EN IEC 60947-6-1:2026

SLOVENSKI STANDARD
oSIST prEN IEC 60947-6-1:2025
01-april-2025
Nizkonapetostne stikalne in krmilne naprave - 6-1. del: Večfunkcijska oprema -
Preklopna stikalna oprema
Low-voltage switchgear and controlgear - Part 6-1: Multiple function equipment -
Transfer switching equipment
Niederspannungsschaltgeräte - Teil 6-1: Mehrfunktionsschaltgeräte - Netzumschalter
Appareillage à basse tension - Partie 6-1: Matériels à fonctions multiples - Equipement
de transfert de source
Ta slovenski standard je istoveten z: prEN IEC 60947-6-1:2025
ICS:
29.120.40 Stikala Switches
29.130.20 Nizkonapetostne stikalne in Low voltage switchgear and
krmilne naprave controlgear
oSIST prEN IEC 60947-6-1:2025 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN IEC 60947-6-1:2025
oSIST prEN IEC 60947-6-1:2025
121A/639/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 60947-6-1 ED4
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2025-02-07 2025-05-02
SUPERSEDES DOCUMENTS:
121A/594/CD, 121A/606B/CC
IEC SC 121A : LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR
SECRETARIAT: SECRETARY:
France Mr Michaël LAHEURTE
OF INTEREST TO THE FOLLOWING COMMITTEES: HORIZONTAL FUNCTION(S):
SC 23K,SC 121B
ASPECTS CONCERNED:
Electromagnetic Compatibility,Safety
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of
CENELEC, is drawn to the fact that this Committee Draft for Vote
(CDV) is submitted for parallel voting.
The CENELEC members are invited to vote through the
CENELEC online voting system.
This document is still under study and subject to change. It should not be used for reference purposes.
Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.
Recipients of this document are invited to submit, with their comments, notification of any relevant “In Some Countries” clauses to
be included should this proposal proceed. Recipients are reminded that the CDV stage is the final stage for submitting ISC clauses.
(SEE AC/22/2007 OR NEW GUIDANCE DOC).

TITLE:
Low-voltage switchgear and controlgear – Part 6-1: Multiple function equipment - Transfer switching
equipment
PROPOSED STABILITY DATE: 2029
NOTE FROM TC/SC OFFICERS:
SC121A officers are supporting the circulation of CDV for IEC 60947-6-1 ED4. Experts are kindly asked to refer to line
numbers when commenting the document.

electronic file, to make a copy and to print out the content for the sole purpose of preparing National Committee positions.
You may not copy or "mirror" the file or printed version of the document, or any part of it, for any other purpose without
permission in writing from IEC.

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CONTENTS
FOREWORD . 7
INTRODUCTION . 9
1 Scope . 10
2 Normative references . 11
3 Terms and definitions . 12
3.1 General . 12
3.2 Alphabetical index of terms . 13
3.3 Transfer switching devices . 15
3.4 Operation of TSE . 17
3.5 Main contact positions . 19
3.6 Symbols and abbreviations . 20
4 Classification . 20
5 Characteristics . 21
5.1 Summary of characteristics . 21
5.2 Type and characteristics of equipment . 21
5.3 Rated and limiting values for the main circuit . 22
5.3.1 General . 22
5.3.2 Rated voltages . 22
5.3.3 Rated operational current (I ) . 22
e
5.3.4 Rated frequency . 22
5.3.5 Rated making and breaking capacities . 22
5.3.6 Short-circuit characteristics . 23
5.4 Utilization category . 23
5.5 Control circuits . 24
5.5.1 General . 24
5.5.2 Electro-mechanical devices operating the main circuit . 24
5.5.3 ATS controller . 24
5.6 Auxiliary circuits . 24
6 Product information . 24
6.1 Nature of information . 24
6.2 Marking . 25
6.3 Instructions for installation, operation and maintenance, decommissioning
and dismantling . 27
6.4 Environmental information . 28
7 Normal service, mounting and transport conditions . 28
8 Constructional and performance requirements . 29
8.1 Constructional requirements . 29
8.1.1 General . 29
8.1.2 Materials . 29
8.1.3 Indication . 30
8.1.4 Equipment suitable for isolation . 30
8.1.5 Opening and closing of main contacts . 30
8.1.6 Clearances and creepage distances . 30
8.1.7 Provision for protective earthing . 31

