Lathe/VFD/DRO issue

While I woulld not reccomend any Vevor mains powered equipment (the fact thay can't get it past UK import inspections supports this), it is not just the lower end of the market that can have EMI / EMC issues.
Some years ago a major international drive producer, based in the USA, replaced an established line of motor drives with a new and impoved model. As usual for a component they were not CE marked but they had done tests to assure customers that their finished products could be compliant.
Unfortunatly we, and a number of other customers, found our products failed emissions with the new drives fitted. The drives can be used in multiple configurations and the OEM had not tested all configurations. I managed to sort our machines out with custom filters on control lines. These lines carried high speed signals so "brute-force" filtering would not work. The OEM were still having troublesolving the issue. They paid for us to do testing with my filters at a UK test house and having seen that they worked, paid for me to go to their development lab in the USA and work on an internal fix. I think they chose us because we were working the drives at the edge of the performance envelope and also were testing to the laboratory emissions standard rater than industrial that covered most of their customers. Together we engineered a internal fix for production drives. I had to visit them because for IP protection they would let me see their design data but not have a copy. I believe we got a substantial discount on all the drives of that range that we bought in the future.

This shows why VFDs are not (or should not) be UKCA or CE marked. The OEM cannot possibly test all configurations a VFD can be used in never mind different cable and enclosure designs.
Legally, even as hobbyists if we build our own system with a VFD we are obliged to ensure it meets the essential requirements ofr various legisaltion including machine safety, electrical safety and EMC. Of course in practice theis is seldom done. Many small businesses don't do it either.
Machine and electrical safety tend to ony affect you and others in your workshop so are less of an issue. You are allowed to judge your own risk.
EMI/EMC however ann affect others, often when everthing is working fine. As hobbyists our best defence is to use quality, branded equipment that comes with comprehensive documentation that includes guidance on EMC and follow the guidance. Most usres of VFDs are not EMC experts so reputable suppliers give good advice to help their customers.

Robert.

Well, hopefully, a final update.

The vfd is now in a cabinet along with the filkter kindly donated by Robert also fitted the donut, the cable is grounded to the cabinet and the 3 earths taken to one of the fixing bolts on the mounting plate and the filter is grounded as well. I have grounded the cable screen to the motor as well as it is a pain to access for the wiring so decided to do it all once and once only.

The good news is that the dro display is now rock steady with the lathe running so many thanks for all the advice and support I've received, especially from Robert who went above and beyond.

Regards

Roger

Hi Rodger,

Great news. I'm glad you got it sorted.

Robert.