PD IEC TR 60909-1:2002

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

Applies to short-circuit currents in three-phase a.c. systems. This technical report aims at showing the origin and the application, as far as necessary, of the factors used to meet the demands of technical precision and simplicity when calculating short-circuit currents according to IEC 60909-0.

This part of IEC 60909 is a technical report applicable to short-circuit currents in three-phase a.c. systems. This technical report aims at showing the origin and the application, as far as necessary, of the factors used to meet the demands of technical precision and simplicity when calculating short-circuit currents according to IEC 60909-0.

Thus this technical report is an addition to IEC 60909-0. It does not, however, change the basis for the standardized calculation procedure given in IEC 60909-0.

NOTE References are given in some cases to offer additional help, not to change the procedure laid down in the standard.