oSIST prEN IEC 63552:2025

SLOVENSKI STANDARD
01-julij-2025
Stikalna naprava za otočenje (SDFI)
Switching device for islanding (SDFI)
Appareil de connexion pour le passage en réseau séparé (SDFI)
Ta slovenski standard je istoveten z: prEN IEC 63552:2025
ICS:
27.015 Energijska učinkovitost. Energy efficiency. Energy
Ohranjanje energije na conservation in general
splošno
29.130.20 Nizkonapetostne stikalne in Low voltage switchgear and
krmilne naprave controlgear
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

23K/121/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 63552 ED1
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2025-05-23 2025-08-15
SUPERSEDES DOCUMENTS:
23K/99/CD, 23K/116A/CC
IEC SC 23K : ELECTRICAL ENERGY EFFICIENCY PRODUCTS
SECRETARIAT: SECRETARY:
France Mr Philippe Vollet
OF INTEREST TO THE FOLLOWING COMMITTEES: HORIZONTAL FUNCTION(S):
TC 8,SC 23B,SC 23E,TC 64,SC 121A
ASPECTS CONCERNED:
Energy Efficiency
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
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TITLE:
Switching device for islanding (SDFI)
PROPOSED STABILITY DATE: 2027
NOTE FROM TC/SC OFFICERS:
After resolution of 23K/99/CD comments, officiers support the circulation of this CDV.
download this electronic file, to make a copy and to print out the content for the sole purpose of preparing National
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2 IEC CDV 63552 ED1 © IEC 2025
1 CONTENTS
3 FOREWORD . 4
4 INTRODUCTION . 6
5 1 Scope . 8
6 2 Normative references . 9
7 3 Terms and definitions . 10
8 4 Classification . 14
9 4.1 General . 14
10 4.2 According to the construction . 15
11 4.3 According to the method of integration . 15
12 4.4 According to the method of operation . 15
13 4.5 According to the kind of current . 16
14 4.6 According to the number of switched poles . 16
15 4.7 According to SRCSD interlocking means . 16
16 4.8 According to the reclosing mode . 16
17 4.9 According to islanding means . 16
18 4.10 According to the type of isolation . 16
19 4.11 According to the type of local sources . 16
20 5 Characteristics . 16
21 6 Markings and product information . 17
22 7 Standard conditions for operation in service . 18
23 8 Requirements for construction and operation . 19
24 8.1 General requirements . 19
25 8.2 Construction requirements . 19
26 8.2.1 Mechanism . 19
27 8.2.2 SDFI operation and interlocking . 20
28 8.2.3 Manual reclosing of the SDFI . 21
29 8.2.4 Voltage and frequency deviations . 22
30 8.2.5 Voltage withstand between open contacts . 22
31 8.3 Reclosing operations (reconnection to grid connected mode) . 22
32 8.4 Operational endurance . 24
33 8.5 EMC . 24
34 9 Type tests . 24
35 9.1 General . 24
36 9.2 SDFI operation and interlocking . 24
37 9.3 Tests for manual reclosing . 24
38 9.4 Verification of operations upon deviations . 25
39 9.5 Test for reclosing operations . 26
40 9.5.1 General . 26
41 9.5.2 SDFI provided for closing without synchronization . 26
42 9.5.3 SDFI provided for reclosing with synchronization . 27
43 9.6 EMC tests . 28
44 9.6.1 General . 28
45 9.6.2 Electromagnetic emission . 28
46 9.6.3 Electromagnetic immunity . 28
47 Bibliography . 30

IEC CDV 63552 ED1 © IEC 2025 3
49 Figure 1 – Example of islandable PEI architecture . 6
50 Figure 2 –Example of SDFI . 15
51 Figure 3 – SDFI operation principle . 20
52 Figure 4 – Example of architecture of a PEI operating in TT in connected mode and
53 becoming TN in island mode . 21
54 Figure 5 – Example of sequence diagram for operation upon source deviation and grid
55 loss for transition to island mode . 22
56 Figure 6 – Grid reconnection – without synchronization (open transition) . 23
57 Figure 7 – Grid reconnection – with synchronization (closed transition) . 23
58 Figure 8 – Example of typical undervoltage ride through capability profile . 26
60 Table 1 – Requirements and position for markings and other product information . 17
61 Table 2 – Values of influencing quantities . 18
62 Table 3 – Immunity tests and performance criteria . 28
63 Table 4 – Performance criteria . 29
4 IEC CDV 63552 ED1 © IEC 2025
66 INTERNATIONAL ELECTROTECHNICAL COMMISSION
67 ____________
69 SWITCHING DEVICE FOR ISLANDING (SDFI)
71 FOREWORD
72 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
73 all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
74 co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
75 in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
76 Publicly Available Specifications (PAS) and Guides (hereafter referred to as "IEC Publication(s)"). Their
77 preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
78 may participate in this preparatory work. International, governmental and non-governmental organizations liaising
79 with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
80 Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
81 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
82 consensus of opinion on the relevant subjects since each technical committee has representation from all
83 interested IEC National Committees.
