Transformer Short-Circuit Current Calculator
Estimate the symmetrical bolted fault current available at transformer secondary terminals using transformer full-load current and nameplate percent impedance.
Full-load current601.4 A
Approx. terminal fault current10,459 A
Approx. fault level8.7 MVA
Transformer-terminal approximation only. Utility/source impedance, feeder impedance, motor contribution, X/R ratio and system configuration are not included.
How this tool works
Approximate secondary fault current = full-load current ÷ (impedance % ÷ 100).
Example
A transformer with 5.75% impedance can theoretically deliver about 17.4 times its full-load current at its secondary terminals when source impedance is ignored.
Common questions
Does this include utility source impedance?
No. Source, conductor, motor and system impedances can materially change available fault current.
Is this a full short-circuit study?
No. It is a transformer-terminal approximation for preliminary checks.