[XCSSA] New computer power supply

[xcssa@xcssa.org]

On Monday 21 May 2007 14:00, xcssa-admin@xcssa.org wrote:
> My friend has now tested his new computer power supply (with a nice
> kill-o-watt meter) and found it makes negligible difference compared

Yeah Charles.. I meant to mention this earlier.. As soon as I saw the sponsors 
of that power supply technology, and I clicked on the theory behind it and 
saw "Power Factor Correction" as the main power saving benefit, it became 
apparent what was up.

The power company is fronting those supplies as "more efficient" and "green" 
because PC digital switching power supplies are inherently "inductive" by 
nature.  That is, in the AC power impedance spectrum of:
  <------------------1.0-------------------->
  Inductive     Pure-Resistive    Capacitive

Where a toaster oven is pure resistive... (Power Factor~1.0)
a PC power supply is fairly inductive (PF<1 ) or a Blender (more Inductive)
and a something like a DC regulated supply might be more capacitive

PC power supplies are inherently "bad" in that they pull inductive, or 
wasteful power (as opposed to say a blow dryer with has a healthy mix of 
inductive and resistive components (mostly resistive IIRC).

Anyway..here's a good site on the theory:
http://www.ibiblio.org/obp/electricCircuits/AC/AC_11.html

But my main point here is that inductive loads (like PC power supplies) waste 
power company power that can not be metered or charged for, so the PC loses 
that $$$.  

Due to the phased nature of inductive current loading, a significant 
percentage of incoming current (or power supply inefficiency in this case) 
gets "reflected" (kind of) back out onto the grid out of phase with the 
metered power and essentially lost in the form of heat.

This means that the power company looses that power and can't charge the 
customer for it.

This is why large industrial centers like assembly lines (lots of motors) and 
data centers with lots of PC servers (like Rackspace, and others) have 
to "capacitive-ly load", or balance their facilities.. otherwise there would 
be megawatts of lost power that the power companies would have to eat right 
out of their bottom lines.

That's why they pitch these "green power supplies" as "more efficient" 
and "green".. They're just trying to ride the green movement wave all the way 
to the bank, as it were. hehe :)

Tweeks


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