prEN IEC 60909:2025
(Main)Short-circuit currents in three-phase a.c. systems - Part 0: Calculation of currents
Short-circuit currents in three-phase a.c. systems - Part 0: Calculation of currents
Kurzschlussströme in Drehstromnetzen - Teil 0: Berechnung der Ströme
Courants de court-circuit dans les réseaux triphasés à courant alternatif - Partie 0: Calcul des courants
Kratkostični toki v izmeničnih trifaznih sistemih - 0. del: Računanje tokov
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Standards Content (Sample)
SLOVENSKI STANDARD
01-junij-2025
Kratkostični toki v izmeničnih trifaznih sistemih - 0. del: Računanje tokov
Short-circuit currents in three-phase a.c. systems - Part 0: Calculation of currents
Kurzschlussströme in Drehstromnetzen - Teil 0: Berechnung der Ströme
Courants de court-circuit dans les réseaux triphasés à courant alternatif - Partie 0: Calcul
des courants
Ta slovenski standard je istoveten z: prEN IEC 60909:2025
ICS:
17.220.01 Elektrika. Magnetizem. Electricity. Magnetism.
Splošni vidiki General aspects
29.240.20 Daljnovodi Power transmission and
distribution lines
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
73/220/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 60909-0 ED3
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2025-05-02 2025-07-25
SUPERSEDES DOCUMENTS:
73/192A/RR
IEC TC 73 : SHORT-CIRCUIT CURRENTS
SECRETARIAT: SECRETARY:
Norway Mr Lars Jakob Paulsen
OF INTEREST TO THE FOLLOWING COMMITTEES: HORIZONTAL FUNCTION(S):
TC 8,TC 17,TC 18,TC 64,TC 88,TC 99,TC 121
ASPECTS CONCERNED:
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:
Short-circuit currents in three-phase a.c. systems - Part 0: Calculation of currents
PROPOSED STABILITY DATE: 2028
NOTE FROM TC/SC OFFICERS:
Maintenace projects was approved by National Committees and documented in 73/191/RQ
The Secretariat has decided to finish ED 3 within the allocated project time. CDV as the next step is the only
way to achieve this.
Note that MT1 will start work on ED 4 as soon as ED 3 is published. Technical comments outside the scope of
the current ED 3 will be handled in the next revision.
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
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2 IEC CDV 60909-0 ED3 © IEC 2025
1 CONTENTS
3 CONTENTS . 2
4 FOREWORD . 5
5 1 Scope . 7
6 2 Normative references . 8
7 3 Terms and definitions . 8
8 4 Symbols, subscripts and superscripts . 13
9 4.1 General . 13
10 4.2 Symbols . 13
11 4.3 Subscripts . 15
12 4.4 Superscripts. 17
13 5 Characteristics of short-circuit currents: calculating method. 17
14 5.1 General . 17
15 5.2 Method of calculation . 18
16 5.2.1 General . 18
17 5.2.2 Equivalent voltage source at the short-circuit location. 20
18 5.2.3 Installations modelled as current sources . 21
19 5.2.4 Calculation assumptions . 22
20 5.2.5 Symmetrical components . 22
21 6 Modelling of electrical equipment for short-circuit calculations . 23
22 6.1 General . 23
23 6.2 Overhead lines and cables . 23
24 6.3 Transformers . 23
25 6.3.1 Two-winding transformers . 23
26 6.3.2 Three-winding transformers . 24
27 6.3.3 Impedance correction factors for two- and three-winding network
28 transformers . 25
29 6.4 Reactors . 26
30 6.4.1 General . 26
31 6.4.2 Shunt reactors . 27
32 6.4.3 Series reactors . 27
33 6.5 Capacitors . 27
34 6.5.1 Shunt capacitors . 27
35 6.5.2 Series capacitors . 27
36 6.6 Non-rotating loads . 27
37 6.7 Network feeders . 27
38 6.8 Synchronous machines . 29
39 6.8.1 General . 29
40 6.8.2 Synchronous generators . 30
41 6.8.3 Synchronous condensers . 31
42 6.8.4 Synchronous motors . 31
43 6.9 Asynchronous machines . 31
44 6.9.1 General . 31
45 6.9.2 Asynchronous generators . 32
46 6.9.3 Asynchronous motors . 32
47 6.10 Power electronic converters . 33
IEC CDV 60909-0 ED3 © IEC 2025 3
48 6.10.1 Power electronic converters with diodes or with thyristors . 33
49 6.10.2 Power electronic converters with semiconductor devices, that can be
50 turned off, e.g. IGBT . 33
51 6.11 Power station units . 33
52 6.11.1 General . 33
53 6.11.2 Power station units with synchronous generators . 33
54 6.11.3 Power station units with asynchronous generator . 35
55 6.11.4 Power station units with doubly fed asynchronous generator . 35
56 6.11.5 Power station units with full size converter . 36
57 6.12 Power plants . 36
58 6.13 Converter-fed motors . 38
59 6.13.1 Converter-fed motors with grid-side converters using diodes or
60 thyristors . 38
61 6.13.2 Converter-fed motors with grid-side converters using semiconductor
62 devices, that can be turned off, e.g. IGBT . 38
63 6.14 FACTS devices and HVDC transmission systems . 38
64 6.14.1 FACTS devices . 38
65 6.14.2 HVDC transmission systems . 39
66 7 Calculation of initial short-circuit currents . 39
67 7.1 General . 39
68 7.1.1 Maximum short-circuit currents . 42
69 7.1.2 Minimum short-circuit currents . 42
70 7.2 Three-phase short circuit . 43
71 7.3 Line-to-line short circuit . 43
72 7.4 Line-to-line short circuit with earth connection . 44
73 7.5 Line-to-earth short circuit . 45
74 8 Calculation of peak short-circuit currents . 45
75 8.1 Single-fed three-phase short circuit . 45
76 8.2 Multiple-fed three-phase short circuits . 47
77 8.3 Unbalanced short circuits . 48
78 9 Calculation of symmetrical breaking currents . 48
79 9.1 Single-fed three-phase short circuits . 48
80 9.1.1 Symmetrical breaking currents fed by synchronous machines . 48
81 9.1.2 Symmetrical breaking current fed by asynchronous machines. 49
82 9.1.3 Symmetrical breaking current fed by power station units with doubly fed
83 asynchronous generator . 51
84 9.1.4 Symmetrical breaking current fed by power station units with full size
85 converter . 51
86 9.1.5 Symmetrical breaking current fed by network feeders . 51
87 9.2 Multiple-fed three-phase short circuits . 51
88 9.3 Single-fed and multiple-fed unbalanced short circuits . 53
89 10 DC component and unbalanced asymmetrical breaking current . 53
90 11 Calculation of steady-state short-circuit currents . 54
91 11.1 General . 54
92 11.2 Three-phase short circuits . 54
93 11.2.1 Steady-state short-circuit currents single-fed by one synchronous
94 machine or one power station unit with synchronous generator. 54
95 11.2.2 Steady-state short-circuit currents of asynchronous machines . 56
96 11.2.3 Steady-state short-circuit currents of power station units with doubly fed
97 asynchronous generators . 56
4 IEC CDV 60909-0 ED3 © IEC 2025
98 11.2.4 Steady-state short-circuit currents of a power station unit with full size
99 converter . 56
100 11.2.5 Steady-state short-circuit currents of a network feeder . 57
...
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