I am trying to find a method that a layman such as I can use to check bolted fault current or Isc.

 

Halfdice... my Gi.Fi.E.S method (pronounced Jiffys) can be used to solve your problem:<pre>
Gi for ‘Given’.
Fi for ‘Find’.
E for ‘Equation’.
S for ‘Solution’.</pre>
Given:
A 3-phase Transformer; rated capacity kVA, 500; kVpri, 4.160V; kVsec, 0.480; Imp Z = 5.5%; and the transformer is supplied wih power from an infinite source.

Find
The 3-ph short-circuit current Isc, on secondary

Equation
The short-circuit kVA-duty is the transformer's rated kVA, divided by its percent impedance, Z presented in decimal form:<pre>
o kVAsc = kVA/(%Z/100) in kVA.
o Isc = kVAsc/[sqrt(3)x(Vsec/1,000)] in Amp.

Solution
o kVAsc = 500/(0.055) = 9,110 kVA.
o Isc = 9,110/(1.732x0.480) = 10,960 A.</pre>
If you need additional information, please let us know!

Regards,
Phil Corso