It has 4 poles printed on the nameplate.

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> On Mar 21, 2019, at 6:15 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?
> 
> 
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