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8.1.8 Stored charge energy circuit . 31
8.1.9 Stored energy closing . 31
8.1.10 Dedicated enclosures for TSE . 31
8.1.11 Communication . 31
8.2 Performance requirements . 32
8.2.1 Operating conditions . 32
8.2.2 Temperature-rise . 33
8.2.3 Dielectric properties . 33
8.2.4 Ability to make, carry, and break under no-load, normal load and
overload conditions . 33
8.2.5 Ability to make and break under short-circuit conditions . 36
8.2.6 Critical load current performance of TSE with DC rating . 37
8.3 Electromagnetic compatibility (EMC) . 37
8.3.1 General . 37
8.3.2 Immunity . 37
8.3.3 Emission . 38
9 Tests . 38
9.1 Kinds of tests . 38
9.2 Type tests . 38
9.2.1 General test conditions . 38
9.2.2 Test sequences . 39
9.2.3 Test sequence I - General performance characteristics. 43
9.2.4 Test sequence II – Operational performance capability . 49
9.2.5 Test sequence III – Short-circuit performance capability . 55
9.2.6 Test sequence IV - Conditional short-circuit current . 58
9.2.7 Test sequence V: critical load current performance of equipment with a
DC rating . 59
9.2.8 Test sequence VI - EMC tests . 62
9.3 Routine tests . 63
9.4 Environmental tests . 66
Annex A (normative) Assignment of utilization categories based on results of tests . 68
Annex B (informative) Items subject to agreement between manufacturer and user . 69
Annex C (normative) Bypass/Isolation Transfer Switch Equipment . 70
C.1 General . 70
C.2 (void) . 70
C.3 (void) . 70
C.4 Classification . 70
C.5 Characteristics . 70
C.6 Product information . 70
C.7 Normal service, mounting and transport conditions . 70
C.8 Constructional and performance requirements . 70
C.8.1 General . 70
C.8.2 Construction requirements . 71
C.8.3 Performance requirements . 72
C.9 Tests . 73
C.9.1 Interlocking function verification. 74
C.9.2 Full assembly tests . 74

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C.9.3 Routine tests . 74
C.10 BTSE typical circuits and main components . 74
C.10.1 Example of operating sequence of a single line fixed type BTSE . 75
C.10.2 Example of operating sequence of a double line fixed type BTSE . 76
C.10.3 Example of operating sequence of a double line withdrawable type

BTSE . 77
C.10.4 Example of operating sequence of a double line load-break
withdrawable type BTSE . 78
C.10.5 Example of operating sequence of a single line withdrawable type BTSE . 79
Annex D (normative) ATSE having closed transition capability . 80
D.1 General . 80
D.2 (void) . 80
D.3 (void) . 80
D.4 Classification . 80
D.5 Characteristics . 80
D.6 Product information . 80
D.7 Normal service, mounting and transport conditions . 81
D.8 Constructional and performance requirements . 81
D.8.1 General . 81
D.8.2 Operating mechanism . 82
D.8.3 Controls, sequence, and limits of operation . 82
D.8.4 Performance requirements . 83
D.9 Tests . 84
D.9.1 General . 84
D.9.2 Test procedure . 84
D.9.3 Figures to clarify closed transition transfer . 85
Annex E (normative) Stand-alone ATS controller . 89
E.1 General . 89
E.2 (void) . 89
E.3 (void) . 89
E.4 Classification . 89
E.5 Characteristics . 89
E.6 Product information . 89
E.6.1 Product instructions for operation . 91
E.7 Normal service, mounting and transport conditions . 92
E.8 Constructional and performance requirements . 92
E.8.1 Constructional requirements . 92
E.8.2 Performance requirements . 94
E.8.3 Electromagnetic compatibility (EMC) . 94
E.9 Tests . 94
E.9.1 General . 94
E.9.2 List of type tests . 94
E.9.3 Wire flexing test . 95
E.9.4 EMC tests . 95
E.9.5 Stand-alone ATS Controller routine test . 95
E.9.6 Environmental tests . 96
E.9.7 Example to clarify stand-alone ATS Controller operating transfer time . 96
Annex F (normative) TSE used with electric driven fire pump control equipment . 97

