Kilowatt Calculator — AC Two-Phase Power Supply (4-Wire)
Determine total kilowatts for a genuine two-phase, four-wire AC load from per-phase RMS voltage, per-phase RMS current, and power factor. Enter any three variables to solve for the fourth.
US + metric
Formula shown
Shareable results
Kilowatt — AC Two Phase (4-Wire)
kW
V AC
PF
A AC
Kilowatts3.91kW(3,910 W)
Total apparent power (2 × E × I)
4.6 kVA
Total real power (2 × E × I × PF)
3,910 W
Formula & method
kW = 2 · E · I · PF / 1000
A two-phase, four-wire supply has two independent single-phase circuits 90 electrical degrees apart. Each phase contributes E × I × PF of real power, so total power is twice the per-phase value. Enter per-phase RMS voltage, per-phase RMS current, and power factor as a decimal from 0 to 1. This is electrical input power, so no efficiency term is used.
Assumes a genuine two-phase, four-wire AC supply with equal per-phase RMS voltage, equal per-phase RMS current, and one representative power factor. For preliminary and educational use; verify the supply configuration, equipment data, and applicable electrical codes.
This calculator determines total real power for a genuine two-phase, four-wire AC load. It ties together total kilowatts, per-phase RMS voltage, per-phase RMS current, and power factor. Enter any three and it returns the fourth.
The formula
kW = 2 · E · I · PF / 1000. A two-phase, four-wire system consists of two single-phase circuits 90 electrical degrees apart, each with its own pair of conductors. Each phase contributes E · I · PF watts of real power, so total power is twice the per-phase value. Dividing by 1000 converts watts to kilowatts.
Use per-phase quantities
Enter the RMS voltage across one phase’s conductor pair and the RMS current in that phase. The calculator assumes both phases have the same voltage, current, and power factor. Do not enter a combined voltage across unrelated conductors; the factor of 2 already adds the two phase powers.
Solve in any direction
Kilowatts — total real electrical power from the two phases.
Current — per-phase RMS current required for a known total load.
Voltage — per-phase RMS voltage implied by the other readings.
Power factor — total real power divided by total apparent power; a result above 1.0 identifies inconsistent inputs.
Confirm that the supply is really two phase
True two-phase, four-wire power is uncommon and survives mainly in legacy installations. It is not the same as North American 120/240 V split-phase service, which is a single-phase, three-wire system, and it is not two conductors taken from a three-phase supply. If the supply is not genuinely two phase with two circuits 90° apart, use the single-phase or three-phase kilowatt calculator.
Kilowatts here mean electrical input power
The result is real electrical power delivered to the load and has no efficiency term. To estimate motor shaft output, multiply by motor efficiency or use the two-phase horsepower calculator.
Worked example
A two-phase, four-wire load drawing 10 A per phase at 230 V per phase and 0.85 power factor has total apparent power 2 × 230 × 10 = 4600 VA. Its total real power is 4600 × 0.85 = 3910 W, or 3.91 kW.
