What is a Short Circuit Current?

What is a Short Circuit Current?

Short circuit current is the maximum amount of current that flows through a power system during the fault occurrence. The short circuit current depends on factors like voltage, total impedance and the type of fault. The short circuit current is represented by Isc....

Basic Formula to Calculate Short Circuit Current

To calculate short circuit current we have different formulas according to different circuits....

Types of Faults

In power system various type of fault can occur such as...

Fault Analysis Methods

For examining short circuit currents in a power system different methods are used for analyzing. Some of the approach methods are per-unit method which does calculations by standardizing voltages, currents, and impedances to a common base value. Another methods is Symmetrical Components Method in which we break down an unbalanced three phase system into three balanced systems so that we can calculate short circuit currents for any type of fault. Also we have Direct Method which Calculates short circuit current directly from a basic formula using actual values of voltages and impedances....

How to Calculate Short Circuit Current

To calculate short circuit current first we analyze the circuit and check the components like it is a generator, transformer or circuit with different impedances. If the given element is generator, we calculate the short circuit current by dividing the generator rated current with the impedance present in the short circuit path. If the given element is transformer, then we calculate the short circuit current by dividing the KVA rating of the source by secondary side voltage of the transformer. If the impedances are given then, we use the general formula for calculating the short circuit current i.e., by dividing pre-fault voltage with total impedance....

Solved Examples on Short Circuit Current

There are some solved examples of calculate short circuit current given by direct method:...

Conclusion

From the above discussion we can conclude that the current flowing at the time of short circuit is called short circuit current. To calculate the short circuit current we have different formulas based on the elements in the circuit. The general formula to get the short circuit current is the ratio of pre-fault voltage to total impedance. To get the short circuit current for transformers we require the KVA rating of the source and secondary side voltage of the transformer. To get the short circuit current for generators we require the generator rated current and the impedance of the short circuit path....

How to Calculate Short Circuit Current – FAQs

What is the Formula for Short Circuit Current?...