didn't someone tell me that telco equipment had 40vdc racks once?

[Billy Crook]

Another consideration is that this would effectively put 42 machines
on the same 12v rail, and the same 5v and so on.  So if a component in
one machine failed in such a way that it shorted across that rail, it
would take all devices on the rail down unless they each had
individual load breakers for each rail.  There's also a fairly good
chance the short would happen during node insertion, so the breaker
would need to be outside of the node, possibly ruling out the cheap
bus-bar idea unless the breakers were inbetween the busbar and chasis.

On Dec 21, 2007 2:00 PM, Brian Kelsay <ripcrd at gmail.com> wrote:
> Unless those DC rack supplies are ten times more expensive to replace and
> more likely to fail than a server power supply and harder to find.
>
>
>
> On Dec 21, 2007 1:52 PM, Jonathan Hutchins <> wrote:
> >
> > The point of all this is that instead of every piece of equipment having
> > it's own switching power supply, with fan, you supply the required
> > voltages to the whole rack from a common pair of fail over power supplies.
> > Each box then gets it's own +12,+5, and -5 (or whatever), and we have one
> >
> > less component per unit to fail.
> >
> > Converting the power once then distributing it really does beat
> > distributing the AC and converting it at each unit, there are savings in
> > equipment cost, efficiency, and cooling.
> >
> > Because of this, a 48 volt distribution system doesn't make as much sense,
> > nor  does it offer as much advantage over a 120/240V AC distribution
> > system.
> >
> >
> >
> >
> >
>
>
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