragraph with the following new text:
Where X × I is greater than 1 000 A, the overload capability verification may be provided by
e
other methods such as computer modelling simulation. The method and the result shall be
described in the test report.
Replace in the eighth paragraph the first occurrence of:
"standard duty cycle sequence"
with
"standard duty cycle sequence based on Table 8"
a
Add to Table 9 the following new footnote referring to cell of 8 × I
e
a
For devices with no controlled acceleration (DOL) and intended for use with an asynchronous motor of design
NE or HE according to IEC 60034-12:2016, I is equal to 8,5 × I
LRP e.
d
Add to the existing footnote of Table 10 the following new text:
For devices with no controlled acceleration (DOL) and intended for use with an asynchronous motor of design
NE or HE according to IEC 60034-12:2016, cos ϕ = 0,35 for I ≤ 100 A: cos ϕ = 0,25; for I > 100 A.
e e
© IEC 2024
8.2.4.3 Requirements for an induction motor test load
Delete items b) to d),and change existing item e) to b).
c
Add a new footnote reference to Table 11, in the cell with the value "8,0" of column "I /I " and
c e
the row "AC-3a, b" with the following new footnote:
c
For devices with no controlled acceleration (DOL) and intended for use with an asynchronous motor of design NE
or HE according to IEC 60034-12:2016, I /I is equal to 8,5.
c e
8.2.5.1 Performance under short-circuit conditions
Delete the last sentence of the first paragraph.

8.3.1 General
Replace the existing second paragraph with the following new text:
Environments A and B of IEC 60947-1:2020 are implemented in this document in 8.3.3.1 as
class A and B equipment according to CISPR 11.
The general electromagnetic environment of the equipment covered by this document is E-III,
industrial according to IEC TR 63216.
Other environments defined by IEC TR 63216 may be selected. The environment E-IV is
relevant for equipment intended for being installed within high voltage power station and
substation. The environment E-II is relevant for accessories such as control device or digital
interfaces not directly supplied by the factory mains (see IEC TR 63216).
Add, at the end the subclause, the following new paragraph:
When a radiocommunication device is embedded into the equipment, 8.4 of IEC 63404:2024
shall apply.
8.3.2.1 General
Delete the existing second, third and fourth paragraphs.

8.3.3.1 General
Add, at the end of the subclause, the following new paragraph:
The limits of CISPR 11 apply for Class B equipment intended to be used in residential areas
connected to public low-voltage distribution systems and for Class A equipment intended to be
used in all locations other than those allocated in residential areas.

– 10 – IEC 60947-4-2:2020/AMD1:2024
© IEC 2024
9.1.4 Sampling tests
Replace, in the last paragraph:
"are under consideration"
with
"apply".
9.1.5.1 General
Replace the existing text of this subclause with the following new text:
Verifications are required when environment withstand data according to 9.1.5.2 or short-circuit
coordination data according to 9.1.5.3 are given in the equipment documentation.

9.1.5.2 Environmental tests
Delete the last existing paragraph.

9.2.5.2 Breakdown of components test
Add, at the end of the first paragraph, the following new text:
This shall include the condition where forced cooling system is made inoperative by physically
preventing its operation. In case of multiple cooling channels, only one channel at a time shall
be made inoperable.
NOTE 1 The forced cooling system can be made inoperative for example by disconnecting the supply of the fan.
Renumber the existing NOTE as NOTE 2.

Add the following new subclause:
9.2.5.3 Test conditions
In case of a forced cooling system made inoperative, the test shall be terminated when a
protective device trips or when the temperature of the semiconductors in the main circuits
stabilize. The temperature shall be measured as for the temperature-rise test according to
9.3.3.3.4. Thermal stability is reached when the variation does not exceed 1 K per hour.

