They aren't fast enough. I had to buy a UPS for just that, we had a custom PLC that had to shut down a lab. Not all UPS's are tolerent of generator input, so they will cost more. You have a blackout for about probably a minute or so before the mains switch. Surge suppressors with a connected equipment warranty are the way to go in general. Isobar surge protectors are one such brand. ONEAC has a nice power conditioner that has never failed me use with the ISOBAR's. Servers and key access systems would be a good use for both.