IEC 60947-4-3:2020

IEC 60947-4-3 ®
Edition 3.0 2020-07
INTERNATIONAL
STANDARD
Low-voltage switchgear and controlgear –
Part 4-3: Contactors and motor-starters – Semiconductor controllers and
semiconductor contactors for non-motor loads
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

IEC Central Office Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.

IEC publications search - webstore.iec.ch/advsearchform Electropedia - www.electropedia.org
The advanced search enables to find IEC publications by a The world's leading online dictionary on electrotechnology,
variety of criteria (reference number, text, technical containing more than 22 000 terminological entries in English
committee,…). It also gives information on projects, replaced and French, with equivalent terms in 16 additional languages.
and withdrawn publications. Also known as the International Electrotechnical Vocabulary

(IEV) online.
IEC Just Published - webstore.iec.ch/justpublished
Stay up to date on all new IEC publications. Just Published IEC Glossary - std.iec.ch/glossary
details all new publications released. Available online and 67 000 electrotechnical terminology entries in English and
once a month by email. French extracted from the Terms and Definitions clause of
IEC publications issued since 2002. Some entries have been
IEC Customer Service Centre - webstore.iec.ch/csc collected from earlier publications of IEC TC 37, 77, 86 and
If you wish to give us your feedback on this publication or CISPR.

need further assistance, please contact the Customer Service

Centre: sales@iec.ch.
IEC 60947-4-3 ®
Edition 3.0 2020-07
INTERNATIONAL
STANDARD
Low-voltage switchgear and controlgear –

Part 4-3: Contactors and motor-starters – Semiconductor controllers and

semiconductor contactors for non-motor loads

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.130.20; 31.180 ISBN 978-2-8322-8550-3

– 2 – IEC 60947-4-3:2020 © IEC 2020
CONTENTS
FOREWORD . 7
INTRODUCTION . 9
1 Scope . 10
2 Normative references . 11
3 Terms, definitions, symbols and abbreviated terms . 11
3.1 General . 11
3.2 Alphabetical index of terms . 12
3.3 Terms and definitions concerning the types of semiconductor controllers and
semiconductor contactors (see Figure 1). 12
3.4 Terms and definitions concerning characteristics of semiconductor
controllers and semiconductor contactors . 13
3.5 Terms and definitions concerning safety aspects . 16
3.6 Symbols and abbreviated terms . 16
4 Classification . 17
5 Characteristics of semiconductor controllers and semiconductor contactors . 17
5.1 Summary of characteristics . 17
5.2 Type of equipment . 17
5.2.1 Kind of equipment . 17
5.2.2 Number of poles . 18
5.2.3 Kind of current . 18
5.2.4 Interrupting medium (air, vacuum, etc.) . 18
5.2.5 Operating conditions of the equipment . 18
5.3 Rated and limiting values for main circuits . 20
5.3.1 Rated voltages . 20
5.3.2 Currents. 20
5.3.3 Rated frequency . 20
5.3.4 Duty cycle values and symbols . 20
5.3.5 Normal load and overload characteristics . 21
5.3.6 Rated conditional short-circuit current . 21
5.3.7 Controller power losses . 22
5.4 Utilization category . 22
5.4.1 General. 22
5.4.2 Assignment of ratings based on the results of tests . 23
5.5 Control circuits . 23
5.6 Auxiliary circuits . 23
5.7 Vacant . 24
5.8 Coordination with short-circuit protective devices (SCPD) . 24
6 Product information . 24
6.1 Nature of information . 24
6.2 Marking . 25
6.3 Instructions for installation, operation, maintenance, decommissioning and
dismantling . 26
6.4 Environmental information . 26
7 Normal service, mounting and transport conditions . 26
7.1 Normal service conditions . 26
7.1.1 Ambient air temperature . 26
7.1.2 Altitude . 27

