Re: PFC capacitor rating

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

Original poster: "Crow Leader by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla-at-lists.symmetric-dot-net>

Below is a pic to go along with the PFC talk everybody has.

Below is a link to a pic pretty much showing the power factor of my air
conditioner with the compressor running. The solid line is the line voltage
and the fat noisy line is the line current. As you can see, the phase
between the two does not match. You can see that the current lags the
voltage. Any mismatch is just power flowing back and forth across your
wiring that is doing no real good work except heating your wires.

http://users.symmetric-dot-net/kkanno/images/Krodak-airconditioner-power-factor.
jpg

As the the AC voltage reverses you an slearly see that the AC unit is
dumping current back into my outlet  again, a wasted flow of electricity.
Capacitors are the opposite of inductors (AC motors) and they fight each
other resulting in circulating currents between themselves, and not your
outlet

I'll see if I can dig find the same pictures after I attach some caps to the
AC plug that makes the waveforms match up better. In this case, I was able
to drop the current the AC unit pulled by just about 2amps with PFC
capacitors installed. They will pull extra current themselves when there is
no inductance to cancel them out (compresssor off).

KEN


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, May 31, 2002 9:03 AM
Subject: Re: PFC capacitor rating


> 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?
> > >
> > >
>
>
>
>