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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In the case of high-voltage feeders with nominal voltages above 35 kV fed by overhead lines, the equivalent impedance 2, may in many cases be considered as a reactance, i.

For two-winding transformers with and without on-load tap-changer, an impedance correction factor KT is to be introduced in addition to the impedance evaluated according to equations 7 to 9: For TCC clipping you can choose one from initial, breaking and steady state currents. Symmetrical currents are applied for relays with DC offset filter.

## IEC-60909 Short-Circuit in EasyPower

This is the only active voltage of the network 1. Calculation of currents 1 General 1.

I,, is the rated current of the generator transferred to the high-voltage side see 4. You can enter equipment data and parameters via user friendly interface. Electric and magnetic circuits IEC 15 1: This phenomenon is not dealt with in this standard. The decaying aperiodic component id.

Systems at highest voltages of kV and above with long transmission lines need special consideration. U nQ is the nominal system voltage at the feeder connection point Q of the power station unit. The IEC standard terminology is used in the user interface and reports.

System diagram and equivalent circuit diagram for network feeders Special considerations are necessary in this case, for instance with the superposition method. When calculating the partial short-circuit current I: Fuses and calculatipn voltage circuit breakers ratings are compared with initial currents. Characterization of short circuits and their currents Their preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with may participate in this preparatory work.

This sgort applies the 1.

The following features are supported: Earth ground trip functions for low voltage circuit breakers or relays use the symmetrical earth ground current.

If Si iev used in spite of this in connection with short-circuit calculations, for instance to calculate the internal impedance of a network feeder at the connection point Q, then the definition given should be used in the following form: In this case, the three-fold zero-sequence current flows through the joint return.

Breaking currents are calculated at 0. Synchronous machines generators, motors, or compensators with terminal-fed static exciters do not contribute to I k in the case calculatioj a short-circuit at the terminals of the machine, but they contribute to l k if there is an impedance between the terminals and the short-circuit location.

The following types of unbalanced short circuits are treated in this standard: With respect to equation 99 in table 3 the steady-state short-circuit current of asynchronous motors is zero in the case of a three-phase short circuit at the terminals figure 12 and equation Remember me on this computer.

### IEC Short-Circuit in EasyPower

The symbols represent physical quantities possessing both numerical values and dimensions that are cirucit of units, provided a consistent unit system is chosen, for example the international system of units SI. In a system of low voltage breakers with ZSI, when the current through any circuit breaker exceeds the short time pickup its restraining signal is sent to upstream circuit breakers. 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.

Q5 This standard meets my needs: T k i and the factor K derived in 4. For high voltage circuit breakers, the peak current is compared with the making capacity and the breaking current is compared with the rated breaking capacity.

The value should be obtained from the manufacturer.