© IEC 2024
Add the following new subclause 9.2.7 after 9.2.6.
9.2.7 Abnormal operating tests
9.2.7.1 General
Before all abnormal operation tests, the test sample shall be mounted, connected, and operated
as described in the temperature-rise test.
Faults that are the direct consequence of an abnormal operating conditions are considered to
be part of that abnormal operating condition.
For equipment without a dedicated enclosure, the equipment shall be tested under the
conditions of 9.2.5.3.
Surgical cotton shall be placed over all openings, handles, flanges, joints and similar locations
on the outside of the enclosure, in a manner which will not significantly affect the cooling when
the test lasts long enough to have significant temperature rise.
Where the equipment under test is specified in its installation manual to require external means
of protection against faults, these specific means shall be provided for the test.
The individual tests shall be performed until terminated by activation of a protective device or
mechanism (internal or external), a component failure occurs that interrupts the fault condition,
or the temperature of the semiconductors or the mechanical switching device, as indicated in
9.3.3.3.4, in the main circuits stabilize. The temperature shall be measured as for the
temperature-rise test according to 9.3.3.3.4. It is assumed that a steady state is reached when
the variation does not exceed 1 K per hour.
9.2.7.2 Loss of phase
This test is not required for a semiconductor motor-starter that meets:
– The test requirements of 9.3.3.6.6 c) for three-pole thermal or electronic overload relays
energized on two poles only;
– In addition to the test of 8.2.1.5.1.2, this test shall be repeated with one pole disconnected
and with the relay energized on only two poles at B times the current setting. The tripping
operation shall occur in less than 2 h, starting from the cold state; and
– The adequacy of the insulation shall be verified by a dielectric test on the controller or
starter. The test voltage shall be applied as specified in 9.3.3.4.1 (4).
A multi-phase equipment shall be operated with each phase (including neutral, if used), in turn,
disconnected at the input. The test shall be performed by disconnecting one phase with the
(with one phase of the load disconnected)
equipment operating at 1,32 times the rated current I
e
and shall be repeated by initially energizing the equipment with one phase disconnected.
The test shall continue according to the conditions of 9.2.7.1, but shall be terminated after
21 min.
If the disconnection of a single phase can decisively be determined to result in a more severe
condition, for example disconnection of the phase with the protective device least likely to
respond to the loss of phase, then the test can be conducted by disconnecting only that phase
instead of each phase in turn.
NOTE If fuses are used, a voltage can remain at the open phase caused by internal impedances within the
equipment connected between the phases.

– 12 – IEC 60947-4-2:2020/AMD1:2024
© IEC 2024
9.2.7.3 Acceptance criteria
As a result of the abnormal operation tests, the equipment shall comply with the following:
a) there shall be no emission of flame, burning particles or molten metal;
b) the surgical cotton shall not have ignited;
c) the connection to protective earth and the earth continuity of the equipment shall not have
opened;
d) doors and covers of enclosed equipment shall remain in place;
e) accessible circuits shall not exhibit hazardous voltages;
f) during and after the test, hazardous live parts at voltages greater than SELV/PELV in
accordance with Annex N of IEC 60947-1:2020 or limited energy source levels of 8.1.14
shall not become accessible;
g) components, e.g. busbar supports, used for the mounting of live parts shall not break away
from their initial position;
h) no conductor shall get pulled out of its terminal connector; and
i) no parts shall be ejected from the enclosure of the enclosed equipment.
The equipment shall comply with the power frequency or DC withstand voltage test of 9.3.3.4.1
(4) following the abnormal operation tests.
The equipment is not required to be operational after testing and can become deformed.
Overcurrent protection integral to the equipment, or required to be used with the equipment, is
allowed to open.
9.3.1 Test sequences
Replace the existing second and third paragraphs by the following new notes:
NOTE 1 More than one test sequence or all test sequences can be conducted on one sample. However, the tests
are conducted in the sequence given for each sample.
NOTE 2 Some tests are included in the sequences solely to reduce the number of samples required, the results
have no significance for the preceding or following tests in the sequence. Therefore, for convenience of testing, these
tests can be conducted on separate new samples and omitted from the relevant sequence. This can only apply to
the following tests when called for:
– 9.3.3.4.1, item 7) of IEC 60947-1:2020, Verification of creepage distances;
– 9.2.5 of IEC 60947-1:2020, Mechanical and electrical properties of terminals;
– Annex C of IEC 60947-1:2020, Degrees of protection of enclosed equipment.

