Georgia IAEI Toolbox
Electrical Formulas
Motor Formulas
Tranformer Formulas
E = Voltage / I = Amps /W = Watts / PF = Power Factor / Eff = Efficiency / HP = Horsepower
AC/DC Formulas  
To Find  Direct Current  AC / 1phase 115v or 120v 
AC / 1phase 208,230, or 240v 
AC 3 phase All Voltages 
Amps when Horsepower is Known 
HP x 746 E x Eff 
HP x 746 E x Eff X PF 
HP x 746 E x Eff x PF 
HP x 746 1.73 x E x Eff x PF 
Amps when Kilowatts is known 
kW x 1000 E 
kW x 1000 E x PF 
kW x 1000 E x PF 
kW x 1000 1.73 x E x PF 
Amps when kVA is known 
kVA x 1000 E 
kVA x 1000 E 
kVA x 1000 1.73 x E 

Kilowatts  I x E 1000 
I x E x PF 1000 
I x E x PF 1000 
I x E x 1.73 PF 1000 
KilovoltAmps  I x E 1000 
I x E 1000 
I x E x 1.73 1000 

Horsepower (output) 
I x E x Eff 746 
I x E x Eff x PF 746 
I x E x Eff x PF 746 
I x E x Eff x 1.73 x PF 746 
Three Phase Values 
For 208 volts x 1.732, use 360 For 230 volts x 1.732, use 398 For 240 volts x 1.732, use 416 For 440 volts x 1.732, use 762 For 460 volts x 1.732, use 797 For 480 Volts x 1.732, use 831 
E = Voltage / I = Amps /W = Watts / PF = Power Factor / Eff = Efficiency / HP = Horsepower
AC Efficiency and Power Factor Formulas  
To Find  Single Phase  Three Phase 
Efficiency  746 x HP E x I x PF 
746 x HP E x I x PF x 1.732 
Power Factor  Input Watts V x A 
Input Watts E x I x 1.732 
Power  DC Circuits 
Watts = E xI 
Amps = W / E 
Ohm's Law / Power Formulas  
P = watts
I = amps R = ohms E = Volts 
Voltage Drop Formulas  
Single Phase (2 or 3 wire) 
VD =  2 x K x I x L CM 
K = ohms per mil foot (Copper = 12.9 at 75°) (Alum = 21.2 at 75°)
L = Length of conductor in feet 

CM=  2K x L x I VD 

Three Phase  VD=  1.73 x K x I x L CM 

CM=  1.73 x K x L x I VD 
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