UPS and power supplies

I've a question re UPS and power:

I've been reading lately about the need for a "clean" power supply. Ideally, I've been thinking about getting a UPS to ensure that the power would never fail in my observatory should I be using my scope/computer/ccd camera.

I've seen a few UPS' in Maplins and was wondering:
When the power enters the UPS, is the output a "clean" regulated power or does the UPS only kick in when the power fails i.e. will the UPS correct for sudden peaks, dips etc in the input power?

Thanks,

I presume you are talking about Computer UPSes here in which case the answer is that they constantly clean the power.

I got one for the scope, they do generate a small bit of heat, but if there is ever a power cut and the sky goes dark, I'll still be able to power the scope and camera

Thanks lads.

They seem to some in various ratings...how do I judge what I need for my observatory?
An example of one is here:
www.maplin.co.uk/Module.aspx?ModuleNo=44...eria=UPS&doy=5m6
They seem to come in VA. What would a 400VA provide power for?

Thanks,

Michael,

Divide the VA rating by the voltage you intend to use to get the maximum output in Amps.

John Murphy is the guy to give you the best advice.

However I strongly suspect you'll need something a bit better than this one. Because of heat loss in the unit and in the transformers you need to overspec the UPS a bit.

What exactly are you looking for Michael, do you want to be able to run the scope for a few hours or for the entire night ?

The average UPS has anything between a 7AmpHour to 18AH battery in it, and are usually 12 V.
If the lx90 takes say 1 amp (a guess, I dont know what it is) at 12v, then theoretically with a 7AH battery, it'll last 3.5 hours. Given losses in 12vdc-240vac, and having a non ideal battery and been conservative, you can easily half that, so you might get an hour or 2 from the UPS.

So now you can see very roughly how to figure how long your system will stay powered.