Uninterruptable Power Supply

April 12th, 2006 by Peter

An uninterruptable Power Supply, often known as a UPS, maintains the power supply to equipment that is sensitive to not being shut down properly. The uninterruptable power supply is situated between the main power supply and the main power input for the equipment. An uninterruptable power supply counters the effects of temporary power outages and other unexpected things from the power supply. Uninterruptable power supply units are used where unexpected shutdown of equipment can possibly be fatal, like in hospitals or airports.

A consumer grade uninterruptable power supply, usually for computers, typically provides a few features. An uninterruptable power supply will allow the computer or computers to keep running for a while after the mains power fails. If you are using a computer at home, sometimes 5 minutes or so give you enough time to save anything you are doing and shut down the computer in the usual manner.

An uninterruptable power supply will also provide some protection from momentary or temporary power drops or brownouts. Without an uninterruptable power supply, small drops in voltage might lead to the computer turning off, resulting in loss of data, then it just turns on again when voltages even out. The uninterruptable power supply will keep the power at steady levels, letting the battery kick in for a moment and protect you from the loss of data that would usually occur.

Uninterruptable power supplies also provide protection against power spikes. Usually occurring when there is a lightning strike, a power spike can destroy computer equipment with momentary high voltages. This not only results in the loss of data at the time of the strike, but also possible damage to your hardware, necessitating expensive repairs.

When shopping for an uninterruptable power supply there are some things on offer with most commercial units. Firstly, they will have a certain rating in VA. How long the UPS will provide power will depend on this and how much power your system draws. Typically a UPS from 500VA to 1000VA will provide enough power to run the computer for 10 minutes or more after power fails, giving enough time to save and shut down. If you want to keep running the computer for longer you will have to get a more powerful and expensive uninterruptable power supply with more VA, but this will cost much more, and basically the cost has a lot to do with the batteries that keep things going through the power outage.

Surge protection comes as part and parcel of a UPS, usually all of the power outlets will run through the surge protection. Check to make sure. Some equipment like printers don’t need a backup power supply and the uninterruptable power supply will have some sockets that bypass the battery backup but still provide surge protection.


Other things to look for are indicators that tell you when the battery has kicked in or when the uninterruptable power supply has been damaged. Sometimes after a heavy power surge the equipment can no longer protect your computer from power disruptions but will still let power pass through to keep your computer going. It sacrifices itself to protect your computer.

A UPS should usually have some kind of interface with the computer, which allows it to be programmed and allows its behavior to be monitored. You may also be able to set up what actions should take place in the event of a power outage, like shutting itself down or such things.

An uninterruptable power supply is becoming a more and more necessary accessory. For very simple computers that don’t do too much you might be able to get away without an uninterruptable power supply, but if you use it for business or for keeping critical information an uninterruptable power supply might allow your computer to pass through the next storm without any problems. The peace of mind when you have one, is priceless.

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