[Asterisk-Users] Prefered server hardware

[Peter Svensson]

On Tue, 18 Jan 2005, Christopher L. Wade wrote:

> Scott Stingel wrote:
> > The reason for an asterisk system to be able to work from -48v is really 
> > only if the end-user customer requires it as part of a spec. - I would 
> > think only a minority of sites would require this though.    These days, 
> > most equipment rooms I've been in can supply lots of backed-up AC.
> 
> Pardon me, my 'ee' experience was a long time ago, but isn't it "easier" 
> to provide clean DC than it is to provide clean AC?

Redundancy is another issue - it is easier to provide redundant feeds if 
there can be no phase misalignment. 

> Basically, if you run all of your power through AC-DC converters then 
> through battery banks (basically capacitors) finally going out to your 
> equipment, any and all problems introduced from your AC source is 
> effectively filtered out.  This is similar to what really expensive UPS 
> units do, except they also convert back to AC as a final step.

They are not that much more expensive anymore. The problem is that with a 
double conversion ups you have slightly lower efficieny, leading to more 
power use and more waste heat. They typically run at 90-95% efficiency.

Peter