9.3.3.3.4 Temperature-rise of the main circuit
Replace the existing first paragraph by the following new text:
Subclause 9.3.3.3.4 of IEC 60947-1:2020 applies with a minimum cross-section of 1 mm with
additions as below, with the exception that a single-phase test shall be conducted with all poles
in the main circuit loaded at their individual maximum rated currents and as stated in 8.2.2.5.

© IEC 2024
9.3.3.4.1 Type tests
Replace the existing text under (3) c) Application of test voltage, with the following new text:
Subclause 9.3.3.4.1 3) c) of IEC 60947-1:2020 applies with the following addition:
The test voltage shall be applied for semiconductor controller or starters with series mechanical
switching device, across the poles of the main circuit, the line terminals being connected
together, and the load terminals connected together.

9.3.3.4.3 Sampling tests for verification of clearances
Delete this subclause.
9.3.3.6.1 General
Add, at the end of the subclause, the following new paragraph:
If the mechanical switching devices is interlocked such that it is not required to make or break
overload currents without direct intervention of the semiconductor switching device, the
effectiveness of the interlocking shall be demonstrated in accordance with 8.2.1.6.

9.3.3.6.6 Relays and releases
a) Operation of under-voltage relays and releases
Add, after "8.2.1.3", "of IEC 60947-1:2020"
c) Thermal and electronic overload relays
Replace in the last paragraph "8.2.1.5.2" with "8.2.1.5.1.2"

9.3.4.1.1 General requirements for short-circuit tests
Delete the second paragraph.
9.3.4.1.2 Test circuit for the verification of short-circuit ratings
Replace the text of the existing first paragraph with the following new text:
The test circuit of 9.3.4.1.2 of IEC 60947-1:2020 applies except that for type 1 coordination, the
fusible element F and the resistance R are replaced by a solid 6 mm wire 1,2 m to 1,8 m in
L
length, connected to the neutral, or to one of the poles of polyphase equipment. In the case of
pole connection, the pole shall be alternated for the successive tests of the test sequence.

– 14 – IEC 60947-4-2:2020/AMD1:2024
© IEC 2024
9.4.1 General
Delete the second paragraph.
Replace the existing third sentence of the fourth paragraph with the following new sentence:
The length of the connections to the motor shall be 3 m or the value specified in the instruction
manual of the equipment.
Add, after the existing third paragraph, the following new paragraph:
When a radiocommunication device is embedded into the equipment, Clause 9 of
IEC 63404:2024 applies.
Delete, in the seventh paragraph:
"chosen by the manufacturer".
Move the existing note in 9.4.3.1 to the end of this subclause, and delete the word:
"Emission".
9.4.2.5 Harmonics and commutation notches
Replace the existing title and text of this subclause with the following:
9.4.2.5 Harmonics in the supply
For soft-starter with electronic overload relay, in order to avoid unwanted tripping, the true RMS
response shall be verified up to the fifth harmonic component at 50 % of the fundamental
component:
– by test according to F.4.1 of IEC 60947-2:2016, if applicable; or
NOTE 1 This test method is applicable when current harmonics can be injected on separated current circuits
from the supply of the controller.
– by simulation, using models for which the validity has to be demonstrated; or
– by design assessment, i.e. confirmation of the correct application of calculations and design
rules, including use of appropriate safety margins.
NOTE 2 Current waveform asymmetry, typically in case of failure of a power semiconductor connected on the
network, is creating a significant unbalance and can affect the current detection of an electronic overload protection
and therefore a true RMS measurement is relevant.

9.4.2.6 Voltage dips and short-time interruptions
Replace the existing paragraph by the following:
This test shall be performed in accordance with IEC 61000-4-11 for rated current less than 16 A
and in accordance with IEC 61000-4-34 for rated current higher than 16 A and with the
performance criterion 3 of Table 13 except for the 0,5 cycle and 1 cycle for which the
performance criterion 2 of Table 13 applies.

© IEC 2024
9.4.3.1 Condition for the emission tests
Add, at the end of the first paragraph, the following:
"with the exclusion of the first and second paragraphs of its subclause 7.1".

9.4.3.2 Conducted radio frequency emission test
Delete the first paragraph.
Delete the fourth and fifth paragraphs.

Table 17 – Terminal disturbance volta
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