SIST EN 60909-0:2002

Short-circuit currents in three-phase a.c. systems - Part 0: Calculation of currents

Applicable to the calculation of short-circuit currents:
- in low-voltage three-phase a.c. systems
- in high-voltage three-phase a.c. systems
operating at a nominal frequency of 50 Hz or 60 Hz.
Systems at highest voltages of 550 kV and above with long transmission lines need special consideration.
The contents of the corrigendum of February 2002 have been included in this copy.

Kurzschlussströme in Drehstromnetzen - Teil 0: Berechnung der Ströme

Courants de court-circuit dans les réseaux triphasés à courant alternatif Partie 0: Calcul des courants

Applicable au calcul des courants de court-circuit:
- dans les réseaux triphasés basse tension à courant alternatif,
- dans les réseaux triphasés haute tension à courant alternatif,
fonctionnant à une fréquence nominale de 50 Hz ou de 60 Hz.
Les réseaux de tensions très élevées, 550 kV et plus, avec lignes de transport de grande longueur nécessitent un traitement particulier.
Le contenu du corrigendum de février 2002 a été pris en considération dans cet exemplaire.

Kratkostični toki v izmeničnih trifaznih sistemih - 0. del: Računanje tokov

General Information

• Status: Withdrawn
• Publication Date: 31-Aug-2002
• Withdrawal Date: 28-Feb-2019
• ICS: 17.220.01 - Electricity. Magnetism. General aspects
• ICS: 29.240.20 - Power transmission and distribution lines
• Technical Committee: NTF - Electricity energy supply systems
• Current Stage: 9900 - Withdrawal (Adopted Project)
• Start Date: 28-Feb-2019
• Due Date: 23-Mar-2019
• Completion Date: 01-Mar-2019
• Ref Project: EN 60909-0:2001 - Short-circuit currents in three-phase a.c. systems - Part 0: Calculation of currents

Relations

• Replaces: SIST HD 533 S1:1998 - Short-circuit current calculation in three-phase a.c. systems
• Effective Date: 01-Sep-2002
• Replaced By: SIST EN 60909-0:2016 - Short-circuit currents in three-phase a.c. systems - Part 0: Calculation of currents
• Effective Date: 07-Jun-2022
• Replaces: SIST HD 533 S1:1998 - Short-circuit current calculation in three-phase a.c. systems
• Effective Date: 29-Jan-2023
• Replaced By: SIST EN 60909-0:2016 - Short-circuit currents in three-phase a.c. systems - Part 0: Calculation of currents
• Effective Date: 01-Sep-2016

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN 60909-0:2002
01-september-2002
1DGRPHãþD
SIST HD 533 S1:1998
.UDWNRVWLþQLWRNLYL]PHQLþQLKWULID]QLKVLVWHPLKGHO5DþXQDQMHWRNRY
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: EN 60909-0:2001
ICS:
17.220.01 Elektrika. Magnetizem. Electricity. Magnetism.
Splošni vidiki General aspects
29.240.20 Daljnovodi Power transmission and
distribution lines
SIST EN 60909-0:2002 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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EUROPEAN STANDARD EN 60909-0
NORME EUROPÉENNE
EUROPÄISCHE NORM August 2001
ICS 17.220.01; 29.240.20 Supersedes HD 533 S1:1991
English version
Short-circuit currents in three-phase a.c. systems
Part 0: Calculation of currents
(IEC 60909-0:2001)
Courants de court-circuit dans les réseaux Kurzschlussströme in Drehstromnetzen
triphasés à courant alternatif Teil 0: Berechnung der Ströme
Partie 0: Calcul des courants (IEC 60909-0:2001)
(CEI 60909-0:2001)
This European Standard was approved by CENELEC on 2001-07-01. CENELEC members are bound to
comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and
notified to the Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republic,
Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway,
Portugal, Spain, Sweden, Switzerland and United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2001 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 60909-0:2001 E

