If we decide to simplify our caleulation of fault current by omitting all
static loads, all resistances, the shunt admittance of each transformer, and the
capacitance of the transmission line, the impedanced iagram reduces to the
per-phase reactance diagram of Fig.1.27. These simplifications apply to fault
calculations only as discussed in Chap.10 and not to power-flow studies, which
are the subject of Chap.9. If a computer is available, such simplification is not
necessary.