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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I tables, charts, graphs, figures Thus the network feeder in figure 4a is represented by its internal impedance Zot, transferred to the LV-side of the transformer see 3. Calculation of a Generator 8.

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 uec with earth connection see figures 3c irc 3d the application of Ks according to equation 22 may lead to results at the non-conservative side. This part of IEC does not deal with the calculation of short-circuit currents in installations on board ships and aeroplanes. The results of the short-circuit current calculation have an acceptable accuracy also in the case of untransposed overhead lines.

It is only necessary to choose the branches which carry partial short-circuit currents at the nominal voltage 600909-0 to the short-circuit location and branches with transformers adjacent to the short-circuit location. These values cannot be used when calculating the aperiodic component id. Connection 609099-0 a Motor The positive-sequence short-circuit impedance zat the short circuit location F is obtained according to figure 5a, when a symmetrical system of voltages of positive-sequence phase order is applied to the short-circuit location F, and all synchronous and asynchronous machines are replaced by their internal impedances.

Except for special cases, the zero-sequence short-circuit impedances at the short-circuit location differ from the positive-sequence and negative-sequence short-circuit impedances. This procedure is not allowed when calculating the peak short-circuit current i.

The zero-sequence system impedance Z,, 6099-0 the motor shall be given by the manufacturer, if needed see 4. T k i and the factor K derived in 4.

For the short-circuit impedances of synchronous generators in the negative-sequence system, the following applies with KG from equation 1 8: Factor q may also be obtained from figure You are currently using the site but have requested a page in the site.

The correction factor Kso shall also idc applied to the zero-sequence system impedance of the power station unit excepting, if present, an impedance component between the star point of the transformer and earth. Factors for the calculation of short-circuit currents in three-phase a. Linand il,, factors for cylindrical rotor generators This occurs in the case of a far-from-generator short circuit. Short circuits may have one or more sources, as shown in figures 11, 12, and Depending on the application of the 609090- it is of interest to know the r.

CE1 TR–I read: E” Subtransient voltage of a synchronous machine f Frequency 50 Hz or 60 Hz Ib Symmetrical short-circuit breaking current r.

If the long-term operating conditions of network transformers before the short circuit are known for sure, then the following equation 12b may be used instead of equation 12a. Xk may be neglected. This standard does not cover short-circuit currents deliberately created under controlled conditions short-circuit testing stations. In meshed networks there are several direct-current time constants. Transformers in Parallel Log In Sign Up.

I,, is the rated current of the equivalent motor M4. For a short circuit at the busbar B in figure 9, the partial short-circuit current of the low-voltage motor group M4 may be neglected, if the condition I,, I 0,Ol ICT3 holds.

Enter the email address you signed up with and we’ll email you a reset link. Neglecting the -zero-sequence capacitances of lines in earthed neutral systems leads to results which are slightly higher than the real values of the short-circuit currents. The calculation of the minimum steady-state short-circuit current in the case of a near-to- generator short circuit, fed by one or’ several similar and parallel working generators with compound excitation, is jec as follows: This phenomenon is not dealt with in this standard.

Table of contents Preface xi Acknowledgments xiii 1 Definitions: The effect of series capacitors can be neglected in the calculation of short-circuit currents, if they are equipped with voltage-limiting devices in parallel, acting if a short circuit occurs. The correction factor Ks shall also be applied to the zero-sequence system impedance of the power station unit, 6090-90, if present, an impedance component ie the star point of the transformer and earth.

## Short Circuits in Power Systems: A Practical Guide to IEC 60909-0, 2nd Edition

For the effective reactance of the generators, introduce: They do not contribute to the symmetrical short-circuit breaking current I, and the steady-state short-circuit current I k. Supply to a Factory The resistance is to be considered if the peak short-circuit current ip or the d.

For simplification of the calculation, groups of motors including their connection cables may be combined to a single equivalent motor see motor M4 in figure 9. RL is the line resistance for a conductor temperature of 20 OC, when calculating the maximum short-circuit currents.

The impedances and z o L of eic and high-voltage cables depend on national techniques and standards and may be taken from IEC or from textbooks or manufacturer’s data. 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.

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Currents calculated with equation 74 are larger than the real symmetrical short-circuit breaking. Example of a meshed network fed from several sources The capacitances of lines overhead lines and cables of low-voltage networks may 60990-0 neglected in the positive- negative- and zero-sequence system.

He has more than 18 years of professional experience in planning and design of electrical power systems. Symmetrical locked-rotor current of an asynchronous motor Rated 6099-0 of electrical equipment Thermal equivalent short-circuit current d. Earthing and protection against electric shock IEC