SHORT-CIRCUIT CURRENTS IN THREE-PHASE A.C. SYSTEMS - PART 1: FACTORS FOR THE CALCULATION OF SHORT-CIRCUIT CURRENTS ACCORDING TO IEC 60909-0
International Electrotechnical Committee
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] or 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 Factor [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-Z branches
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
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.
| Document Type | Standard |
| Status | Current |
| Publisher | International Electrotechnical Committee |
| Committee | TC 73 |
