Electric motor rpm/horsepower help?

[Njguy]

I am designing an electric motor on paper and figuring out the power consumption is easy and I can get a decent estimate of the torque produced. However in order to figure out the horsepower (output) on paper I need to figure out the RPM.

Does anyone know of a simulation tool that will figure out RPM based on torque with a simulated load? I can't figure out the math. If anyone does have a math example I would appreciate it. Thanks.

 

[crutschow]

One horsepower is 33,000 ft-lb/min. If the torque is given in ft-lb then it's a simple calculation to convert torque and rpm to HP, you don't need a simulator. The HP is (torque x 2[LATEX]\pi[/LATEX] x RPM) / 33,000.

 

[tcmtech]

(Torque in foot pounds times RPM's) divided by 5252 equals horsepower.

If you have a 1000 watt input power on a 75% efficient motor that would be putting out very close to one horsepower of mechanical effort. If you know your torque you can find your RPM's or if you know your RPM's you can find your torque.

Is this a DC motor or an AC motor?

If it's AC and you know the input frequency and number of poles you can calculate its RPM from that then work your torque back from there.

 

[Njguy]

If you know your torque you can find your RPM's or if you know your RPM's you can find your torque.

Is this a DC motor or an AC motor?

If it's AC and you know the input frequency and number of poles you can calculate its RPM from that then work your torque back from there.

It is a DC motor and the frequency does not dictate the RPM the RPM dictates the frequency, meaning the faster the rotor spins the higher the frequency. As for the torque the radius of the rotor is 1-1/2 inches, the torque is ~180 (1-1/2 inch pounds) which i believe equals 270 inch pounds of torque. I have no idea how to turn this into RPM as is is dependent on the load it seems.