Generator Load and Motor Power Calculator
Estimate steady electrical load and motor shaft output from voltage, current and efficiency.
Formula
DC: P = VI; 1φ: P = VIPF; 3φ: P = √3VIPF; shaft = Pη/100
Voltage (AC: RMS): 230 V · Current (AC: RMS): 10 A · Electrical load (kW) ≈ (230 V)×(10 A)×(0.8)÷1000 · Motor shaft output (kW) ≈ (1.84)×(90)÷100
How to use
- Choose DC, single-phase or balanced three-phase.
- Enter voltage, current, power factor and motor efficiency.
- Read electrical load and motor shaft power in kW.
Examples
- At 200 V, 10 A and PF 0.5, a single-phase motor takes 1 kW; 90% efficiency gives 0.9 kW at its shaft.
Frequently asked questions
Which AC readings are required?
For sinusoidal AC use RMS values; balanced three-phase uses line-to-line voltage and line current. PF is ignored for DC.
Which efficiency is used?
Motor shaft-output/electrical-input efficiency, not generator efficiency. Use the value at your operating load.
Does this select a generator rating?
No. Starting surges, reserve capacity, kVA limits and unbalanced loads need separate assessment.
Sources
Updated: