Telco switching offices rectify commercial power to charge their DC storage
batteries (-48VDC nominal, typically -52VDC). All high availability
equipment runs on the -48VDC. These are typically sized to power all of the
critical equipment in that office for ~24 hours. They also usually have
diesel generators to handle longer outages.

Cellular base stations also usually have battery backups to power the cell's
equipment and handle HVAC as well. They usually do not have their own
generators and rely on the Telco to provide a mobile generator to recharge
the batteries.


"Homer J Simpson" wrote in message
news:JJklh.108425$hn.22742@edtnps82...

"William R. Walsh" m
wrote in message news:hBjlh.332105$1i1.275680@attbi_s72...

How big? I've noticed the telephone company's local switching office has
a
plug for a generator on it.

I've never seen them actually use it and have no idea what it might keep
powered. Maybe it's just for the climate control stuff.

We had an extended power cut here and the Telco had to haul a generator
around to recharge the batteries to keep exchanges and cell towers
working.