Tool
Fault Analysis Lab
Symmetrical-components short-circuit analysis for a source-transformer-cable feeder — pick a fault type, location and resistance, and see the resulting three-phase current and voltage waveforms and phasors, before and after the fault.
In plain terms
Simulates what happens electrically when something goes wrong on a power line — a wire touching the ground, or two wires touching each other. It calculates how much current would flow and what the voltage would look like nearby, using the same standard method (symmetrical components) electrical engineers have used by hand for decades — just instant, and shown visually instead of on paper.
Network & fault
01 / inputOne phase to ground — by far the most common fault type in practice (≈70-80%).
Assumed Dyn (delta HV, grounded-star LV) — the standard arrangement for HV/MV distribution transformers, and the reason the grid source doesn't appear at all in the zero-sequence path below.
R, X — left to right.
0.121 kA fault current
Line-ground fault, 40% along the line — equivalent MVA at the largest phase current ≈ 4 MVA.
Reading point
02 / readoutRight at the fault location itself.
IA
0.121 kA
∠-89°
IB
0.000 kA
—
IC
0.000 kA
—
I0 (ground)
0.040 kA
VA
0% nom.
—
VB
171% nom.
∠-149°
VC
171% nom.
∠150°
Min. voltage
0%
Waveform & phasors
Solid = during fault, at At the fault. Dashed = pre-fault.
How this is built: symmetrical- components fault analysis (Fortescue transform + sequence networks) — the same closed- form method used in fault studies and relay-testing tools, not an iterative power flow. Positive- and negative-sequence impedances are treated as equal throughout; the transformer's zero-sequence impedance is assumed equal to its positive-sequence impedance; pre-fault load current is neglected (standard practice for a maximum fault- current study — it's also why MP2, downstream of the fault, reads ~0 current here). The transformer is assumed Dyn, so the grid source never enters the zero-sequence path — only the transformer and its grounding impedance do. Per-unit values referred to a fixed 100 MVA system base internally; every result shown is scaled back to real kV/kA, so the choice of base has no effect on any number above.
Further reading
- J. J. Grainger & W. D. Stevenson Jr., Power System Analysis, McGraw-Hill — symmetrical components and fault current calculation.
- J. D. Glover, M. S. Sarma & T. J. Overbye, Power System Analysis and Design, Cengage Learning — sequence networks and per-unit fault studies.
- IEC 60909-0, Short-circuit currents in three-phase AC systems — Part 0: Calculation of currents — the industry standard this engine's method follows in spirit, though this tool computes exact fault currents rather than IEC 60909's standardized correction-factor approximations.