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I've got a quite expensive LCD monitor (~$1000) and I wish to protect it from instabilities in the power line. So I intend to get a UPS for it.

I see two types of UPS devices which differ on the output waveform - it's either a stepped approximation to a sinewave or a pure sinewave (rather expensive SmartUPS series). I've heard stories that some devices are intolerable to a non-pure sinewave and their power units just burn out for some reason.

Can anybody tell me whether it's a good idea to attach an expensive designer monitor to such a UPS with non-sine output or better grab a more expensive one which generates a pure sinewave?

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You don't need a full UPS unless you want to watch during a power break. There are a number of Filters that do the same job without the UPS function.

Pure sine wave or not, that is really up to the equipment you attach. Some equipment are really picky and some less.

(some one with expert knowledge in electronic might correct me here)
A switched power supply I can imagine is less picky because it regulates the power over a fat capacitor and is less sensitive to variations on power. The, now outdated, transformers are more sensitive because they are pendent of a more stable power.

Whatever your choice is, make sure it can supply your equipment correctly.
I use a 3000VA for my server rack and it works fine, but a 1000VA was not enough for a smaller laser printer. Check your equipment and let a dealer help you to decide the power size.

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Most UPS makers say to not attach a laser printer. I believe they have huge start-up power demands - presumably due to the need to heat up the fusing roller to it's operating temperature as fast as possible. An LCD monitor will have very low and consistent power needs. Visitor may just need a surge suppressor. – RedGrittyBrick Jan 20 '11 at 14:45
@RedGrittyBrick, Well, the laser printer was just an example of why it's important to check the power consumption. I didn't say that you should attach laser printers to an UPS. Even if you acquire a "Surge suppressor / filter" you need to check the power consumption. That and the UPS being overkill, was my point. – Max Kielland Jan 20 '11 at 15:09

I imagine you've already solved this but just for future reference, several manufacturers including Monster and APC make comparatively cost effective solutions that are what Max was referring to.

The ones I typically use for LCD tv's, which can be quite sensitive to bad power run about $159CAD and will support up to 30A of 110V or 15A or 220V so they would be sufficient for your entire computer system including the monitor. They won't give you the backup time but utilize the same technology and a large capacitor or small battery depending on the model. The power is conditioned down to 12/24V then regulated and inverted to 110/220V within 2V and full sine wave. These also condition out any ground noise which can actually be just as much of a problem.

I use these for entertainment systems and monitors/projectors. If you want to have backup power for your computer as well it may still make sense to get a larger UPS. Either way it's always better from a wear and tear perspective to shell out a few extra bucks for the full sine wave equipment if your protecting expensive gear.


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