Energy
Motor Current Calculator
Calculate estimated full-load motor current from motor power, voltage, power factor and efficiency.
Use the motor mechanical output rating from the nameplate.
Enter line-to-line voltage for a three-phase motor.
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Estimated Full-Load Current
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Estimated RMS line current at the entered motor operating conditions.
Motor current
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Mechanical output power
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Electrical input power
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Apparent power
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Reactive power
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Motor efficiency
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Power factor
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System
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Method:
Mechanical motor output power is converted to required electrical real input power using:
Pin =
Pout ÷ η
where η is motor efficiency.
For a balanced three-phase motor:
Pin =
√3 × V × I × PF
therefore:
I =
Pout ÷
(√3 × V × PF × η)
For a single-phase motor:
I =
Pout ÷
(V × PF × η)
Apparent power is:
S = Pin ÷ PF
Reactive power magnitude is:
Q =
√(S² − P²)
For three-phase calculations, the entered voltage is line-to-line RMS voltage and the calculated current is line current.
This calculator estimates operating current from entered efficiency and power factor. Actual motor nameplate full-load current may differ because motor characteristics vary by manufacturer, design, voltage, speed, loading and applicable standards. Use nameplate or manufacturer current data for equipment protection and final electrical design.