Ignoramus12852 wrote:
I am thinking about something. 480 VAC drives can be bought for next
to nothing. What they have is an inverter circuit and control
circuit.

They probably would not run on 240v because the internal transformer
that would supply voltage to the control circuit would supply only 1/2
voltage.
Most modern VFDs use a little inverter off the main DC supply,
not a separate 60 Hz transformer.
They also might have an indervoltage sensor. I cannot think
of more things that depend on 480 volts being there.

Yes, they most certainly do, and will shut down below some
particular voltage.
So, if a hack could be done and a 1:2 transformer inserted between
480v inputs and the control circuit, then the drive would become a
240v drive with the same amp rating (and half HP).
Well, the little inverter could be rewound, or replaced with a
60 Hz transformer, once you figure out the several DC voltages
it supplies to the works. Then, you could track down the
resistor voltage divider for the voltage sensing and change
that. You would have to convert various things when programming
the drive, because it still thinks it is producing 480 output.
All the current logic should work fine without any changes or
conversions, and Hz is still Hz. If you could find a 5 Hp 480 V
VFD, that would make a dandy 1 Hp 240 V VFD, if the above
conversions weren't too hard to accomplish. If you found a
pallet of 480 V VFDs of the same make and model, this could be a
very profitable exercise. I'm not sure it would be such a great
deal to have to trace all this out on a one-by-one basis.

Jon