EN 60909-3:2003

SLOVENSKI SIST EN 60909-3:2004

STANDARD
junij 2004
Short-circuit currents in three-phase a.c systems - Part 3: Currents during two
separate simultaneous line-to-earth short-circuits and partial short-circuit currents
flowing through earth
ICS 17.220.01 Referenčna številka
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

EUROPEAN STANDARD EN 60909-3
NORME EUROPÉENNE
EUROPÄISCHE NORM November 2003

ICS 17.220.01; 29.240.20
English version
Short-circuit currents in three-phase a.c systems
Part 3: Currents during two separate simultaneous line-to-earth
short-circuits and partial short-circuit currents flowing through earth
(IEC 60909-3:2003)
Courants de court-circuit dans les réseaux Kurzschlussströme in Drehstromnetzen
triphasés à courant alternatif Teil 3: Ströme bei Doppelerdkurzschluss
Partie 3: Courants durant deux court-circuits und Teilkurzschlussströme über Erde
monophasés simultanés séparés à la terre (IEC 60909-3:2003)
et courants de court-circuit partiels
s'écoulant à travers la terre
(CEI 60909-3:2003)
This European Standard was approved by CENELEC on 2003-11-01. 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, Hungary, Iceland, Ireland, Italy, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Portugal, Slovakia, 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

© 2003 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 60909-3:2003 E
Foreword
The text of document 73/127/FDIS, future edition 2 of IEC 60909-3, prepared by IEC TC 73, Short-circuit
currents, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as
EN 60909-3 on 2003-11-01.
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 (dop) 2004-08-01

– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2006-11-01

Annexes designated "normative" are part of the body of the standard.
Annexes designated "informative" are given for information only.
In this standard, annex ZA is normative annexes A and B are informative.
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 60909-3:2003 was approved by CENELEC as a European
Standard without any modification.
__________
- 3 - EN 60909-3:2003
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 60909-0 2001 Short-circuit currents in three-phase a.c. EN 60909-0 2001
systems
Part 0: Calculation of currents

NORME CEI
INTERNATIONALE
IEC
60909-3
INTERNATIONAL
Deuxième édition
STANDARD
Second edition
2003-09
Courants de court-circuit dans les réseaux
triphasés à courant alternatif –
Partie 3:
Courants durant deux courts-circuits monophasés
simultanés séparés à la terre et courants de court-
circuit partiels s'écoulant à travers la terre
Short-circuit currents in three-phase
a.c. systems –
Part 3:
Currents during two separate simultaneous
line-to-earth short circuits and partial short-
circuit currents flowing through earth
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60909-3 © IEC:2003 – 3 –
CONTENTS
FOREWORD . 7
1 Scope .11
2 Normative reference .13
3 Terms and definitions .13
4 Symbols.17
5 Currents during two separate simultaneous line-to-earth short circuits.19
5.1 Calculation method .19
5.1.1 Initial symmetrical short-circuit current.19
5.1.2 Peak short-circuit current, symmetrical short-circuit breaking current
and steady-state short-circuit current .23
5.1.3 Distribution of line-to-earth short-circuit currents during two separate
simultaneous line-to-earth short circuits.23
6 Partial short-circuit currents flowing through earth in the case of an unbalanced
short circuit.25
6.1 Calculation method .25
6.1.1 General.25
6.1.2 Line-to-earth short circuit in a station.25
6.1.3 Line-to-earth short circuit far outside a station .29
6.1.4 Line-to-earth short circuit in the vicinity of a station .33
6.1.5 Reduction factor for overhead lines and cables.35
Annex A (informative) Example for the calculation of two separate simultaneous line-
to-earth short-circuit currents .41
Annex B (informative) Examples for the calculation of partial short-circuit currents
through earth .45
Figure 1 – Driving point impedance Z of an infinite chain, composed of the earth-wire
P
impedance Z = Z´ ·d and the footing resistance R of the towers, with equal
W W T T
distances d between towers.15
T
Figure 2 – Driving point impedance Z of a finite chain with n towers, composed of
Pn
the earth-wire impedance Z = Z´ ·d , the footing resistance R of the towers with
W W T T
equal distances d between towers and the earthing impedance Z (Equation (28)) of
T EB
a station B.17
Figure 3 – Characterization of two separate simultaneous line-to-earth short circuits
"
and the current I .19
kEE
Figure 4 – Partial short-circuit currents in the case of a line-to-earth short circuit inside
the station B.27
Figure 5 – Partial short-circuit currents in the case of a line-to-earth short circuit at
tower T of an overhead line.29
Figure 6 – Distribution of the total earth current I .31
Etot
Figure 7 – Partial short-circuit currents in the case of a line-to-earth short circuit
at tower n of an overhead line in the vicinity of station B .33
Figure 8 – The magnitude r of the reduction factor for non-magnetic earth wires
in relation to soil resistivity ρ .39
Figure A.1 – Two separate simultaneous line-to-earth short circuits on a single fed
radial line, see Table 1.41

60909-3 © IEC:2003 – 5 –
Figure B.1 – Line-to-earth short circuit inside station B – System diagram for stations
A, B and C .47
Figure B.2 – Line-to-earth short circuit inside station B – Positive-, negative- and zero-
sequence systems with connections at the short-circuit location F within station B.47
Figure B.3 – Line-to-earth short circuit outside stations A, B and C at tower T of an
overhead line – System diagram for stations A, B and C. .51
Figure B.4 – Line-to-earth short circuit outside the stations A, B and C at tower T of an
overhead line – Positive- negative- and zero-sequence systems with connections
at the short-circuit location F .53
Figure B.5 – Earth potentials u = U /U with U = 1,912 kV and u =
ETn ETn ET ET EBn
U /U with U = 0,972 kV, if the line-to-earth short circuit occurs at the towers n
EBn EB EB
= 0, 1, 2, 3, in the vicinity of station B according to 6.1.4 (see the example for n = 10 in
Clause B.4). .63
Table 1 – Calculation of initial line-to-earth short-circuit currents in simple cases.23
Table 2 – Resistivity ρ and equivalent earth penetration depth δ for different soil types.35

60909-3 © IEC:2003 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
SHORT-CIRCUIT CURRENTS IN THREE-PHASE AC SYSTEMS –
Part 3: Currents during two separate simultaneous
line-to-earth short circuits and partial short-circuit currents
flowing through earth
FOREWORD
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