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Re: Inductive Kick LTR Pig Systems
Hi Jeff,
On 26 Aug 00, at 16:51, Tesla list wrote:
> Original poster: "Jeff W. Parisse" <jparisse-at-teslacoil-dot-com>
>
> > for 10kVA input. The problem is the power factor is really bad! Do
> people
> > use PFC caps with pig systems?? I assume the "limit" of such a system is
> > the AC line current available. PFC caps may do wonders for getting more
> > bang for the same current. PFC cap could easily pull that power factor
> > right in.
>
> I believe most people use inductive ballast (i.e. series variacs or welders)
> on pig systems. Can't inductors also be used to correct power factor? I'm
> guessing the power company uses cheap oil and paper PFC caps on the
> pole because it is cheaper than inductors on the pole (weight and money).
>
>
> Jeff
Inductors can be used if the load has a capacitive component.
Any power factor correcting scheme has the aim of making
whatever is hooked to the supply appear to be a pure
resistance so that current draw is in phase with voltage and
proportional to it. IMO, a pig coil with a cap which is mains-
resonant with the ballast (transformed) should not require
much if any PFC since the mains is seeing a resistive (series-
resonant) circuit most of the time punctuated by transient
appearances of L(ballast) when the gap fires. It would be
interesting to model this and see how much PFC capacitance
should be added to average out the spikes of L that appear at
BPS.
By the same token, I would have thought a similar
consideration should apply to a NST (or should it?). For
example, I use a paralleled pair of 15/60's on occasions,
sometimes with a resonant cap and other times with an LTR cap.
The variac grunts and heaves with no PFC applied but with a
modest 60uF or so, things are very calm. That is a lot less
capacitance than I've read about others using.
What do others think? What are your experiences?
Regards,
Malcolm