Originally Posted by
qwertysimo
Thanks mactec.
I am not getting your power supply comment. This is unit with a single phase 230 V input and three phase output, max 400 Hz. Do you mean how stable is 230 V on input? No issue here.
It is a water cooled spindle. No cutter overloading, always calculating the chipload, no stalling ever. No play so the bearings are OK. Cutting in 12k to 18k RPM range most the time. No spindle overheating, water loop shows max 35 deg Celsius (following the ambient temp). VFD itself has a internal fan and the VFD unit is placed in good ventilated electrical box.
I cannot remember a situation that the actual RPM would vary from the set value within those 4 years! RPM was always spot on no matter of (reasonable) load.
Now it jumps like crazy, unpredictable. I can cut a straight slot in MDF and RPM will vary from 11k to 12k...
Can you explain please? Hook voltmeter to input phase and neutral terminals to see fluctuation of input voltage? No issue here, pretty stable 230 to 235 V.