थ्री-फेज मोटर पावर कैलकुलेटर

The mechanical shaft output power of a three-phase motor is P = √3 × V_L × I_L × cos φ × η, where V_L is line voltage, I_L is line current, cos φ is power factor, and η is motor efficiency.

Without η, the formula gives the total electrical input power. With η, it gives the shaft (mechanical) output power.

kW (kilowatt) is active power that does useful work. kVA is apparent power — the total power drawn from the supply. kVAR is reactive power used to maintain magnetic fields in motors and transformers.

They form the power triangle: S² = P² + Q².

Typical power factors at full load:

• 0.80–0.90 — Standard induction motors
• 0.40–0.55 — Motors at 25% partial load
• 0.95–1.00 — Synchronous motors or PFC-corrected

Power factor drops significantly at partial loads.

Efficiency η = P_output / P_input. Typical ranges: 85–96% depending on motor size and class (IE1 to IE4). A 15 kW IE3 motor may have η ≈ 0.915.

Always include η when computing electrical input from mechanical output power.

1 HP (mechanical) = 0.7457 kW, or 1 kW ≈ 1.341 HP.

Motor nameplate HP is mechanical shaft output. To get electrical input: P_elec = HP × 0.7457 / η.