7.1.3 Atmospheric conditions . 27
7.1.4 Shock and vibrations. 27
7.2 Conditions during transport and storage . 27
7.3 Mounting . 27
7.4 Electrical system disturbances and influences . 27
8 Constructional and performance requirements . 28
8.1 Constructional requirements . 28
8.1.1 General. 28
8.1.2 Materials . 28
8.1.3 Current-carrying parts and their connections . 29
8.1.4 Clearances and creepage distances . 29
8.1.5 Actuator . 29
8.1.6 Indication of the contact position . 29
8.1.7 Additional requirements for equipment suitable for isolation . 29
8.1.8 Terminals . 29
8.1.9 Additional requirements for equipment provided with a neutral pole . 30
8.1.10 Provisions for protective earthing . 30
8.1.11 Enclosures for equipment . 30
8.1.12 Degrees of protection of enclosed equipment. 30
8.1.13 Conduit pull-out, torque and bending with metallic conduits . 30
8.1.14 Limited energy source . 30
8.1.15 Stored charge energy circuit . 32
8.1.16 Fault and abnormal conditions . 32
8.1.17 Short-circuit and overload protection of ports . 33
8.2 Performance requirements . 33
8.2.1 Operating conditions . 33
8.2.2 Temperature-rise . 34
8.2.3 Dielectric properties . 35
8.2.4 Normal load and overload performance requirements . 36
8.2.5 Coordination with short-circuit protective devices . 41
8.3 EMC requirements . 41
8.3.1 General. 41
8.3.2 Immunity . 41
8.3.3 Emission . 43
9 Tests . 43
9.1 Kinds of tests . 43
9.1.1 General. 43
9.1.2 Type tests . 43
9.1.3 Routine tests . 44
9.1.4 Sampling tests . 44
9.1.5 Special tests . 44
9.2 Compliance with constructional requirements . 45
9.2.1 General. 45
9.2.2 Electrical performance of screwless-type clamping units . 45
9.2.3 Ageing test for screwless-type clamping units . 45
9.2.4 Limited energy source test . 45
9.2.5 Breakdown of components . 46
9.2.6 Wire flexing test . 47
9.3 Compliance with performance requirements . 47

– 4 – IEC 60947-4-3:2020 © IEC 2020
9.3.1 Test sequences . 47
9.3.2 General test conditions . 48
9.3.3 Performance under no load, normal load and overload conditions . 48
9.3.4 Performance under short-circuit conditions . 56
9.4 EMC tests . 59
9.4.1 General. 59
9.4.2 EMC immunity tests . 60
9.4.3 EMC emission tests . 61
9.5 Routine and sampling tests . 63
9.5.1 General. 63
9.5.2 Operation and operating limits . 63
9.5.3 Dielectric tests . 63
Annex A (normative) Marking and identification of terminals . 65
A.1 General . 65
A.2 Marking and identification of terminals of semiconductor controllers and

semiconductor contactors . 65
A.2.1 Marking and identification of terminals of main circuits . 65
A.2.2 Marking and identification of terminals of control circuits. 65
Annex B (informative) Typical service conditions for semiconductor controllers and
semiconductor contactors . 66
B.1 Control of resistive heating elements . 66
B.2 Switching of electric discharge lamp controls . 66
B.3 Switching of incandescent lamps . 66
B.4 Switching of transformers. 67
B.5 Switching of capacitor banks . 67
Annex C Vacant . 68
Annex D Vacant . 69
Annex E Vacant . 70
Annex F (informative) Operating capability . 71
Annex G Vacant . 74
Annex H Vacant . 75
Annex I (normative) Modified test circuit for short-circuit testing of semiconductor
contactors and semiconductor controllers . 76
Annex J (informative) Vacant . 78
Annex K (normative) Examples of overvoltage category reduction . 79
K.1 General . 79
K.2 Insulation to the surroundings . 79
K.2.1 Circuits connected directly to the supply mains . 79
K.2.2 Insulation between circuits . 80
Annex L (normative) Additional requirements and tests for equipment with protective
separation . 84
L.1 General . 84
L.2 Terms and definitions . 84
L.3 Requirements . 84
L.3.1 Test method for implementing protective impedance . 84
L.3.2 Touch current measurement . 85
Bibliography . 87

Figure 1 – Semiconductor control devices . 13
Figure 2 – Methods of connecting . 19
Figure F.1 – Thermal stability test profile . 71
Figure F.2 – Overload withstand test profile . 72
Figure F.3 – Blocking and commutating capability test profile . 73
Figure I.1 – Modified circuit for short-circuit testing of semiconductor devices . 76
Figure I.2 – Timeline for the short-circuit test of 9.3.4.1.6 . 77
Figure K.1 – Basic insulation evaluation for circuits connected directly to the origin of
the installation mains supply . 79
Figure K.2 – Basic insulation evaluation for circuits connected directly to the mains
supply . 80
Figure K.3 – Basic insulation evaluation for equipment not permanently connected to
the mains supply . 80
Figure K.4 – Basic insulation evaluation for insulation between circuits connected
directly to the origin of the installation mains supply and that are declared galvanically

separated . 81
Figure K.5 – Basic insulation evaluation for insulation between circuits connected
directly to the mains supply and that are declared galvanically separated . 81
Figure K.6 – Basic insulation evaluation for insulation between circuits not permanently
connected directly to the mains supply and that are declared galvanically separated . 82
Figure K.7 – Basic insulation evaluation for insulation between circuits connected
directly to the origin of the installation mains supply and that are declared galvanically
separated where internal SPDs are used . 82
Figure K.8 – Basic insulation evaluation for insulation between circuits connected
directly to the mains supply and that are declared galvanically separated where

internal SPDs are used . 83
Figure K.9 – Basic insulation evaluation for insulation between circuits connected
directly to the mains supply and that are declared galvanically separated . 83
Figure L.1 – Protection by means of protective impedance. 85
Figure L.2 – Measuring instrument . 86