84 3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
85 Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
86 Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
87 misinterpretation by any end user.
88 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
89 transparently to the maximum extent possible in their national and regional publications. Any divergence between
90 any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
91 5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
92 assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
93 services carried out by independent certification bodies.
94 6) All users should ensure that they have the latest edition of this publication.
95 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
96 members of its technical committees and IEC National Committees for any personal injury, property damage or
97 other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
98 expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
99 Publications.
100 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
101 indispensable for the correct application of this publication.
102 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
103 rights. IEC shall not be held responsible for identifying any or all such patent rights.
104 IEC XXXXX has been prepared by subcommittee 23K: Electrical Energy Efficiency products, of
105 IEC technical committee 23: Electrical accessories. It is an International Standard.
106 The text of this International Standard is based on the following documents:
Draft Report on voting
23K/XX/FDIS 23K/XX/RVD
108 Full information on the voting for its approval can be found in the report on voting indicated in
109 the above table.
110 The language used for the development of this International Standard is English.
111 This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
112 accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
113 at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
114 described in greater detail at www.iec.ch/standardsdev/publications.
115 In this document, the following print types are used:
116 – conformity statements: in italic type.

IEC CDV 63552 ED1 © IEC 2025 5
117 The committee has decided that the contents of this document will remain unchanged until the
118 stability date indicated on the IEC website under webstore.iec.ch in the data related to the
119 specific document. At this date, the document will be
120 • reconfirmed,
121 • withdrawn,
122 • replaced by a revised edition, or
123 • amended.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates
that it contains colours which are considered to be useful for the correct understanding
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6 IEC CDV 63552 ED1 © IEC 2025
127 INTRODUCTION
128 IEC 60364-8-82 has the objective to ensure that the low-voltage electrical installation is
129 compatible with the existing and future ways to deliver safely and functionally the electrical
130 energy to current-using equipment wherever the electrical energy comes from the DSO or local
131 generation. IEC 60364-8-82 provides requirements and recommendations that apply to low-
132 voltage electrical installations connected or not to a distribution network able to operate:
133 – with local power supplies, and/or
134 – with local storage units,
135 and that monitors and controls the energy from the locally connected sources delivering it to:
136 – current-using equipment, and/or
137 – local storage units, and/or
138 – distribution networks.
139 Such electrical installations are designated as prosumer's electrical installations (PEIs) by IEC
140 60364-8-82 which defines specific devices (or functions) to ensure the correct and safe
141 operation of PEI depending on their operating mode. In the case of an islandable PEI, IEC
142 60364-8-82 defines a “Switching Device For islanding (SDFI), identified as device 4 in Figure 1
143 (reproduced from IEC 60364-8-82:2022, Figure 4).
145 Figure 1 – Example of islandable PEI architecture

Key
1 Distribution network 8 Non-sheddable loads (sensitive loads)
2 Point of connection (POC) 9 Sheddable loads (adjustable loads)
3 Main switching device 10 Solar generator
4 Switching device for islanding (SDFI) 11 Electrical energy storage system
5 System referencing conductor switching device 12 Other generator (wind, etc.)
6 Source switching device 13 Main distribution board

7 Load switching device
IEC CDV 63552 ED1 © IEC 2025 7
147 The objectives of this document is to define the functions, requirements and tests of a SDFI in
148 line with the requirements stated in IEC 60364-8-82.
