IEC 60947-1:2007/AMD2:2014

Amendment 2 - Low-voltage switchgear and controlgear - Part 1: General rules

Amendement 2 - Appareillage à basse tension - Partie 1: Règles générales

General Information

• Status: Published
• Publication Date: 08-Sep-2014
• ICS: 29.130.20 - Low voltage switchgear and controlgear
• Technical Committee: SC 121A - Low-voltage switchgear and controlgear
• Drafting Committee: MT 5 - TC 121/SC 121A/MT 5
• Current Stage: DELPUB - Deleted Publication
• Start Date: 22-Apr-2020
• Completion Date: 26-Oct-2025

Relations

• Amends: IEC 60947-1:2007 - Low-voltage switchgear and controlgear - Part 1: General rules
• Effective Date: 05-Sep-2023
• Revised: IEC 60947-1:2020 - Low-voltage switchgear and controlgear - Part 1: General rules
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 60947-1 ®
Edition 5.0 2014-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
A MENDMENT 2
AM ENDEMENT 2
Low-voltage switchgear and controlgear –
Part 1: General rules
Appareillage à basse tension –
Partie 1: Règles générales
IEC 60947-1:2007-06/AMD2:2014-09(en-fr)

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IEC 60947-1 ®
Edition 5.0 2014-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
A MENDMENT 2
AM ENDEMENT 2
Low-voltage switchgear and controlgear –

Part 1: General rules
Appareillage à basse tension –

Partie 1: Règles générales
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XA
ICS 29.130.20 ISBN 978-2-8322-1798-6

– 2 – IEC 60947-1:2007/AMD2:2014

© IEC 2014
FOREWORD
This amendment has been prepared by subcommittee 17B: Low-voltage switchgear and

controlgear, of IEC technical committee 17: Switchgear and controlgear.

The text of this amendment is based on the following documents:

FDIS Report on voting
121A/15/FDIS 121A/21/RVD
Full information on the voting for the approval of this amendment can be found in the report
on voting indicated in the above table.
The committee has decided that the contents of this amendment and the base 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• withdrawn,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.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
_____________
1.1 Scope and object
Replace the existing text of this subclause by the following new text:
This standard applies, when required by the relevant product standard, to low-voltage

switchgear and controlgear hereinafter referred to as "equipment" or "device" and intended to
be connected to circuits the rated voltage of which does not exceed 1 000 V a.c. or
1 500 V d.c.
This standard states the general rules and common safety requirements for low-voltage
switchgear and controlgear, including:
– definitions;
– characteristics;
– information supplied with the equipment;
– normal service, mounting and transport conditions;
– constructional and performance requirements;
– verification of characteristics and performance;
– environmental aspects.
© IEC 2014
This standard does not apply to low-voltage switchgear and controlgear assemblies which are

dealt with in IEC 61439 series, as applicable.

1.2 Normative references
Delete the existing reference to "IEC 60439-1:1999" and its Amendment 1.

Replace the existing references by the following new references:

IEC 60664-1:2007, Insulation coordination for equipment within low-voltage systems – Part 1:

Principles, requirements and tests

IEC 61000-3-3:2013, Electromagnetic compatibility (EMC) – Part 3-3: Limits – Limitation of
voltage changes, voltage fluctuations and flicker in public low-voltage supply systems, for
equipment with rated current ≤16 A per phase and not subject to conditional connection
IEC 61000-4-2:2008, Electromagnetic compatibility (EMC) – Part 4-2: Testing and
measurement techniques – Electrostatic discharge immunity test
IEC 61000-4-4:2012, Electromagnetic compatibility (EMC) – Part 4-4: Testing and
measurement techniques – Electrical fast transient/burst immunity test
IEC 61000-4-6:2013, Electromagnetic compatibility (EMC) – Part 4-6: Testing and
measurement techniques – Immunity to conducted disturbances, induced by radio-frequency
fields
IEC 61000-4-8:2009, Electromagnetic compatibility (EMC) – Part 4-8: Testing and
measurement techniques – Power frequency magnetic field immunity test
CISPR 11:2009, Industrial, scientific and medical equipment – Radio-frequency disturbance
characteristics – Limits and methods of measurement
Amendment 1 (2010)
Add, to the existing references, the new amendments as follows:
IEC 60947-5-1:2003, Low-voltage switchgear and controlgear – Part 5-1: Control circuit
devices and switching elements – Electromechanical control circuit devices
Amendment 1 (2009)
IEC 61000-3-2:2005, Electromagnetic compatibility (EMC) – Part 3-2: Limits – Limits for
harmonic current emissions (equipment input current ≤ 16 A per phase)
Amendment 1 (2008)
Amendment 2 (2009)
IEC 61000-4-3:2006, Electromagnetic compatibility (EMC) – Part 4-3: Testing and
measurement techniques – Radiated, radio-frequency, electromagnetic field immunity test
Amendment 1 (2007)
Amendment 2 (2010)
IEC 61000-4-13:2002, Electromagnetic compatibility (EMC) – Part 4-13: Testing and
measurement techniques – Harmonics and interharmonics including mains signalling at a.c.
power port, low-frequency immunity tests
Amendment 1 (2009)
Add the following new normative references as follows:

