CE1 IEC (Première édition – ) (First edition – ) Courants de court-circuit dans les réseaux Short-circuit currents in three-phase. IEC Edition INTERNATIONAL. STANDARD. NORME. INTERNATIONALE. Short-circuit currents in three-phase a.c. systems –. Buy IEC SHORT-CIRCUIT CURRENTS IN THREE-PHASE A.C. SYSTEMS – PART 0: CALCULATION OF CURRENTS from SAI Global.
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The estimation according to equation 28 is not allowed in the case of three-winding transformers. For a synchronous generator use Rm see 3.
This first edition cancels and replaces IEC published in and constitutes a technical revision. The values of positive-sequence and negative-sequence impedances can differ from each other only in the case of rotating machines. Table of contents Preface xi Acknowledgments xiii 1 Definitions: Definitions,principles and rules IEC 1: IkP Steady-state short-circuit current at the terminals poles of a generator with compound excitation Initial symmetrical short-circuit current r.
I is not iwc all ci For the effective reactance of the generators, introduce: T k i and the factor K derived in 4.
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In existing low-voltage systems it is possible to determine the short-circuit impedance on the basis of measurements at the location of the prospective short circuit considered. It does not take into account adjustable time delays of tripping devices. Figure 20 describes this situation with balanced and unbalanced short circuits with earth connection at the short-circuit location F.
Thus the network feeder in figure 4a is represented by its internal impedance Zot, transferred to the LV-side of the transformer see 3. Within the accuracy of this standard, it is often sufficient to determine the short-circuit current at the short-circuit location F as being the sum of the absolute values of the individual partial short- circuit currents.
However, parties to agreements based on this part of IEC are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. Phasor diagram of a synchronous generator at rated conditions For currents during two separate simultaneous single-phase line-to-earth short circuits in an isolated neutral system or a resonance earthed neutral system, see IEC IEC- lire: Figure 3 – Characterization of short circuits and their currents Figure 4 shows an example of the equivalent voltage source at the short-circuit location F as the only active voltage of the system fed by a transformer without or with on-load tap-changer.
Normally, the steady-state short-circuit current Ik is smaller than the symmetrical short-circuit breaking 06909-0 1. Factor q for the calculation of the symmetrical short-circuit breaking current of asynchronous motors The three impedance correction factors given 60909–0 equation 13 shall be introduced also to the negative-sequence and to the zero-sequence systems of the three-winding transformer.
Calculation irc a Load Circuit CE1- Instead of: I 1 unacceptable, marketing specialist other For grounded systems the influence of motors on the line-to-earth short-circuit current cannot be neglected. They do not contribute to the symmetrical short-circuit breaking current I, and the steady-state short-circuit current I k.
Calculation of currents 1 General 1.
The factor K shall, be calculated according to 4. Calculation of a Generator 69009-0. The impedance of the network feeder and the transformer are related to the LV-side and the last one is also corrected with KT see 3.
Design and Calculation of aWind Farm 8. This is admissible, because the impedance correction factor KTfor network transformers is introduced.
Short Circuits in Power Systems: A Practical Guide to IEC 60909-0, 2nd Edition
Special methods to calculate i, with sufficient accuracy are given in 4. If underexcited operation of the power station unit is expected at some time for instance to a large extent especially in pumped storage plantsthen only when calculating unbalanced short- circuit currents with earth connection see figures 3c and 3d the application of Ks according to equation 22 may lead to results at the non-conservative side.
The object of the IEC is to promote international co-operation on all questions concerning standardization in the electrical and electronic fields. For this calculation method, an equivalent voltage source at the short-circuit location is iecc. For other ,values of minimum time delay, linear interpolation between curves is acceptable. The peak short-circuit current i, at a short-circuit location F, fed from sources which are not meshed with one another, in accordance with figure 12, is the sum of the partial short-circuit currents: In all cases it is possible to determine the short-circuit current at the short-circuit location F with the help of an equivalent voltage source.