Table 1 – Utilization categories . 23
Table 2 – Relative levels of severity . 23
Table 14 – Limits for limited energy sources without an over-current protective device . 31
Table 15 – Limits for limited energy sources with an over-current protective device . 31
Table 16 – Limits for limited energy source with current limiting impedance . 32
Table 3 – Temperature-rise limits for insulated coils in air and in oil . 35
Table 4 – Minimum overload current withstand time (T ) in relation to overload current
x
ratio (X) . 37
Table 5 – Minimum requirements for thermal stability test conditions . 37
Table 6 – Minimum requirements for overload current withstand test conditions . 38
Table 7 – Making and breaking capacity test – Making and breaking conditions
according to utilization categories for the mechanical switching device . 39
Table 8 – Conventional operational performance – Making and breaking conditions
according to utilization categories for the mechanical switching device . 40
Table 9 – Specific performance criteria when EM disturbances are present . 42
Table 10 – Thermal stability test specifications . 52
Table 11 – Blocking and commutating capability test specifications . 54

– 6 – IEC 60947-4-3:2020 © IEC 2020
Table 12 – Terminal disturbance voltage limits for conducted radio-frequency emission
(AC mains power port) . 62
Table 13 – Radiated emissions test limits . 63
Table A.1 – Main circuit terminal markings . 65
Table K.1 – Drawing keys . 79

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 4-3: Contactors and motor-starters –
Semiconductor controllers and semiconductor
contactors for non-motor loads

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as "IEC
Publication(s)"). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60947-4-3 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 third edition cancels and replaces the second edition published in 2014. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) scope exclusions;
b) editorial correction of notes and hanging paragraphs;

– 8 – IEC 60947-4-3:2020 © IEC 2020
c) safety aspects related to:
– general aspects;
– limited energy circuits;
– electronic circuits;
d) mention of dedicated wiring accessories;
e) power consumption measurement;
f) alignment to IEC 60947-1:2020;
g) alignment with IEC 60947-4-2 when appropriate.
The provisions of the general rules dealt with IEC 60947-1 are applicable to this part of
IEC 60947 series where specifically called for. Clauses and subclauses, tables, figures and
annexes of the general rules thus applicable are identified by reference to IEC 60947-1:2020.
The text of this document is based on the following documents:
FDIS Report on voting
121A/357/FDIS 121A/368/RVD
Full information on the voting for the approval of this document can be found in the report on
voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 60947 series, published under the general title Low-voltage
switchgear and controlgear, can be found on the IEC website.
The following differing practices of a less permanent nature exist in the countries indicated
below.
5.5 USA and Canada
8.1.14.1 Canada
Table 14 USA
Table 15 USA
9.4.3.2 USA
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
INTRODUCTION
This document covers low-voltage semiconductor controllers and semiconductor contactors
(solid-state contactors) intended for the use with non-motor loads. As semiconductor
controllers, they have many capabilities beyond the simple switching on and off of non-motor
loads. As semiconductor contactors, they perform the same functions as mechanical
contactors, but utilize one or more semiconductor switching devices in their main poles.
The devices may be single-pole or multi-pole (see 3.5.1 of IEC 60947-1:2020). This document
refers to complete devices rated as a unit incorporating all necessary heat-sinking material
and terminals. It includes devices with all necessary terminals, which are supplied with or
without heat-sink in knocked-down form for combination by the users, when the manufacturer
gives with the device detailed information about choosing the heat-sink and mounting the
device on the heat-sink.
– 10 – IEC 60947-4-3:2020 © IEC 2020
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 4-3: Contactors and motor-starters –
Semiconductor controllers and semiconductor
contactors for non-motor loads