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F.1 General . 97
F.2 Normative references . 97
F.3 Terms and definitions. 97
F.4 Classification . 97
F.5 Characteristics . 97
F.6 Product information . 97
F.7 Normal service, mounting and transport conditions . 98
F.8 Constructional, functional, and performance requirements . 98
F.8.1 General . 98
F.8.2 Manual operating means for maintenance and servicing . 98
F.8.3 Voltage sensing . 98
F.8.4 Initiation of transfer to secondary supply source . 98
F.8.5 Frequency monitoring of generator source . 99
F.8.6 Indicators of transfer . 99
F.8.7 Integral protective devices . 99
F.8.8 Generator starting contacts . 99
F.8.9 Power circuit components . 99
F.8.10 Operating mechanism . 99
F.9 Tests . 99
F.9.1 General . 99

Figure 1 – Example of operating sequences for TSE with three positions . 28
Figure 2 – Test circuit for connection to source I and source II supplies . 65
Figure 3 - Test circuit for the verification of making and breaking capacities . 66
Figure C.1 – Single line fixed type BTSE . 75
Figure C.2 – Double line fixed type BTSE . 76
Figure C.3 – Double line withdrawable type BTSE . 77
Figure C.4 – Double line load-break withdrawable type BTSE . 78
Figure C.5 – Single line withdrawable type BTSE . 79
Figure D.1 – Additional control circuit and external disconnecting devices . 83
Figure D.2 – Open transition . 85
Figure D.3 – Closed transition. 85
Figure D.4 – Example to describe a typical open and closed transition operating
sequence . 86
Figure D.5 – Example of an operating sequence with a fail to open position II contacts
within 100 ms during a return transfer in closed transition . 87
Figure D.6 – Example of an operating sequence with a fail to open both position I and
position II contacts during a return transfer in closed transition and showing the
removal of the condition by signalling an external device to open (source II) . 88
Figure E.1 – Example to show the stand-alone ATS Controller operating transfer time. 96

Table 1 – Utilization categories . 24
Table 2 (1 of 2) – Product information . 25
Table 3 – Verification of making and breaking capacity – Conditions for making and
breaking corresponding to the utilization categories . 34

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Table 4 – Verification of operational performance – Conditions for making and breaking
corresponding to the utilization categories . 35
Table 5 – Value of the test current for the verification of the ability to operate under

short-circuit conditions . 36
Table 6 – Value of the test current for the verification of the ability to operate under
short-circuit conditions (harmonized table) . 37
Table 7 – Acceptance criteria of immunity test . 38
Table 8 – List of type tests (overall scheme of test sequences) . 40
Table 9 – List of type tests to which a derived TSE shall be submitted . 41
Table 10 – Number and duration of operating cycles for the making and breaking
capacity test . 51
Table 11 – Number and rate of operating cycles for the electrical and mechanical
operational performance tests for type A utilization categories . 52
Table 12 – Number and rate of operating cycles for the electrical and mechanical
operational performance tests for type B utilization categories . 53
Table 13 – Temperature-rise limits for terminals and accessible parts. 54
Table 14 – Number of operating cycles corresponding to the critical load current . 61
Table 15 – Test circuit parameters for Table 14 . 61
Table 16 – Test sequence V: Critical load current performance of equipment with a DC
rating . 61
Table D.1 – Product information . 81
Table E.1 – Product information . 90
Table E.2 – List of type tests for the stand-alone ATS Controller. 95
Table F.1 – Product information . 97

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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 6-1: Multiple function equipment –
Transfer switching equipment
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,
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preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
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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
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60947-6-1 has been prepared by sub-committee 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 2005, and its
Amendment 1:2013. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
– clarification of scope and object;
– clarification of terms and definitions;
– removal of unnecessary definitions;
– modification of characteristics;

