If I know Hz input of a motor, how do I know RPM?
If I know Hz input of a motor, how do I know RPM?
(OP)
Hello. We just installed a variable speed drive to our 1150 RPM motor. The drive has a digital readout that reads Hz. We can vary this between 0 and 60. How do I know what my resulting RPMs are for the motor?
Kevin.
Kevin.





RE: If I know Hz input of a motor, how do I know RPM?
Assuming you are talking an induction motor,
Syncronous RPM = (120 * Frequency) / (# of Poles)
120 is a constant
example: RPM = 120 * 60 / 4 = 1800 RPM
RE: If I know Hz input of a motor, how do I know RPM?
RE: If I know Hz input of a motor, how do I know RPM?
So it appears that 1150 RMP is at rated frequency (50 or 60 Hz.
I assume the motor is rated for 60 hZ, then ,as an example, at 40 hz the speed should be approximately
(40/60)*1150 = 767 RPM. This of course assumes that the slip remains constant over the range of speed involved.
RE: If I know Hz input of a motor, how do I know RPM?
3600/1200=3pole
and the slip is (1200-1150)/1200=0.04
RE: If I know Hz input of a motor, how do I know RPM?
Do you mean 6 pole motor? As in three pole pairs.
RE: If I know Hz input of a motor, how do I know RPM?