– 4 – IEC 60947-1:2007/AMD2:2014

© IEC 2014
IEC 60092-504:2001, Electrical installations in ships – Part 504: Special features – Control

and instrumentation
IEC 60300-3-5:2001, Dependability management – Part 3-5: Application guide – Reliability

test conditions and statistical test principles

IEC 61508 (all parts), Functional safety of electrical/electronic/programmable electronic

safety-related systems
IEC 61649:2008, Weibull analysis

IEC 62061:2005, Safety of machinery – Functional safety of safety-related electrical,
electronic and programmable electronic control systems
IEC 62430:2009, Environmentally conscious design for electrical and electronic products
IEC 62474:2012, Material declaration for products of and for the electrotechnical industry
ISO 13849-1:2006, Safety of machinery – Safety-related parts of control systems – Part 1:
General principles for design
2 Definitions
Replace, in the alphabetical list, the existing references to these terms, modified by
Amendment 1, by the following new references:
Electronically controlled electromagnet . 2.3.36
Maximum cross-section . 2.3.35
Minimum cross-section . 2.3.34
Multiple tip contact system . 2.3.33
Replace, in the alphabetical list, the entry "Over-current discrimination" by the following new
entry:
Over-current selectivity . 2.5.23
Add, in the alphabetical list, the following new terms and references:
Flexible conductor . 2.3.32
Individual enclosure . 2.2.23
Insulation coordination barrier . 2.1.23

Rated control circuit supply voltage . 2.5.67
Rated control circuit voltage . 2.5.66
Rigid conductor . 2.3.31
Solid conductor . 2.3.29
Solid insulation . 2.1.22
Stranded conductor . 2.3.30

2.1 General terms
Add, at the end of the existing subclause, the following new terms and definitions:
2.1.22
solid insulation
solid insulating material interposed between two conductive parts

© IEC 2014
2.1.23
insulation coordination barrier

solid insulating material that is not an integral part, provided for the purpose of increasing

either creepage distances or clearance distances or both

2.2 Switching devices
Add, at the end of the existing subclause, the following new term and definition:

2.2.23
individual enclosure
enclosure designed and dimensioned to contain one equipment only
2.3 Parts of switching devices
Add, after the existing definition 2.3.28 added by Amendment 1, the following new terms and
definitions and renumber the existing definitions 2.3.29 to 2.3.32 as 2.3.33 to 2.3.36
respectively:
2.3.29
solid conductor
conductor consisting of a single wire
NOTE 1 The solid conductor may be circular or shaped.
NOTE 2 Solid conductor is defined as class 1 conductor in IEC 60228, or by IEC 60344, or equivalent AWG/kcmil.
[461-01-06, modified]
2.3.30
stranded conductor
conductor consisting of a number of wires, all or some of which are wound in a helix
NOTE Stranded conductor is defined as class 2 conductor in IEC 60228, or by IEC 60344, or equivalent
AWG/kcmil.
[151-12-36, modified]
2.3.31
rigid conductor
solid or stranded conductor having wires of such diameters, or so assembled, that the
conductor is not suitable for use in a flexible cable

2.3.32
flexible conductor
stranded conductor having wires of diameters small enough and so assembled that the
conductor is suitable for use in a flexible cable
NOTE Flexible conductor is defined as class 5 or class 6 conductor in IEC 60228, or by IEC 60344, or equivalent
AWG/kcmil.
[461-01-11, modified]
2.5 Characteristic quantities
2.5.23
over-current discrimination
Replace the existing term by the new following term:

– 6 – IEC 60947-1:2007/AMD2:2014

© IEC 2014
over-current selectivity
Replace, in the existing note of this definition, the word “discrimination” by “selectivity”.