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– modification of utilization categories definitions;
– introduction of new markings requirements;
– addition of new requirements for clearances and creepage distances;
– addition of new requirements and tests for mechanical and electrical interlocks;
– clarification of transfer sequences;
– modification of requirements for rated short-time withstand currents;
– modification of new requirements for electromagnetic compatibility;
– clarification of performance requirements for CB type TSE, in alignment with requirements
stated in IEC 60947-2;
– addition of new test sequence V: Critical load current performance of equipment with DC
ratings.
The text of this International Standard is based on the following documents:
FDIS Report on voting
121A/XXX/FDIS 121A/XXX/RVD
Full information on the voting for the approval of this International 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, published under the general title Low-voltage
switchgear and controlgear, can be found on the IEC website.
This document shall be read in conjunction with IEC 60947-1:2020, Low voltage switchgear and
controlgear – Part 1: General rules.
The provisions of the general rules are applicable to IEC 60947-6-1 where specifically called
for. General rules clauses and subclauses thus applicable as well as tables, figures and
appendices are identified by reference to IEC 60947-1:2020, for example, 1.2.3, Table 4, or
Annex A of IEC 60947-1:2020.The committee has decided that the contents of this publication
will remain unchanged until the stability date indicated on the IEC website 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 National Committees are requested to note that for this publication the stability date
is 2022
THIS TEXT IS INCLUDED FOR THE INFORMATION OF THE NATIONAL COMMITTEES AND WILL BE DELETED
AT THE PUBLICATION STAGE.
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 publication using a colour printer.

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1 INTRODUCTION
2 The availability of power in low voltage electrical installations is playing an ever increasing role
3 in modern society. In actual fact, this requirement is a fundamental characteristic for the
4 creation of economically and functionally efficient installations. A system able to switch a load
5 from one source to another safely and with minimum disturbance to the load reduces problems
6 caused by faulty conditions in the normal supply to the minimum.
7 All these operations, commonly known as “transfer switching”, control the installations and can
8 be done automatically, remotely or manually.
9 Therefore, an installation with installed “transfer switching” capability:
10 – ensures the continuity of production processes;
11 – provides a backup source of power if the main network is out of service;
12 – reduces the effect caused by network faults on parts of the installation;
13 – achieves a good compromise between reliability, simplicity and cost-effectiveness;
14 – provides the facility manager and managing system with a power source able to supply all
15 or part of the installation.
16 Key factors motivating customers to use Transfer Switch Equipment (TSE) include:
17 – the continuous world growth population, the increasing number of electronic devices and
18 the new demands of electric vehicles;
19 – the mediated pressure on climate change with a resulting increase in the cost of energy;
20 – the evolution of the electricity market with a greater number of alternate energy sources;
21 – the user’s expectations of better grid reliability, better economic performance, and a desire
22 to manage their energy.
23 Stakeholders involved in the management of electricity also have new expectations:
24 – customers want to reduce the cost of their energy and to have a quality energy supply;
25 – suppliers want to reinforce confidence to their customers;
26 – producers expect to optimize their investments;
27 – governments and regulators are willing to create a competitive and sustainable energy
28 market.
29 Today, the performance of Transfer Switching Equipment is defined by TSE manufacturers and
30 also by this document. Consultants, integrators, facility managers and end users rely on this
31 document for their power availability needs.
32 Transfer switching are often realised by implementing a transfer function within the electrical
33 installation, but this critical function may not be appropriately designed. Using a TSE following
34 the requirements of this document ensure the safety and the performance of the transfer
35 function which are necessary for reaching the objectives listed above.
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38 LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –
40 Part 6-1: Multiple function equipment –
41 Transfer switching equipment
44 1 Scope
45 This document applies to transfer switching equipment (TSE), to be used in power systems for
46 ensuring the continuity of the supply and allowing the energy management of the installation,
47 by transferring a load between power supply sources, the rated voltage of which does not
48 exceed 1 000 V AC or 1 500 V DC.
49 Specific requirements for bypass/isolation transfer switch equipment are given in Annex C,
50 ATSE having closed transition capability are given in Annex D, stand-alone ATS controllers are
51 given in Annex E, TSE for electric driven fire pump controllers are given in Annex F.
52 It covers:
53 – manually operated transfer switching equipment (MTSE);
54 – remotely operated transfer switching equipment (RTSE);
55 – automatic transfer switching equipment (ATSE), including the controller.
56 – stand-alone ATS controllers;
57 – bypass/isolation transfer switch equipment (BTSE);
58 – ATSE having closed transition capability;
59 – fire pump TSE.
60 It does not cover:
61 – TSE configurations that are not fully manufacturer type tested and/or marked according to
62 this document as a complete transfer switch;
63 – auxiliary contacts (for guidance, see IEC 60947-5-1);
64 – transfer switches used in explosive atmospheres (for guidance, see IEC 60079 (all parts));
65 – embedded software design (for guidance, see IEC TR 63201);
66 – cybersecurity aspects (for guidance, see IEC TS 63208);
67 – TSE rated for direct-on-line starting asynchronous motor of design NE and HE, according
68 to IEC 60034-12:2016. (for guidance, see AC-3e utilisation category according IEC 60947-
69 4-1:2018);
70 – other types of TSE under consideration including overlapping neutral TSE, multi-source TSE
71 (i.e. TSE with more than two sources of supply), TSE with load-shedding functions and bus-
72 tie TSE;
73 – static transfer switches covered by IEC 62310 series.
74 NOTE TSE used for safety services and for emergency escape lighting systems as described in IEC 60364-5-56 are
75 subject to specific rules and/or legal requirements.
76 The object of this document is to state:
77 1) the characteristics of the equipment;
78 2) the conditions of the equipment with respect to:
79 a) operation for which the equipment is intended;

