IEC 60909 PDF

This calculation is based on IEC (, c), “Short-circuit currents in three-phase a.c. systems – Part 0: Calculation of currents” and. EasyPower offers a complete and accurate solution to short-circuit calculations in three-phase AC systems using the IEC standard. You can enter. IEC Edition INTERNATIONAL. STANDARD. NORME. INTERNATIONALE. Short-circuit currents in three-phase a.c. systems –.

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In the case of unbalanced short circuits, the impedance correction factor KSOfrom equation 24 shall be applied to both the positive-sequence and the negative-sequence system impedances of the power station unit. IEC TR2- lire: Xk may be neglected.

Short-circuit impedances of a three-phase a. EasyPower supports the following four types of short-circuit conditions as per IEC Example of a meshed network fed from several sources Any branch may be a series combination of several impedances. The factor K shall, be calculated according to 4. 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.

Calculation of a Transformer 8. IEC Short-circuit currents in three-phase a c.

IEC-60909 Short-Circuit in EasyPower

While using fuses or current-limiting circuit-breakers to protect substations, the initial symmetrical short- circuit current is first calculated as if these devices were not available. This method applies the 1. All other static converters are disregarded for the short-circuit current calculation according to this standard.


As long as RIX remains smaller than 0,3 in all branches, it is not necessary to use the factor 1, No short-circuit current on the low-voltage or lec the high-voltage side of the transformer in figure 20 is higher than the highest balanced or unbalanced short-circuit current in the case of an intact HV-feeding see figure He has more than 18 years of professional experience in planning and design of electrical power systems.

Iiec all cases I L is equal to Ikv,because the short circuits are far-from-generator short circuits see 1. You can also view the remote branch currents and remote bus voltages.

These values cannot be used when calculating the aperiodic component id. With respect to equation 99 in table 3 the steady-state short-circuit current of ic motors is zero in the case of a three-phase short circuit at the terminals figure 12 and equation Peak current based on method c: Phasor diagram of a synchronous generator at rated conditions The values can isc displayed in magnitude, magnitude and angle, or in real and imaginary quantities.

660909 unbalanced faults, equations 868788 and 89 are used. Meshed Network 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 Using this method, the currents in each line conductor are found by superposing the currents of the three symmetrical component systems: Breaking currents are calculated at 0.


Despite these assumptions being not strictly true for the power systems considered, the result of the calculation does fulfil the objective to give results which are generally of acceptable accuracy. Idc 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 an LV motor 8.

The values are given in table 1 NOTE The introduction of a voltage factor c is necessary for various reasons. I,, is the rated current of the equivalent motor M4.

IEC Short-Circuit in EasyPower

Would you like to change to the site? Ikpis the steady-state short-circuit current of a generator at a three-phase terminal short-circuit.

IkP Steady-state short-circuit current at the terminals poles of a generator with compound excitation Initial symmetrical short-circuit current r.