8 IEC CDV 63552 ED1 © IEC 2025
152 SWITCHING DEVICE FOR ISLANDING (SDFI)
154 1 Scope
155 This International Standard applies to switching device for islanding, hereafter referred to as
156 SDFI, for household and similar uses, primarily intended to be used for energy efficiency (EE)
157 purposes with local production and/or storage of energy.
158 SDFI are intended to be installed in low voltage prosumer electrical installations (PEI) able to
159 operate in island mode as defined in IEC 60364-8-82, so called islandable PEI.
160 SDFI are used to disconnect the PEI from the grid to allow operating the PEI in island mode
161 and further reconnect the PEI to the grid.
162 They are intended to be used in islandable PEI which operate:
163 – in direct feeding mode and island mode (delivering the electrical energy to current-using
164 equipment of the PEI);
165 – and in reverse feeding mode to the grid (delivering the electrical energy to the grid).
166 NOTE 1 Switching of a PEI to island mode can be subject to local regulations (grid codes) or to specific agreement
167 with system operators.
168 SDFI are part of the electrical installation.
169 This document applies to SDFI for operation in AC single or multiphase main circuits with rated
170 voltages not exceeding 440 V AC, frequencies of 50 Hz, 60 Hz or 50/60 Hz. They are intended
171 to be used in installations with prospective short circuit currents not exceeding 25 000 A.
172 NOTE 2 DC operations are not covered by this edition and are kept under consideration for a future revision of this
173 document.
174 The SDFI is composed at least of one switching unit (SU) and a control unit (CU) to monitor its
175 switching operations from grid connected to island mode and reverse wise.
176 The SDFI can be provided with a communication interface for exchange with external systems
177 such as the CEM (Customer Energy Manager).
178 NOTE 3 See IEC 63402 series for CEM standards, under development.
179 According to the intended use, the SDFI can be interlocked with a system referencing conductor
180 switching device (SRCSD) or it can be integrated with a SRCSD in a single unit.
181 NOTE 4 See IEC 63445 for SRCSD standard.
182 NOTE 5 According to its intended use, the SDFI can also be used as an interface switch with the interface protection
183 (integrated or not). See 3.20 and 3.21.
184 SDFI are intended for use in circuits where protection against electrical shock and overcurrent
185 is provided according to installation rules for low voltage electrical installations, unless the SDFI
186 already contains such protective function. SDFI are not requested to provide isolation function
187 and overcurrent protection according to IEC 60364-8-82. However, the isolation function can
188 be provided by a SDFI fulfilling the requirements of the relevant product standards.
189 SDFI are normally installed by instructed persons (IEC 60050-195:2021, 195-04-02) or skilled
190 persons (IEC 60050-195:2021, 195-04-01). They are normally used by ordinary persons
191 (IEC 60005-195:2021, 195-04-03) and do not require maintenance.
192 It is important to note that the main overcurrent protective device of installations cannot be used
193 as a SDFI in single dwellings or similar islandable PEI (see Annex D.5 of IEC 60364-8-82:2022)

IEC CDV 63552 ED1 © IEC 2025 9
194 2 Normative references
195 The following documents are referred to in the text in such a way that some or all of their content
196 constitutes requirements of this document. For dated references, only the edition cited applies.
197 For undated references, the latest edition of the referenced document (including any
198 amendments) applies.
