Quote Originally Posted by wmgeorge View Post
I run my air cooled spindle at 12,000 rpm all day nothing happens, the min speed is set at 9,000 rpm. Grounding since its a 3 phase has zero to do with it as the ground is for protection or equipment ground when something goes wrong. Shielding or lack of, why would that make the motor burn out?? VFD Parameters set wrong, very well could be, mactec54 can handle that and I would sure check before I installed another spindle. I will agree, the wiring is nothing I would be proud of.
Not all these spindles are created equal some have a minimum RPM of 18,000 his could well of been one of them we don't have the spindle spec's

A Ground is very important for these spindles as they can be damaged by the EMI when they don't use a shielded cable, if they have a Ground wire the EMI and Rotor Voltage will use the Ground wire and save the spindle