Re: PFC capacitor rating

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

Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla123-at-pacbell-dot-net>

Hi Godfrey,

I have to disagree. All transformers could use a little power factor
correction including externally
ballasted pole pigs regardless of current limiting type. The amount of
correction required for best
efficiency will vary (some may show no benefit if PF is already high). I
think there are 2 myths
floating around:
1 - that inductive ballasting will correct the power factor.
2 - that if the power factor were corrected, inductive ballasting would
screw it up.

For 1 above, increasing current via inductive ballast will reduce the
"ballast + transformer series
inductance - slightly".  This reduces L, but it doesn't really "adjust for
efficiency". It may "appear"
to as one typically finds an area on the ballast where the coil runs best,
but that could be a lot of
possibilities. Some have reported reduced output on each side of the
ballast position where the coil
runs best. I have not experienced this in this way. There is a position on
the ballast where the coil
does run best, but as I move beyond that value, the system is given more
current until it begins to act
as if it is overcoulped (which it probably is) - but no decrease in spark
length. The sparks continue
and can grow until racing sparks start, ballast gets hot, etc.. One
possibility for the ballast
position may be more to do with the ballast itself - but just a passing
thought.

Anyway, it could probably run more efficienctly with the correct C value
added for the "ballast +
transformer".

For 2 above, if the correct amount of C is added to include the "ballast
position inductance", then 2
above won't apply.

My bottom line: The transformer adds an inductive reactance. The ballast
adds additional inductive
reactance. Reducing the additional inductance to "half it's value" can't
provide power factor
correction for best efficiency.

I'll be the first to admit that I've got a pole pig and I have yet to add
PFC. I am window shopping
however. I just need to find something in the neighborhood of 700VAC caps
for 240V operation (ballast
transients).

Take care,
Bart

Tesla list wrote:

> Original poster: "Loudner, Godfrey by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <gloudner-at-SINTE.EDU>
>
> Hello Steve
>
> PFC is not needed for non-shunted transformers like pole pigs. Shunted
> transformers like neon sign transformers need PFC.
>
> Godfrey Loudner
>
> > -----Original Message-----
> > From: Tesla list [SMTP:tesla-at-pupman-dot-com]
> > Sent: Thursday, May 30, 2002 12:15 AM
> > To:   tesla-at-pupman-dot-com
> > Subject:      PFC capacitor rating
> >
> > Original poster: "Steve White by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> > <slwhite-at-zeus.ia-dot-net>
> >
> > I want to use some motor run caps that I have to provide PFC for my 10 KVA
> > pig-powered coil. The caps are rated at 370 VAC, so the voltage rating is
> > fine
> > for 240 VAC power. What I am wondering is do these capacitors have enough
> > power
> > handling capacity? There is no KVAR rating on these capacitors, only
> > voltage
> > and capacitance. They are GE motor run caps and are about 6" tall. What
> > sort of
> > PFC caps do other people use for their pig-powered coils?
> >
> >