199 IEC 60669-2-4, Switches for household and similar fixed-electrical installations – Part 1:
200 Particular requirements – Isolating switches
201 IEC 60898-1, Electrical accessories – Circuit-breakers for overcurrent protection for household
202 and similar installations – Part 1: Circuit-breakers for a.c. operation
203 IEC 60898-2, Electrical accessories – Circuit-breakers for overcurrent protection for household
204 and similar installations – Part 2: Circuit-breakers for AC and DC operation
205 IEC 60947-2, Low-voltage switchgear and controlgear – Part 1: Circuit-breakers
206 IEC 60947-3, Low-voltage switchgear and controlgear – Part 3: Switches, disconnectors,
207 switch-disconnectors and fuse-combination units
208 IEC 60947-10, Low-voltage switchgear and controlgear – Part 10: Semiconductor Circuit-
209 Breakers
210 IEC 62991:2022, Particular requirements for source switching equipment (SSE)
211 IEC 63445:2025, System referencing conductor switching device
212 IEC 61000-4-2, Electromagnetic compatibility (EMC) – Part 4-2: Testing and measurement
213 techniques – Electrostatic discharge immunity test
214 IEC 61000-4-3, Electromagnetic compatibility (EMC) – Part 4-3: Testing and measurement
215 techniques – Radiated, radio-frequency, electromagnetic field immunity test
216 IEC 61000-4-4, Electromagnetic compatibility (EMC) – Part 4-4: Testing and measurement
217 techniques – Electrical fast transient/burst immunity test
218 IEC 61000-4-5, Electromagnetic compatibility (EMC) – Part 4-5: Testing and measurement
219 techniques – Surge immunity test
220 IEC 61000-4-6, Electromagnetic compatibility (EMC) – Part 4-6: Testing and measurement
221 techniques – Immunity to conducted disturbances, induced by radio-frequency fields
222 IEC 61000-4-8, Electromagnetic compatibility (EMC) – Part 4-8: Testing and measurement
223 techniques – Power frequency magnetic field immunity test
224 IEC 61000-4-11, Electromagnetic compatibility (EMC) – Part 4-11: Testing and measurement
225 techniques – Voltage dips, short interruptions and voltage variations immunity tests for
226 equipment with input current up to 16 A per phase
227 IEC 61000-6-1, Electromagnetic compatibility (EMC) – Part 6-1: Generic standards – Immunity
228 standard for residential, commercial and light-industrial environments
229 CISPR 14-1, Electromagnetic compatibility – Requirements for household appliances, electric
230 tools and similar apparatus – Part 1: Emission

10 IEC CDV 63552 ED1 © IEC 2025
231 3 Terms and definitions
232 For the purposes of this document, the following terms and definitions apply.
233 ISO and IEC maintain terminological databases for use in standardization at the following
234 addresses:
235 • IEC Electropedia: available at https://www.electropedia.org/
236 • ISO Online browsing platform: available at https://www.iso.org/obp
237 3.1
238 electrical energy management system
239 EEMS
240 system monitoring, operating, controlling and managing energy resources and loads of the
241 installations
242 Note 1 to entry: The EEMS can be a dedicated system or part of an integrated system, such as a home and building
243 electronic system (HBES) or building management system (BMS or BACS) or other similar management system.
244 [SOURCE: IEC 60364-8-82:2022, 82.3.7]
245 3.2
246 Customer Energy Manager
247 CEM
248 internal automation function for optimizing the energy consumption, production and storage
249 within the premises according to the preferences of the customer using internal flexibilities and
250 typically based on external information received through the Energy Management Gateway and
251 possibly other data sources
252 Note 1 to entry: A EEMS as defined in 3.1 of this standard and in 3.2.1 of IEC 60364-8-1:2019 provides the same
253 function as a CEMS except that the EEMS is limited to electrical energy management.
254 [SOURCE: IEC 63402-1:2025, 3.1.1, modified – Note 1 to entry added.]
255 3.3
256 Energy Management Gateway
257 EMG
258 access point (functional entity) sending and receiving smart grid related information and
259 commands between an actor in the Grid and the CEM, letting the CEM decide how to process
260 the events
261 Note 1 to entry: The communication is often ensured through an internet connection.
262 [SOURCE: IEC 63402-1:2025, 3.1.3]
263 3.4
264 Switching device for islanding
265 SDFI
266 device dedicated to the change from grid connected mode to island mode and from island mode
267 to connected mode for an islandable PEI, functionally speaking, to separate/link the local
268 sources from/to the distribution network
269 Note 1 to entry: See also 3.21.
270 [SOURCE: 1st paragraph of IEC 60364-8-82:2022, 82.6.3.4.3]
271 3.5
272 System referencing conductor switching devices
273 SRCSD
274 device connected between the system referencing conductor and the local earthing
275 arrangement of the PEI
IEC CDV 63552 ED1 © IEC 2025 11
276 [SOURCE: IEC 63445:2025, 3.3]
277 3.6
278 source switching equipment
279 SSE
280 equipment able to select (power) sources when certain conditions are met or following human
281 intervention
282 Note 1 to entry: For example, SSE for back-up applications may contain one or more switching devices and all
283 associated control means for disconnecting load circuits from one source and reconnecting them to another source
284 when certain conditions are met.
