Assuming infinite bus leads to overestimating fault current. While this ensures you buy breakers with high interrupting ratings (safe against explosions), it can be overly expensive.
): Now, factor in the transformer’s Impedance (%Z), which is usually found on the nameplate. available fault current formula
Suppose we have a 3-phase system with a line-to-line voltage of 480 V and a total impedance of 0.1 Ω. Using the formula: Assuming infinite bus leads to overestimating fault current