EN 61660-2:1997

SLOVENSKI STANDARD
01-oktober-1998
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Short-circuit currents in d.c. auxiliary installations in power plants and substations - Part
2: Calculation of effects
Kurzschlußströme in Gleichstrom-Eigenbedarfsanlagen in Kraftwerken und
Schaltanlagen - Teil 2: Berechnung der Wirkungen
Courants de court-circuit dans les installations auxiliaires alimentées en courant continu
dans les centrales et les postes - Partie 2: Calcul des effets
Ta slovenski standard je istoveten z: EN 61660-2:1997
ICS:
17.220.01 Elektrika. Magnetizem. Electricity. Magnetism.
Splošni vidiki General aspects
29.240.01 2PUHåMD]DSUHQRVLQ Power transmission and
GLVWULEXFLMRHOHNWULþQHHQHUJLMH distribution networks in
QDVSORãQR general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

NORME
CEI
INTERNATIONALE
IEC
61660-2
INTERNATIONAL
Première édition
STANDARD
First edition
1997-06
Courants de court-circuit dans les installations
auxiliaires alimentées en courant continu
dans les centrales et les postes –
Partie 2:
Calcul des effets
Short-circuit currents in d.c. auxiliary installations
in power plants and substations –
Part 2:
Calculation of effects
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61660-2 © IEC:1997 – 3 −
CONTENTS
Page
FOREWORD . 5
Clause
1 General . 7
1.1 Scope. 7
1.2 Normative references. 9
1.3 Symbols and units . 9
1.4 Definitions. 15
2 Electromagnetic effect on rigid conductors . 17
2.1 General. 17
2.2 Calculation of electromagnetic forces. 19
2.3 Calculation of stresses in rigid conductors and forces on supports . 21
2.4 Design load for post insulators, their supports and connectors. 33
3 Thermal effect on bare conductors and electrical equipment . 33
3.1 General. 33
3.2 Calculation of temperature rise . 35
Tables . 39
Figures .47
Annexes
A Equations for calculations of diagrams . 67
B Bibliography. 74

61660-2 © IEC:1997 – 5 −
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SHORT-CIRCUIT CURRENTS IN DC AUXILIARY INSTALLATIONS
IN POWER PLANTS AND SUBSTATIONS –
Part 2: Calculation of effects
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 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 61660-2 has been prepared by IEC technical committee 73: Short-
circuit currents.
The text of this standard is based on the following documents:
FDIS Report on voting
73/85/FDIS 73/98/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.
Annexes A and B are for information only.
IEC 61660 consists of the following parts, under the general title: Short-circuit currents in d.c.
auxiliary installations in power plants and substations:
– Part 1: 1997: Calculation of short-circuit currents
– Part 2: 1997: Calculation of effects
– Part 3: 199X: Examples of calculations (in preparation)

