Re: Debian Compatable UPS?
> Alvin Oga wrote:
> >imho, apc is probably the worst consumer grade ups there is ...
If a APC SmartUPS XL (1kVA) is consumer grade, then it is expensive alright.
I have heard bad things about APC, but it probably applies only to their
el-cheapo product lines.
> > - they have lots of $$$ to do marketing/sales because
> > you have to buy new ones every 6mon-year or new batteries
Well, my SmartUPS XL is on production for more than one year so far. The
AVR works wonderfully (my main is a bit high, at ~125V so the AVR is
*always* on), too. It sustains the current load I placed on it for > 1h,
and plays by the book, shutting the load down cleanly and powering it up
cleanly later.
> >- you will find out the ups is not working when your main 110vac power
> > goes out ( brown out or dead for more than san 30sec, which any ups
> > should survive )
> > - very very few people hit the "ups test" button to make
> > sure the servers keeps working even if the ups is unplugged
> > from power ( way better to test than the silly fake front panel
> > test button )
If your UPS does NOT do automatic battery tests using a considerable load
periodically, it is trash. And yes, a APC SmartUPS XL does it every two
weeks, and it puts enough load to drain the battery about 15% in 3s. If the
battery survives that, it won't crap out the next time it is needed.
> >- keeping batteries fully charged is tricky biz
It fucks the batteries up royally to keep them under constant charge, yes.
The UPS must have a histeresis controler with a low watermark on 90% and a
high watermark on >95%. This is relatively easy to do, though.
> So what's your recommendation for Debian compatible UPS?
Anything that is fully supported by "nut", **with** a smart protocol.
A good UPS must:
1. have NVRAM (yes, exactly) to store configuration
2. let you program it to shut the load down when battery is below a
certain level (low watermark), and to only power the load up again when it has
detected a power cycle in the main power *AND* the battery level
is above a certain level (high watermark).
3. Have low and high watermarks for charging the batteries too
4. perform auto-diagnostics, battery and inverter tests frequently, and
NOTIFY the PC of any malfunctions (or at the very least emulate a
loss of power and low battery level to do a clean load shutdown, then
turn itself off until rearmed).
5. report to the PC (using a known protocol) when the battery is getting
low (this is MUCH different than reporting when the main power is
down, which is the crap you get with generic relay-based RS232
"dumb" UPSes).
6. A damn good AVR with line noise suppresion
7. PWM control of the inverters, with less than 10% THD on the output
waveform
8. Active fan cooling for the inverter bridge when P > 750VA and the
bridge is on.
9. Response time < 4ms with sensivity control and main power quality
(THD) monitoring
Bonus points for:
1. PC control of load power state (i.e. immediate power down and power
cycle).
2. Output waveform smooting using a transformer (big, heavy and
expensive!), for < 0.1% THD in the output waveform
3. Response time = 0ms (power tank) for units with P < 5kVA
4. Line voltage monitoring available to the PC
5. Battery voltage and draw rate available to the PC
6. Remaining battery *time* available to the PC [at current draw rate]
--
"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot
Henrique Holschuh
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