Uninterruptible Power Supply
Also known as: UPS, battery backup
A device with a built-in battery that provides a few minutes of backup power to your computer or critical electronics when the mains supply fails, giving you time to save work and shut down safely.
An Uninterruptible Power Supply (UPS) is a battery-backed power device that sits between your wall outlet and your equipment. When the mains power cuts out, the UPS switches to its internal battery instantly — typically in under 10 milliseconds — keeping your computer, router, NAS, or critical equipment running for several minutes. That window is enough to save open files, shut down gracefully, and avoid the data corruption and hardware stress of a sudden power loss.
For most home users, a basic UPS rated at 600VA to 1500VA provides 5-15 minutes of runtime depending on the load. A typical desktop computer plus monitor plus router will run for 10-15 minutes on a 1000VA UPS. If you work from home in an area with frequent outages — common in many parts of India — a UPS pays for itself the first time it saves an unsaved document.
A UPS also conditions the power feed, smoothing out voltage spikes and dips that can shorten the life of sensitive electronics. It is different from a surge protector (which only stops spikes) and different from an inverter (which provides longer backup at lower switching speed for household lighting and fans).