208 3 phase to 220 single phase

Just run phase to phase, no conversion needed.

Depends on what you are powering. Most motors will accept an input voltage of up to 10% below the nameplate rating. So if you have a NEMA designed motor that says 220V, it will be fine with as low as 198V. It will draw more current, but it is made to do that.

If the motor is an IEC design and is rated for 240V, the lowest voltage it is likely to accept is 216V, which is not low enough for a 208V system.

If the load is a resistive heater, the heater will put out less heat. If you are heating up a batch of something, it will just take longer to get it to temperature. If you are l;ooking for a specific heat output for something like a sputtering chamber however, you may never get there.

If your load is a switch mode power supply, most likely it has a wide input voltage tolerance and you are fine. But if it is a linear power supply, the output voltage will be proportionately lower.

guest: or you could use a 12 volt boost transformer to raise it to 220. perry

If you must have the 220v single phase and your device cannot tolerate the voltage difference, an autotransformer will do the trick.

Here is a random selection from searching that illustrates the wide range in off-the-shelf products available.

I really think that most modern machinery will not have a problem since they are designed for a much wider range of voltages for the very reason you are asking us this question. Read the label or look up your device on the internet if not readable.

Let us know what you come up with.

Regards, CJM