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EN 60909-0:2001 - 2 -
Foreword
The text of document 73/119/FDIS, future edition 1 of IEC 60909-0, prepared by IEC TC 73,
Short-circuit currents, was submitted to the IEC-CENELEC parallel vote and was approved by
CENELEC as EN 60909-0 on 2001-07-01.
This European Standard supersedes HD 533 S1:1991.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (d'op) 2002-04-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2004-07-01
Annexes designated "normative" are part of the body of the standard.
In this standard, annexes A and ZA are normative.
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 60909-0:2001 was approved by CENELEC as a European
Standard without any modification.
__________

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- 3 - EN 60909-0:2001
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
This European Standard incorporates by dated or undated reference, provisions from other
publications. These normative references are cited at the appropriate places in the text and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions of any
of these publications apply to this European Standard only when incorporated in it by amendment or
revision. For undated references the latest edition of the publication referred to applies (including
amendments).
NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
Publication Year Title EN/HD Year
IEC 60038 (mod) 1983 Nominal voltages for low-voltage public HD 472 S1 1989
electricity supply systems
IEC 60050-131 1978 International Electrotechnical --
Vocabulary (IEV)
Chapter 131: Electric and magnetic
circuits
IEC 60050-151 1978 Chapter 151: Electrical and magnetic--
devices
IEC 60050-195 1998 Chapter 195: Earthing and protection--
against electric shock
1)
IEC 60056 (mod) 1987 High-voltage alternating-current circuit- HD 348 S7 1998
breakers
IEC 60071-1 1993 Insulation co-ordination EN 60071-1 1995
Part 1: Definitions, principles and rules
IEC 60781 1989 Application guide for calculation of HD 581 S1 1991
short-circuit currents in low-voltage
radial systems
IEC 60865-1 1993 Short-circuit currents - Calculation of EN 60865-1 1993
effects
Part 1: Definitions and calculation
methods
2)
IEC 60909-1 Short-circuit currents calculation in--
three-phase a.c. systems
Part 1: Factors for the calculation of
short-circuit currents in three-phase
a.c. systems according to IEC 60909-0

1)
HD 348 S7 is based on IEC 60056:1987 + A3:1996.
2)
To be published.

---------------------- Page: 4 ----------------------

EN 60909-0:2001 - 4 -
Publication Year Title EN/HD Year
IEC 60909-2 1992 Electrical equipment - Data for short---
circuit current calculations in
accordance with IEC 60909
IEC 60909-3 1995 Part 3: Currents during two separate--
simultaneous single phase line-to-earth
short circuits and partial short-circuit
currents flowing through earth
2)
IEC 60909-4 Part 4: Examples for the calculation of--
short-circuit currents
IEC 60949 1988 Calculation of thermally permissible--
short-circuit currents, taking into
account non-adiabatic heating effects
IEC 60986 1989 Guide to the short-circuit temperature--
limits of electric cables with a rated
voltage from 1,8/3 (3,6) kV to
18/30 (36) kV

2)
To be published.

---------------------- Page: 5 ----------------------

NORME CEI
INTERNATIONALE IEC
60909-0
INTERNATIONAL
Première édition
STANDARD
First edition
2001-07
Courants de court-circuit dans les réseaux
triphasés à courant alternatif –
Partie 0:
Calcul des courants
Short-circuit currents in three-phase
a.c. systems –
Part 0:
Calculation of currents
 IEC 2001 Droits de reproduction réservés  Copyright - all rights reserved
Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in
utilisée sous quelque forme que ce soit et par aucun procédé, any form or by any means, electronic or mechanical,
électronique ou mécanique, y compris la photocopie et les including photocopying and microfilm, without permission in
microfilms, sans l'accord écrit de l'éditeur. writing from the publisher.
International Electrotechnical Commission 3, rue de Varembé Geneva, Switzerland
Telefax: [phone] e-mail: [e-mail] IEC web site http://www.iec.ch
CODE PRIX
Commission Electrotechnique Internationale
XB
PRICE CODE
International Electrotechnical Commission
Pour prix, voir catalogue en vigueur
For price, see current catalogue

