[nSLUG] Power Loss and UPSs

Miles Thompson miles at allnovascotia.com
Mon Nov 5 19:39:26 AST 2007


At 10:41 AM 11/5/2007, you wrote:

> > that will hold 50+
> > servers up for 2 hours.  That is a lot of battery power.
> >
>
>  In our colo rooms(there are 3 in the 2 cities) we have a ~200 machines
>(about ~150 of them in the main server room)
>all on monitored UPS's, and each location has a gas generator that kicks
>in after 30 seconds and
>lasts 4 to 5 days with guaranteed fuel delivery for longer periods. The
>generators get tested Every Friday morning.
>Thankfully the longest we've ever had to run on them was 8 hours and
>that was during Hurricane Juan.
>
>Unfortunately my house doesn't have a generator and we are still without
>power, so last nights entertainment was
>my wife, daughter and I huddled around a laptop watching a DVD eating
>Pizza :)
>
>  Anyone know what decent generators run these days that run for at least
>6 hours? If they are cheap enough I might pick one up and keep it around
>for days like this.


Greg,

You did say "decent", whatever that means.

We have a 4,500 watt Porter Cable with a 9 HP Honda engine. The 
neatest thing about this genset is its surge capacity, which is 9,000 
watts. That makes running the house on the genset pretty relaxing, as 
not everything kicks in at the same time.

Our boiler is oil-fired with an indirect-fired water heater, so if 
the municipality manages to keep the water plant running, we're 
pretty comfortable. With a little care we can run the coffee maker, 
then unplug it and make toast - high resistance loads like toasters, 
irons, electric kettles etc. are killers - they are usually v. high wattage.

So, our generator is 4500 watt, with 9,000 watt surge, which means it 
handles the starting loads for motors - sump pump, freezer, fridge, 
and the like - very well. But watch out - some manufacturers, King is 
one example, label a generator with the surge capacity. So the "4,500 
watt" King sitting down at the hardware store is rated for only 3,500 
watts of continuous output.

Gas or diesel? I would prefer a diesel, as long as it was a reliable 
starter in chilly weather. Small diesel generators were  really 
expensive when we bought ours that November following Hurricane Juan. 
There is a place on the Halifax side of Windsor that sells 
economically priced diesels - worth checking.

These puppies suck gas like you would not believe - ours will give us 
close to 6 hr on 10 l of gas; a diesel would be two-thirds more to 
double that. Diesle oil is furnace oil - as observed earlier, if you 
heat with oil you can feed the same stuff to your genset.

Diesel oil stinks, but it's a LOT LESS FLAMMABLE. I have 5 - 10l 
plastic jugs of gas out on the deck, well separated from one another. 
Can't and won't store it in the house. Diesel fuel you could.

Gas needs to be stabilized. Buy gas stabilizer and add it to your 
fuel jugs before you fill them, then it's well mixed. Stabilized gas 
is good for a year, but it's better if you cycle it through the car.

Gas jugs - they have to seal TIGHTLY. You do not want to lose those 
nice, volatile high ends which help an engine start easily. Gas from 
your jugs should feel "sharp", not greasy, and should smell sharp, not oily.

The big thing for us is starting, quickly and reliably. For us the 
generator is most often needed in conditions like 2:30 on Sunday 
morning, or one of those storms in the spring when we get heavy snow, 
followed by rain and wind, followed by tree limbs falling on the 
power lines and taking the power out.

That's also when our sump pump is often running on a 90 second duty 
cycle. When the power goes out we need electricity NOW!

The Honda is great for starting. Open the fuel valve, close the 
choke, pull the cord and it's running. If not on the first pull, on 
the second. Tried it at -15 - same thing. It starts reliably - every time.

How often have we used it? For about 3 days following "White Juan", 
for a couple of days after the storm which followed Remembrance Day, 
what - two-three years ago? And for various periods of 6 to 8 hours 
ever since. It's one of the smartest buys we have ever made.

Preventive maintenance is really nothing more than running it under 
load for a half-hour every month (Mummy, why does that man have his 
electric frying pan and kettle hooked up to that noisy machine?), and 
changing the oil spring and fall.

Challenges: Keeping it dry when operating in a  rain storm is a big 
one. We don't have that perfected yet, but rain is better than fine 
snow which will get sucked into the generator head. Also lock it 
securely with a case hardened chain and an equally durable lock, one 
of those with a circular key or equivalent. Generators are highly 
prized and easy to sell. Keep it locked to something when it's 
running - in a silent neighbourhood the house with a genset stands out.

What would I like? A 10,000 watt unit may let us run the electric 
stove - now we use a propane camp stove when the power is out. I also 
think I'd like diesel, because then if the time it has to be run is 
protracted I'd have a source of fuel right at hand.

If I could afford it, a slow speed generator would be really nice. 
These little gas ones run at 3,600 RPM because they have two-pole 
heads. A four-pole head can be run at half that speed. As sweet as 
that thing sounds when you first start it, the racket becomes very 
irksome. Slower speed and a good muffler would be super.

That's it.

Miles



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