Series reactor — current-limiting calculator
Enter the system voltage, the grid short-circuit capacity and the reactor inductance: you get the short-circuit current with and without the reactor, the reduction, the voltage that appears across the reactor during a fault, and the effect of the ±10% inductance tolerance. Everything is computed from the IEC 60909 formula stated under the results — nothing is a lookup table.
| Grid Ssc | Ik without | Ik with reactor | Reduction |
|---|---|---|---|
| 100 MVA | 6,351 A | 4,833 A | 23.9% |
| 200 MVA | 12,702 A | 7,801 A | 38.6% |
| 315 MVA | 20,005 A | 10,055 A | 49.7% |
| 500 MVA | 31,754 A | 12,352 A | 61.1% |
| 1000 MVA | 63,509 A | 15,334 A | 75.9% |
Basis: IEC 60909 simplified maximum short-circuit current — Ik = c·Un / (√3·(Zgrid + Zreactor)), c = 1.1; Zgrid = Un²/Ssc; Zreactor = 2πfL. Linear-inductance assumption; no lookup values.
⚠ The fault current is far above the rated current, so the iron core saturates deeply: the figures above are a conservative linear-inductance estimate. The real limiting effect requires the manufacturer L–I saturation curve — ask the reactor supplier for it.
Where it is used: series reactors are placed in front of power-electronic converters (solid-state transformers, VFDs, PV/BESS inverters) to smooth the converter current, damp high-frequency harmonics and — most importantly — limit the fault current that would otherwise destroy the semiconductor switches.