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60909-0  IEC:2001 – 3 –
CONTENTS
FOREWORD. 9
1 General . 13
1.1 Scope .13
1.2 Normative references . 15
1.3 Definitions . 17
1.4 Symbols, subscripts and superscripts. 25
1.4.1 Symbols . 25
1.4.2 Subscripts . 29
1.4.3 Superscripts . 31
2 Characteristics of short-circuit currents: calculating method. 31
2.1 General.31
2.2 Calculation assumptions. 35
2.3 Method of calculation . 35
2.3.1 Equivalent voltage source at the short-circuit location . 35
2.3.2 Application of symmetrical components . 41
2.4 Maximum short-circuit currents . 45
2.5 Minimum short-circuit currents . 47
3 Short-circuit impedances of electrical equipment. 47
3.1 General.47
3.2 Network feeders . 49
3.3 Transformers . 51
3.3.1 Two-winding transformers . 51
3.3.2 Three-winding transformers . 53
3.3.3 Impedance correction factors for two- and three-winding
network transformers . 57
3.4 Overhead lines and cables . 59
3.5 Short-circuit limiting reactors . 61
3.6 Synchronous machines . 61
3.6.1 Synchronous generators . 61
3.6.2 Synchronous compensators and motors . 65
3.7 Power station unit . 65
3.7.1 Power station units with on-load tap-changer. 65
3.7.2 Power station units without on-load tap-changer. 69
3.8 Asynchronous motors. 71
3.8.1 General . 71
3.8.2 Contribution to short-circuit currents by asynchronous motors . 73
3.9 Static converters. 77
3.10 Capacitors and non-rotating loads . 77
4 Calculation of short-circuit currents . 79
4.1 General.79
4.2 Initial symmetrical short-circuit current I ′′ . 83
k

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60909-0  IEC:2001 – 5 –
4.2.1 Three-phase short circuit. 83
4.2.2 Line-to-line short circuit . 95
4.2.3 Line-to-line short circuit with earth connection. 99
4.2.4 Line-to-earth short circuit .101
4.3 Peak short-circuit current i .101
p
4.3.1 Three-phase short circuit.101
4.3.2 Line-to-line short circuit .105
4.3.3 Line-to-line short circuit with earth connection.105
4.3.4 Line-to-earth short circuit .107
4.4 DC component of the short-circuit current .107
...........................................................107
4.5 Symmetrical short-circuit breaking current I
b
4.5.1 Far-from-generator short circuit .107
4.5.2 Near-to-generator short circuit .109
..........................................................................117
4.6 Steady-state short-circuit current I
k
4.6.1 Three-phase short circuit of one generator or one power station unit .117
4.6.2 Three-phase short circuit in non-meshed networks.121
4.6.3 Three-phase short circuit in meshed networks.123
4.6.4 Unbalanced short circuits.123
4.6.5 Short circuits at the low-voltage side of transformers, if one line conductor
is interrupted at the high-voltage side .125
4.7 Terminal short circuit of asynchronous motors.127
4.8 Joule integral and thermal equivalent short-circuit current .129
Annex A (normative) Equations for the calculation of the factors m and n .137
Figure 1 – Short-circuit current of a far-from-generator short circuit with
constant a.c. component (schematic diagram).31
Figure 2 – Short-circuit current of a near-to-generator short circuit with
decaying a.c. component (schematic diagram).33
Figure 3 – Characterization of short circuits and their currents.37
′′
Figure 4 – Illustration for calculating the initial symmetrical short-circuit current I
k
in compliance with the procedure for the equivalent voltage source .39
Figure 5 – Short-circuit impedances of a three-phase a.c. system at
the short-circuit location F.43
Figure 6 – System diagram and equivalent circuit diagram for network feeders .49
Figure 7 – Three-winding transformer (example) .55
Figure 8 – Phasor diagram of a synchronous generator at rated conditions .63
Figure 9 – Example for the estimation of the contribution from the asynchronous motors
in relation to the total short-circuit current.75
Figure 10 – Diagram to determine the short-circuit type (figure 3) for the highest
short-circuit current referred to the symmetrical three-phase short-circuit current at
the short-circuit location when the impedance angles of the sequence
impedances Z , Z , Z are identical .81
(1) (2) (0)
Figure 11 – Examples of single-fed short circuits.85
Figure 12 – Example of a non-meshed network .89

