Formulas for quick calculation of horsepower and power

QUICK ESTIMATE FORMULAS • Horsepower Formulas • Torque Formulas • AC Motor Formulas • Electrical Formulas • Acceleration Formulas
HORSEPOWER FORMULAS
For Rotating Objects	HP =

	Where	T = Torque (lbft) N = Speed (rpm)

Objects in Linear Motion	HP =

	Where	F = Force (lbs) V = Velocity (ft/min)

For Pumps	HP =


	HP =
	Where	GPM = Gallons per Minute Head = Height of Water (ft) Efficiency of Pump = %/100 PSI = Pounds per Inch Specific Gravity of Water = 1.0 1 CuFt per Sec. = 448 GPM 1 PSI = A Head of 2.309 ft (water weight) 62.36 lbs per CuFt at 62°F

For Fans and Blowers	HP =

	HP =

	HP =
	Where	CFM = Cubic Feet per Minute PSF = Pounds per Square Foot PIW = Inches of Water Gauge PSI = Pounds per Square Inch Efficiency of Fan = %/100

For Conveyors	HP (verticle)

	HP (horizontal)
	Where	F = Force (lbs) V = Velocity (ft/min) Coef. of Friction • Ball or Roller Slide = 0.02 • Dovetail Slide = 0.20 • Hydrostatic Ways = 0.01 • Rectangle Ways with Gib = 0.01 to 0.25

TORQUE FORMULAS
	T =	HP x 5252
		N
	Where	T = Torque (LbFt) HP = Horsepower N = Speed (rpm)

	T =	F x R
	Where	T = Torque (LbFt) F = Force (Lbs) R = Radius (Ft)

	Ta (accelerating)	WK2 x Change in RPM
		308 x t (Sec)
	Where	Ta = Torque (LbFt) WK2 = Inertia at Motor Shaft (LbFt)2 t = Time to Accelerate (Sec) Note: To change LbFt2 to InLbSec2, Divide by 2.68 To change InLbSec2 to LbFt2, Mult. by 2.68

AC MOTOR FORMULAS
	Sync Speed =	Freq x 120
		Number of Poles
	Where	Sync Speed = Synchronous Speed (Rpm) Freq = Frequency (Hz)

	% Slip =	(Sync Speed - FL Speed) x 100
		Sync Speed
	Where	FL Speed = Full Load Speed (Rpm) Sync Speed = Synchronous Speed (Rpm)

	Reflected WK2 =	WK2 of Load
		(Reduction Ratio)2

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