Per-Unit Base-Change Calculator
Convert per-unit impedance values from one base to another while preserving physical equivalence.
Original Base Values
New Base Values
About This Calculator
This calculator converts per-unit impedance values between different base quantities. It applies the standard base-change formula, showing intermediate scaling factors for transparency.
The calculator detects when voltage bases differ and provides a warning, as this typically indicates a transformer boundary where special care is required to ensure correct base propagation.
When to Use This Calculator
- Normalising manufacturer data to a system-wide MVA base
- Combining equipment data from different sources
- Converting between per-unit bases in multi-voltage networks
- Verifying impedance values during model review
Important Notes
- All voltage inputs should be line-to-line RMS values
- When voltage bases follow transformer ratios correctly, no voltage base change is needed across transformers
- The physical impedance (in ohms) remains unchanged; only the per-unit representation changes
For the theory behind base changes, see: Per-Unit System: Changing Base Across Transformers and Networks.
For base quantity derivations, see: Per-Unit System: Base Quantities and Their Relationships.
To convert physical R, L, C values to per-unit, use the: Physical-to-Per-Unit Impedance Calculator.