[geeks] Re: Big 48v batteries...

[Ken Hansen]

In a typical AT&T/Baby Bell Central Office (never been in any other, assume it is similar) the battery room is typically in the basement, and consists of a *large* number of cells, each about 18" square on the bottom, and about 30-36" tall. The cells are open on top, and it is a full-time job for one person (union, natch!)to monitor and supervise the battery backup.

The cells are arranged similar to a conventional UPS, in that all power goes from the Public Utility feeds (they have two, each from a differnt source, and entering the building from different sides,to prevent a cable cut from shutting down the facility) through the cells, and then to the equipment (switches, etc.).

When Public Utility power is lost, there is a cutover from public power to the battery array. once that cutover is made, the backup generator is started up, and as soon as the generator is producing stable power, the facility is cutover to the generator, still run through the wet cells in the basement. (in case the generator dies, the batteries take over, and to clean the power - neither Public or privately generated electricity is fed directly to any revenue generating equipment,it all runs through the batteries).

Many folks that work in telco Central Offices wind up with 18" square, 30-36" tall aquariums, since they swap out the wet cells every number of years, and any cracked/imperfect containers are replaced. ;^)

After the facility has been on the generator for any extended period of time, an assessment is made as to when the public power will be restored, and if needed, additional fuel supplies are requested. Typical COs keep something on the order of a 24 hour supply.

One particullary large AT&T facility (where theyprint the bills, or atleast did some of them) used to have two jet engines in back of the facility for backup power. When additional fuel is needed, it is ordered up from the local airport (EWR - Newark).

Sorry, the nuts-and-bolts of the telco industry is very interesting (to me at least)...

Ken

-----Original Message-----
From: Bill Bradford [mailto:mrbill at mrbill.net]
Sent: Friday, April 20, 2001 3:50 PM
To: geeks at sunhelp.org
Subject: Re: [geeks] Re: geeks digest, Vol 1 #64 - 14 msgs


On Fri, Apr 20, 2001 at 03:05:36PM -0400, Joshua D. Boyd wrote:
> What's this 48v thing people are talking about?

Most all "proper" telco equipment runs on -48VDC instead of 115V AC.

Easier to provide backup power / battery plants / etc.

Bill

-- 
Bill Bradford
mrbill at mrbill.net
Austin, TX
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