Simple Method for Basic Short Circuit Current Calculations

simple method for short circuit study calculations

In order to dig deep into the easy way to calculate the short circuit current calculations, we must first develop our knowledge base on the basics of short circuit analysis.

“A Short Circuit current analysis is used to determine the magnitude of the short circuit current which the system is capable of producing and compares the magnitude of the short circuit magnitude with the interrupting rating of the overcurrent protective devices (OCPD).”

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Short Circuit Study & its Importance in Power Systems

A basic electrical theorem say that the short circuit current actually depends upon the two most important parameters:

With the help of the basic formula, we can easily calculate the short circuit current at the fault location and with the help of those values, we can analyze the system and install protective devices and protect the facility from any major harm or damage.


There are many methods to calculate the short circuit currents, however, we will give you the basic idea of how we can calculate the short circuit currents in a simple AC distribution system.

Read on to find out the easiest way to calculate a short circuit current.

arc fault occur in power systems

What does this mean? and why is it important to the simple calculation?

Suppose, if we have a 480 V/220 V step-down transformer which has an impedance of 5%, this means that 5% of 480 V i.e. 24 V, applied to its primary side will cause rated load current flow in its secondary.

If 5% of primary voltage will cause such current, then 100% of primary voltage will cause 20 times (100 divided by 5) full-load-rated secondary current to flow through a short circuit on its secondary terminals.

Now that we understand the basic variables that determine the short-circuit currents, let’s do a simple calculation for the same One Line diagram that has been mentioned earlier.

In order to prevent short circuit incidents within an industrial or commercial setting, get to know an easier method to determine short circuit current calculations in detail here.

Let us know if you have any queries regarding this topic and do provide us with your feedback in the comments.

Hiring a professional electrical engineer to conduct an Arc Flash Analysis and Short Circuit Study is a great way to ensure the safety of your facility and workers against unwanted incidents.

AllumiaX, LLC is one of the leading providers of Power System Studies in the northwest. Our matchless services and expertise focus on providing adequate analysis on Arc Flash, Transient Stability, Load Flow, Snubber Circuit, Short Circuit, Coordination, Ground Grid, and Power Quality.

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