Delete the existing source "[441-17-15]".

Add, after the existing definition 2.5.65, the following new terms and definitions:

2.5.66
rated control circuit voltage
U
c
rated voltage which is controlling the input signal of the control device
2.5.67
rated control circuit supply voltage
U
s
rated voltage applied to energize the power supply terminals of the control circuit
4 Characteristics
Add, in the existing table, the following new line:
Characteristic Symbol Subclause
Pole impedance of the switching device Z 4.3.7

Replace, in the existing line "Rated conditional short-circuit current", the symbol " – " by " I ",
q
as follows:
Characteristic Symbol Subclause
Rated conditional short-circuit current I 4.3.6.4
q
Replace the existing line “Rated control supply voltage” as follows:
Characteristic Symbol Subclause
Rated control circuit supply voltage U 4.5.1
s
4.3.6.1 Rated short-time withstand current (I )
cw
Replace the existing text of this subclause by the following new text:
The rated short-time withstand current of an equipment is the value of short-time current,
assigned to the equipment by the manufacturer, that the equipment can carry without
damage, under the test conditions specified in the relevant product standard.
4.3.6.4 Rated conditional short-circuit current
Replace the existing title of this subclause by the following new title:
4.3.6.4 Rated conditional short-circuit current (I )
q
Add, before the existing Subclause 4.4, the following new subclause:

© IEC 2014
4.3.7 Pole impedance of the switching device (Z)

The pole impedance may be stated by the manufacturer and is determined by measuring the

voltage drop resulting from the current flowing through the pole.

4.5.1 Electrically or electronically controlled circuits

Replace the existing fourth dashed item, modified by Amendment 1, by the following new
dash:
– rated control circuit supply voltage U (a.c., d.c.), where applicable;
s
Replace the existing Note 1 added by Amendment 1 by the following new note:
NOTE 1 Distinction is made between the rated control circuit voltage U and the rated control circuit supply
c
voltage U which may be different from U due to the presence of built-in transformers, rectifiers, resistors,
s c
electronic circuitry, etc.
Delete the existing Note 2 added by Amendment 1.
Replace the existing paragraph after Note 2, added by Amendment 1, by the following new
paragraph:
The correct operating conditions are based upon a value of the control circuit supply voltage
not less than 85 % of its rated value U , with the highest value of control circuit current
s
flowing, nor more than 110 % of its rated value.
5.1 Nature of information
Replace the existing eighteenth dashed item under “Characteristics” by the following new
dash:
– control circuit supply voltage, kind of current and frequency, if different from those of the
control coil;
Add, in the existing list “Characteristics” after the item “suitability for isolation”, the following
two new dashed items:
– pole impedance of the switching device (Z);
– material declaration as per Annex W;
5.3 Instructions for installation, operation and maintenance
Move the first sentence of the second existing paragraph to the end of the first paragraph.

Replace the second sentence of the second paragraph by the following new sentence:
For equipment only suitable in environment A (see 7.3.1), the manufacturer shall provide the
following notice in documentation, available as information to potential customers and with the
product for users:
Add, after the existing Subclause 5.3, the following new subclause:
5.4 Environmental information
Material declarations according to Annex W shall be provided if required by the relevant
product standard.
– 8 – IEC 60947-1:2007/AMD2:2014

© IEC 2014
6.1.1 Ambient air temperature
Replace, in the existing Note 1 “IEC 60439-1” by “IEC 61439 series”.

