Electrical / Mechanical Application Formulas

Power - AC Circuits, Power - DC Circuits, Mechanical, Fans & Blowers, Pump Motors

 OHMS LAW

Volts (E) = Amps (I) x Ohms (R)
Amps (I) = Volts (E) / Ohms (R)
Ohms (R) = Volts (E) / Amps (I)R=Ohms, E=Volts, I=Amperes

POWER - AC CIRCUITS

Abbreviations:

Eff. = Efficiency
 PF = Power Factor
 KW = Kilowatts
 HP = Horsepower
    
Efficiency =     746 x Output HP
Input Watts     

 3ÿ KW =     Volts x Amps x PF x 1.732
1000    

3ÿ Amps =     746 x HP
1.732 x Volts x Eff. x PF     
 
3ÿ Eff. =     746 x HP
1.732 x Volts x Amps x PF     
 
3ÿ PF =     Input Watts
Volts x Amps x 1.732     
 
1ÿ KW =     Volts x Amps x PF
1000     
 
1ÿ Amps =     746 x HP
Volts x Eff. x PF     
 
1ÿ Eff. =     746 x HP
Volts x Amps x PF     
 
1ÿ PF =     Input Watts
Volts x Amps     
 
HP (3ÿ) =     Volts x Amps x 1.732 x Eff. x PF
746     
 
HP (1ÿ) =     Volts x Amps x Eff. x PF
746     
 
1 KW = 1000 Watts
 

POWER - DC CIRCUITS
Watts =      Volts x Amps
    
Amps =     Watts
Volts     
HP =     Volts x Amps x Eff.
746    

MECHANICAL
Torque =     HP x 5250
RPM     

(Result is lb.ft. Multiply by 12 for lb.in.)

    
Torque =     HP x 63025
RPM     

(Result is in lb.in. Divide by 12 for lb.ft.)
   
HP =      Torque (lb.ft) x RPM
5250     
HP =     Torque (lb.in.) x RPM
63025     
1 HP =     3 lb. ft. @ 1750 RPM     
1 HP =     36 lb.in. @ 1750 RPM     
        
FAN AND BLOWER MOTORS

Abbreviations:

CFM = Cubic Feet per Minute
Pressure lb.in./ sq.ft.

 
HP =      CFM x Pressure
33000 x Eff.     
       

PUMP MOTORS
Abbreviations:
GPM - Gallons per Minute
S.G. - Specific Gravity
Eff. = Pump Efficiency
HP =     GPM x Head in Feet x S.G.
3960 x Eff.     
Head in Feet =     2.31 P.S.I.G.