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RE: srsg idea to prevent losses



Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Gary.Lau-at-compaq-dot-com>

Actually, it IS necessary to have a spark as the conductor in a spark gap.
It has to do with quenching, or when the gap stops conducting.  In a spark
gap, conduction ceases at one of the primary notches, when all of the
primary energy has been transferred to the secondary side.  A spark "knows"
when to stop conducting by virtue of the gap current, when it reaches a
minimum.  A mechanical contact's on-duration is dictated strictly by the
mechanics of the design and it would be nearly impossible to design it so
that the switch opens with microsecond accuracy just at a primary notch.
If the on-time was too long, the energy would slosh back and forth between
the primary and secondary, wasting energy in the gap and other loss mechanisms.

Of course, the fact that the contacts will arc in the "normal" fashion well
in advance of mechanical closure means that the above is purely academic.
Also, rotary contacts spinning at 1800 or 3600 RPM with zero clearance
between them will guarantee an electrode crash.

Regards, Gary Lau
MA, USA

 -----Original Message-----
From: 	Tesla list [mailto:tesla-at-pupman-dot-com] 
Sent:	Wednesday, March 20, 2002 2:55 PM
To:	tesla-at-pupman-dot-com
Subject:	Re: srsg idea to prevent losses

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Colin,

Since the voltage across the gaps is high, they will tend to arc over about
1/4 inch before the contacts actually touch.  Depending on the speed of the
electrodes, the firing process my be all finished by the time the contacts
actually do touch.  Maybe like 0.0003 second.  Even a fast 3600 RPM gap
will only move the electrodes 6.5 degrees in that short time.  So I think
early firing from high voltage arcover will be a big problem.  However, it
really can't hurt and may be better anyway as far as losses go.  The actual
"spark" in the gap is totally unneeded and only wastes power.  The problem
is it is hard to get rid of ;-)

Cheers,

	Terry


At 04:09 PM 3/20/2002 +0000, you wrote: 
>hi all,
>        im concidering an idea with my rotary gap and would like to run it 
>by you all
>now it could be totally stupid or it could work
>let me know what you think
> 
>im going to run my gap without spark gap but instead have the rotor 
>electrodes touch a spring loaded contact so it brushes by it when running
>i have achieved the actual building of this unit but just wondered whether 
>it needs to spark to work
> 
>i was hoping this would reduce losses in the spark
>i am a newbie to all this only 4 months and have two coils my best putting 
>out 4'
> 
>please let me knoew what you think of this idea
>many thanks 
>colin haeth
> 
>