These Sorensen DCS55-55 units have been tested for full functionality.They are very nice units. They come with a 14 day 100 % money back guarantee. They have GPIB programming capability, OVP, stand by mode. This unit requires 190-250Vac input. It can be wired for single phase which limits power output to 2500 watts or it can be wired for 3 phase which allows 3000 watts.