What Is the Per-Unit System Impedance Base Conversion Calculator?
Per-unit normalization expresses voltage, current, and impedance as decimal fractions of defined base values.
How Does the Per-Unit System Impedance Base Conversion Calculator Work?
Physical impedance in ohms is conserved while scaling inversely with voltage base squared and directly with apparent power base.
Per-Unit System Impedance Base Conversion Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
Z_{ ext{pu,new}} = Z_{ ext{pu,old}} left( rac{V_{ ext{base,old}}}{V_{ ext{base,new}}}
ight)^2 left( rac{S_{ ext{base,new}}}{S_{ ext{base,old}}}
ight)
Standard formula for shifting per-unit impedance across different power and voltage bases.
How to Use the Per-Unit System Impedance Base Conversion Calculator
- Input original nameplate per-unit impedance, original kV and MVA bases, and target new system bases.
Step-by-Step Example Calculation
Transformer Base Conversion to 100 MVA Study Base
Input Values:
zPerUnitOld:0.08
kvBaseOld:13.8
mvaBaseOld:25
kvBaseNew:13.8
mvaBaseNew:100
Worked Steps: New per-unit impedance Z_pu,new = 0.3200 p.u. (physical impedance is 0.609 Ω).
Understanding Your Result
Shows new per-unit impedance along with physical impedance in ohms and original/new base impedances.
Factors That Affect the Result
- Voltage base mismatches have quadratic impact on per-unit impedance.
When Should You Use This Calculator?
- Assembling bus admittance matrices (Y-bus) for load flow and short-circuit studies.
Assumptions & Limitations
- Applies to 3-phase balanced power systems.
Frequently Asked Questions
Calculation Accuracy & Reference Note
Exact power systems per-unit transformation.