According to Ofgem's 2005 annual report, every year eight out of ten users suffer interruptions to their power supplies, though the winter storms of 2002/3 pushed that figure up to nine out of ten. Even a brief outage lasting only milliseconds, which barely makes house lights flicker, can be enough to bring down a computer and lose whatever work is in progress.

A computer is also at risk from spikes and surges in the mains supply, caused by adverse weather or other users, and from dirty electricity contaminated by electromagnetic and radio interference, all of which can damage a PC.

If you live in a well-populated urban area where power is carried through underground cables, and if your PC is used for entertainment rather than business, you may not think it worth protecting against power outages: a simple anti-surge socket-block and line cleaner for around £20 may be all that's required. But if your PC runs your business, and especially if you live in a rural area more prone to mains supply interruptions, an uninterrupted power supply (UPS) becomes essential.

Belkin's F6H650ukUNV model is aimed at home users and small businesses seeking to protect a single PC and its peripherals. It houses six standard UK power sockets arranged in two banks of three. One bank is surge protected only, and the other bank is both surge and power protected, so in the event of an interruption to the mains supply, any device connected to the UPS bank will continue to operate for up to 15 minutes.

Very few UPS devices use standard 13A sockets, the majority of industrial and commercial models relying on the neater IEC 320 kettle-type power connections, but there's a distinct advantage to standard sockets, which is that they will accept the bulky AC adapters supplied with routers, modems and laptops.

This Belkin UPS is rated at 650VA/390W. An average PC system unit operates at between 80W and 150W, depending how it is being used, while a 19in TFT monitor requires 20W-40W, so there's ample leeway to protect a router or modem and still stay within the 390W capacity. Printers, scanners and any other devices which do not need to be protected by UPS can be attached to the three surge-protected sockets.

Belkin claims that the UPS provides 10-15 minutes of protection for the average PC. We tested it several times using a fairly ordinary system with twin hard disks, a 19-inch monitor and an ADSL router (total 180W). After pulling the mains plug the system ran for an average of ten minutes before emitting its low-power warning beeps, and for a further three minutes before shutting down. This is ample time to save current work, copy it to a laptop or USB stick and gracefully close down the PC. To fully recharge the sealed lead-acid battery inside the UPS takes 12 hours.

Software is provided for the host PC. It displays statistics regarding the state of the power supply and the current load on the UPS (useful if you don't have an external power meter), but more importantly it can save your work and close down the PC in the event of a power failure when you're not around.

It will even email or page you to let you know what it has done, and it can run a batch file of your own devising if you have any special procedures to run in the event of a power outage. For the software to work, the UPS must be connected to the PC using the serial or USB cables (supplied), but it works equally well without the software if unattended close-downs are not required.

Unfortunately the UPS is a butt-ugly, squat, grey monster that's slightly bigger than a shoebox (363 x 141 x 107mm) and weighs in at over 6kg. Fortunately you'll never have to carry it far and it will spend its life hidden under a desk.

Verdict
The Belkin F6H650ukUNV is remarkable value for money (if you buy online you can get one for a little over £50) and it comes with everything you need. It takes standard plugs, operates for long enough to see you through short interruptions or let you close down in the case of longer ones, and is completely silent.

Company: Belkin

Contact: 01933 352000

Tags: power supply power outage ac adapter personal computer power supplies business electronics and electrical electronics