Convert between motor input power, shaft output power and horsepower.
A motor nameplate states shaft output, not electrical input, so input power is always higher by the efficiency factor. Those losses become heat that the enclosure and ventilation must remove. Confusing nameplate kW with electrical demand undersizes supply cables and switchgear by around 10 per cent.
Motor Power
Input = √3 V I cos φ; shaft output = input × efficiency
Input = √3 V I cos φ; shaft output = input × efficiency A motor nameplate states shaft output, not electrical input, so input power is always higher by the efficiency factor. Those losses become heat that the enclosure and ventilation must remove.
Confusing nameplate kW with electrical demand undersizes supply cables and switchgear by around 10 per cent.
This calculator takes 5 inputs: Supply voltage, Full-load current, Power factor, Motor efficiency, Phases. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.