7.1.2.2 Glow wire testing
Replace, in the existing note, "IEC 60695-2-2" by "IEC 60695-11-5".

Add, at the end of existing note, the following new sentence:

The needle flame test is used as an alternative test for addressing flame retardancy requirements for shipboard
applications.
7.1.4 Clearances and creepage distances
Replace the existing text of this subclause by the following new three subclauses:
7.1.4.1 General
For equipment tested according to 8.3.3.4 of this standard, minimum values are given in
Table 13 and Table 15.
Electrical requirements are given in 7.2.3.
In the other cases, guidance for minimum values is given in the relevant product standard.
NOTE Depending on the risk level (severity of harm and the probability of occurrence), the non-accessibility to
hazardous-live parts is considered under normal service conditions (see 6.1) or under single-fault conditions (see
4.2 of IEC 61140:2001, 7.1.10 and Annex N).
7.1.4.2 Insulation coordination barriers for creepage distances
When solid insulation is used as an insulation coordination barrier to comply with required
creepage distances, the material used shall comply with the glow wire requirements in 7.1.2.2
or the flammability requirements in 7.1.2.3.
7.1.4.3 Insulation coordination barriers for clearance distances
When solid insulation is used as an insulation coordination barrier to comply with required
clearance distances and does not physically support or maintain the relative position of
uninsulated parts involved, the barrier material shall comply with the glow wire requirements
in 7.1.2.2 and shall conform to the glow-wire test requirements of 8.2.1.1.1 at a temperature
of 650 °C or the AI values in Table M.2. Alternatively the material shall comply with the
requirements in 7.1.4.2.
7.2.1.2 Limits of operation of power operated equipment
Replace, in the first existing paragraph, “control supply voltage” by “control circuit supply
voltage”.
Replace, in the existing paragraph, after the note, “rated control supply voltage” by “rated
control circuit supply voltage”.
Replace, in the first (one occurrence) and second dashed items (two occurrences) of the fifth
existing paragraph, introduced by Amendment 1, “rated control supply voltage” by “rated
control circuit supply voltage”.

© IEC 2014
7.2.1.4 Limits of operation of shunt releases

Replace, in the existing paragraph, “rated control supply voltage” by “rated control circuit

supply voltage”.
7.2.2.5 Control circuits
Add, after the existing text, the following new paragraph:

Digital inputs and/or digital outputs contained in switchgear and controlgear, and intended to
be compatible with programmable logic controllers (PLCs) are covered by Annex S.

7.2.2.8 Other parts
Replace, in the existing text, "plastics and insulating materials" by "insulating parts".
7.2.3.3 Clearances
Replace, in the second sentence of the second paragraph, "are higher than" by "are equal to
or higher than".
7.2.3.5 Solid insulation
Delete the last existing sentence of this subclause.
Add, at the end of this subclause, the following new note:
NOTE For more information on the design of solid insulation, see 5.3.1 of IEC 60664-1:2007.
Add, before the existing Subclause 7.3, the following new subclause:
7.2.8 Pole impedance
Where the pole impedance is given, it shall be tested according to 8.3.3.8.
7.3.3.1 Equipment not incorporating electronic circuits
Replace the existing text of this subclause by the following new text:
The requirements for electromagnetic emissions for equipment not incorporating electronic
circuits are deemed to be satisfied, and no verification is necessary.

NOTE For equipment not incorporating electronic circuits, electromagnetic disturbances can only be generated by
equipment during occasional switching operations. The duration of the disturbances is less than 200 ms in accordance
with CISPR 22.
The frequency, the level and the consequences of these emissions are considered as part of
the normal electromagnetic environment of low-voltage installations.
7.3.3.2.1 Limits for high-frequency emissions
Replace the first three existing paragraphs of this subclause by the following new text and
new note:
The high-frequency (greater than 9 kHz) continuous emissions from equipment incorporating
electronic switching circuits shall not exceed the limits specified in the relevant product
standard, based on CISPR 11 for environment A and for environment B.
NOTE One-time disturbances no longer than 200 ms need no further evaluation.

– 10 – IEC 60947-1:2007/AMD2:2014

© IEC 2014
8.2 Compliance with constructional requirements

th
Replace, in the 4 existing dash of the list, “the mechanical properties of terminals” by “the

mechanical and electrical properties of terminals”.

8.2.4.1 General conditions for tests

Replace, in the second sentence, the reference to "IEC 60028" by "IEC 60228".

