Re: "Mysterious" system crashes

Doug Phillips wrote:
On Nov 15, 8:34 pm, bradhamilton <bradhamil...@xxxxxxxxxxx> wrote:

Richard B. Gilbert wrote:

[...]


Yes, I've thought about the "small" APC units that I see for sale at
HW stores, but I've never experienced these problems until this week,
so I never saw a need for one. I guess I'll price some units (keeping
in mind that I need to match capacity with my estimated power draw
from the CPU, disks and disk shelves). My wife keeps asking me what I
want for Yule - perhaps I have a legitimate need...

"Disk Shelves" implies a rather large installation. How many VA for the
whole thing?

PWS433au: 100-120 VAC 5.5A (550-660 VA?)
2 fully-populated BA356 (top-gun blue) shelves: 100-120 VAC 7.0A
(1400-1680 VA?)

For an approximate total of:

1950-2340 VA

Assuming my math is not too far off, then approximately $675-750 for an
APC rated at 2500 VA.

Out of my price range as a mere hobbyist. :-(


VA and the Amp rating on your tags are peak draw. Watts are average
draw. Figure Watts at around 65% of VA. You probably won't draw 2500
VA unless you power-up everything simultaneously. My 17" CRT monitor
(when it's awake) draws as much as my system box (an LCD flat-panel is
on my Dear Santa list;)

You could probably buy two smaller UPS's for less than the cost of one
large one. I have a 1600 watt and a 900 watt UPS (on two outlets, same
20amp circuit) in my "main" room with similar power requirements to
yours (different equipment, but about the same draw.) I think I paid
around $200US for the larger, and around $100 for the smaller. The
batteries cost around $30 to replace (the large unit has 2 batteries)
so if you can find the UPS' used you can save money. I've even
connected two smaller units in series before to gain up-time and been
lucky enough not to fry anything. (The UPS manufactures probably don't
recommend doing that, though, although I've never seen a warning on
any of the units I've bought saying not to do it. But then again, who
reads that stuff anyway;-)


Some of the larger units make provision for an external battery pack to give you extended run time. I have one such unit: SmartUPS 700 (from memory). I imagine that a lot of the others could be kludged to take external battery packs for extended run time. I don't think I would want to try charging such external battery packs from a kludged unit!
Note that automobile batteries are NOT suitable for this service. The application requires so called "deep drain" batteries which are very different internally from automobile batteries.

A major oil company found this out the hard way years ago. A lightning strike took out the primary power at one of their refineries and what should have been a minor inconvenience turned into a major disaster. The UPSs failed left and right, because automobile batteries had been installed, and did not give them the time needed for a clean shut down or to bring up auxiliary power. They lost the steam boiler almost immediately which meant that, among other things, they couldn't vaporize the "crud" prior to "flaring it off". Instead the crud dribbled onto the ground and made a major environmental mess!


.

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