Current Calculation [repack]: Fault

( I_f = 1.0 / 0.09 = 11.11 , \textpu )

[ I_f = \fracV_thZ_th ] where ( V_th ) is the prefault voltage at the fault point (usually 1.0 pu), and ( Z_th ) is the Thevenin equivalent impedance seen from the fault point (resistance + reactance). In high-voltage systems, resistance is often neglected, giving: fault current calculation

[ Z_util = \fracS_baseS_sc = \frac101000 = 0.01 , \textpu ] ( I_f = 1

( S_base = 10 , \textMVA ), ( V_base, HV = 115 , \textkV ), ( V_base, LV = 13.8 , \textkV ). resistance is often neglected