IEC 60865-1:2011

IEC 60865-1 ®
Edition 3.0 2011-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Short-circuit currents – Calculation of effects –
Part 1: Definitions and calculation methods

Courants de court-circuit – Calcul des effects –
Partie 1: Définitions et méthodes de calcul

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IEC 60865-1 ®
Edition 3.0 2011-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Short-circuit currents – Calculation of effects –
Part 1: Definitions and calculation methods

Courants de court-circuit – Calcul des effects –
Partie 1: Définitions et méthodes de calcul

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XA
ISBN 978-2-88912-771-9
ICS 17.220.01; 29.240.20
– 2 – 60865-1  IEC:2011
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms, definitions, symbols and units . 7
3.1 Terms and definitions . 7
3.2 Symbols and units . 9
4 General . 12
5 Rigid conductor arrangements . 13
5.1 General . 13
5.2 Calculation of electromagnetic forces . 13
5.2.1 Calculation of peak force between the main conductors during a
three-phase short-circuit . 13
5.2.2 Calculation of peak force between the main conductors during a line-
to-line short-circuit . 13
5.2.3 Calculation of peak value of force between coplanar sub-conductors . 14
5.3 Effective distance between main conductors and between sub-conductors . 14
5.4 Calculation of stresses in rigid conductors . 16
5.4.1 Calculation of stresses . 16
5.4.2 Section modulus and factor q of main conductor composed of sub-
conductors . 17
5.4.3 Permitted conductor stress . 20
5.5 Structure loads due to rigid conductors . 21
5.6 Consideration of automatic reclosing . 21
5.7 Calculation with special regard to conductor oscillation . 22
5.7.1 General . 22
5.7.2 Determination of relevant natural frequency . 23
5.7.3 The factors V , V , V , V and V . 23
F σm σs rm rs
6 Flexible conductor arrangements . 26
6.1 General . 26
6.2 Effects on horizontal main conductors . 27
6.2.1 General . 27
6.2.2 Characteristic dimensions and parameter . 27
6.2.3 Tensile force F during short-circuit caused by swing out (short-
t,d
circuit tensile force) without dropper in midspan . 30
6.2.4 Dynamic change of sag due to elongation of conductor and change of
shape of the conductor curve . 31
6.2.5 Tensile force F during short-circuit caused by swing out (short-
t,d
circuit tensile force) with dropper in the middle of the span . 32
6.2.6 Tensile force F after short-circuit caused by drop (drop force) . 33
f,d
6.2.7 Horizontal span displacement b and minimum air clearance a . 33
h min
6.3 Effects on vertical main conductors (droppers) . 34
6.4 Effects on bundled conductors . 35
6.4.1 Characteristic dimensions and parameter . 35
6.4.2 Tensile force F in the case of clashing sub-conductors . 38
pi,d
6.4.3 Tensile force F in the case of non-clashing sub-conductors . 38
pi,d
6.5 Structure loads due to flexible conductors . 41
6.5.1 Design load for post insulators, their supports and connectors . 41

60865-1  IEC:2011 – 3 –
6.5.2 Design load for structures, insulators and connectors with tensile
forces transmitted by insulator chains . 41
6.5.3 Design load for foundations . 42
7 The thermal effect on bare conductors . 42
7.1 General . 42
7.2 Calculation of thermal equivalent short-circuit current . 42
7.3 Calculation of temperature rise and rated short-time withstand current
density for conductors . 43
7.4 Calculation of thermal short-time strength for different durations of the short-
circuit . 44
Annex A (normative) Equations for calculation of diagrams . 46
Bibliography . 51

Figure 1 – Factor k for calculating the effective conductor distance . 15
1s
Figure 2 – Loading direction and bending axis for multiple conductor arrangements . 18
Figure 3 – Factor e for the influence of connecting pieces in Equation (17) . 24
Figure 4 – Factors V , V and V to be used with the three-phase and line-to-line
F σm σs
short-circuits . 25
Figure 5 – Factors V and V to be used with three-phase automatic reclosing . 26
rm rs
Figure 6 – Maximum swing out angle δ for a given maximum short-circuit duration T . 30
max k1
Figure 7 – Factor ψ for tensile force in flexible conductors . 31
Figure 8 – Geometry of a dropper . 33
Figure 9 – ν as a function of ν . 37
2 1
180°
Figure 10 – ν ·sin as a function of a /d . 37
3 s
n
Figure 11 – ξ as a function of j and ε . 38
st
Figure 12 – η as a function of j and ε . 41
st
Figure 13 – Relation between rated short-circuit withstand current density (T = 1 s)
kr
and conductor temperature . 44

Table 1 – Effective distance a between sub-conductors for rectangular cross-section
s
dimensions . 16
Table 2 – Maximum possible values of V V , V V , V V . 19
σm rm σs rs F rm
Table 3 – Factors α, β, γ for different busbar support arrangements . 20
Table 4 – Factor q . 22
Table 5 – Section moduli W of main conductors with two or more stiffening elements
m
between two adjacent supports. The stiffening elements are black. . 22
Table 6 – Recommended highest temperatures for mechanically stressed conductors
during a short-circuit . 43

– 4 – 60865-1  IEC:2011
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SHORT-CIRCUIT CURRENTS –
CALCULATION OF EFFECTS –
Part 1: Definitions and calculation methods

FOREWOR
...