For a feeder where the voltage is given and its impedance or reactance is known, its short circuit MVA is equal to kV^2 divided by its impedance in ohms.
For instance, a 2000KVA, 5.75%Z transformer has a SC MVA = Rated MVA / Z = 2 / 0.0575 = 34.8MVA, where Z is the transformer impedance in p.u. The short circuit MVA of each is equal to its MVA rating divided by its own per unit impedance. Generators, motors, transformers are normally given their own rated MVA, X/R ratios and impedance ratings. Each basic component within the industrial electrical distribution system is pre-assigned a single short circuit MVA factor (SC MVA) based on the impedance it adds to the system ( Figure 1 b).
