These 50KVA 120/240V 1Ø 3W transformer have an Impedance of 0.9 Percent.
The local PoCo chart shows 23640 fault current @ 240 volts for these 0.9 % nameplate Impedance.
The .9 in the above fault current calculation(s), is as Don noted, for worst case scenario of transformers 25 KVA and larger do to the +/- 10% variation of the nameplate impedance.