Originally Posted by
A_Camera
I run some tests after I posted those comments yesterday. It was very late so I only run a few minutes tests with several RPM and never ever got the current above 0.6A. There is no way I believe that after a few seconds at low RPM you can burn any motor. Something else must have gone wrong in your case, but of course, if the VFD is wrongly configured then that may fry the spindle. My VFD is configured for 10Hz minimum frequency but it will not start rotating below around 200 RPM. Anyway, I run tests yesterday at 500, 1000 and 2000 RPM for several minutes and nothing happened. I am monitoring the VFD and the spindle, so I have the data for several critical parameters, which means that I know the health of both. The spindle was luke warm (30 degrees C), but remember that I drilled a lot of holes and milled aluminium for several hours before the test. I guess that if I would have started at room temperature it would have stayed there for hours.