UPSes - MinuteMan, others?

[Andrew W. Gaunt]

Out wonderful telcom system was designed by the department of redundacy 
department.

Ben Scott wrote:

> On 8/10/06, hewitt_tech <hewitt_tech at comcast.net> wrote:
>
>> This discussion reminds me of a Murphy's Law corollary - "An expensive
>> transistor being protected by a fast acting fuse will protect the 
>> fuse by
>> blowing first!".
>
>
>  Heh.  I've heard a variation on that before -- appropriately enough:
> "A $1000 UPS will sacrifice itself to protect a 5 cent fuse".
>
>> Seriously though, in the military communications sites
>> derive all their power from an inverter being fed by two series of 
>> Excide
>> battery strings.
>
>
>  Yah, the commercial telephone companies do the same thing.  In a
> telco CO (central office), *everything* runs off of 48 VDC -- even the
> lights in many installations.  They run off batteries which are
> continuously trickle charged.  If line power fails, the batteries just
> stop charging for a while.  They use two sets of batteries, two
> charging sets, and two power distribution wiring.  All the equipment
> has two power inputs.  Most COs have an auto-start generator, too.
> It's really the right way to do things.
>
>  I often wonder why the IT industry doesn't come up with something
> along those lines.  While redundant-everything is more then most
> people want, the flow of power is much more appropriate.  With a
> conventional setup, we convert from AC to DC to AC to DC, as we go
> from line to UPS to computer power supply to computer.  It would be
> nice if we could leave the inverter out, leave the PC PSU out, and
> just go from AC to DC in the UPS, and then run DC directly into the
> PC.  Less heat, less space, more efficiency, longer runtimes.  I'm
> sure if, say, APC teamed up with Dell, they could make quite a
> killing.
>
> -- Ben
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