Backup Power Schemes
wb8foz at nrk.com
Fri Aug 8 23:38:43 UTC 1997
Eric Osborne sez:
> OK, let's see if we can turn this thread from BBN-bashing into something
> a bit more constructive. I've seen several posts in the past few days
> concerning optimal power backup strategies, both short and long term
> (battery, diesel, and/or nuclear). Anybody out there care to share your
Putting on my EE hat:
48vdc string, everything running off it is the #1 best
answer from reliability. Time proven by THE paranoid folks
in the world, Bell System Practices.
But the initial expense, space, weight, safety aspects,
ventilation; all make this unlikely for anything except
a tariff-funded CO. And it need generators. You can not
really store many hours of energy in oxides of lead; it
just costs too much. [Last time I asked, RBOC CO's had
several hours worth of battery; in theory long enough
to get a semi-mounted unit there if the local generator
That takes us back to UPSi on equipment, and generators. Technologies
Gasoline engine -- used for smallest. Mucho fire code hassles.
Diesel. The old-line standby. Fuel is much safer to store,
but needs tending. The block must be kept heated in cold
climates if you want it to start. All sizes - Cat makes
'em as big as you want -- I've helped tend a pair of
600kw units in a third world county....
Gas Turbine. Not very fuel-efficient, but much less routine
maint than Diesels. Also smaller.
All share the same hassles to some extent or another. They have to
be run, UNDER LOAD, an hour+ per month. They need the oil changed.
They need clean fuel; #2 Diesel tends to grow weird bugs that clog
the filters. The propane and natural gas can feed modified gasoline
piston engines and turbines. Some Diesels run on a fix of #2 and
gases. [The ultimate example -- a sewage plant will recover sewer
gas and use it w/Diesel. If your userbase is full of BS; or your
tie curls and your boss has 2 horns, you might go this route...]
Natural gas has advantages of no storage hassles; propane does
not go stale.
In short, they all need tending. Regularly.
As for installing, there are a million details. Ventilation. Fire
codes. Noise & Neighbors. Floor loading. Power transfer. Load
segregation [what is, and what's NOT, an emergency load...]
Hire an engineering fire with experience in your locale -- this
is not a task for anything less.
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