Download Citation on ResearchGate | Applying IEC , Fault Current Calculations | Rather than the short-circuit current that would occur in a specific. Applying IEC , short-circuit current calculations. Abstract: Rather than the short-circuit current that would occur in a specific instance, IEC derives. The initial short circuit current for a is as per IEC Equation
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As described in the methodology the solution is obtained using the equivalent voltage source at the short-circuit location, symmetrical components impedance network, and the voltage factor c. 60099 1 unacceptable, marketing specialist other The impedance correction factor shall be applied also to the negative-sequence and the zero- sequence impedance of the transformer when calculating unbalanced short-circuit currents.
You can view the currents in various formats such as phase currents for A, B and C phases or in symmetrical components: Any branch may be a series combination of several impedances. Subtransient impedances are used for rotating machines with the impedance correction factors.
For simplification, it is permitted to use the 609099 value for IC as for the three- phase short circuit. When calculating short-circuit currents in systems with different voltage levels, it is necessary to transfer impedance values from one voltage level to another, usually to that voltage level at which the short-circuit current is to be calculated.
Additional information may be found in IEC The short-circuit calculation provides the phase angle of the branch currents and the bus voltages at various equipment.
Medium-voltage motors have to be considered in the calculation of maximum short-circuit current see 2. Shoft Steady-state short-circuit current at the terminals poles of a generator with compound excitation Initial symmetrical short-circuit current r.
This can lead to a situation where shory partial short-circuit currents are too small to operate any further protection device, particularly in the case of minimum short-circuit currents.
Neglecting the -zero-sequence capacitances of lines in earthed neutral systems leads to results ehort are slightly higher than the real values of the short-circuit currents. Figure 21 – Factor m for the heat effect of the d.
U, is the nominal voltage of the system; ur, is the rated voltage cirrcuit the generator; ZGK is the corrected subtransient impedance of the generator; 2, is the subtransient impedance of the generator in the positive-sequence system: 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.
All other static converters are disregarded for the short-circuit current calculation according to this standard.
IEC-60909 Short-Circuit in EasyPower
EasyPower compares the short circuit results with protective device short-circuit ratings and displays the results in the text report and in the single line diagram. 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 made 660909 follows: Factor p for calculation of short-circuit breaking current 1, The text of this standard is based on the following documents: DC component of short-circuit current at breaking times: Capacitors and non-rotating loads are not included in the calculations.
Sequential short circuits are not considered. Short-circuit current of a near-to-generator short circuit with decaying a. You can display short-circuit tick marks for initial, breaking and steady state currents.
IEC Short-Circuit in EasyPower
The transformer correction factor K T for two winding units with or without on-load tap changer LTC is calculated as follows per section 3. Remember me on this computer. In general, the calculation according to 4.
The capacitances of lines overhead lines and cables of low-voltage networks may be neglected in the positive- negative- and zero-sequence system.
Asymmetrical currents for the initial and the four breaking time intervals are also calculated for use in protective device coordination. The object of the IEC is to promote international co-operation on all questions concerning standardization in the electrical and electronic fields. I quality of writing The superposition method gives the short-circuit current related to the one caldulation flow presupposed.