An Uninterruptible Power Supply (UPS) is a battery backup unit that plugs in between your computer & the wall socket. If the power to your computer is suddenly cut, or drops significantly even for a moment, a UPS will cut in instantly & automatically supply power from its built-in battery. You then have time to safely save your documents & shut down properly. The time available to keep running on battery depends on the size of the UPS & the current drawn by the equipment. Usually it is rated for 5 to 15 minutes for a controlled shutdown, but can run much longer, if you’re prepared to pay for a higher rated unit.
UPS systems also provide protection against electricity spikes & surges that can damage circuitry. Usually, surge protection is provided on all sockets which have battery backup protection. A UPS may also have one or more sockets that provide surge protection only. This is useful for attaching devices that don’t specifically need a battery backup, such as printers, scanners & other computer accessories.
You don’t have to experience a blackout to get the benefit of having a UPS. If you’ve ever noticed all the lights suddenly dimming momentarily, you’ve probably experienced a ‘brownout’. That may be all that’s needed to make your computer suddenly turn off without warning — & without saving. These power fluctuations seem to be more common lately, & they can play havoc with delicate equipment. Personally I use a UPS on both our computer & entertainment equipment, & am glad to pay for the extra “peace of mind”!