PSU Power Factor - Does it matter?

  • Thread starter Thread starter Jim Taylor
  • Start date Start date
J

Jim Taylor

I looked at the .pdf file for the Seasonic (never heard of them) Super
Silencer 400 power supply found on this page
(http://www.siliconacoustics.com/seasonicsupersilencer400watt.html)
which, if correct, means I haven't understood how we're billed for
electric power. I thought we were billed in kilowatt hours (and my
bill does *say* KWH), however Seasonic is saying we're billed in KVA
hours. Which is right?

Seasonic claims that their PS, supplying 300W DC 24/7, can save you up
to $485/year in electric power over a generic PS. That sounds like
pure BS to me. The 80% efficiency and 99% power factor does sound
good but not that good.

They're using these numbers (my current system added):

Their PSU Generic PSU My system
PSU efficiency 80% 68% 68%
PSU power factor 99% 50% 65%
System load (DC output) 300W 300W ?
Watts input (AC input) 375W 441W 150W*
VA input 378VA 882VA 227VA
Utility rate KVAH $0.11 $0.11 $.10/KWH?
Power consumption/yr 3318KVAH 8086KVAH 730KWH**
Electric bill/yr $365 $850 $73?

* input to UPS (computer, 19" monitor, modem, speakers), CPU<2%
100VA/59W (.59pf) for computer only, 123VA/77W if 100% CPU load
** averaging 2KWH/day.

Obviously I can't save $485/yr but would I save anything at all if I
buy a PS with active power factor correction for my next system?
If not, what's the advantage of having it?

Can a PS like the Seasonic run on an APC UPS which doesn't have a true
sine wave output? They don't say a word about it in their .pdf file.
I know PC Power & Cooling says you can't for their APF supplies
because spikes on the line (from electrical storms too maybe?) might
cause the supply to switch to the wrong input voltage (they offer a
free mod to make it 120VAC only).
 
Jim Taylor said:
I looked at the .pdf file for the Seasonic (never heard of them) Super
Silencer 400 power supply found on this page
(http://www.siliconacoustics.com/seasonicsupersilencer400watt.html)
which, if correct, means I haven't understood how we're billed for
electric power. I thought we were billed in kilowatt hours (and my
bill does *say* KWH), however Seasonic is saying we're billed in KVA
hours. Which is right?

Seasonic claims that their PS, supplying 300W DC 24/7, can save you up
to $485/year in electric power over a generic PS. That sounds like
pure BS to me. The 80% efficiency and 99% power factor does sound
good but not that good.

They're using these numbers (my current system added):

Their PSU Generic PSU My system
PSU efficiency 80% 68% 68%
PSU power factor 99% 50% 65%
System load (DC output) 300W 300W ?
Watts input (AC input) 375W 441W 150W*
VA input 378VA 882VA 227VA
Utility rate KVAH $0.11 $0.11 $.10/KWH?
Power consumption/yr 3318KVAH 8086KVAH 730KWH**
Electric bill/yr $365 $850 $73?

* input to UPS (computer, 19" monitor, modem, speakers), CPU<2%
100VA/59W (.59pf) for computer only, 123VA/77W if 100% CPU load
** averaging 2KWH/day.

Obviously I can't save $485/yr but would I save anything at all if I
buy a PS with active power factor correction for my next system?
If not, what's the advantage of having it?

Can a PS like the Seasonic run on an APC UPS which doesn't have a true
sine wave output? They don't say a word about it in their .pdf file.
I know PC Power & Cooling says you can't for their APF supplies
because spikes on the line (from electrical storms too maybe?) might
cause the supply to switch to the wrong input voltage (they offer a
free mod to make it 120VAC only).
Click to expand...

This sounds like BS to me. Unless the AC to DC converters for standard power
supplies results in large inductive load AND you're running A LOT of them
AND you're on an electric service plan that actually measures and charges
for poor power factor (i.e. a large commercial or industrial rate) then this
is BS.
 
Jim Taylor said:
I looked at the .pdf file for the Seasonic (never heard of them) Super
Silencer 400 power supply found on this page
(http://www.siliconacoustics.com/seasonicsupersilencer400watt.html)
which, if correct, means I haven't understood how we're billed for
electric power. I thought we were billed in kilowatt hours (and my
bill does *say* KWH), however Seasonic is saying we're billed in KVA
hours. Which is right?

Seasonic claims that their PS, supplying 300W DC 24/7, can save you up
to $485/year in electric power over a generic PS. That sounds like
pure BS to me. The 80% efficiency and 99% power factor does sound
good but not that good.
Click to expand...

considering that your machine will only cost you about $200 (or less)a year
in electricity
if they agree to send you a check for $285 every year
you should get it <g>
 
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