IEC TR 60909-2:2008

Short-circuit currents in three-phase a.c. systems - Part 2: Data of electrical equipment for short-circuit current calculations

IEC 60909-2:2008(E) comprises data of electrical equipment collected from different countries to be used when necessary for the calculation of short-circuit currents in accordance with IEC 60909-0. It may be applied for calculating short-circuit currents in low-voltage networks if they are in accordance with typical equipment employed in the user's country. The collected data and their evaluation may be used for medium- or high-voltage planning purposes and also for comparison with data given by manufacturers or electricity suppliers. For overhead lines and cables the electrical data may in some cases also be calculated from the physical dimensions and the material following the equations given in this report. This second edition cancels and replaces the first edition published in 1992 and constitutes a technical revision. The significant technical changes with respect to the previous edition are as follows:
- Subclause 2.5 gives equations and examples for the calculation of the positive-, the negative- and the zero-sequence impedances and reduction factors for high-, medium and low-voltage cables with sheaths and shields earthed at both ends.
- Subclause 2.7 gives equations and figures for the calculation of the positive-sequence impedances of busbar configurations.

General Information

• Status: Published
• Publication Date: 12-Nov-2008
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 17.220.01 - Electricity. Magnetism. General aspects
• ICS: 29.240.20 - Power transmission and distribution lines
• Technical Committee: TC 73 - Short-circuit currents
• Current Stage: PPUB - Publication issued
• Start Date: 15-Feb-2009
• Completion Date: 13-Nov-2008

Standards Content (Sample)

IEC/TR 60909-2
Edition 2.0 2008-11
TECHNICAL
REPORT
Short-circuit currents in three-phase a.c. systems –
Part 2: Data of electrical equipment for short-circuit current calculations

IEC/TR 60909-2:2008(E)
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IEC/TR 60909-2
Edition 2.0 2008-11
TECHNICAL
REPORT
Short-circuit currents in three-phase a.c. systems –
Part 2: Data of electrical equipment for short-circuit current calculations

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
X
ICS 17.220.01; 29.240.20 ISBN 978-2-88910-327-0
– 2 – TR 60909-2 © IEC:2008(E)
CONTENTS
FOREWORD.4
1 General .6
1.1 Scope and object.6
1.2 Normative references .6
2 Data for electrical equipment .6
2.1 General .6
2.2 Data of typical synchronous machines.7
2.3 Data of typical two-winding, three-winding and auto-transformers.10
2.4 Data of typical overhead lines, single and double circuits .14
2.5 Data of typical high-voltage, medium-voltage and low-voltage cables .20
2.6 Data of typical asynchronous motors .35
2.7 Busbars.38
Annex A (informative) Information from National Committees.42
Bibliography.43

Figure 1 – Subtransient reactance of synchronous machines 50 Hz and 60 Hz
(Turbogenerators, salient pole generators, motors SM and condensers SC) .8
Figure 2 – Rated Voltage U and rated power factor cosϕ of synchronous machines
rG rG
(Turbo generators, salient pole generators, motors and condensers 50 Hz and 60 Hz) .9
Figure 3 – Unsaturated and saturated synchronous reactance of two-pole turbo
generators 50 Hz and 60 Hz (relative values).9
Figure 4 – Three-winding transformer (No. 6 of Table 3). .12
Figure 5 – Rated short-circuit voltage u of unit transformers in power stations (ST)
kr
with or without on-load tap-changer .13
Figure 6 – Rated short-circuit voltages u of network transformers .14
kr
' '
Figure 7 – Positive-sequence reactance X = X of low-voltage and medium-voltage
(1) L
overhead lines 50 Hz, Cu or Al, with one circuit according to Equation (15) of
IEC 60909-0 .16
' '
Figure 8 – Positive-sequence reactance X = X of overhead lines 50 Hz (60 Hz-
(1) L
values converted to 50 Hz) .19
Figure 9 – Type of overhead lines.20
Figure 10 – Single-core cable 64 kV / 110 kV with lead sheath [4] .23
Figure 11 – Reduction factor depending on the inducing current for cables with one
lead sheath and two overlapping steel tapes, f = 50 Hz [3].35
Figure 12 – Reduction factor depending on the inducing current for cables with three
lead sheaths and two overlapping steel tapes, f = 50 Hz [3] .35
Figure 13 – Ratio I /I of low-voltage and medium-voltage asynchronous motors,
LR rM
50 Hz and 60 Hz .37
Figure 14 – Product cosϕ xη of low-voltage and medium-voltage motors, 50 Hz
rM rM
and 60 Hz .38
Figure 15 – Geometric mean distance g = g = g of the main conductors .39
L1L1 L2L2 L3L3
'
Figure 16 – Factor α and β for the calculation of X given in Equation (34) .40
(1)
TR 60909-2 © IEC:2008(E) – 3 –
Table 1 – Actual data of typical synchronous generators, motors and condensers .7
Table 2 – Actual data of typical two-winding transformers (NT: network; ST: power
station) .10
Table 3 – Actual data of typical three-winding transformers .11
Table 4 – Actual data of typical autotransformers with and without tertiary winding .12
Table 5 – Actual data of typical overhead lines 50 Hz and 60 Hz .18
Table 6 – Actual data of typical electric cables.21
Table 7 – Equations for the positive-sequence and the zero-sequence impedance of
cables.22
Table 8 – Single-core cables 64/110 kV, 2XK2Y, 3 × 1 × 240 . 1 200 rm, Cu with lead
sheath .24
Table 9 – 10-kV-cables N2XS2Y .25
Table 10 – 20-kV-cables N2XS2Y .26
Table 11 – Positive-sequence and zero-sequence impedance of four low-voltage
single-core cables NYY 4 × 1 × q . (Case No. 2a in Table 7) .27
n
Table 12 – Low-voltage cable NYY .29
Table 13 – Low-voltage cable NYY with three and a half copper conductors .30
Table 14 – Low-voltage cable NYCWY with four copper conductors .32
Table 15 – Low-voltage cable NYCWY.33
Table 16 – Actual data of typical asynchronous motors .36
Table 17 – Actual data of distribution busbars.38
'
Table 18 – Example for the calculation of X for busbars using Figures 15 and 16 .41
(1)
Table A.1 – Information received from National Committees .42

– 4 – TR 60909-2 © IEC:2008(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
_____________
SHORT-CIRCUIT CURRENTS IN THREE-PHASE AC SYSTEMS –

Part 2: Data of electrical equipment
for short-circuit current calculations

FOREWORD
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The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a technical report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC 60909-2, which is a technical report, has been prepared by IEC technical committee 73:
Short-circuit currents.
This technical report is to be read in conjunction with IEC 60909-0 and IEC 60909-3.
This second edition cancels and replaces the first edition published in 1992. This edition
constitutes a technical revision.
The significant technical changes with respect to the previous edition are as follows:

TR 60909-2 © IEC:2008(E) – 5 –
– Subclause 2.5 gives equations and examples for the calculation of the positive-, the
negative and the zero-sequence impedances and reduction factors for high-, medium
and low-voltage cables with sheaths and shields earthed at both ends.
– Subclause 2.7 gives equations and figures for the calculation of the positive-sequence
impedances of busbar configurations.
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
73/142/DTR 73/145/RVC
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This p
...