When to Use This Calculator
Use this calculator when you know balanced three-phase symmetrical RMS fault current and line-to-line voltage and need the equivalent fault MVA at that bus.
Enter Fault Values
Formula Summary
Fault MVA = √3 × kVLL × kA
Using kV and kA directly produces MVA.
Example
A symmetrical fault current of 20.92 kA at 13.8 kV represents approximately 500 MVA of fault level.
Limitations
Fault MVA is a convenient expression of short-circuit strength. It is not real power consumed by the fault and does not by itself establish equipment interrupting or withstand duty.
Confirm whether source data is symmetrical RMS current, asymmetrical current, or peak current before using this conversion.
Common Mistakes
- Using phase-to-neutral voltage instead of line-to-line voltage.
- Entering amps as kA or kV as volts.
- Assuming fault MVA is real load power.
- Using fault MVA alone for interrupting or withstand ratings.
Reference Notes
This is a standard balanced three-phase short-circuit conversion. Confirm the current basis and study method before applying results to equipment-duty decisions.