[Prev][Next][Index][Thread]

Re: Secondary Coil Electrostatic Charge

Date:          Tue, 19 Mar 1996 08:37:50 +0700
From:          tesla-at-grendel.objinc-dot-com
To:            73663.1536-at-compuserve-dot-com, BrittB7556-at-aol-dot-com, JOHNBATES3-at-aol-dot-com,
               abourass-at-red-lake.lakeheadu.ca, atech-at-ix-dot-netcom-dot-com,
               davide-at-mailhost.accesscom-dot-net, gpaul-at-mgl.ca, jbiehler-at-teleport-dot-com,
               jfalcon-at-getnet-dot-com, jmonty-at-sat-dot-net, kg7bz-at-whitemtns-dot-com, logue-at-uis.edu,
               osburnw-at-UTKVX.UTCC.UTK.EDU, pinsky-at-acc-dot-net, rmessick-at-dttus-dot-com,
               rnicker-at-quartz.idbsu.edu, rwstephens-at-host.ptbo.igs-dot-net,
               shu95mmc-at-reading.ac.uk, stevej-at-dji-dot-com, yiorgos-at-ix-dot-netcom-dot-com
Subject:       Re: Secondary Coil Electrostatic Charge

>From jim.fosse-at-bdt-dot-com Tue Mar 19 01:18 MST 1996
>Received: from bdt.bdt-dot-com (root-at-bdt-dot-com [140.174.173.10]) by uucp-1.csn-dot-net (8.6.12/8.6.12) with SMTP id VAA10856 for <tesla-at-grendel.objinc-dot-com>; Mon, 18 Mar 1996 21:47:30 -0700
From: jim.fosse-at-bdt-dot-com (Jim Fosse)
To: tesla-at-grendel.objinc-dot-com
Subject: Re: Secondary Coil Electrostatic Charge
Date: Tue, 19 Mar 1996 04:27:50 GMT

tesla-at-grendel.objinc-dot-com On Mon, 18 Mar 1996 08:32:03 +0700, you
wrote:


>Hello Everybody,
>
>I am Robert Stephens and new to this group.  I've been following your 
>mail exchange for the past week with interest.  The subject of 
>electroststic charge being deposited on the surface of the TC 
>secondary winding has been an interesting topic of discussion over 
>the past few days.  I see that several of you now have surmised the 
>correct mechanism of storage of this charge (dielectric polarization, 
>and to a lesser degree static surface charge of the insulation on the 
>secondary windings), but can anyone explain WHY an alternating 
>current high voltage source like a TC can charge dielectrics 
>(capacitors) just like a Van de Graaff generator?  
>
[snip]
>-a properly coupled TC with a well designed top load terminal, even a 
>large coil driven to multi megavolt levels will have hardly any 
>secondary residual surface charge after a good run.
>-an overcoupled secondary will develop firecracker hot areas of 
>surface charge in a specific zone, or zones along its length.  This 
>occurs in those areas where the coil will begin to arc across its own 
>windings if pushed hard enough.
>
YES, I've observed the same - 10 hemisphere => charge 28" toroid => no
charge.

[snip]
> IF YOU TRY THIS SAME 
>EXPERIMENT WITH A VAN DE GRAAFF GENERATOR INSTEAD OF THE 
>SPARK GAP DRIVEN T.C. YOU WILL GET EXACTLY THE SAME EFFECT!
>
>The answer to this phenomenon is hidden in the term DAMPED SINUSOID.  
>There, I just gave it away.
>
Robert,
	Given a damped wave form: at some point, the damped waveform
is to weak to cause a discharge. That leaves the previous half cycle's
charge on the object.

	jim

>>Jim Fosse,

>>You're almost there, but it has nothing to do with an actual 
>>discharge (corona).   That first 180 degrees of the big whallop that 
>>comes off the top of the TC (corona or not) goes either positive or 
>>negative depending on when you look at it in reference to the 
>>charging polarity of the system capacitance.  Let's say it goes 
>>positive +100%.  During the second 180 degrees of the first RF cycle 
>>it will swing negative,  but since we're dealing with a 'damped 
>>sinusoid' it has already diminished in amplitude, so it goes negative 
>>say only -70%, it then goes positive again maybe to + 40% and then 
>>negative to -20% and then quickly dies out.  That big initial whallop 
>>of +100% followed by an opposite or partially cancelling -70% high 
>>voltage waveform leaves a residual DC charge on dielectrics in its 
>>immediate area.  If that 100% represents 1 megavolt (easily achieved 
>>with a modest 15KV 120MA neon powered system), then that +30%
>> residual is 300,000 volts DC!  At these kind of voltages even the
>> microscopic capacitance represented by a small section of plastic dielectric
>> on the outside of the secondary winding  can store enough charge to give 
>>a person a nasty shock!
>>Note that a vacuum tube powered Tesla coil which operates in CW,
>>generates a continuous wave train of equal amplitude, SYMMETRICAL RF
>> sinusoids and that this type of TC does not demonstrate this residual DC
>> static charging effect, on its own secondary or on nearby surfaces.

>>Happy coiling, R.W.S.