On Mon, 13 Aug 2007 14:25:34 GMT, Robert Redelmeier
wrote:
In comp.dcom.lans.ethernet w_tom wrote in part:
On Aug 12, 9:21 am, Robert Redelmeier
wrote:
You overstate your case. Both "Standby" and "power conditioning"
UPSes are readily abailable in the smaller sizes:
So where is the double conversion UPS selling for $85?
Well, USENET normally frowns on any sort of commercial postings,
but since you asked, you might try:
http://shop1.outpost.com/product/2962265
but I make no promises. The stepped ouput sine-approx would appear
to be your "double-conversion". You may have different preferred
vendors.
You didn't read the APC paper in your previous post otherwise you
would see that the APC 350VA unit you are suggesting for $70 is NOT a
double conversion type. It is a basic line interactive BACK-UPS. That
means the load runs on normal mains supply - along with all the
voltage variations and noise - as it does without the UPS. Only when
the mains fails does switchover occur and the load then runs from
battery powered SMPS converter (18 min at 50% load) - which will be
free of the mains input voltage fluctuations and noise.
Using this type of UPS is almost useless in cleaning up power. It is
true that the UPS does have the usual surge protection devices you
might find in a multi outlet power distribution board - but that's
about all.
APC make a range of Smart UPS RT which are double conversion and
models start at 1500VA and with a ERP of $1,150. It is generally not
economical to use D?C for loads less than this value.
http://www.apcc.com/products/family/index.cfm?id=223
There is another APC document which compares the BACK-UPS andf the D/C
UPS
http://www.apcmedia.com/salestools/J...QSBR_R0_EN.pdf
Sanyo Denki do make a 1KVA D/C UPS but they won't be cheap either
http://www.netmotion.com/htm_files/ot_ups.htm
If there is no problem with the RELIABILITY of mains supply, but it is
just fluctuating and noisy, then a D/C UPS may not be needed. It may
be cheaper to use a power conditioner. APC make a range of these as
well
http://www.apcc.com/products/family/index.cfm?id=307