AC-Fault

Open in app →

A three-phase-to-ground fault applied to a transmission line, then cleared.

One-line view: a balanced $3\varphi$ 230 V source feeds a transmission line into a 500 Ω load. A three-phase-to-ground (ABCG) fault of 0.1 Ω is switched onto the bus at $t=1.05$ s and removed 100 ms later.

A balanced three-phase source feeds a transmission line into a resistive load. At t = 1.05 s a low-impedance (0.1 Ω) three-phase-to-ground (ABCG) fault is switched in for 100 ms and then removed, so you can watch the line voltages collapse while the fault is on and recover once it clears. The two plots follow the phase quantities right through the disturbance.

Before the fault the bus sits at its normal balanced 230 V. When the 0.1 Ω short to ground snaps on at 1.05 s it pins the faulted bus voltage to nearly zero and draws a large fault current — the collapse you see on the plots. After 100 ms the fault clears and the voltages spring back to normal. This is the canonical protection scenario (detect, ride through, recover), and a good demo of why EMT tools model faults as switched elements. The run spans 2 s at a ≈20 µs step; try changing the fault type (e.g. a single line-to-ground) or its resistance to see how the collapse changes.