Substation Bus Fault Current: 5.71 kA at 13.8 kV

A 69 kV utility source (1,500 MVA fault level) feeding a 12 MVA, 8% transformer and a 13.8 kV bus. The utility at 0.008 pu plus the transformer at 0.08 pu give a bus fault of 12 MVA ÷ (√3 × 13.8 kV × 0.088) = 5.71 kA.