Adding to Bob's stuff:<br><br>I installed a natural gas 15kW back-up generator system at my house. It does good sine wave form except for the bottom of the cycle being very noisy. Thus my APC UPS's (the big expensive one that power my rack) was very unhappy when the generator kicked in. I was able to turn down the sensitivity on the UPS and get good performance.<br>
<br>The natural gas version is a good idea for me as when the power goes out for my neighbors, they won't be using gas either except for a stove or two. Generac brand. Next step up would be a water cooled version with a much better generator/inverter for an extra $2k. My system was $3k and I did the install myself (except for the gas line run) and also had to replace my house main fuse box and upgrade to 200A breaker box.<br>
<br>This system kicks in once a week and runs to exercise itself. While it is on, the power is OFF at the main so it is safe for repair crews.<br><br><div class="gmail_quote">On Tue, May 20, 2008 at 12:47 AM, Bob Toxen <<a href="mailto:transam@verysecurelinux.com">transam@verysecurelinux.com</a>> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">You need to define "inexpensive".<br>
<br>
Some UPSes work with some generators. If the generator generates true<br>
60Hz sine wave output then any UPS should work. However some modern<br>
generators only approximate the sine wave (see below).<br>
<br>
That said, my Yahama model 2400 (2000 Watts of 120V 60Hz continuous)<br>
works great with my new and old APC UPSes. (I haven't tried it with<br>
my one off-brand UPS.) It cost me $1200 plus shipping less a $100<br>
rebate and I'm very happy with it. It also can power a window AC and<br>
refrigerator at the same time to survive days-long outages following<br>
major weather events.<br>
<br>
Suggestions:<br>
<br>
1. Read the details on any generator you're considering to see if it<br>
uses an AC generator or DC generator driving an inverter. The<br>
AC generator should produce a true sine wave that will drive any<br>
AC device The DC generator may not.<br>
<br>
2. Consider how quiet the generator (engine actually) is. Most,<br>
especially cheap ones are VERY nosy, comparable to a lawn mower.<br>
Unless you're in the country your neighbors and the cops will<br>
force you to shut it down after a short time.<br>
<br>
3. I recommend a gasoline-powered generator over a propane-powered<br>
one because you have an automatic 15 gallon or so reserve in your<br>
car's gas tank if you have a siphon hose. The propane ones do<br>
burn cleaner. In either case be sure to stock enough fuel to cover<br>
a long outage. If you use gasoline, occasionally dump your<br>
reserves into your car and replenish them as old gas is bad gas.<br>
<br>
4. Consider finding a retail store with display models of generators<br>
that they will run for you. Plug in your UPS and a load such as<br>
a small lamp with a 100W bulb to see if the UPS likes the AC.<br>
<br>
5. Honda makes the quietest generators and are considered of the<br>
highest quality. Look for the DB (noise) rating.<br>
<br>
6. To avoid a computer crash you'll have to be able to start the<br>
generator and switch the UPSes from the wall socket to the generator<br>
within a few minutes (5-10 depending on the health of your UPS<br>
batteries). That includes recognizing a failure and finding a<br>
flashlight to get around in the dark.<br>
<br>
This means at least keeping a heavy cable from the generator to<br>
where the UPSes plug into the wall.<br>
<br>
I use 12 AWG cable and have a relay that automatically switches<br>
the UPSes from the wall socket to the generator when it detects AC<br>
from the generator. In the office I have a lamp driven directly<br>
from the generator so I know when there is generator power (and<br>
allows me to see) and an indicator light showing if the UPSes<br>
are receiving AC from either feed (e.g., after the relay).<br>
<br>
<br>
Technical reasons for generator/UPS incompatibility:<br>
<br>
The problem with UPSes is that some are too sensitive to input power,<br>
especially requiring a true sine wave. Nowadays many generators<br>
generate low voltage DC internally and then use an inverter (like the<br>
second half of a UPS) to generate the 120VAC.<br>
<br>
Why? Because it allows them to vary the RPM of the generator to match<br>
power (wattage -- or Volt Amps for the EEs here) requirements and use<br>
less fuel at lower power draws. This is unlike a true AC generator<br>
where the RPM must be precisely regulated because the frequency (Hz)<br>
is proportional to the RPM.<br>
<br>
This is the same reason why plugging one UPS into another one to get<br>
standby power for a longer time frequently will not work. (I have<br>
done this successfully with APC UPSes but there is a risk of frying<br>
circuits.)<br>
<font color="#888888"><br>
Bob Toxen<br>
<a href="mailto:bob@verysecurelinux.com">bob@verysecurelinux.com</a> [Please use for email to me]<br>
<a href="http://www.realworldlinuxsecurity.com" target="_blank">http://www.realworldlinuxsecurity.com</a> [My book:"Real World Linux Security 2/e"]<br>
</font><div><div></div><div class="Wj3C7c"><br>
On Mon, May 19, 2008 at 06:25:47PM -0400, Brian W. Neu wrote:<br>
> I've had it with Marietta power. They're as reliable as a campaign promise.<br>
><br>
> Does anyone have a story of producing reliable power from some kind of<br>
> inexpensive generator set-up? I've tried some kind of rental deal<br>
> previously which didn't come remotely close to working. Is the secret<br>
> having a true AC->DC->AC converting UPS?<br>
> _______________________________________________<br>
> Ale mailing list<br>
> <a href="mailto:Ale@ale.org">Ale@ale.org</a><br>
> <a href="http://mail.ale.org/mailman/listinfo/ale" target="_blank">http://mail.ale.org/mailman/listinfo/ale</a><br>
_______________________________________________<br>
Ale mailing list<br>
<a href="mailto:Ale@ale.org">Ale@ale.org</a><br>
<a href="http://mail.ale.org/mailman/listinfo/ale" target="_blank">http://mail.ale.org/mailman/listinfo/ale</a><br>
</div></div></blockquote></div><br><br clear="all"><br>-- <br>-- <br>James P. Kinney III <br>