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Re: [TCML] PFC Question (again)--more
We did not use the resistors on the Big Bruiser --- only the air core choke
which was a 4" ID PVC tube. On all future machines we use both the chokes
and resistors. We always ground one leg using a pole xmfr as then we only
have to make one filter for a single hot leg.
DC
On Thu, May 29, 2008 at 10:39 PM, Jim Mora <wavetuner@xxxxxxxxx> wrote:
> Hi DC,
>
> Are all the resistors and the air coil on one leg? I seem to remember Big
> Bruiser had a slightly longer choke, but I don't remember the resistors or
> where they were mounted.
>
> Thanks,
> Jim Mora
>
> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
> Of DC Cox
> Sent: Thursday, May 29, 2008 8:20 AM
> To: Tesla Coil Mailing List
> Subject: Re: [TCML] PFC Question (again)--more
>
> This is another reason why even pole xmfrs should have some transient
> protection. I use a network of 12 parallel resistors, 600 Ohms each, 200
> Watts, in series with the output. After the resistor network I always use a
> 3" ID x 10" long air core choke wound with #14 600 volt PVC wire. This is
> insulated from ground on a pair of stand-off insulators. I have this data
> in schematic form is anyone should need it.
>
> I know many people don't but good engineering practice dictates they
> should. Even robust pole xmfrs don't like harsh transients for long
> periods
> of time. Lightning strikes, by contrast, are very short duration as
> compared to running a xmfr for 1-2 minutes.
>
> Dr. Resonance
>
> On Wed, May 28, 2008 at 10:00 PM, bartb <bartb@xxxxxxxxxxxxxxxx> wrote:
>
> > Hi John,
> >
> > Your right. The inductive ballast on PIGs and PTs do change the LTR/STR
> > scenario. I however always look at this as based on the transformer
> alone.
> > But your right, the ballast changes that scenario. Even though JAVATC
> states
> > that LTR is intended for internally ballasted transformers such as NST's,
> I
> > still personally look at LTR as a general transformer situation (which I
> > probably should not). You've done well to point out the issues. This
> isn't
> > the first time! We've been down this road in the past as you know. I
> agree
> > with all you've said in this post and in the other posts that I missed
> out
> > on replying (had to take wife to hospital the last couple days, so TCML
> was
> > just not possible).
> >
> > Anyway, great postings on this subject. I could not agree more. But I
> will
> > say that all of us (you included) really don't know if PIG's are truly
> > running LTR, STR, near or at resonance. I've always assumed STR given my
> > personal situation and how I likely relate to the coiling world. The fact
> > is, we might be running STR. When you hit that STR value near 1.4, your
> > basically riding the edge of resonance, but just enough to allow a little
> > voltage calming. Were all likely hitting that area. I honestly doubt LTR
> in
> > pig (just a hunch). Not just from a massive cap size scenario or even the
> > ballast inductive affect on what is or is not LTR, but the fact that when
> > you run a coil in slight resonant charge mode (always near resonance in
> > either direction), there are always some good sparks to be realized if
> > there is sufficient "power" regardless.
> >
> > I run STR on a small coil and get great spark lengths, but I have the
> power
> > in the transformer to make it happen. This would not have been possible
> if
> > the coil was not running near resonance at a 1.4 ratio. Well, maybe I
> speak
> > too soon. I haven't tried a larger ratio and maybe I should. But, it does
> > incredible for it's situation. Who's to say that Kevin's larger coil
> would
> > not do as well scaled appropriately. That is my rub. Even though PIG's
> and
> > PT's are externally ballasted (not always), doesn't indicate that they
> must
> > be running LTR. They can certainly be running well in STR mode as well.
> BPS
> > is certainly part of their efficiency, but when it comes to power and
> > sparks, efficiency isn't always the winner. Considering the costs and
> size
> > of components, it's probably economical to do the great spark lengths
> > inefficiently. I hate to say that (as I'm into alternative energies and
> the
> > like), but the cost of reality probably dictates that situation more than
> > anything else.
> >
> > My bottom line is that I'm not sure and I'm pretty sure no one else is
> > either. If I had the resources and funds, I would strive for efficiency
> in
> > spark length. I know you would also. We all would if we could.
> >
> > Bart
> >
> > FutureT@xxxxxxx wrote:
> >
> >> In a message dated 5/27/2008 4:22:54 P.M. US Eastern Standard Time,
> >> FutureT@xxxxxxx writes:
> >>
> >>
> >>
> >>> David,
> >>>
> >>>
> >>
> >>
> >>
> >>> I didn't do the calcs lately but I think it's close to resonant,
> >>> maybe slightly LTR. He's running at 120 bps. At 120 bps,
> >>> you pretty much have to use resonant or LTR to get good power
> >>> throughput.
> >>>
> >>
> >>
> >>
> >>> John
> >>>
> >>>
> >>
> >>
> >> Also (adding to my posting here). Resonant and LTR have a
> >> different meaning for pig and PT coils than for NST coils. For an NST
> >> coil the resonant sized cap or LTR value cap is
> >> a certain value. For a pig or PT coil, the setting of the ballast
> >> determines if the coil operates in STR, resonant, or LTR mode.
> >> At the pig or PT's rated power, there may be a particular value
> >> cap for LTR or resonant. But such a coil can be run at more
> >> or less than it's rated power. For example at 120 bps, a small cap
> could
> >> be
> >> installed on a pig coil, a certain amount of ballast can be cranked
> >> in to make it resonant, and it will run, but at less than the
> >> transformer's rated power. For example let's say the resonant
> >> value is 0.3uf. A cap of only 0.03 can be installed, and the correct
> >> amount of ballast can be cranked in to give resonant operation,
> >> and the coil will run. It won't draw much power, and sparks will
> >> be short, but it will be running in resonant mode. Also an "LTR"
> >> value cap can be installed on the pig coil, and the needed ballast
> >> can be cranked in to give resonant operation. Perhaps the
> >> transformer will draw twice it's rated power, but it will still be
> >> able to operate in resonant mode, despite having an "LTR" value
> >> cap. Sparks will be very long in this case. In any case resonant
> >> operation depends a lot on the ballast setting for pig and PT coils,
> >> unlike for NST coils which have a fixed leakage inductance, and
> >> a fixed resonant cap value. If a pig or PT coil is run with a small
> >> cap at high bps, then the ballast L has to be reduced to let in
> >> more power (if long sparks are desired). Then the coil is truly
> >> running in STR mode.
> >> John
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >> **************Get trade secrets for amazing burgers. Watch "Cooking with
> >> Tyler Florence" on AOL Food. (
> >> http://food.aol.com/tyler-florence?video=4&?NCID=aolfod00030000000002)
> >> _______________________________________________
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> >>
> >>
> >>
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> >
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