Author Topic: PMDX-107 SPindle Speed Calibration question  (Read 2369 times)

ifeliciano

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PMDX-107 SPindle Speed Calibration question
« on: March 21, 2017, 04:21:44 PM »
How critical is it to perform this calibration? My spindle is running at almost max speed, 23560 rpm, with VR3 turned CCW all the way. This was based on a cheap non-contact laser tach.

Steve Stallings

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Re: PMDX-107 SPindle Speed Calibration question
« Reply #1 on: March 21, 2017, 05:06:35 PM »
Calibration is non-critical. Getting within 5% is excellent. Getting
within 10% is usually acceptable

Assuming your spindle is a typical 3 phase 400 Hz induction motor,
it will not run 24,000 RPM at 400 Hz because all induction motors
will run slightly slower than synchronous speed. This is called the
slip angle and is essential to how an induction motor works.

If speed accuracy is important to you, I would suggest that you
use your control program to request some lower speed such as
20,000 and calibrate at that speed because you can get the VFD
to generate a higher frequency as needed there whereas the VFD
probably has a hard limit of 400 Hz at the top of the range and
cannot run over-frequency to compensate for the slip angle.
Steve Stallings
www.PMDX.com