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Re: Sparklength inquiry
JohnF, Greg, Bart -
Apparently we all agree with the fact that the TC spark length is related
to input power. However, we differ in how this relationship varies with
power. For example the following listing compares the JohnF streamer sparks
with the JHCTES controlled spark lengths.
Power Input JohnF JHCTES
680 W 42" 15"
2100 W 64" 35"
8400 W 128" 97"
10 KW 15' 9.3'
26 KW 25' 18.3'
33.6 KW 21' 23'
67 KW 31' 38'
109 KW 45' 55'
134 KW 42' 64'
538 KW 84' 180'
Note that both curves cross at about 33.6 KW with a 21 and 23 ft spark
length. The streamer sparks are longer below this level and shorter above
compared to the controlled sparks. The JHCTES data is from the computer
program and the Fig 2 graph in the TC Design Manual. This graph is based on
power levels to only 60 KW and has been extended to higher power levels
without actual test confirmation.
Both curves are based on actual data from coilers and should be
consistent in their relationship which they are not. The streamer spark
curve should show a constantly longer spark length and the controlled spark
curve should show a constantly shorter spark length. There obviously is
something wrong with one or both curves. Also the data is assuming the coil
is operating at best efficiency which may not be the condition.
It should be noted that the square root curve flattens out and ends up
with very little increase in spark length regardless of power input. This
would make a lightning bolt a couple miles long almost impossible? The
average lightning bolt has about 150 joules of energy.
As both curves are based on limited coiler data the only way to solve the
problem is to collect more data from coilers. I agree a good survey would
be useful. Who is going to do the 538 KW test?
John Couture
--------------------------
At 04:18 AM 9/24/98 -0600, you wrote:
>Original Poster: Greg Leyh <lod-at-pacbell-dot-net>
>
>> Original Poster: FutureT-at-aol-dot-com
>
>> I posted the square law suggestion some time ago, based on my
>> results with the sync gap coils in which I obtained 42" sparks using
>> 620 watts, and 64" sparks using 1570 watts. I was relating input
>> power to spark length. I then scaled up the spark lengths using the
>> square law, and your 25' spark TC fit well on the curve. This
>> posting was before I improved the efficiency of my coils, the old
>> figures were:
>>
>Power input (revised) spark length toroid dia (inches)
>> 680 W 620W actual 42" 20
>> 2100 W 1570W actual 64" 30
>> 8400 W 6280W 128" 60
>> 33.6kW 25kW 21' 120
>> 67kW 31' 240
>> 134kW 100kW 42' 480
>> 538kW 400kW 84' 960
>> 1.6MW 168' 1920
>> ***new** 5.1MW 300'
>
>> I noted in my posting above that this chart was created before I
>> improved the efficiency of my coils. I added a new column in the
>> chart above, and plugged in the values for my present efficiency
>> of my coils (see chart). Using these new values, I show a need
>> for only 5.1MW to develop the 300 foot spark, which by coincidence(?)
>> agrees exactly with your figure.
>>
>> John Freau
>
>Here's another correlating datapoint for your curve --
>At the NZ site, Electrum produced a 40 - 45ft ground strike
>(observed 3 times) with 109kVA on the main transformers.
>There's this one particular plant (called a 'flux' plant?!)
>that seems to attract strikes, when the wind is right.
>
>My two coils land pretty close to the square-law curve
>that is defined by your two coils.
>And Ed's halfwave coil lands fairly close as well, beating
>the revised curve by about 20%. But a halfwave coil should
>be more efficient at producing spark length -- since the spark
>channel is supported at both ends, the ends of the spark need
>be only as thick as the base of a single spark half its size.
>
>So with 5 data points that span over 7 octaves of power,
>it would seem that a simple square-law is a good fit.
>
>Can it be that easy? Here's where a good survey would
>come in useful.
>--
>
>
>-GL
>www.lod-dot-org
>
>
>
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