285 Note 2 to entry: For example, SSE for grid connected PEI defined in IEC 60364-8-82:2022 may contain one or more
286 switching devices and associated control means for switching load circuits from one normal source to another source,
287 when certain conditions are met, maintaining the loads always energized.
288 [SOURCE: IEC 62991:2022, 3.1.28]
289 3.7
290 combined SSE
291 C-SSE
292 SSE based on the association of switching devices complying with the IEC 60669 series, and
293 with IEC 60898-1 or IEC 60898-2, or with IEC 61095, and with its associated control means for
294 managing the switching operation(s) of the SSE
295 Note 1 to entry: Combined SSE may be based on individual devices or on devices mechanically assembled together
296 in a dedicated unit (e.g. two switches assembled together, two switches assembled together with the control unit or
297 parts of the control unit). In the case of assembled devices, assembling may be done by the manufacturer or on site
298 (e.g. by the installer or the panel builder).
299 Note 2 to entry: For SSE based on switching devices where certain tests are already covered by other product
300 standards, it is not necessary to repeat those tests.
301 [SOURCE: IEC 62991:2022, 3.1.29]
302 3.8
303 prosumer
304 entity or party which can be both a producer and a consumer of electrical energy
305 [SOURCE: IEC 60364-8-82:2022, 82.3.5]
306 3.9
307 prosumer's electrical installation
308 PEI
309 low-voltage electrical installation connected or not to a distribution network able to operate:
310 – with local power supplies, and/or
311 – with local storage units,
312 and that monitors and controls the energy from the connected sources delivering it to:
313 – current-using equipment, and/or
314 – local storage units, and/or
315 – distribution network.
316 [SOURCE: IEC 60364-8-82:2022, 82.3.6]
317 3.10
318 islandable PEI
319 PEI intended for operating either being connected to a distribution network or being
320 disconnected from the distribution network
321 Note 1 to entry: An islandable PEI is in a connected mode or an intentionally island mode.

12 IEC CDV 63552 ED1 © IEC 2025
322 [SOURCE: IEC 60364-8-82:2033, 82.3.15]
323 3.11
324 island mode
325 operating mode in which the PEI is disconnected from the distribution network
326 Note 1 to entry: An island mode can be either the result of the action of automatic protections or the result of a
327 deliberate action.
328 [SOURCE: IEC 60050-692:2017, 692-02-11, modified – The term "electric island" has been
329 replaced with "island mode", the definition has been adapted to the PEI and Note 2 to entry has
330 been deleted.]
331 3.12
332 direct feeding mode
333 operating mode in which the distribution network supplies the PEI
334 Note 1 to entry: Local storage units can supply current-using equipment or be charged by local power supplies
335 and/or the distribution system.
336 [SOURCE: IEC 60364-8-82:2022, 82.3.9]
337 3.13
338 reverse feeding mode
339 operating mode in which the PEI supplies the distribution network
340 Note 1 to entry: Local storage units can supply current-using equipment and/or the distribution system or be
341 charged by local power supplies.
342 [SOURCE: IEC 60364-8-82:2022, 82.3.10]
343 3.14
344 connected mode
345 operating mode in which the PEI is connected to the distribution network
346 EXAMPLE Direct feeding mode, reverse feeding mode or no feeding mode (i.e. without any energy exchange
347 between the PEI and the distribution network).
