[ExI] Power factor for
hkeithhenson at gmail.com
Fri Nov 27 16:57:34 UTC 2009
On Fri, Nov 27, 2009 at 5:00 AM, Brent Neal <brentn at freeshell.org> wrote:
> On 25 Nov, 2009, at 22:26, Keith Henson wrote:
>> and I don't understand what Brent is talking about. Can you explain?
> CFLs lead in phase due to an either real or effective capacitor in the
> ballast, as I understand it. Therefore, you want to include an
> inductor in the circuit to bring in back in phase and the power factor
> back up to 1. Most CFLs produced today have a 0.5-0.6 PF.
When when fluorescent lamps ballasts started to be produced 50-60
years ago they ran a lagging power factors because the current limiter
was an inductor. http://en.wikipedia.org/wiki/Fluorescent_lamp
http://members.misty.com/don/f-lamp.html (I took one of these apart
when I was about 8.) Later capacitors were added to partly correct
the poor PF.
Correcting the power factor of small lamps using a bridge rectifier
into a capacitor would be very expensive, a few hundred grams of
copper and iron.
> Keith, you're an EE, aren't you?
BSEE 1969, U of Arizona. Did a modest amount of power circuit design,
up to a current controlled 15 kW square wave generator. (Phase angle
controlled 400 Hz, 700 volt output.)
>You should know power factors and
> phasors better than I do. Physicists are dirty hacks compared to EEs
> when talking about this stuff. :) Most of my info comes from an EE who
> works in designing lighting systems.
I think he may be a bit out of date. Current designs use this kind of circuit
and have power factors of 0.99 or so. I have designed and put into
production power factor correction power supply circuits of this
kind--which was why I didn't understand where a penny inductor would
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