How do I Convert FPM to RPM

Pembily

Hi I have two different values for feet per minute

9076 ft/min and 503ft/min

I have no diameters or anyting just those numbers - it was a reading from a feedback unit for a Star Delta connection running a motor and I need them in rev/min and have no idea how to convert!!!

Help please

Thanks

Michael Collins

Can't be done from the information you've given, simple as.

What is the feet per second a measure of, exactly? Is it the speed of a point at the edge of some rotating disc? If so you will need the circumference of the disc (or the diameter / radius).

2011

Can't be done from the information you've given, simple as.

Exactly.


This may help:

The circumference = pi x the diameter of the disc
Revelutions per min = distance min / circumference

Esto Fidelis

Hi,

I work in this area, you do not have enough info to help with working this out, but I will post some points and if you like to come back i will try and help.

Are you trying to work out the rpm of a geared motor on say a conveyor or something like this. Please supply motor, speed, gear ratio, shaft size, dia of conveyor head drum. You say star delta, this is a method of starting the method so I assume the motor is running at a fixed speed ie not variable speed with an inverter.

Or are you trying to get a digital readout from the application similar to HMI screen. You say you have 2 different readings, what format are you getting the readings . Is it as feedback from an encoder or tacho generator through a PLC on a HMI or something like this.

Post anything else you may have and i will take a look at it and see if i can help.

bnt

I agree - you need a radius to convert between linear and angular velocities. If this is an academic assignment of any sort, you could still get the marks if you pick a sensible value for the diameter, as long as you say so clearly in your answer.