Re: Cheap parts for high-power resistive ballast (for pole transformer). (fwd)

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Original poster: <sroys@xxxxxxxxxxxxxxxxx>



---------- Forwarded message ----------
Date: Thu, 2 Jun 2005 12:53:34 -0700
From: Dr. Resonance <resonance@xxxxxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: Re: Cheap parts for high-power resistive ballast (for pole
    transformer). (fwd)



For pole xmfr systems it's best to use an inductive external ballast.  An 
airgap of 1/16th inch is filled with a tight fitting piece of plastic and 
epoxied in place.  The gap is cut with a band saw.

Dr. Resonance
>
>
> ---------- Forwarded message ----------
> Date: Thu, 2 Jun 2005 08:26:40 -0700 (PDT)
> From: J. Aaron Holmes <jaholmes@xxxxxxxxxxxxxxxxxx>
> To: High Voltage list <hvlist@xxxxxxxxxx>
> Subject: RE: Cheap parts for high-power resistive ballast (for pole
>    transformer).
>
> (this thread is getting long...oh well, the list is
> pretty quiet, too)
>
> Okee dokey, I've got my new transformers.  Yes,
> there's an "s" on the end there; I picked up two.
> When I got down to the salvage yard and saw how big
> and heavy the 50kVA units were, I opted for two 25kVA
> units instead.  They'll do the same job but can
> actually be moved by a human :)  These 25kVA's are
> actually smaller (the cans, that is) than my old
> 15kVA!  They're also about 20 years younger, which
> probably explains it.
>
> Anyway, my intent when I picked up two was to run them
> in parallel (or series for nearly 30kV--another bonus
> to having two instead of one), but then I had another
> thought:  Several people have mentioned using
> isolation transformers together with heater elements
> to create a sort of hybrid resistive/inductive
> ballast.  That is, they talk about putting the
> elements in series with one side of the isolation
> transformer and the pig in series with the other side.
> Does this really offer any advantages?  Maybe for
> Telsa coil operation it could improve the rise time
> after the cap discharges...I suppose I can visualize
> that...but for a Jacob's ladder?  It's just a
> continuous short circuit, so I don't see how this
> isolation transformer arrangement accomplishes
> anything.  But I thought I'd ask.  Perhaps I could use
> the two low-voltage windings of one of the
> transformers kind of like an isolation transformer,
> with one winding in series with the heater elements
> and the other in series with the other pig.  It might
> work :)
>
> Regards,
> Aaron, N7OE
>
>
>
>