On Thu, 01 May 2008 08:35:12 -0700, Darren New <dne### [at] sanrrcom>
wrote:

>Stephen wrote:
>> This is true as most people know but where does the phone company get
>> its 50 volt dc come from. I suspect it is from an electricity company.
>
>Batteries charged off of the grid, or off of generators started when the 
>batteries get low if the electricity is off.

IIRC in the UK, the power to charge the batteries comes from the grid
with a standby generator in case that fails. 

>Ever see a room with hundreds of cubic feet of glass cases full of acid 
>and lead? It's pretty cool.
>

Yes, but I thought that it was pretty boring. Racks and racks of black
batteries in an awkward space. I one spent three days in a cathodic
protection room faultfinding a data logger. Who would have thought of
looking for a fuse between the outer and inner skins of the processing
unit? :(

>You could run a normal-sized central office off batteries for several 
>days, or several weeks if you start up the generators occasionally, 
>without any outside services. If everyone with knowledge disappeared, 
>the phone system would probably run three to four months before it broke 
>down enough to have a major network partition.

Interesting 

>(All this was from my days in the local telcos 15 years ago in the US, 
>so it has probably changed since all the deregulation really had its 
>effects.)
-- 

Regards
     Stephen

Post a reply to this message