61660-2 © IEC:1997 – 7 −
SHORT-CIRCUIT CURRENTS IN DC AUXILIARY INSTALLATIONS
IN POWER PLANTS AND SUBSTATIONS –
Part 2: Calculation of effects
1 General
1.1 Scope
This part of IEC 61660 describes a method for calculation of the mechanical and thermal
effects on rigid conductors caused by short-circuit currents in d.c. auxiliary installations in
power plants and substations. Such systems may contain the following items of equipment
which act as sources, as well as contributing to the short-circuit currents:
– rectifiers in three-phase a.c. bridge connection for 50 Hz;
– stationary lead-acid batteries;
– smoothing capacitors;
– d.c. motors with independent excitation.
This standard provides a method which has wide application, and which gives results of
sufficient accuracy. The calculation method is based on substitute functions, which cause
approximately the same maximum stresses in the conductors and the same forces on the
supports as the actual electromagnetic force.
The standardized calculation procedures of clauses 2 and 3 are applicable for the
electromagnetic effect on rigid conductors and the thermal effect on bare conductors and
electrical equipment, respectively.
For cables and insulated conductors, however, reference is made to IEC 60949 and
IEC 60986, for example.
Only d.c. auxiliary installations in power plants and substations are dealt with in this standard.
In particular, the following points should be noted:
– The calculation of short-circuit currents should be based on IEC 61660-1.
– Short-circuit duration used in this standard depends on the protection concept, and
should be considered in that sense.
– These standardized procedures are adjusted to practical requirements, and contain
simplifications with safety margins. Testing or more detailed methods of calculation or both
may be used.
– In clause 2 of this standard, only the stresses caused by short-circuit currents are
calculated. Furthermore, other stresses can exist, such as those caused by dead-load,
operating forces, or earthquakes. The combination of these loads with the short-circuit
loading should be part of an agreement and/or given by standards, for example erection
codes.
61660-2 © IEC:1997 – 9 −
1.2 Normative references
The following normative documents contain provisions which, through reference in this text
constitute provisions of this part of IEC 61660. At the time of publication, the editions indicated
were valid. All normative documents are subject to revision, and parties to agreements based
on this part of IEC 61660 are encouraged to investigate the possibility of applying the most
recent editions of the normative documents indicated below. Members of IEC and ISO maintain
registers of currently valid International Standards.
IEC 60865-1: 1993, Short-circuit currents — Calculation of effects – Part 1: Definitions and
calculation methods
IEC 60865-2: 1994, Short-circuit currents — Calculation of effects – Part 2: Examples of
calculation
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
IEC 61660-1: 1997, Short-circuit currents in d.c. auxiliary installations in power plants and
substations – Part 1: Calculation of short-circuit currents
1.3 Symbols and units
All equations used in this standard are quantity equations in which quantity symbols represent
physical quantities possessing both numerical values and dimensions.
The symbols used in this standard and their exemplary SI units are given in the following lists.
1.3.1 Symbols for clause 2: electromagnetic effects
A Impulse for determining the parameters of the substitute rectangular A s
i
function
A Cross-section of one subconductor m
s
a Centre line distance between conductors m
a Effective distance between neighbouring main conductors m
m
a Effective distance between subconductors m
s
a Centre line distance between subconductor 1 and subconductor n m
1n
a Centre line distance between subconductors m
1s
b Dimension of a subconductor perpendicular to the direction of the force m
b Dimension of a main conductor perpendicular to the direction of m
m
the force
c Factor for the influence of connecting pieces 1
D Outer diameter of tubular conductor m
d Dimension of a subconductor in the direction of the force m

61660-2 © IEC:1997 – 11 −
d Dimension of a main conductor in the direction of the force m
m
E Young's modulus N/m
F Force acting between two, parallel, long conductors during a short circuit N
F Force between main conductors caused by the substitute rectangular N
R
function
F Force between subconductors caused by the substitute rectangular N
Rs
function
F Force on support (peak value) N
d
F Force between main conductors during a short circuit (peak value) N
m
F Force between subconductors during a short circuit N
s
f Relevant natural frequency of a main conductor Hz
c
f Relevant natural frequency of a subconductor Hz
cs
g Value of acceleration of gravity m/s
n
2 3
I Value for determining of the parameters of the substitute rectangular A s
g
function
I Current of the substitute rectangular function for the calculation of the A
R
force between main conductors
I Current of the substitute rectangular function for the calculation of the A
Rs
force between subconductors
I Quasi steady-state short-circuit current A
k
i Peak short-circuit current A
p
i , i Instantaneous values of current in conductors in the sections of the A
1 2
standard approximation function
i , i Instantaneous values of currents in the conductors L1 and L2 A
L1 L2
J Second moment of main conductor area m
J Second moment of subconductor area m
s
k Number of sets of spacers or stiffening elements 1
k Factor for effective conductor distance between subconductor 1 and 1
1n
subconductor n
k Factor for effective conductor distance 1
1s
l Centre line distance between supports m
l Centre line distance between connecting pieces m
s
Mass per unit length of main conductor kg/m
m′
Mass per unit length of subconductor kg/m
m′
s
m Total mass of one set of connecting pieces kg
z
m ,m , Factors for determining the parameters of the substitute rectangular 1
g1 g2
function
m ,m ,
Ig1 Ig2
m ,m
θ1 θ2
n Number of subconductors of a main conductor 1
p Ratio I /i 1
k p
q Factor of plasticity 1
R Stress corresponding to the yield point N/m
p 0,2
s Wall thickness of tubes m
61660-2 © IEC:1997 – 13 −
T Short-circuit duration s
k
T Vibration period of the main conductor s
me
T Vibration
...