348 [SOURCE: IEC 60364-8-82:2022, 82.3.11]
349 3.15
350 Interlock (of an SDFI with an SRCSD)
351 means to prevent simultaneous closing of SRCSD and SDFI, under all conditions
352 [SOURCE: IEC 63445:2025, 3.11]
353 3.16
354 Synchronization
355 condition of an electrical system intentionally allowing the connection of two voltage sources in
356 parallel for a short duration
357 Note 1 to entry: The local power source when set in grid forming mode is a voltage source.
358 [SOURCE: IEC 62991:2022, 3.1.17, modified – Replacing “different power” by “voltage”, adding
359 “condition of an” in the definition and adding the note]
360 3.17
361 open transition
362 break before make transfer operation that intentionally breaks the load current from one source
363 for a period of time prior to making it to the other source
364 Note 1 to entry: SSE with open transition may operate with a time delay e.g. for power backup application.

IEC CDV 63552 ED1 © IEC 2025 13
365 [SOURCE: IEC 60947-6-1:2021, 3.4.7, modified – Note 1 to entry has been added.]
366 3.18
367 closed transition
368 make before break transfer operation that intentionally makes the load current of a second
369 synchronized source for a short period of time before breaking it from the first source
370 [SOURCE: IEC 60947-6-1:2021, 3.4.9]
371 3.19
372 isolation
373 isolating function
374 function intended to cut off the supply from all or a discrete section of the installation by
375 separating the installation from every source of electrical energy for reasons of safety
376 [SOURCE: IEC 60898-1:2015, 3.6.10]
377 3.20
378 interface protection
379 combination of protection relay functions which open the interface switch of a generating unit
380 and prevents its closure, whichever is appropriate, in the case of:
381 – a fault on the electric power distribution network;
382 – an unintentional islanding situation;
383 – voltage and/or frequency being outside the tolerance of their operating ranges for
384 continuous operation.
385 [SOURCE: IEC TS 62786-1:2023, 3.1.14, modified - “distribution” added in the first indent.]
386 3.21
387 interface switch
388 switch (circuit breaker, switch or contactor) installed in the prosumer’s electrical installation, for
389 separating the part(s) of the prosumer’s electrical installation that contains at least one
390 generation unit from the network
391 Note 1 to entry: See also Figure 1 of IEC TS 62786-1:2023.
392 Note 2 to entry: In some situations, the interface switch can be used to enable island operation of part of the
393 prosumer’s electrical installation, if technically feasible.
394 [SOURCE: IEC TS 62786-1:2023, 3.1.33, note 1 modified - reference to the IEC standard
395 adding and replaced “producer’s network” by “prosumer’s electrical installation” ]
396 3.22
397 monitored source deviation
398 variation in the measured power source characteristics that exceeds predetermined limits
399 EXAMPLE Abnormal changes in voltage or frequency of the power source are source deviations.
400 [SOURCE: IEC 60947-6-1:2021, 3.4.2, modified – Replacing "supply" by "source" and removing
401 the note.]
402 3.23
403 voltage source deviation
404 change in voltage level from the nominal voltage of the monitored source
405 Note 1 to entry: In this document, the term is often used stating only the term “source”.
406 [SOURCE: IEC 60947-6-1:2021, 3.4.3, modified – Replacing "supply" by "source" and adding
407 the note.]
14 IEC CDV 63552 ED1 © IEC 2025
408 3.24
409 frequency source deviation
410 change in frequency from the nominal operating frequency of the monitored source
411 Note 1 to entry: In this document, the term is often used stating only the term “source”.
412 [SOURCE: IEC 60947-6-1:2021, 3.4.4, modified – Replacing "supply" by "source" and adding
413 the note.]
414 3.25
415 point of connection
416 POC
417 reference point where the prosumer's electrical installation is connected to the distribution
418 network
419 Note 1 to entry: A PEI can have several points of connection for resilience.
420 Note 2 to entry: In IEC 60364 (all parts), the concept of origin of the installation is also used, origin of the installation
421 meaning the point at which energy is delivered to the electrical installation. The POC is a specific origin of the
422 installation, the one connected to the distribution network. Other origins of the installation can be the connection to
423 the local power supply, to the storage system.
424 Note 3 to entry: Connection or disconnection of the prosumer electrical installation from the distribution network
425 generally occurs at the POC.
