Dual Athlon MP 1U units

Robert G. Brown rgb at phy.duke.edu
Sun Jan 27 13:39:39 EST 2002

On Sat, 26 Jan 2002, Bari Ari wrote:

> Bari Ari wrote:
> > A power factor corrected power supply will match the capacitive loads of 
> > the semiconductors on the motherboard to raise the power factor closer 
> > to 1. Resistive loads account for very little on a well designed 
> > motherboard.
> Just to clarify -- Resistive loads other than the semiconductors.
> Bari

Dear Bari,

You mean resistive loads other than the ones with resistance that
actually produce the heat we're talking abotu?


Just kidding.  In the spirit of correcting our goofball errors, my own
algebra was off by 1/sqrt 2.  Let's try:

  P_av = 1/2 V_max I_max \cos{\delta} = V_rms I_rms \cos{\delta|

so that V_rms = 1/sqrt{2} V_max and I_rms = 1/sqrt{2} I_max.  So if peak
voltage is 120V and peak current is 1.7A and \delta = 0 (power factor
unity), peak power is 204 W and average power is 102 W.

My error is worse than your error.  I actually teach this stuff -- you'd
think I could get it right... :-o>-  (<- "Oh, my!" smiley.)


Robert G. Brown	                       http://www.phy.duke.edu/~rgb/
Duke University Dept. of Physics, Box 90305
Durham, N.C. 27708-0305
Phone: 1-919-660-2567  Fax: 919-660-2525     email:rgb at phy.duke.edu

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