ELECTRICAL / CALCULATOR
Motor Rated Current
Estimate three-phase motor rated current from shaft power, line voltage, power factor and efficiency.
Input Parameters
Edit the example values. Results update as you type.
Enter a decimal greater than 0 and no greater than 1.
Enter 1 when the input is electrical active power.
Results
- Estimated Motor Rated Current
- 29.791A
- Active Input Power
- 16.667kW
Formula
I = P / (√3 × U × cosφ × η)Substitution
I = 15,000 / (√3 × 380 × 0.85 × 0.9) = 29.791 ACalculation Steps
- Convert input power to 15,000 W.
- Use efficiency to obtain electrical input power, then divide by √3, line voltage and power factor.
Result Explanation
This steady-state line current is estimated from shaft output power. Check nameplate data and actual starting conditions before setting protection.
Formulas and FAQ
I = P / (√3 × U × cosφ × η)Can the estimated current set an overload relay?
Use the estimate for preliminary sizing. Set protection using the motor nameplate current for its actual connection and voltage, and the manufacturer's instructions.