426 [SOURCE: IEC 60050-617:2009, 617-04-01 modified – The definition has been adapted to the
427 PEI and the notes to entry have been added.]
428 3.26
429 control unit
430 all part(s) intended for managing the operation(s) of the switching unit (of the
431 SDFI) including the operating means
432 Note 1 to entry: Depending on the type of SDFI, the control unit may include different features such as manual
433 operating means, sensing, interlock, synchronization, control of settings, etc. For the purposes of this document,
434 control means do not include means intended for purposes other than controls, e.g. local or remote signalling.
435 [SOURCE: IEC 62991:2020, 3.1.35, modified – replacing "SSE" by "SDFI" in the definition and
436 in the note, and removing notes 2, 3 and 4.]
437 4 Classification
438 4.1 General
439 The general concept of an SDFI is shown Figure 2 with the main functional units a SDFI within
440 its environment.
IEC CDV 63552 ED1 © IEC 2025 15
EEM/CEM (6)
SDFI (1)
CU (2)
SU (3)
SRCSD (4)
(5)
(10)
442 Key
5 Interlock (of the SRCSD with SDFI)
1 Switching Unit (SU)
6 Electrical Energy Management (EEM) or the
2 Control Unit (CU)
Customer Energy Manager (CEM)
1 Switching device for islanding (SDFI)
7 Grid
2 Control unit (CU) 8 Local source(s)
9 Loads
3 Switching unit (SU)
10 Earth
4 System referencing conductor Switching Device
(SRCSD)
443 Figure 2 –Example of SDFI
444 NOTE 1 Control unit with or without sensing means (also called measurement circuits).
445 NOTE 2 Sensing means can be part of the SDFI (e.g. part of the control unit) or the overall CEM system.
446 NOTE 3 According to this standard, the CU is supposed to integrate control means for the operations (e.g.
447 synchronization check before reclosing) and the interlock with the SRCSD.
448 NOTE 4 The control unit, sensing unit and any connecting accessories can be delivered assembled together in the
449 factory with the switching unit or assembled on site.
450 SDFI shall be classified according to 4.2 to 4.11.
451 4.2 According to the construction
452 SDFI with a switching unit (SU) based on:
453 – switches complying with the IEC 60669-2-4 or IEC 60947-3;
454 – circuit-breakers complying with IEC 60898-1, IEC 60898-2, IEC 60947-2 or IEC 60947-10.
455 NOTE For SDFI based on switching devices where certain tests are already covered by other product standards, it
456 is not necessary to repeat those tests.
457 4.3 According to the method of integration
458 – SDFI with the SRCSD not integrated in a single device;
459 – SDFI with the SRCSD integrated in a single device.
460 NOTE SDFI can be based on separate devices or with all devices assembled together into a single device but with
461 the switching unit based on 4.2. See Figure 2.
462 4.4 According to the method of operation
463 – electrically controlled: SDFI with an integrated control unit (CU) for managing its switching
464 operations. This may or may not include automatic islanding function upon voltage or
465 frequency deviations;
466 – manually (non-electrically) controlled;

16 IEC CDV 63552 ED1 © IEC 2025
467 – or both electrically controlled and manually (non-electrically) controlled.
468 When manual mode is available and if the SDFI is used as the interface switch, it shall be
469 ensured that the manual mode does not prevent the SDFI from opening upon orders received
470 from the interface protection.
471 NOTE The SDFI can also have communication interfaces for SDFI remotely controlled by the CEM.
472 4.5 According to the kind of current
473 – for AC use;
474 – for DC use (under consideration).
475 4.6 According to the number of switched poles
476 – Single-pole SDFI;
477 – Two-pole SDFI;
478 – Three-pole SDFI;
479 – Four-pole SDFI.
480 4.7 According to SRCSD interlocking means
481 – SDFI without interlocking;
482 – SDFI with mechanical or electrical interlocking means.
483 NOTE When the SDFI is integrated with the SRCSD according to 4.1 in a single device, the interlock is also
484 integrated.
485 4.8 According to the reclosing mode
486 – SDFI without synchronization (open transition);
487 – SDFI with synchronized reclosing (closed transition).
488 4.9 According to islanding means
489 – SDFI without automatic islanding means;
490 – SDFI with automatic islanding means.