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60909-0  IEC:2001 – 7 –
Figure 13 – Short-circuit currents and partial short-circuit currents for three-phase
short circuits between generator and unit transformer with or without on-load tap-changer,
or at the connection to the auxiliary transformer of a power station unit and at the
auxiliary busbar A .89
Figure 14 – Example of a meshed network fed from several sources.97
Figure 15 – Factor κ for series circuit as a function of ratio R/X or X/R.101
Figure 16 – Factor μ for calculation of short-circuit breaking current I .111
b
Figure 17 – Factor q for the calculation of the symmetrical short-circuit breaking
current of asynchronous motors .113
Figure 18 – λ and λ factors for cylindrical rotor generators .119
min max
Figure 19 – Factors λ and λ for salient-pole generators .119
min max
Figure 20 – Transformer secondary short circuits, if one line (fuse) is opened on the
high-voltage side of a transformer Dyn5 .125
Figure 21 – Factor m for the heat effect of the d.c. component of the short-circuit current
(for programming, the equation for m is given in annex A).131
Figure 22 – Factor n for the heat effect of the a.c. component of the short-circuit current
(for programming, the equation for n is given in annex A) .133
Table 1 – Voltage factor c.41
Table 2 – Factors α and β for the calculation of short-circuit currents with equation (90)
Rated transformation ratio t = U /U .127
r rTHV rTLV
Table 3 – Calculation of short-circuit currents of asynchronous motors in the case of
a short circuit at the terminals (see 4.7) .129

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60909-0  IEC:2001 – 9 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SHORT-CIRCUIT CURRENTS IN THREE-PHASE AC SYSTEMS –
Part 0: Calculation of currents
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the 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, the IEC publishes International Standards. 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. The 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 the 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 National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form of
standards, technical specifications, technical reports or guides and they are accepted by the National Committees
in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any divergence
between the IEC Standard and the corresponding national or regional standard shall be clearly indicated in the
latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of
patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60909-0 has been prepared by IEC technical committee 73: Short-
circuit currents.
This first edition cancels and replaces IEC 60909 published in 1988 and constitutes a technical
revision.
The text of this standard is based on the following documents:
FDIS Report on voting
73/119/FDIS 73/121/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
Annex A forms an integral part of this standard.

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60909-0  IEC:2001 – 11 –
This part of IEC 60909 shall be read in conjunction with the International Standards, Technical
Reports and Technical Specifications mentioned below:
– IEC TR 60909-1,— Short-circuit current calculation in three-phase a.c. systems – Part 1:
Factors for the calculation of short-circuit currents in three-phase a.c. systems according
1)
to IEC 60909-0
– IEC TR3 60909-2:1992, Electrical equipment – Data for short-circuit current calculations in
accordance with IEC 60909
– IEC 60909-3:1995, Short-circuit current calculation in three-phase a.c. systems – Part 3:
Currents during two separate simultaneous single-phase line-to-earth short circuits and
partial short-circuit currents following through earth
– IEC TR 60909-4:2000, Short-circuit current calculation in three-phase a.c. systems – Part 4:
Examples for the calculation of short-circuit currents
The committee has decided that the contents of this publication will remain unchanged until 2007.
At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
The contents of the corrigendum of February 2002 have been included in this copy.
________
1)
 To be published.

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60909-0  IEC:2001 – 13 –
SHORT-CIRCUIT CURRENTS IN THREE-PHASE AC SYSTEMS –
Part 0: Calculation of currents
1 General
1.1 Scope
This part of IEC 60909 is applicable to the calculation of short-circuit currents:
• in low-voltage three-phase a.c. systems
• in high-voltage three-phase a.c. systems
operating at a nominal frequency of 50 Hz or 60 Hz.
Systems at highest voltages of 550 kV and above with long transmission lines need special
consideration.
This part of IEC 60909 establishes a general, practicable and concise procedure leading to results,
which are generally of acceptable accuracy. For this calculation method, an equivalent voltage source at
the short-circuit location is introduced. This does not exclude the use of special methods, for example the
superposition method, adjusted to particular circumstances, if they give at least the same precision. The
superposition method gives the short-circuit current related to the one load flow presupposed. This
method, therefore, does not necessarily lead to the maximum short-circuit current.
This part of IEC 60909 deals with the calculation of short-circuit currents in the case of balanced
or unbalanced short circuits.
In case of an accidental or intentional conductive path between one line conductor and local
earth, the following two cases must be clearly distinguished with regard to their different
physical properties and effects (resulting in different requirements for their calculation):
• line-to-earth short circuit, occurring in a solidly earthed neutral system or an impedance
earthed neutral system;
• a single line-to-earth fault, occurring in an isolated neutral earthed system or a resonance
earthed neutral system. This fault is beyond the scope of, and is therefore not dealt with in,
this standard.
For currents during two separate simultaneous single-phase line-to-earth short circuits in an
isolated neutral system or a resonance earthed neutral system, see IEC 60909-3.
Short-circuit currents and short-circuit impedances may also be determined by system tests, by
measurement on a network analyzer, or with a digital computer. In existing low-voltage systems
it is possible to determine the short-circuit impedance on the basis of measurements at the
location of the prospective short circuit considered.