1 Scope
This document applies to semiconductor controllers and semiconductor contactors for non-
motor load intended to be connected to circuits, the rated voltage of which does not exceed
1 000 V AC.
It covers their use:
– for operations of changing the state of AC electric circuits between the ON-state and the
OFF-state;
– with or without bypass switching devices;
– as controller, for reducing the amplitude of the RMS AC voltage.
This document does not apply to:
– electromechanical contactors (see IEC 60947-4-1);
– short-circuit protective device associated with semiconductor controllers and
semiconductor contactors (see IEC 60947-4-1 (MPSD), IEC 60947-2 and IEC 60947-3);
– semiconductor motor controller or soft-starter equipment (see IEC 60947-4-2);
– semiconductor converters (see IEC 60146 (all parts));
– solid-state relays (see IEC 62314);
– use of the product within explosive atmospheres (see IEC 60079 (all parts));
– software and firmware requirements (see IEC TR 63201);
– cyber security aspects (see IEC TS 63208).
Contactors and control-circuit devices used in semiconductor controllers and contactors are
considered compliant with the requirements of their relevant product standard. Where
mechanical switching devices are used, they are considered meeting the requirements of their
own IEC product standard and the additional requirements of this document.
The object of this document is to state as follows:
– the characteristics of semiconductor controllers and semiconductor contactors;
– the conditions with which semiconductor controllers and semiconductor contactors comply
with reference to:
a) their operation and behaviour in normal and abnormal operating conditions including
overcurrent operating conditions;
b) their dielectric properties;
c) the degrees of protection provided by their enclosures, where applicable;
d) their construction including safety measures against electric shock, fire hazard and
mechanical hazard;
– 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.

2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the referenced document (including
any amendments) applies.
IEC 60445, Basic and safety principles for man-machine interface, marking and identification
– Identification of equipment terminals, conductor terminations and conductors
IEC 60715, Dimensions of low-voltage switchgear and controlgear – Standardized mounting
on rails for mechanical support of switchgear, controlgear and accessories
IEC 60730-1, Automatic electrical controls – Part 1: General requirements
IEC 60947-1:2020, Low-voltage switchgear and controlgear – Part 1: General rules
IEC 60947-4-1, Low-voltage switchgear and controlgear – Part 4-1: Contactors and motor-
starters – Electromechanical contactors and motor-starters
IEC 61000-3-2, Electromagnetic compatibility (EMC) – Part 3-2: Limits – Limits for harmonic
current emissions (equipment input current ≤ 16 A per phase)
IEC 61000-3-3, 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 61000-3-11, Electromagnetic compatibility (EMC) – Part 3-11: Limits – Limitation of
voltage changes, voltage fluctuations and flicker in public low-voltage supply systems –
Equipment with rated current ≤ 75 A and subject to conditional connection
IEC 61000-3-12, Electromagnetic compatibility (EMC) – Part 3-12: Limits – Limits for
harmonic currents produced by equipment connected to public low-voltage systems with input
current > 16 A and ≤ 75 A per phase
IEC 61000-4-5, Electromagnetic compatibility (EMC) – Part 4-5: Testing and measurement
techniques – Surge immunity test
IEC 61140:2016, Protection against electric shock – Common aspects for installation and
equipment
CISPR 11:2015, Industrial, scientific and medical equipment – Radio-frequency disturbance
characteristics – Limits and methods of measurement
CISPR 11:2015/AMD1:2016
ISO 2859-1:1999, Sampling procedures for inspection by attributes – Part 1: Sampling
schemes indexed by acceptance quality limit (AQL) for lot-by-lot inspection
ISO 2859-1:1999/AMD1:2011
3 Terms, definitions, symbols and abbreviated terms
3.1 General
For the purposes of this document, the terms and definitions given in Clause 3 of IEC 60947-
1:2020, as well as the following terms, definitions, symbols and abbreviated terms apply.

– 12 – IEC 60947-4-3:2020 © IEC 2020
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.2 Alphabetical index of terms
Term Reference
A Abnormal operating condition 3.5.1
Accessible part 3.5.2
B Bypassed semiconductor controller 3.4.18
C Current-limit function 3.4.1
F FULL-ON 3.4.6
G Galvanic opening 3.4.20
Galvanic separation 3.4.21
H Hazardous-live-part 3.5.3
I Instantaneous switching 3.4.9
L Limited energy source 3.5.4
Load control 3.4.2
O OFF-state 3.4.7
OFF-state current 3.4.8
OFF-time 3.4.17
ON-state 3.4.5
ON-time 3.4.16
Operating capability 3.4.11
Operating cycle 3.4.10
Overcurrent protective means OCPM 3.4.15
Overload current profile 3.4.12
P Protective impedance 3.5.5
R Ramp-down 3.4.4
Ramp-up 3.4.3
Rating index 3.4.13
Reasonably foreseeable misuse 3.5.6
S Semiconductor controller 3.3.1
Semiconductor contactor 3.3.2
Semiconductor controller power losses 3.4.19
Single fault condition 3.5.7
T Trip-free semiconductor controller 3.4.14

3.3 Terms and definitions concerning the types of semiconductor controllers and
semiconductor contactors (see Figure 1)
3.3.1
semiconductor controller
semiconductor switching device that provides a switching function for an AC electrical load
and an OFF-state
Note 1 to entry: Because hazardous levels of the OFF-state current (3.4.8) exist in a semiconductor controller,
the load terminals are considered as live parts at all times.