491 NOTE operation of the SDFI with automatic islanding means is based on voltage and frequency source deviations.
492 4.10 According to the type of isolation
493 – SDFI not suitable for isolation;
494 – SDFI suitable for isolation.
495 NOTE IEC 60364-8-82 ED1 does not require isolation for the SDFI.
496 4.11 According to the type of local sources
497 – SDFI suitable for use with any kind of local sources excluding generators;
498 – SDFI suitable for use with any kind of local sources including generators .
499 5 Characteristics
500 The characteristics of the switching unit of an SDFI are covered by:
501 – IEC 60669-2-4 or IEC 60947-3 for SDFI based on switches;
502 – IEC 60898-1, IEC 60898-2, IEC 60947-2 or IEC 60947-10 for SDFI based on circuit-
503 breakers.
504 The characteristics of the control unit and auxiliary circuits are covered by IEC 62991:2022,
505 clause 5.4. In addition, the following characteristics apply to the control unit and auxiliary
506 circuits:
507 – the voltage and frequency deviation limits;

IEC CDV 63552 ED1 © IEC 2025 17
508 – the characteristics of control circuits and auxiliary circuits (e.g. rated voltage and currents,
509 limits) if any;
510 The maximum number of operating cycles shall be declared. The preferred number of operating
511 cycles is: 4 000, 6 000, 12 000 and 25 000, where 4 000 is the requested minimum value.
512 6 Markings and product information
513 Identification of the SDFI shall comply with relevant IEC product standards according to
514 manufacturer’s declaration based on clause 4 and relevant items of Table 1.
515 Table 1 – Requirements and position for markings and other product information
a a a
Marking or information item Markings Documentation
a Manufacturer's name or trademark b
X
V
b Type designation, catalogue number or serial number b
X
V
c Reference to product standard X X
d Method of construction (4.2) X
e Method of SRCSD integration (4.3) X
f Method of operation (4.4) X
g Number of switched poles (4.6) X
h Method for SRCSD interlocking (4.7) X
i Reclosing mode (4.8) X
j Type of islanding means (4.9) X
k Suitability for isolation (4.10) X
l SDFI suitability with local sources (4.11) X

m Rated voltage(s) and symbol for nature of supply(ies) c
X
X
n Rated frequency(ies) c
X
X
o Voltage and frequency source deviations, phase angle(s)
X
limits, if applicable
p Rated current(s) (I )
X
n
q Rated making and breaking capacity in amperes (I )
X
m
r Rated conditional short circuit current (Inc) X
s SCPD characteristics X
t Utilization categories and corresponding current(s), if
X
applicable
u Number of operating cycles (5) X
v Reclosing time delay, if applicable X
w Rated impulse withstand voltage X
x Degree of protection  X
y Position/orientation of use, if necessary X
z Indication of switch(es) positions X
aa Wiring diagram, unless correct connection mode is evident c
X
X
ab Length of insulation to be removed before the insertion of
c
X
X
the conductor into the screwless type terminal, if applicable
ac Type of terminals and symbol "r" for the suitability to
c
X
X
f
accept rigid conductors only
ad Rated control circuit supply voltage(s), rated control circuit
b
supply current(s), rated control circuit supply frequency X
V
and symbol for the nature of the supply, as applicable

18 IEC CDV 63552 ED1 © IEC 2025
a a a
Marking or information item Markings Documentation
X: applies. V: visible once installed.
a
Apply to the control unit and other auxiliaries (e.g. interlock), as relevant. For the switching unit, requirements
for markings and documentation as defined in the relevant IEC product standard apply according to the method
of construction (see 4.2)
b
If, for small devices, the available space is insufficient, these markings may not be visible.
c
Markings apply specifically to the control unit and to the interlock, if provided (see 4.7)
516 If the SDFI is provided with embedded functions/units covered by other standards, identification
517 of such functions shall comply with the relevant IEC product standard according to clause 4.
518 Relevant standards shall be stated by manufacturers in the technical documentation.
519 Correct indication of the terminals for the source and load sides shall be provided, e.g. in/out,
520 source/loads, etc.
521 If the SDFI is delivered as individual devices to be assembled together on site when integrated
522 in a distribution board (e.g. by the insta
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