Now I've sent this to the list, I'm questioning whether or not a 3 pole motor is really an option... I'm pretty certain they have to have an even number of poles.... I wish I was home and I'd just grab the appropriate reference guide off of the shelf.
On Thu, Mar 21, 2019 at 8:15 PM Forrest Christian (List Account) <[email protected]> wrote: > > What is the nameplate RPM and Hertz on this motor? > > Assuming a 4 pole motor, you'll have (frequency*120)/poles = RPM > > So if you have a 4 pole motor running at 10Hz, you'll find that it runs at > 10*120/4 = 300 RPM After the 15:1 gearbox, you'd have 20 RPM at 10 Hz. > > It's linear so 2 RPM per HZ. So at 5 Hz you should get 10RPM. So you've > got something off. > > Let's assume that you are just wrong with the poles. 26 RPM * 15 = 390RPM. > Then, (10*120)/poles = 390. 1200/poles=390. Looks like it might > be a 3 pole motor. > > Back the other way: > > 3 Pole Motor @ 10 hz = 10*120/3 = 400 rpm / 15:1 = 26.666 RPM. That's in > the right range. > > Would 26.666RPM be in the range of your measurement/VFD accuracy? > > -- - Forrest -- AF mailing list [email protected] http://af.afmug.com/mailman/listinfo/af_af.afmug.com
