In article .com,
Never Enough Money wrote:
Andy, I'm trying to understand how 60 hertz and the number of poles
maps to RPM.
I'm not too bright when it comes to motors so please indulge me an
ignorant question.

I'm visualizing an amature and 4 windings in the stator. Now 60 hz
going in seems to mean that the strongest e-field (or B-filed) woudl
change at 4 tiems that rate. This would give 240 RMP. So I must be
missing something...what? Please avoid the tempatation to say "A
brain."


1) you multiplied where you should have divided

2) you forgot to account for the number of seconds in a minute


60 hz == 3600 cycles/minute

4 pole motor == 3600/4 == 900 rpm.