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NCEES PE Power — Oct 2025 Blueprint
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8. Transmission and Distribution Analysis
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E. Fault current analysis
E. Fault current analysis
Three-phase + unbalanced (line-to-ground, line-to-line, double-line-to-ground) fault calculations.
Lessons
Lesson 1
Three-phase fault analysis — symmetrical and unbalanced
Thevenin reduction, 3-φ symmetrical fault, sequence networks for SLG / LL / DLG, fault impedance, breaker sizing, motor contribution.
Lesson 2
Unbalanced fault analysis — sequence networks (LG / LL / LLG / 3-φ)
Symmetrical-component analysis via Fortescue decomposition: connect positive / negative / zero sequence networks per fault type — LG=series, LL=pos∥neg, LLG=pos series with (neg∥zero), 3-φ=pos only. Z1, Z2, Z0 per generator / transformer / line. ETAP / SKM / EasyPower / PowerWorld automate via sequence Y-bus / Z-bus.