Single and Three Phase Motor HP Formulas
Single Phase Motor Horsepower Calculation if HP is unknown such as a Compressor:
Existing Compressor Information:
Single Phase Voltage is 230 Volts.
Full Load Amps are 20.72.
% Efficiency is .86.
Power Factor is .91.
Service Factor is 1.15.
Single Phase Motor HP = (E x I x %Eff x PF)/746
Step 1: Single Phase Motor HP = (230 Volts x 16 Amps x .86 %Efficiency x .91 Power Factor)/(746 Watts)
Step 2: Single Phase Motor HP = 3005.18/(746 Watts)
Step 3: Single Phase Motor HP = 4.02 HP
Three Phase Motor Horsepower Calculation if HP is unknown such as a Compressor:
3 Phase Motor HP = (E x I x %Eff x PF x 1.73)/746
3 Phase Motors are 73% more powerful than a comparable motor in single phase. 1.73 is the square root of the number 3 which represents the three legs of increased power.