Gary Wooding wrote:
A friend has acquired an elderly lathe with a dual-wound 3ph motor. It
has 6 wires going in to it, and is intended for 415v 3ph UK supply, but
he only has a normal single phase 240v domestic supply. He has been told
that he cannot use a single to 3ph VFD with dual-wound 3ph motors. Is
this true? If so, why?

What does "dual wound" mean? Is this a dual voltage motor, or a
two-speed motor? Either CAN be used with a VFD, but you have to match
the VFD to the motor voltage. In the UK, I think 415 is the ONLY
3-phase power available, they don't use 208, 230 and 460 V like we
do in the US. If your friend gets a 460 V VFD and programs it for
415 V at 50 Hz, the motor should be fine. Then, of course, you need
to supply the VFD with at least 440 V AC. A suitable step-down
transformer can be wired backwards to step up 240 to 480. That might
be too high for the VFD or the motor. But, it probably will work fine.

Jon