8.2.4.7 Electrical performance of screwless-type clamping units

Replace, in the existing Note 1 introduced by Amendment 1, the references "(2.3.30)" and

"(2.3.31)" by "(2.3.24)" and "(2.3.35)" respectively.
Replace the existing Note 2 introduced by Amendment 1 by the following new note:
NOTE 2 For the largest cross-sectional area the test current generally applied is I or I declared for the
th the
product. For the smallest cross-sectional area, the test current is given in Table 4 and Table 5 of IEC 60947-7-
1:2009.
8.2.4.8 Ageing test for screwless-type clamping units
Replace, in the existing Note 1 introduced by Amendment 1, the references "(2.3.30)" and
"(2.3.31)" by "(2.3.34)" and "(2.3.35)" respectively.
Replace the existing Note 2 introduced by Amendment 1 by the following new note :
NOTE 2 For the largest cross-sectional area the test current generally applied is I or I declared for the
th the
product. For the smallest cross-sectional area, the test current is given in Table 4 and Table 5 of IEC 60947-7-
1:2009.
8.3.2 General test conditions
Replace, in the existing note, “IEC 60439” by “IEC 61439 series”.
8.3.2.1 General requirements
Delete the existing note.
8.3.2.2.3 Recovery voltage
Replace, in the existing Note 1, "system voltage" by "supply network voltage".
8.3.3.2.1 Power operated equipment

Replace, in the second existing paragraph, introduced by Amendment 1, “rated control supply
voltage” by “rated control circuit supply voltage”.
Replace the fifth existing paragraph added by Amendment 1 by the following new paragraph:
The value of the capacitor shall be
C = 30 + 200 000 / (f × U)
where
C is expressed in nF;
f is the minimum rated frequency expressed in Hz;
U is the maximum value of U expressed in V.
s
© IEC 2014
8.3.3.3.1 Ambient air temperature

Replace the second existing paragraph by the following new paragraph:

During the test, the ambient temperature shall be between +10 °C and +40 °C and shall not

vary by more than 10 K. The ambient temperature shall not vary by more than 3 K during the

last quarter of the test or the last hour of the test, whichever is the shorter. The test shall be

conducted until this condition is achieved.

Delete the third existing paragraph of this subclause.

8.3.3.4.1 Type tests
Delete Note 2 in the existing item 1).
Renumber, in the existing item 1), “Note 3” and “Note 4” added by Amendment 1 as “Note 2”
and “Note 3” respectively.
Replace, in the existing item 3) c), the text modified by Amendment 1 by the following new
text and new note:
The test voltage shall be applied to for 60 s in accordance with items i), ii) and iii) of 2) c)
above.
NOTE For devices already type-tested according to this standard and its Amendment 1 or earlier, a re-testing
according to 60 s is not necessary.
Replace, in the existing item 6), the existing text “Under consideration” by "Equipment with
d.c. ratings only shall be tested with d.c. test voltage".
Add, before the existing Subclause 8.3.4, the following new subclause:
8.3.3.8 Pole impedance
The pole impedance shall be determined during the test and with the conditions given in
8.3.3.3.4. The test in an enclosure is not deemed necessary even if the switching device can
be used in an individual enclosure.
The voltage drop U shall be measured between the line and load terminals (terminals
d
included) of the switching device using the same measuring points as for the temperature
rise. The measurement shall be performed after a time sufficient for the temperature-rise to
reach a steady-state value.
The impedance per pole is defined as follows:
Z = U / I [Ω]
d th
The declared value (see 5.1 modified by this Amendment 2), in the case of multiple identical
poles, shall be the average value obtained from the tests.
Care should be taken that voltage drop measurement does not significantly affect the
temperature rise nor affect significantly the impedance.
NOTE The method is the same irrespective of the number of poles of the switching device.
8.4 Tests for EMC
Replace the existing text of this subclause by the following new text:

– 12 – IEC 60947-1:2007/AMD2:2014

© IEC 2014
Emission and immunity tests are type tests and shall be carried out using the manufacturer’s

instructions for installation in accordance with the reference EMC standards.

