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Re: Rotor BPS

Subject:      Re: Rotor BPS
       Date:  Fri, 30 May 1997 22:27:51 -0700
       From:  Bert Hickman <bert.hickman-at-aquila-dot-com>
Organization: Stoneridge Engineering
         To:  Tesla List <tesla-at-pupman-dot-com>
 References:  1


Tesla List wrote:
> 
> Subject:     Re: Rotor BPS
>       Date:  Thu, 29 May 1997 18:39:58 -0500
>       From:  Chuck Curran <ccurran-at-execpc-dot-com>
>         To:  Tesla List <tesla-at-pupman-dot-com>
> References:  1
> 
> Tesla List wrote:
> >
> > Subject:  Re: Rotor BPS
> >   Date:   Mon, 26 May 1997 18:45:14 -0600
> >   From:   "DR.RESONANCE" <DR.RESONANCE-at-next-wave-dot-net>
> >     To:   "Tesla List" <tesla-at-pupman-dot-com>
> >
> > To: Gary Weaver
> >
> > RSG with 10 -12 electrodes running non-synchro at 1800 RPM on a 12" dia.
> > wheel seem to work fine from 6-15 KVA.  The air generated by the 1/2
> > dia.
> > electrodes whirling around seems to do a fine job of quenching.  With
> > larger coils it is very important to elevate the sec. for best coupling.
> > We run some of our systems with up to 4-8 inches of elevation above a
> > flat
> > copper tubing spiral.  Not much performance gain noted at 3600 RPM.
> >
> > Hope this helps out.
> >
> > DR.RESONANCE-at-next-wave-dot-net
> >
> 
> Hello DR. RESONANCE, Richard Hull & All:
> 
>         I have a question that I hope can be directed at both of you and
> the
> group based on comments by you,  read over the last month or so.  First,
> a short update on my situation--I've basically made little progress on
> my new coil due to the record cold and rain in south eastern
> Wisconsin--worst since 1888!
>         O.K., the point made in the post above, about the secondary
> being 4-8
> inches above the primary and I believe Richard also mentioned something
> about 3-4 weeks ago that led me to understand most of the time you
> avoided raising the primary above the very bottom of the
> secondary---that is where I am real curious.  On my 8" dia. secondary
> from last year I first tuned it with the flat primary and secondary
> bottom turn on the same plane, running around 6 KW input.  I started to
> raise the primary in 1/2" increments believing the coupling and K would
> increase resulting in a better spark.  This took place over a 2 week
> period with the primary ending up about 3 1/2" or so above the bottom
> turn of the secondary.  I attempted to run the autotransformer to the
> same point for a comparison between each test point.  I believed at that
> time that the most intense and longest spark (80"+) was occurring at
> that 3 1/2" point.
>         Now I'm sitting here with my 15 1/4" diameter by 58" long
> secondary
> that has been collecting mostly dust for 5 weeks.  I must set up outside
> to run this puppy and I've been a bit shy doing this in the rain at 42
> degrees (F).  I finally corrected an electrical power unit difficulty (
> I'll skip that story for now) and last week got a few dry moments to run
> it's third test, which resulted in classical primary/secondary
> overcoupled type of arcs.  I had raised the primary to about 6 or 7
> inches above the bottom secondary turn to achieve a measured K of .25
> right from the start with the result being wonderful arcs from primary
> to secondary with no toroid breakout so I quickly shut it down.  The
> very first test gave 6-8 foot arcs and blew a fuse with no arcs.
>         Finally the question-- my present understanding is that you must
> be,
> based on the posts be elevating the secondary to a point where your K
> must drop down to a low level, guessing maybe .08, or .12???  Have I
> missed the boat here?  I had expected with what I had learned in working
> with my 8" coil tuning process that raising the primary would provide
> better output, assuming the system design allowed for the greater K.
> Now the discussion is suggesting another point that I don't have a clear
> view/understanding of right now.  Boy, I only have 3" of clearance right
> now when I roll it out of the garage and that's without the toroid!
> What I am wondering is that with the bigger coils, is there less
> attention to the K value and more to eliminating pri/sec arcs by
> increasing clearances?  I have a 2 1/2" air gap between the pri/sec
> windings and thought this would be O.K.
>         They are actually predicting that the rain will stop (I really
> don't
> believe it) and it will reach 75 Degrees F this weekend.  I have dropped
> the primary to be on the same plane as the lowest/first turn of the
> secondary and plan to smoke test this weekend.  If the mood strikes you,
> any comments would be of interest.  Thanks in advance!
> 
> Chuck Curran
> Cedarburg, WI

Chuck and all,

Chuck, you've built a very well-crafted, beautifully made system! After
having the oportunity to see your coil a couple of weeks back, I can
understand why you might be seeing the higher coupling factor. The
larger diameter primary is sharing more flux lines with the secondary. A
k=0.25 is still too high for most 2-coil systems. If you lower this to
the 0.18 to 0.22 range, you should be in the right ballpark. If you
still get arc-overs from the bottom section of the secondary to the
innermost primary turn, some additional rolled LDPE sheeting may be in
order, or you may want to remove another inside primary turn. 

Once you get this beast tweaked in, it is going to really haul!! Good
luck, Chuck!

And... safe coiling to you!

-- Bert --