29 May
2007
29 May
'07
7:12 p.m.
On Tue, 29 May 2007, Mark Hull-Richter wrote:
On 5/29/07, Jim Perrin jperrin@gmail.com wrote:
Watts = Volts x Amps. I usually use a sliding scale based on # of machines.
That has to be the stupidest marketing strategy ever devised. Most people (yeah, me too) know that, but why can't they SAY so instead of using "VA"?...
This formula is correct for a resistive load; however, it completely ignores the reactive load. The correct formula is:
watts = power_factor X volts X amps
You consume volt-amps, but can only use for amps. There are various regulations in place regarding the minimum power factor -- decent power supplies have a power factor of better than 90%.
Steve Friedman