Re: UPS Advice

["Andy Whitfield" <andywhitfield2002@xxxxxxxxxxx>]

Gareth,

I deal solely in UPSs for a living.  Thought you might appreciate=20
some general info about UPSs.

Cheap ones tend to be cheap for a reason.
They use smaller or less batteries.  The 1200va you linked to uses 2x=20
12v 7Ah which is the same batteries used by APC Smart 700va.  So=20
shorter back up times.
Some cheaper ones output a square wave (as opposed to a sine wave)=20
when running on batteries.  This causes interference for audio/video=20
applications.  It doesn't say on the Ebuyer one whether it's square=20
wave or sine wave output when on batteries.
Most UPSs (when mains IS present) do NOT keep the output voltage at a=20
set value.  They will pass through the mains voltage between approx=20
210v to 255v. so if you mains voltage is bouncing around then that's=20
what you will get out of the UPS.
If your mains is hovering around the 210v OR 255v then the UPS output=20
voltage will jump about a great deal as it switches between batteries=20
and mains (or bucks & boosts see below).
More info below on the different technologies.

There are 3 main types of UPS.
1) Standby Type.  These are generally old or cheap ones.  They have a=20
bit of filtering and switch to batteries if the mains voltage goes=20
below approx 210v or above approx 255v.  They usually have less=20
batteries than the other 2 types.  When on batteries their output is=20
typically a square wave.

2) Line Interactive.  Most UPSs are line interactive (such as APC=20
Smart).  These have filtering but also can buck (reduce) or boost the=20
mains voltage.  So can cope with mains voltage of approx 175v to 275v=20
without using the batteries.  When mains is present, they keep the=20
output voltage within a range (approx 210 to 255v) rather than at a=20
specific voltage.  Generally more battery capacity than Standby=20
type.  When on batteries their output is typically a sine wave.

3) True Online (not to be confused with 'online').  Also called=20
double conversion, these continually convert the AC mains to DC and=20
back to AC for perfect sine wave output.  Particularly good for PCs=20
or sensitive equipment in noisy environments or audio/video systems=20
such as home cinema.  The output voltage is kept at a steady 230v (or=20
can be set to 240v).  Batteries are NOT used in the double conversion=20
process.  Because of the double conversion process the fan runs=20
continually so the is some fan noise.  More battery capacity than=20
Standby type.  The output is always a perfect sine wave regardless of=20
whether running on mains or batteries.

I have many tonnes in stock of all types.
Top of the range double conversion here
http://www.automatedhome.co.uk/postt200.html
I also have cheaper true online double conversion UPSs (some older=20
models and some smaller models.  Most tower but a few rackmount).  A=20
couple of UKHA regulars have bought true online UPSs from me recently.

And Line interactive APC and Compaq UPSs.
I see a reply from Nigel Giddings and he uses Compaq 3000va UPSs.  I=20
presume the model is R3000h?
I can do a very good price on these with new batteries if interested?
=A3160 for R3000h with new batteries though these are missing their=20
battery trays so will need a little bit of work to secure the=20
batteries.  The is a guy on Ebay asking =A3275 for new batteries and he=20
has sold a few!
Also tower version (T2400h) with very good original batteries.  =A395

Plus many other models and sizes of UPS.
Cheaper prices for bulk or cash purchases.

Regards
Andy Whitfield (also known as UPS man  :-)

--- In ukha_d@xxxxxxx, Gareth Cook <g@u...> wrote:
> All
>
> I want to add a UPS to my DLP Projector - we have plenty of power=20
drops
> here for whatever reason (sometimes for hours on end), and the Node=20
0
> stuff is on battery backup. We had a cut once when watching a film=20
and Im
> paranoid about the PJ getting damaged because it can't cool down.
>
> Now my power specs for the PJ are :
>
> Rated Voltage AC 100?240 V
> Input Current 3.6 A
> 50/60 Hz
> Power Consumption 345 W
>
> Reckon this ebuyer special will do the trick ? I've tried a small=20
APC UPS
> 500VA unit but that just says overload when the PJ fires up.
>
> http://www.ebuyer.com/customer/products/index.html?
rb=3D4107930027&action=3Dc2hvd19wcm9kdWN0X292ZXJ2aWV3&product_uid=3D62751
>
> Thanks !
>
>  Gareth Cook
>  SWG EMEA North Account Manager
>  IBM SWG - BTE Office - Lotus Park, Staines, TW18 3AG
>  Office: +44 (0)1784 445166 - Mobile: +44 (0)7980 445166
>  AIM Chat : TheBoyG - MSN Chat : chat@g...
>  email: g@xxxxxxx