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60909-0  IEC:2001 – 15 –
The calculation of the short-circuit impedance is in general based on the rated data of the
electrical equipment and the topological arrangement of the system and has the advantage of
being possible both for existing systems and for systems at the planning stage.
In general, two short-circuit currents, which differ in their magnitude, are to be calculated:
• the maximum short-circuit current which determines the capacity or rating of electrical
equipment; and
• the minimum short-circuit current which can be a basis, for example, for the selection of
fuses, for the setting of protective devices, and for checking the run-up of motors.
NOTE The current in a three-phase short circuit is assumed to be made simultaneously in all poles. Investigations of
non-simultaneous short circuits, which may lead to higher aperiodic components of short-circuit current, are beyond
the scope of this standard.
This standard does not cover short-circuit currents deliberately created under controlled
conditions (short-circuit testing stations).
This part of IEC 60909 does not deal with the calculation of short-circuit currents in installations
on board ships and aeroplanes.
1.2 Normative references
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this part of IEC 60909. For dated references, subsequent amendments to,
or revisions of, any of these publications do not apply. However, parties to agreements based on
this part of IEC 60909 are encouraged to investigate the possibility of applying the most recent
editions of the normative documents indicated below. For undated references, the latest edition
of the normative document referred to applies. Members of IEC and ISO maintain registers of
currently valid International Standards.
IEC 60038:1983, IEC standard voltages
IEC 60050(131):1978, International Electrotechnical Vocabulary – Chapter 131: Electric and
magnetic circuits
IEC 60050(151):1978, International Electrotechnical Vocabulary – Chapter 151: Electric and
magnetic devices
IEC 60050-195:1998, International Electrotechnical Vocabulary – Part 195: Earthing and
protection against electric shock
IEC 60056:1987, High-voltage alternating-current circuit-breakers
IEC 60071-1:1993, Insulation coordination – Part 1: Definitions, principles and rules
IEC 60781:1989, Application guide for calculation of short-circuit currents in low-voltage radial
systems
IEC 60865-1:1993, Short-circuit currents – Calculation of effects – Part 1: Definitions and calculation
methods

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60909-0  IEC:2001 – 17 –
IEC TR 60909-1, Short-circuit currents calculation in three-phase a.c. systems – Part 1: Factors
1)
for the calculation of short-circuit currents in three-phase a.c. systems according to IEC 60909-0
IEC TR3 60909-2:1992, Electrical equipment – Data for short-circuit current calculations in
accordance with IEC 60909
IEC 60909-3:1995, Short-circuit current calculation in three-phase a.c. systems – Part 3:
Currents during two separate simultaneous single phase line-to-earth short circuits and partial
short-circuit currents flowing through earth
IEC TR 60909-4:2000, Short-circuit current calculation in three-phase a.c. systems – Part 4:
Examples for the calculation of short-circuit currents
IEC 60949:1988, Calculation of thermally permissible short-circuit currents, taking into
account non-adiabatic heating effects
IEC 60986:1989, Guide to the short-circuit temperature limits of electrical cables with a rated
voltage from 1,8/3 (3,6) kV to 18/30 (36) kV
1.3 Definitions
For the purposes of this part of IEC 60909, the definitions given in IEC 60050(131) and the
following definitions apply.
1.3.1
short circuit
accidental or intentional conductive path between two or more conductive
...