Re: PFC question

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jeremy Scott by way of Terry Fritz <teslalist-at-qwest-dot-net>" <supertux1-at-yahoo-dot-com>


Normally without a PFC, maximum voltage and
maximum available current are out of phase in the
secondary. So, at any given point the average 'power'
level from the secondary is less than what you put
into the primary due to the properties of the
transformer core. That energy is usually lost as heat.
A PFC capacitor will start to discharge through the
primary when the AC line voltage starts to drop from
it's peak. The PFC therefore 'delays' the collapse of
the field around the core. The effect is that current
and voltage in the secondary are still not in phase,
but their peaks are 'aligned'. Since the capacitor
helps maintain core saturation, less power is required
from the wall, and what you get out is usually 95% of
what you put in.


--- Tesla list <tesla-at-pupman-dot-com> wrote:
 > Original poster: "Richard W. by way of Terry Fritz
 > <teslalist-at-qwest-dot-net>" <potluck-at-xmission-dot-com>
 >
 > Hi everyone,
 >
 > I've played with PFC a bit but not much. I had added
 > 100uf to a 15/30 NST
 > and noticed a marked decrease in the primary current
 > by means of an ammeter
 > in series with the primary. I loaded the secondary
 > with a water resistor
 > but hadn't a means to monitor the secondary output
 > current, just didn't
 > know how.
 >
 > Anyway, will adding PFC to the primary side also
 > decrease the secondary
 > output current?
 >
 > Thanks!
 >
 > Rick W.
 >
 >