Compare balanced 3-phase and 2-phase ratings at identical per-phase load conditions in kW, kVA, watts, or horsepower, or calculate both systems from per-phase voltage, current, and power factor. This is a conditional rating comparison, not a physical supply conversion.

Ideal rating comparison with unchanged per-phase load. Two-phase means phases 90ยฐ apart. This is not split-phase service, physical conversion or equipment sizing.

Changing this unit reinterprets the entered number.

3 Phase to 2 Phase Formula

The following formula is used to calculate the equivalent 2-phase rating from a balanced 3-phase rating.

P2ฯ† = (2) / (3) P3ฯ†

For a balanced N-phase system, the total power can also be expressed as PN = N ร— Vphase ร— Iphase ร— PF.

Variables:

  • P2ฯ† is the equivalent 2-phase power rating
  • P3ฯ† is the original 3-phase power rating
  • Vphase is the phase voltage
  • Iphase is the phase current
  • PF is the power factor

To calculate the equivalent 2-phase rating, multiply the 3-phase rating by 2/3, assuming the same phase voltage, current, and power factor.

What is 3 Phase to 2 Phase Conversion?

3 phase to 2 phase conversion is the process of translating a balanced three-phase power rating into the equivalent rating for a two-phase system under the same per-phase electrical conditions. Since the total power in a balanced system is proportional to the number of phases, a 2-phase system delivers two-thirds of the power of an otherwise comparable 3-phase system. Here, two-phase means two balanced phases 90ยฐ apart, not split-phase service. The 2/3 factor applies only when each phase voltage, current and power factor stays unchanged; it does not determine the input/output power of conversion equipment or size that equipment.

How to Calculate 3 Phase to 2 Phase Conversion?

The following steps outline how to calculate the equivalent 2-phase value from a 3-phase rating.

  1. First, determine the balanced 3-phase power rating.
  2. Next, confirm that the phase voltage, phase current, and power factor are assumed to remain the same.
  3. Then multiply the 3-phase rating by 2/3 using the formula P2ฯ† = (2/3) ร— P3ฯ†.
  4. Finally, check your answer with the calculator above.

Example Problem:

Use the following variables as an example problem to test your knowledge.

3-Phase Power Rating (P3ฯ†) = 30 kW

Equivalent 2-Phase Power Rating (P2ฯ†) = 20 kW

3 Phase to 2 Phase Conversion Table

The table below lists sample conversions using the relationship P2ฯ† = (2/3) ร— P3ฯ†.

3-Phase Power Conversion Factor Equivalent 2-Phase Power
3 kW ร— 2/3 2 kW
6 kW ร— 2/3 4 kW
9 kW ร— 2/3 6 kW
12 kW ร— 2/3 8 kW
15 kW ร— 2/3 10 kW
30 kW ร— 2/3 20 kW
45 kW ร— 2/3 30 kW

This calculation compares ideal balanced ratings under the stated per-phase assumptions. Real phase-conversion equipment needs its own power-balance, losses and rating analysis. If you know the 3-phase rating and the phase conditions are the same, the equivalent 2-phase rating is simply two-thirds of that original value.