Note 2 to entry: 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.
Note 3 to entry: See 3.4.3 of IEC 60947-1:2020 for the definition of semiconductor switching device.
3.3.2
semiconductor contactor
semiconductor controller, in which the switching function is limited to
FULL-ON
Note 1 to entry: A semiconductor contactor can also contain mechanical switching devices.
Device Functional unit diagram
Semiconductor
controller
Semiconductor controller
in series with a mechanical
switching device
Bypassed semiconductor
controller
Figure 1 – Semiconductor control devices
3.4 Terms and definitions concerning characteristics of semiconductor controllers
and semiconductor contactors
3.4.1
current-limit function
ability of the semiconductor controller to limit the load current to a specified value
Note 1 to entry: It does not include the ability to limit the instantaneous current under conditions of short circuit.
3.4.2
load control
any deliberate operation which causes changes in the effective power available to the load
through variation of either
– an imposed operating cycle (i.e. variation of the cyclic duration factor F and/or the number
of operating cycles per hour S, see 5.3.4
or
– the load terminal voltage (for example, through phase-angle control)
or
– a combination of these
Note 1 to entry: Switch-on is a mandatory form of load control that is recognized separately.
Note 2 to entry: Load control can be performed by semiconductor contactor, if an external switching device or
control circuit causes the cyclic transition from the OFF-state to the FULL-ON state and back again (i.e. load
control by operating cycle).
3.4.3
ramp-up
switching (switch-on) function which causes the transition from the OFF-state (or from the
open state, in the case of a semiconductor controller in series with a mechanical switching
device) to the ON-state (i.e. to the FULL-ON state or to a load control operation) over a
defined period of time (the ramp-up time)

– 14 – IEC 60947-4-3:2020 © IEC 2020
3.4.4
ramp-down
switching (switch-off) function which causes the transition from the ON-state (i.e. either from
FULL-ON or from a load control operation) to the OFF-state (or the open state, in the case of
a semiconductor controller in series with a mechanical switching device) over a defined period
of time (ramp-down time)
3.4.5
ON-state
condition of a semiconductor controller when the conduction current can flow through its main
circuit
3.4.6
FULL-ON
condition of a semiconductor controller when the controlling functions are set to provide
normal full-voltage excitation to the load
3.4.7
OFF-state
condition of a semiconductor controller when no control signal is applied and no current
exceeding the OFF-state current flows through the main circuit
3.4.8
OFF-state current
I
OFF
current which flows through the main circuit of a semiconductor contactor in the OFF-state
3.4.9
instantaneous switching
switching function which causes the instantaneous transition from the ON-state (i.e. either
from FULL-ON or from a load control operation) to the OFF-state (or the open state, in the
case of a semiconductor controller with mechanical switching device) or vice versa
Note 1 to entry: In the case of switch-off, the term "instantaneous" is used to mean the minimum opening time
(see 3.7.39 of IEC 60947-1:2020).
Note 2 to entry: In the case of switch-on, the term "instantaneous" is used to mean make time (see 3.7.43 of
IEC 60947-1:2020) plus the transient time determined only by external circuit impedance.
3.4.10
operating cycle
succession of operations from one state to the other and back
to the first state
Note 1 to entry: A succession of operations not forming an operating cycle is referred to as an operating series.
3.4.11
operating capability
under prescribed conditions, ability to perform a series of operating cycles without failure
3.4.12
overload current profile
current-time coordinate specifying the requirement to accommodate overload currents for a
period of time (see 5.3.5.2)
3.4.13
rating index
rating information organized in a prescribed format unifying rated operational current and the
corresponding utilization category, overload current profile, and the duty cycle or OFF-time
(see 6.1 e))
3.4.14
trip-free semiconductor controller
semiconductor controller which establishes and sustains an OFF-state condition which cannot
be overridden in the presence of a trip condition
Note 1 to entry: In the case of semiconductor controller in series with a mechanical switching device, the term
"OFF-state condition" is replaced by the term "OPEN position".
3.4.15
overcurrent
...