The product standard shall specify any particular test condition (e.g. use of an enclosure) and

additional measures necessary to verify the performance criteria of the product (e.g.

application of dwell times).
Add, before the existing Subclause 8.4.2, the following new subclause:

8.4.1.2.9 Harmonics in the supply

Under consideration.
Table 1 – Standard cross-sections of round copper conductors and approximate
relationship between mm and AWG/kcmil sizes
Replace, in the existing title of this table, “Standard” by “Nominal” and in the header of this
table “Rated” by “Nominal”.
Table 3 – Temperature-rise limits of accessible parts (see 7.2.2.2 and 8.3.3.3.4)
In order to delete the reference to footnote b, replace the headline “Parts which need not be
b
touched during normal operation :” by “Parts which need not be touched during normal
operation”.
Table 4 – Tightening torques for the verification of the mechanical strength of screw-
type terminals
Replace, in the existing title of this table,“(see 8.3.2.1, 8.2.6 and 8.2.6.2)” by “(see 8.2.4.2 and
8.3.2.1)”.
Figure 14 – Verification of short-circuit making and breaking capacities on d.c.
Replace the existing figure by the following new figure (addition of "A " in Figure 14b)):
© IEC 2014
a) Calibration of the circuit
Prospective peak making
current = A
b) Oscillogram corresponding to
a break after the current has
passed its maximum value
Short-circuit breaking capacity:
Current I = A at voltage U = B
Short-circuit making capacity:
Current I = A at voltage U = B
c) Oscillogram corresponding to a
break before the current has
reached its maximum value
Short-circuit breaking capacity:
Current I = A at voltage U = B
2 2
Short-circuit making capacity:
Current I = A at voltage U = B
IEC
Table 12A – Dielectric test voltage corresponding to the rated insulation voltage
b
Replace the existing footnote of this table by the following new footnote:
b
Test voltages based on 6.1.3.4.1, fifth paragraph, of IEC 60664-1:2007.
Annex A – Examples of utilization categories for low-voltage switchgear and
controlgear
Replace the existing title and text of this annex by the following:

– 14 – IEC 60947-1:2007/AMD2:2014

© IEC 2014
Annex A
(informative)
Harmonisation of utilization categories

for low-voltage switchgear and controlgear

The IEC 60947 series contains different parts specifying requirements for different types of

low-voltage switchgear. Standards for products covered by the IEC 60947 series have been

developed at different periods of time and by various working groups. It results in many

utilization categories for similar applications in the IEC 60947 series.
The objective of this annex is to give the harmonisation framework for the low-voltage
switchgear and controlgear as given in Table A.1. A future objective under consideration is to
specify a common set of requirements for testing of the products from different parts of the
IEC 60947 series.
The intended benefits are to:
– simplify the standards by bringing all similar categories together under one common set of
categories;
– help the user in the selection of equipment for specific applications.
Table A.1 – Utilization categories used in the IEC 60947 series
Nature Category Relevant
of Typical switched load IEC product
c d
current Proposed Present standard
a.c. AC-20 AC-20 No-load condition
AC-21 AC-21 Resistive loads, including moderate overloads
IEC 60947-
3:2008, Amd
AC-22 AC-22 Mixed resistive and inductive loads, including moderate
1 (2012)
overloads
AC-23 AC-23 Motor loads or other highly inductive loads
AC-1 AC-1 Non-inductive or slightly inductive loads
AC-2 AC-2 Slip-ring motors or switching of mixed resistive and inductive
loads, including moderate overloads
AC-3 AC-3 Squirrel-cage motors
a b
AC-4 AC-4 Squirrel-cage motors: plugging , inching
IEC 60947-
4-1:2009,
AC-5a AC-5a Discharge lamp ballasts
Amd 1
(2012)
AC-5b AC-5b Incandescent lamps
AC-6a AC-6a Transformers
AC-6b AC-6b Capacitor banks
AC-8 AC-8a Hermetic refrigerant compressor
AC-8 AC-8b
AC-2a AC-52a Slip ring motor stators: 8 h duty with on-load currents for
start, acceleration, run
AC-2b AC-52b Slip ring motor stators: intermittent duty
AC-3a AC-53a Squirrel-cage motors: 8 h duty with on-load currents for start,
acceleration, run IEC 60947-
4-2:2011
AC-3b AC-53b Squirrel-cage motors: intermittent duty
AC-8a AC-58a Hermetic refrigerant compressor motors with automatic
resetting of overload releases: 8 h duty with on-load currents
for start, acceleration, run
© IEC 2014
Nature Category Relevant
of Typical switched load IEC product
c d
current Proposed Present standard

