Electrical / Mechanical Application Formulas

HomeElectrical / 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.