OldNuc wrote:There is no safe way to do this without having a good diagram of this motor with all the necessary values. Failure to have this info will probably result in motor winding insulation failure sooner or later. Go buy a grinder with a 3 phase motor and it becomes child's play to convert to variable speed. Single phase motors come in several configurations and few of those designs if any are easily modified for VFD.

Thanks Rich. Appreciate your input and am learning a lot from your posts.

3 phase motor grinder isn't easily available and is also more expensive. Not practical if the goal is just to have a play at variable rpm

Dyrlaegen wrote:It looks like mine ABI FR204F is 1-phase in and 3-phase out. Could this work as well or do we have to get an single phase - single phase?

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Manual: http://www.abi.nl/assets/uploads/Downlo ... 20V2.2.pdf

The single-phase motor doesn't work a "three-phase output" inverter. You will need a "single-phase input - single-phase output inverter.

samuellaw178 wrote:Thanks Rich. Appreciate your input and am learning a lot from your posts.

3 phase motor grinder isn't easily available and is also more expensive. Not practical if the goal is just to have a play at variable rpm

Most commercial grinders are available as 3 phase from the factory. Usually they are much lower cost as a used item as 3 phase power is not common in most locations where low power demand is common and that includes homes, and coffee shops. They are so unpopular that finding one used is the first trick.

Back to one of my earlier posts on this subject: you must have the actual motor wiring schematic and winding data for the motor in question before you can come up with a properly functioning variable frequency drive.

Now a person can just go ahead and guess then hook up whatever seems like it will work. The result will most likely be the release of the magic smoke sooner or later and that may end up being a minor effect as electrocution is not out of the question either.

Reducing the RPM of the 3 phase motor with a VFD requires also reducing the applied voltage as RPM is decreased so as to not overheat the windings and cause an insulation failure. Reducing the voltage reduces the developed torque and horsepower.