Rotating Horsepower

Rotation horsepower, abbreviated as \(HP_r\), is converting the objects horsepower into rotational motion.  It is a unit of power that is used to describe the power output of rotating machinery, such as engines, turbines, and motors.  It is a measure of the amount of power required to rotate a shaft or other rotating component at a given speed.  The unit of rotating horsepower is often used in the context of the design and operation of rotating machinery, as well as in the evaluation of its efficiency and performance.  One rotating horsepower is equivalent to 745.7 watts.

 

Rotating Horsepower formula
\(\large{ HP_r = \frac{ \tau \; s }{ 5252 } }\)
Symbol	English	Metric
\(\large{ HP_r }\) = rotating horsepower	\(\large{\frac{lbf-ft}{sec}}\)	\(\large{\frac{Btu}{s}}\)
\(\large{ \tau }\)  (Greek symbol tau) = torque	\(\large{lbf-ft}\)	\( N-m \)
\(\large{s}\) = rotation shaft speed, RPM	\(\large{\frac{ft}{sec}}\)	\(\large{\frac{m}{s}}\)

• \(\large{ 1 \; HP  =  5252\; RPM }\)   When charting torque and horsepower, the math always cross at 5252 RPM.

 

Rotating Horsepower formula
\(\large{ RHP =  \tau \; \frac{ s }{ 33,000 } \; 2 \; \pi }\)
Symbol	English	Metric
\(\large{ HP_r }\) = rotating horsepower	\(\large{\frac{lbf-ft}{sec}}\)	\(\large{\frac{Btu}{s}}\)
\(\large{ \tau }\)  (Greek symbol tau) = torque	\(\large{lbf-ft}\)	\( N-m \)
\(\large{s}\) = rotational shaft speed, RPM	\(\large{\frac{ft}{sec}}\)	\(\large{\frac{m}{s}}\)
\(\large{ \pi }\) = Pi	\(\large{3.141 592 653 ...}\)

• \(\large{ 1 \; HP  =  33,000 \; \frac{lbm-ft}{min}  }\)