I am working with a 7 1/2 HP Air Compressor motor.
It is 240V 28A 1Ph.
The system voltage is 208.
Someone installed a 3kVA Buck-Boost, but the website for Jefferson Electric (transformer manufacturer)lists a 1kVA unit (minimum) for a 7 1/2 HP motor.
I don't see a problem with an oversized unit, but am not sure.
Anyone have any insight?

Thanks.

I see no significant safety or functionality issues with a larger buck-boost. It might even provide better motor starting.

The larger core will mean more core losses over the life of the unit, even when the air compressor is off.

-Jon