Quote Originally Posted by Kitwn View Post
The spindle is connected using screened 3-core cable with the screen connected to the mains earth inside the VFD and to the body of the spindle and hence to the frame of the machine.
If you have earthed your frame then surely you have created an earth loop by connecting the VFD cable shield at the spindle end.? I don't earth the spindle end and never have noise problems.