FOREWORD

1 General

1.1 Scope and object

1.2 Reference documents

1.3 Application of the factors

1.3.1 Factor c

1.3.2 Factors K[G] and K[S] of K[SO]

1.3.3 Factors K[G,S], K[T,S] or K[G,SO], K[T,SO]

1.3.4 Factor K[T]

1.3.5 Factors [kappa]

1.3.6 Factors [mu], [lambda] and [q]

1.3.7 Factors [m] and [n]

1.3.8 Contribution of asynchronous motors to the

initial symmetrical short-circuit current

1.4 Symbols, subscripts and superscripts

1.4.1 Symbols

1.4.2 Subscripts

1.4.3 Superscripts

2 Factors used in IEC 60909-0

2.1 Voltage factor c for the equivalent voltage source

at the short-circuit location

2.1.1 General

2.1.2 Calculation methods

2.1.3 Equivalent voltage source at the short-circuit

location and voltage factor c

2.1.4 A simple model illustrating the meaning of the

voltage factor c

2.2 Impedance-correction factors when calculating the

short-circuit impedances of generators, unit

transformers and power-station units

2.2.1 General

2.2.2 Correction factor K[G]

2.2.3 Correction factors for power station units with

on-load tap changer

2.2.4 Correction factors for power station units without

on-load tap changer

2.2.5 Influence of the impedance correction factor for

power-station units when calculating short-circuit

currents in meshed networks and maximum

short-circuit currents at worst-case load flow

2.3 Impedance correction factor K[T] when calculating the

short-circuit impedances of network transformers

2.3.1 General

2.3.2 Example for a network transformer S[rT] = 300 MVA

2.3.3 Statistical examination of 150 network transformers

2.3.4 Impedance correction factors for network

transformers in meshed networks

2.4 Factor [kappa] for the calculation of the peak short-circuit

current

2.4.1 General

2.4.2 Factor [kappa] in series R-L-circuits

2.4.3 Factor [kappa] of parallel R-L-circuits

2.4.4 Calculation of the peak short-circuit current i[P]

in meshed networks

2.4.5 Example for the calculation of [kappa] and i[P] in

meshed networks

2.5 Factor [mu] for the calculation of the symmetrical

short-circuit breaking current

2.5.1 General

2.5.2 Basic concept

2.5.3 Calculation of the symmetrical short-circuit breaking

current I[b] with the factor [mu]

2.6 Factor [lambda] (lambda[max], lambda[min]) for the calculation

of the steady-state short-circuit current

2.6.1 General

2.6.2 Influence of iron saturation

2.7 Factor [q] for the calculation of the short-circuit breaking

current of asynchronous motors

2.7.1 General

2.7.2 Derivation of factor [q]

2.7.3 Short-circuit breaking currents in the case of

unbalanced short circuits

2.8 Factors [m] and [n] for the calculation of the Joule integral

or the thermal equivalent short-circuit current

2.8.1 General

2.8.2 Time-dependent three-phase short-circuit current

2.8.3 Factor [m]

2.8.4 Factor [n]

2.8.5 Factor [n] in IEC 60909-0, figure 22

2.9 Statement of the contribution of asynchronous motors or groups

of asynchronous motors (equivalent motors) to the initial

symmetrical short-circuit current

2.9.1 General

2.9.2 Short circuit at the terminals of asynchronous motors

2.9.3 Partial short-circuit currents of asynchronous motors

fed through transformers

2.9.4 Sum of partial short-circuit currents of several

groups of asynchronous motors fed through several

transformers

Bibliography

Figures and Tables