Agreed.... if it is actually printing a 540 watt UPS will probably hold it for about a quarter of a second. I have a commercial grade Liebert GTX 6000 for our JV33 but that also has the RIP computer and the Summa cutter on it too and then we have a second one for our server rack to provide power to the 2 servers, SAN, and network equipment. If we are printing that massive Liebert will run the printer and RIP for about 30 minutes (shows 340 minutes when the printer is idle lol). You do not necessarily need that much but I like the idea that I greatly reduce the chances of a ruined job. At a minimum I can abort a job in progress in between panels and properly shut everything down. Another thing on a commercial grade UPS is that it will likely have true pure sine-wave output, power factor correction, in addition to full protection for surges, sags, spike, brownouts, etc. Also has full monitoring capabilities and communicates with the servers/rip that are attached to automatically and properly (cleanly) shut them down when the battery gets to 2 minutes remaining.
Asuma01 - The buck booster your electrician installed is because you have something that needs a solid 230 or 240 volts (I'm guessing you bought an HP Latex) and your incoming utility power is only giving you 208 to 220 or so volts. The buck booster does not provide any sort of protection it just boost voltage a small amount.