Re: Capacitor Size and BPS

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "C. Sibley" <a37chevy@xxxxxxxxx>

Thank you, exactly the advice I was seeking.  I had
pretty much decided upon .06 to .09 uF on my own,
sounds like I'm in the ball park...

Curt.

--- Tesla list <tesla@xxxxxxxxxx> wrote:

> Original poster: "David Rieben"
> <drieben@xxxxxxxxxxxxxxx>
>
> Hi Curt,
>
> The size of your capacitor will be determined not
> only by the size of your transformer and its ability
> to readily recharge the capacitor after each
> discharge
> cycle but also by the chosen BPS. 120 BPS is not the
> "magic" number
> BTW, unless you're intending
> upon running in synch mode (assuming 60 Hz mains
> frequency). For our friends in Europe with 50 Hz
> mains service, 100 BPS would be the proper set-
> ting for synchronous operation. Many pig coilers opt
> to run
> asynchronous with a variable speed DC motor driven
> rotory gap. Many
> find optimal BPS ranges in the 200 to 400 BPS range
> when running
> asynch. Obviously, you wouldn't be able to effective
> charge a larger
> capacitor as well running say
> 300 BPS as opposed to running 120 BPS with a given
> transformer size,
> so the synch rotary gapped coils (SRSG) often do
> employ a larger
> primary capacitor than an equally rated
> asynch rotary gap driven coil. If you plan to
> operate your
> 5 kVA, 11" coil synch, I would suggest at least .1
> uFd for
> the primary capacitor size and you may want to go
> somewhat (but not a
> lot) smaller for the capacitor if running asynch,
> maybe
> .05 to .075 uFd, depending how high BPS you intend
> to run.
> Higher BPS doesn't offer as much energy per bang but
> since you're
> firing more bangs per second, the total output power
> will still be
> similar to the synch 120 BPS and the available power
> from the
> transformer is the limiting factor. Many coilers
> note increased spark
> length by increasing the BPS with an asynch driven
> coil,
> within reason. Emperical research has shown that
> there isn't any
> advantage by running BPS higher than 500 to 600 and
> the output
> spark length actually begins to go down for a given
> input power
> when BPS ranges are pushed beyond that. Besides
> that, very high
> BPS rep rate is VERY hard on the primary capacitor
> ;^0
>
> Also, because of the relatively large size of
> capacitor that would
> be required for LTR with a pig transformer, many
> pole pig coilers
> keep their primary caps smaller than resonant (STR),
> even when
> running synch. With a 5 kVA, 14.4 kV pig,  Bart
> Anderson's
> Java Tesla coil designer program shows .167 uFd as
> LTR for a SRSG
> driven coil and a "mere" .096 uFd as LTR for a sta-
> tic gap driven coil, although a static gap would not
> be a good idea
> for processing that much power (BIG quenching
> problems).
>
> Good luck with your project and keep us informed of
> its progress.
>
> David Rieben
>
>
> ----- Original Message ----- From: "Tesla list"
> <tesla@xxxxxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Sent: Friday, December 23, 2005 1:43 PM
> Subject: Capacitor Size and BPS
>
>
> >Original poster: "C. Sibley" <a37chevy@xxxxxxxxx>
> >I'm trying to get a better understanding of the
> >appropriate size capacitor for a Pole Pig driven
> coil.
> >  Obviously a larger capacitor will give a bigger
> bang,
> >but too big will charge too slowly and may not
> achieve
> >120 BPS.  As I understand it, 120 BPS is the magic
> >number, anything lower essentially means charging
> >cycles are missed and total power transfer is less?
> >Correct me here if I'm wrong...
> >So I'm seeking advice on capacitor size for a 5KVA
> 11"
> >Coil.  Any advice?
> >Thanks,
> >Curt.
>
>
>
>



		
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