How Much Back Up Time Do You Need When Power Goes Out?
The backup time is proportional to the load that is connected to the UPS. The more the load, the less the backup time. You can have backup time as little as 5 minutes which will enable you to shutdown the equipment connected to the UPS before the power fails; or many hours of backup time so you can keep your equipment running until mains power returns. Longer backup time and higher protection levels cost more than short backup times and lower protection levels.
A UPS system is often used to provide uninterrupted power after mains fail until a generator starts up.