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Re: Gap Losses

Tesla List wrote:
> 
> >From couturejh-at-worldnet.att-dot-netWed Sep 25 22:10:41 1996
> Date: Wed, 25 Sep 1996 22:08:02 +0000
> From: "John H. Couture" <couturejh-at-worldnet.att-dot-net>
> To: tesla-at-pupman-dot-com
> Subject: Re: Gap Losses
> 
> At 04:25 AM 9/25/96 +0000, you wrote:
> >From rwall-at-ix-dot-netcom-dot-comTue Sep 24 22:21:55 1996
> >Date: Tue, 24 Sep 1996 04:18:51 -0700
> >From: Richard Wayne Wall <rwall-at-ix-dot-netcom-dot-com>
> >To: tesla-at-pupman-dot-com
> >Subject: Gap Losses
> >
> >9/24/96
> >
> >Has anyone ever experimentally measured gap losses?  Where and in what
> >form is this energy lost from the primary circuit?  Is this energy
> >merely heat, light and other forms of EM energy?  Can it be measured
> >and analysed or is it merely assumed to be the difference between
> >energy input into the tank circuit minus energy coupled to the
> >secondary coil?
> >
> >
> >RWW
> >
> 
> Richard -
> 
> If you could measure this loss it is interesting to speculate on what you
> would find.
> In the Tesla Coil Notebook a computer printout is shown for a typical 1000
> watt input coil. The overall efficiency is 31 percent and the RMS voltage is
> 9020 volts. The maximum losses are, therefore, (1000)x(1-.31) = 690 watts.
> Assuming half of the losses are in the spark gap, the gap losses are 690 x
> .5 = 345 watts. If the current thru the spark gap is measured it should be
> about 345/9020 = .038 amps or 38 ma RMS. Is there anyone who would like to
> try this? I would be willing to send them a JHCTES computer printout on
> their coil to give them the necessary information for this test.
> 
> What are your comments? Do you have a better method of solving this problem?
> 
> Jack Couture


Jack, I think you are talking about averaged or RMS current here.  In a 
1000 watt coil, depending on the capacitor,input voltage, and gap 
construction, the current in the gap's arc channel should be as high as 
200 amps in a super system and as low as 50 amps in a poor one.  These 
are instantaneous values based on the capacitor discharge.  It is a very 
complex waveform of voltage and current across the gap.  It is not 
predictable or caluculable to a precise degree. 

 A really crude and imprecise value would to divide the peak input 
voltage(12.75KV) by the surge impedance (SQRT L/C) of the tank circuit. 
Let's assume .02ufd and a 40uh primary.  Zsurge=~45ohms... Thus Igap= 
285amps peak!  Peak impulse power = 3.6 megawatts! This will never 
happen!  The curent will always be far less due to a number of causitive 
agents.  (Gap impedance, distributed circuit losses, etc)  As a matter of 
fact for 99% of the time, the current will be zero (0).  A 1000 watt coil 
might expect 100 peak amps in the tank and a peak power of about a 
megawatt.

Richard Hull, TCBOR