AC-8b AC-58b Hermetic refrigerant compressor motors with automatic

resetting of overload releases: intermittent duty

AC-1 AC-51 Non-inductive or slightly inductive loads

IEC 60947-
4-3:1999
AC-5a AC-55a Discharge lamps ballast

Amd 1
AC-5b AC-55b Incandescent lamps
(2006)
AC-6a AC-56a Transformers
Amd 2
(2011)
AC-6b AC-56b Capacitor banks
AC-12 AC-12 Resistive loads and solid-state loads with isolation by
optocouplers
IEC 60947-
5-1:2003
AC-13 AC-13 Solid-state loads with transformer isolation
Amd 1
AC-14 AC-14 Small electromagnetic loads
(2009)
AC-15 AC-15 a.c. electromagnetic loads
AC-12 AC-12 Resistive loads and solid state loads with optical isolation IEC 60947-
5-2:2007
AC-140 AC-140
Small electromagnetic loads with holding (closed) current
Amd 1
≤ 0,2 A, e.g. contactor relays
(2012)
AC-1 AC-31 Non inductive or slightly inductive loads
AC-2 AC-32 Slip-ring motors or switching of mixed resistive and inductive loads,
including moderate overloads
IEC 60947-
AC-3 AC-33 Squirrel-cage motors 6-1:2005
AC-5a AC-35 Discharge lamp ballast
AC-5b AC-36 Incandescent lamps
AC-40 AC-40 Distribution circuits comprising mixed resistive and reactive
loads having a resultant inductive reactance
AC-1 AC-41 Non-inductive or slightly inductive loads
AC-2 AC-42 Slip-ring motors or switching of mixed resistive and inductive
IEC 60947-
loads, including moderate overloads
6-2:2002
Amd 1
AC-3 AC-43 Squirrel-cage motors
(2007)
a b
AC-4 AC-44 Squirrel-cage motors: plugging , inching
AC-5a AC-45a Discharge lamp ballasts
AC-5b AC-45b Incandescent lamps
AC-7a AC-7a Slightly inductive loads for household appliances and similar
IEC 61095:2
applications
AC-7b AC-7b Motor-loads for household applications
d.c. DC-20 DC-20 Connecting and disconnecting under no-load conditions
DC-21 DC-21 Resistive loads, including moderate overloads
IEC 60947-
3:2008, Amd
DC-22 DC-22 Mixed resistive and inductive loads, including moderate
1 (2012)
overloads (e.g. shunt motors)
DC-23 DC-23 Highly inductive loads (e.g. series motors)
DC-1 DC-1 Non-inductive or slightly inductive loads
IEC 60947-
Shunt-motors
DC-3 DC-3
4-1:2009,
Amd 1
Series-motors
DC-5 DC-5
(2012)
DC-6 DC-6 Incandescent lamps
DC-12 DC-12 Control of resistive loads and solid-state loads with isolation
IEC 60947-
by optocouplers
5-1:2003
Amd 1
DC-13 DC-13 Control of electromagnets

– 16 – IEC 60947-1:2007/AMD2:2014

© IEC 2014
Nature Category Relevant
of Typical switched load IEC product
c d
current Proposed Present standard

(2009)
DC-14 DC-14 Control of electromagnetic loads having economy resistors in

circuit
DC-12 DC-12 Control of resistive loads and solid state loads with optical IEC 60947-

isolation 5-2:2007
Amd 1
DC-13 DC-13 Control of electromagnets
(2012)
DC-1 DC-31 Non-inductive or slightly inductive loads
IEC 60947-
DC-3 DC-33 Shunt-motors
6-1:2005
DC-6 DC-36 Incandescent lamps
DC-40 DC-40 Distribution circuits comprising mixed resistive and reactive
loads having a resultant inductive reactance
IEC 60947-
DC-1 DC-41 Non-inductive or slightly inductive loads
6-2:2002
Shunt-motors
DC-3 DC-43 Amd 1
(2007)
Series-motors Incandescent lamps
DC-5 DC-45
DC-6 DC-46 Incandescent lamps
a
By plugging is understood stopping or reversing the motor rapidly by reversing motor primary connections
while the motor is running.
b
By inching (jogging) is understood energizing a motor once or repeatedly for short periods to obtain small
movements of the driven mechanism.
c
Utilization categories intended to be harmonized throughout product standards in their future editions.
d
Present utilization category as defined in the referred edition of the product standard in the last column until it
is changed to the proposed utilization category.

