THREE-PHASE POWER CALCULATORVolts and amps
Volts and amps
are only the beginning.
Translate RMS voltage and current into apparent power, estimated real electrical input and estimated mechanical output—with every assumption visible.
POWER RELATIONSHIPS
Three-phase power uses more than volts and amps.
The DOE motor-systems guide gives the balanced three-phase electrical input relationship below. It uses RMS line-to-line voltage, mean RMS line current and power factor.
Pinput (kW) = √3 × Vline-line × I × PF ÷ 1,000Single-phase comparison: P (kW) = V × I × PF ÷ 1,000. Mechanical output also requires efficiency.
| Quantity | What it means | Do not assume |
|---|---|---|
| kVA | Apparent power: voltage-current product with the phase multiplier. | It is not automatically the kW performing work. |
| Input kW | Estimated real electrical power after power factor. | It is not motor shaft output. |
| Output kW / hp | Estimated mechanical output after efficiency. | It is not the entire machine's input requirement. |
Electrical-planning boundary.
This reference explains terms and arithmetic. It does not size conductors, overcurrent protection, transformers, disconnects, grounding, arc-flash protection or a branch circuit. Use the exact machine documentation, the authority having jurisdiction and qualified electrical professionals. Servicing also requires an applicable hazardous-energy control program.