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80 b) operation and behaviour in case of specified abnormal conditions, for example, short-
81 circuit;
82 c) dielectric properties;
83 3) the tests intended to confirm that these conditions have been met and the methods for performing
84 these tests;
85 4) the product information to be provided by the manufacturer.
87 2 Normative references
88 The following documents are referred to in the text in such a way that some or all of their content
89 constitutes requirements of this document. For dated references, only the edition cited applies.
90 For undated references, the latest edition of the referenced document (including any
91 amendments) applies.
92 IEC 60068-2-2:2007, Environmental testing – Part 2-2: Tests - Test B: Dry heat
93 IEC 60417, Graphical symbols for use on equipment (available at http://www.graphical-
94 symbols.info/equipment)
95 IEC 60715:2017, Dimensions of low-voltage switchgear and controlgear – Standardized mounting on
96 rails for mechanical support of switchgear, controlgear and accessories
97 IEC 60812, Failure modes and effects analysis (FMEA and FMECA)
98 IEC 60947 (all parts), Low-voltage switchgear and controlgear
99 IEC 60947-1:2020, Low-voltage switchgear and controlgear – Part 1: General rules
100 IEC 60947-2:2016, Low-voltage switchgear and controlgear – Part 2: Circuit-breakers
101 IEC 60947-2:2016/AMD1:2019
102 IEC 60947-3:2020, Low-voltage switchgear and controlgear – Part 3: switches, disconnectors,
103 switch-disconnectors and fuse-combination units
104 IEC 60947-4-1:2023, Low-voltage switchgear and controlgear – Part 4-1: Contactors and motor-
105 starters - Electromechanical contactors and motor-starters
106 IEC 61000-4-13:2002, Electromagnetic compatibility (EMC) – Part 4-13: Testing and
107 measurement techniques – Harmonics and interharmonics including mains signalling at a.c.
108 power port, low-frequency immunity tests
109 IEC 61000-4-13:2002/AMD1:2009
110 IEC 61000-4-13:2002/AMD2:2015
111 CISPR 11:2015, Industrial, scientific and medical equipment – Radio-frequency disturbance
112 characteristics – Limits and methods of measurement
113 CISPR 11:2015/AMD1:2016
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114 3 Terms and definitions
115 3.1 General
116 For the purposes of this document, the terms and definitions given in Clause 3 of IEC 60947-
117 1:2020, and the following apply.
118 ISO and IEC maintain terminological databases for use in standardization at the following
119 addresses:
120 • ISO Online browsing platform: available at http://www.iso.org/obp
121 • IEC Electropedia: available at http://www.electropedia.org/

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122 3.2 Alphabetical index of terms
123 Reference
124 A
125 ATS (Automatic Transfer Switch) controller . 3.3.9
126 Automatic transfer switching equipment (ATSE) . 3.3.4
127 Available source . 3.4.11
129 B
130 Backup TSE (of a BTSE) . 3.3.13
131 Bypass / Isolation mode (of a BTSE) . 3.3.17
132 Bypass mode (of a BTSE) . 3.3.15
133 Bypass transfer switching equipment (BTSE) . 3.3.11
135 C
136 Contact transfer time . 3.4.5
137 Class CB TSE . 3.3.7
138 Class CC TSE . 3.3.8
139 Class PC TSE . 3.3.6
140 Closed transition . 3.4.9
142 D
143 Derived transfer switching equipment (derived TSE) . 3.3.5
144 Dedicated wiring accessories . 3.3.10
146 F
147 Fire pump TSE .
...