>
> Power factor for pulsed loads, such as an LED light bulb gets messy and
> a full blown solution is not able to fit within the confines of the bulb
> itself. And, reading the real and reactive power for a device that
> doesn't have a sine wave current draw is not trivial.
>
> I bought 3 different LED bulbs from Home Depot and Walmart, they have
> power factor values between .47 and .6!! Later I got some energy star
> rated bulbs and they measured .88 to .92. I'm thinking of dissecting the
> energy star bulbs just to find out what makes them tick.
>
> GL.
>
> Art

I'd always thought of power factor being due to reactive but linear loads.
Switching power supplies (or any AC to DC converter that has diodes
directly driving capacitors) are nonlinear loads where the instantaneous
AC line current is not proportional to the instantaneous AC line voltage.
"Power factor correction" for nonlinear loads generally takes the form of
a boost converter between the diodes and the filter capacitor so the
capacitor is charged through the whole cycle with the instantaneous AC
line current being proportional to the instantaneous AC line voltage.

Harold



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