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Use this formula to estimate motor horsepower

Use this formula to estimate motor horsepower

Horsepower (hp) = Voltage x Amperage x % EFF x power factor x 1.73/746

Where:
Voltage is the average of the three voltages measured: (A-B + A-C + B-C)/3
Amperage is the average current of the three phase measured: (A+B+C)/3
% EFF is motor efficiency per motor nameplate
Power factor is the ratio of true power (kW) to apparent power (kVA). In the absence of power factor measurement tools, a rule of thumb is to estimate power factor at 0.85
1.73 is a constant used when calculating three-phase power
746 is the constant for converting watts to horsepower (746 watts = 1 Hp)

Example: How much horsepower is a 25 hp motor producing at 472 volts and drawing an average of 20 amps per phase with a motor nameplate marking of 90 % efficiency?

 

Horsepower (hp) = Voltage x Amperage x % EFF x power factor x 1.73/746

 

                         = 472V x 20A x 0.90 x 0.85 x 1.73/746 = 17 Hp