Liebert psa is a line interactive ups that provides up to five minutes of back up time at full load more than enough time to save work in progress and shut down the connected equipment usb shutdown software and a usb cable are also included the ups offers three or six battery backed outlets and one or two surge only outlets the ups is available in 500va 650va 1000va and 1500va sizes 120v and 230v models flexibility available in four sizes including 500 650 1000 and 1500va 120v