Electronics Expert Wanted for Advice

hello, I am looking for someone good in electronics for some advice about a project i am working on. Its about "automatic change over switches" (also called "automatic switch over") This is very simple, basically I have 2 power sources (240v each - which are always both online) and need an automatic change over switch to go from 1 source to the other when one fails. I found such switch but the problem is that when switching from 1 source to the other theirs a slight downtime (1 second) - this downtime is what i need to avoid.(because the applicants i'm powering the computers, and they restart with such slight downtime) i was UNABLE to find a switch without any downtime. (could you guide me if you know any such switch exist?) an idea: maybe a solution would be to include a capacitor before the load, so that during the slight downtime the load have electricity? note: so far, the only solution i know of is to get a ups before the load (ie: during the switchover downtime the load will be powered by a ups) - but i want to avoid this solution, its way overkill for my setup. this bid is for me to ask you questions about the above setup thanks for bidding! jo