I = Amperes

E = Volts

kW = Kilowatts

kVA = Kilo volt-Amperes

HP = Horsepower

% eff. = Percent Efficiency

pf = Power Factor

Single-Phase

TO FIND :-

Amperes when kVA is known �> I = kVA x 1000 / EAmperes when horsepower is known �> ( HP x 746) / ( E x % eff. x pf )Amperes when kilowatts are known �> ( kW x 1000 ) / ( E x pf )Kilowatts �> ( I x E x pf ) /1000Kilovolt-Amperes �> ( I x E ) / 1000Horsepower �> ( I x E x % eff. x pf ) / 746Watts �> E x I x pfEnergy Efficiency �> Load Horsepower x 746 / Load Input kVA x 1000Power Factor @ cos ? �> Power Consumed /Apparent Power ( W / VA ) @ ( kW / kVA )Two-Phase

TO FIND :-

Amperes when kVA is known �> I = ( kVA x 1000 ) / ( E x 2 )Amperes when horsepower is known �> ( HP x 746) / ( E x 2 x % eff. x pf )Amperes when kilowatts are known �> ( kW x 1000 ) / ( E x 2 x pf )Kilowatts �> ( I x E x 2 x pf ) /1000Kilovolt-Amperes �> ( I x E x 2 ) / 1000Horsepower �> ( I x E x 2 x % eff. x pf ) / 746Watts �> E x I x 2 x pfEnergy Efficiency �> Load Horsepower x 746 / Load Input kVA x 1000Power Factor @ cos ? �> Power Consumed /Apparent Power ( W / VA ) @ ( kW / kVA )Three-Phase

TO FIND :-

Amperes when kVA is known �> I = ( kVA x 1000 ) / ( E x 1.73 )Amperes when horsepower is known �> ( HP x 746) / ( E x 1.73 x % eff. x pf )Amperes when kilowatts are known �> ( kW x 1000 ) / ( E x 1.73 x pf )Kilowatts �> ( I x E x 1.73 x pf ) /1000Kilovolt-Amperes �> ( I x E x 1.73 ) / 1000Horsepower �> ( I x E x 1.73 x % eff. x pf ) / 746Watts �> E x I x 1.73 x pfEnergy Efficiency �> Load Horsepower x 746 / Load Input kVA x 1000Power Factor @ cos ? �> Power Consumed /Apparent Power ( W / VA ) @ ( kW / kVA )

Others Formula

kW = hp x .746

Torque in lb-ft = hp x 5250 / rpmMotor synchronous speed in rpm = 120 x Hz / number of polesThree-phase full-load amp= hp x .746 / 1.73 x kV x effi ciency x power factorRated motor kVA = hp (.746) / efficiency x power factorkW loss = hp (.746) (1.0 � effi ciency) / efficiencykVA in-rush = percent in-rush x rated kVAApproximate voltage drop (%) = motor kVA in-rush x transformer impedance / transformer kVAStored kinetic energy in kW-sec = 2.31 x (total Wk2) x rpm2 x 107Inertia constant (H) in seconds = stored kinetic energy in kW-seconds / hp (.746)Conversion factors: CV = (metric hp) = 735.5 watts = 75 kg-m/sec Wk2 (lb-ft) = 5.93 x GD2 (kg-m2)Ventilating-air requirements: 100-125 cfm of 400C air at 1/2-in. water pressure for each kW of lossDegrees C = (Degrees F-32) x 5/9Degrees F = [(Degrees C) x 9/5 ] + 32