Annex K – Vacant
Replace the existing title and text of this annex by the following:

© IEC 2014
Annex K
(normative)
Procedure to determine reliability data for electromechanical

devices used in functional safety applications

K.1 General
K.1.1 Overview
Provision of these data is optional, at the discretion of the manufacturer.
K.1.2 Scope and object
This annex specifies procedures for the provision of specific data characterising the
performance of electromechanical devices in functional safety applications for high demand or
continuous mode of operation as defined in IEC 61508.
This method is not applicable to electronic parts.
NOTE 1 Non electromechanical devices should refer to IEC 61508-6 for guidance on the calculation of the
probability of failure ratio. Failure rate of electronic parts should be evaluated with reliability data handbook for
example IEC/TR 62380.
NOTE 2 The use of reliability data according to this annex is not appropriate for low demand applications. Low
demand mode of operation is under consideration.
These data are required by functional safety standards including IEC 61508 series,
IEC 62061, ISO 13849-1.
The product standard shall define the function(s) and the failure modes that will be
considered.
K.1.3 General requirements
The specific data for functional safety shall be obtained with this procedure.
The procedure is based on statistical analysis of test results in order to generate reliability
data.
The requirements of this annex may be further specified by the relevant product standard in
terms of relevant tests, failure modes and their ratios.
The confidence level related to failure rate calculation during the useful life of the device shall
be at least 60 %.
NOTE The parameters associated with the reliability data are chosen for being consistent with those of other
products also used in functional safety applications.
The statistical data obtained according to this annex are valid only during the useful life of the
device.
In this annex, to keep statistical consistency, the term "time" can refer to the number of
operation cycles.
This annex does not consider replacement of parts of the devices during test and application.

– 18 – IEC 60947-1:2007/AMD2:2014

© IEC 2014
K.2 Terms, definitions and symbols

K.2.1 Terms and definitions
K.2.1.1
reliability (performance)
ability of an item to perform a required function under given conditions for a given time

interval
[191-02-06, modified]
K.2.1.2
useful life
under given conditions, the time interval beginning at a given instant of time, and ending when
the failure rate becomes unacceptable
NOTE The useful life may be expressed in number of operations.
K.2.1.3
constant failure rate period
that period, if any, in the life of a non-repaired item during which the failure rate is
approximately constant
[191-10-09]
K.2.1.4
overall lifetime
lifetime of the device which should not be exceeded in order to maintain the validity of the
estimated failure rates due to random hardware failures
NOTE 1 Overall lifetime covers also periods of non-use e.g. storage. The overall lifetime is expressed in number
of years.
NOTE 2 It corresponds to T according to IEC 62061 and to T according to ISO 13849-1.
1 M
K.2.1.5
censoring
termination of the test after either a certain number of failures or a certain time at which there
are still items functioning
K.2.1.6
suspension
situation in which an item that either has not failed or has not failed in the manner under
investigation, i.e. failed due to some other cause, is removed from test
K.2.1.7
no-make-break-current utilization
conditions in which the switching device makes and breaks without load
K.2.1.8
time to failure
operating time accumulated from the first use, or from restoration, until failure
NOTE The time to failure may be expressed in number of operations.
K.2.2 Symbols
number of samples tested
n
number of failures
r
© IEC 2014
number of operating cycles
t
η Weibull characteristic life or scale parameter

β Weibull shape parameter
number of operations per hour
c
assessed failure rate (upper limit) at confidence level of 60 % expressed in per
λ
u
operation
λ failure rate expressed in per hour

dangerous failure rate expressed in per hour
λ
D
coefficient of determination
r
K.3 Method based on durability test results
K.3.1 General method
In order to address random hardware failure the method is based on results given by
continuous monitoring of the devices under the appropriate durability test.
K.3.2 Test requirements
The test environment shall be in accordance with Clause 6 and any related requirements from
the relevant product standard.
Mechanical durability shall be determined in accordance with 7.2.4.3.1. For the no-make-
break-current utilization the mechanical durability is applicable.
Electrical durability shall be determined in accordance with 7.2.4.3.2 using the utilization
c
...