Electricity calculator group

Electric Motors Calculators

Estimate motor current, speed, slip, torque, starting demand, loading, and drive behavior.

Use the correct definition of motor power

Separate electrical input power from mechanical shaft output. Efficiency connects them, while power factor affects AC current but not shaft power directly.

Record phase arrangement, line voltage, frequency, speed, duty, starting method, enclosure, and temperature. A nameplate value may describe a rating rather than the present load.

Electric Motors calculators by result

Motor Power CurrentCalculate motor current from input power and supply voltage.Horsepower KilowattConvert mechanical horsepower to kilowatts.Three-Phase Motor CurrentCalculate three-phase line current from real electrical input power.Motor Starting CurrentCalculate starting current from full-load current and starting multiple.Locked-Rotor kVACalculate locked-rotor kVA from line voltage and locked-rotor current.Motor EfficiencyCalculate motor efficiency from shaft output power and electrical input power.Motor TorqueCalculate shaft torque from shaft power and speed.Synchronous Motor SpeedCalculate synchronous speed from frequency and motor poles.Motor SlipCalculate motor slip from synchronous speed and measured speed.Motor Poles FrequencyFind the theoretical and nearest even motor pole count from frequency and synchronous speed.VFD Motor SpeedCalculate estimated motor speed from base speed and frequency ratio.VFD Energy SavingsCalculate estimated power after speed reduction from original fan power and speed fraction.Motor CapacitorEstimate motor capacitor size from capacitor current, supply voltage, and frequency.Motor Overload SettingCalculate overload current setting from nameplate current and setting factor.Motor Cable Power LossCalculate cable loss from motor current and cable resistance.Motor Service FactorCalculate permitted service-factor load from rated horsepower and service factor.Motor Starting kVACalculate starting demand from rated kVA and starting multiple.Motor Energy ConsumptionCalculate motor energy from average input power and operating time.Motor Power FactorCalculate motor power factor from real input power and apparent input power.Motor Acceleration TimeCalculate acceleration time from speed change and average acceleration.

Current, starting, and protection

Running current, starting current, locked-rotor kVA, and starting kVA describe different operating periods. Cable and protective-device checks must accommodate both steady duty and starting behavior.

Three-phase current uses real electrical input power, line voltage, and power factor. If only shaft power is known, first account for efficiency.

Speed, poles, torque, and drives

Synchronous speed comes from frequency and pole count; measured rotor speed is lower when an induction motor carries load. Valid pole counts are discrete and normally even.

VFD speed and fan-energy pages are estimates. Reduced-speed cooling, minimum speed, harmonics, torque demand, and the actual load curve may limit savings.

Capacitors and mechanical duty

Motor capacitor sizing needs capacitor current, voltage, and frequency to obtain capacitance. Manufacturer winding design remains the final authority.

Torque and acceleration calculations should be checked against inertia, load profile, service factor, bearing limits, and thermal duty.