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RE: Arc length vs pwrRe: Arc length vs pwr
At 04:25 AM 10/2/96 +0000, you wrote:
>From gowin-at-epic-1.nwscc.sea06.navy.milTue Oct 1 21:46:43 1996
>Date: Tue, 1 Oct 1996 08:17:53 -0000
>From: Dan Gowin <gowin-at-epic-1.nwscc.sea06.navy.mil>
>To: "'tesla-at-pupman-dot-com'" <tesla-at-pupman-dot-com>
>Subject: RE: Arc length vs pwr
>
>
>
>----------
>From: Tesla List[SMTP:tesla-at-poodle.pupman-dot-com]
>Sent: Saturday, September 28, 1996 5:25 PM
>To: Tesla-list-subscribers-at-poodle.pupman-dot-com
>Subject: Re: Arc length vs pwr
>
>>From couturejh-at-worldnet.att-dot-netSat Sep 28 14:51:15 1996
>Date: Sat, 28 Sep 1996 17:22:14 +0000
>From: "John H. Couture" <couturejh-at-worldnet.att-dot-net>
>To: tesla-at-pupman-dot-com
>Subject: Re: Arc length vs pwr
>
>At 04:25 AM 9/27/96 +0000, you wrote:
>>From 100624.504-at-CompuServe.COMThu Sep 26 22:18:21 1996
>>Date: 26 Sep 96 14:27:22 EDT
>>From: Alan Sharp <100624.504-at-CompuServe.COM>
>>To: Tesla List <tesla-at-poodle.pupman-dot-com>
>>Subject: Re: Arc length vs pwr
>>
>>> Several years ago I went thru this process and published a graph in the
>>>Tesla Coil Design Manual. The graph was made from data I had collected from
>>>over three dozen coils built by myself and other coilers. The data was
>>>converted by math regression into equations that could be made into graphs
>>>and used by a computer.
>>
>>I'd be interested to know what spark lengths are achievable at say
>>500W, 1KW, 2KW, 5KW and 10KW with 2 coil and magnifier systems.
>>
>>Arc length to grounded rods please - no fish stories.
>>
>>Give me something to aim at with the MOSFET's.
>>
>>Alan Sharp (UK)
>>
>
>Alan -
>
>The TCD Manual graph shows typical Tesla coil spark lengths vs wattage as
>follows:
>
>500 w/11 in, 1 KW/20 in, 2 KW/32 in, 5 KW/64 in, 10 KW/110 in
>
>The graph is for classical coils only and the curve is non-linear. The spark
>lengths are for horizontal sparks from a toroid to a ground point. I do not
>have enough information presently available to make a meaningful graph for
>magnifiers or tube and solid state Tesla coils. In the TCD Manual I
>guesstimate that the theoretical spark length for magnifiers would be up to
>about 1.5 times the classical coil length. However, I have not seen data to
>indicate this is possible when rigid test comparisons are made.
>
>Note that the spark lengths shown by the graph can vary greatly depending on
>several factors. For example, spark lengths for the same wattage are greater
>with pole transformers than for neons. Also, the spark lengths are increased
>when the Tesla coil primary voltage and/or the secondary coil inductance are
>increased, etc. These variables are taken into consideration by the JHCTES
>computer program.
>
>Hope this helps.
>
>Jack Couture
>
>
>Mr. Couture,
> This can't be correct. My current coil uses a 1KW (9KV+120Ma)
>neon sign transformer with .03 uF of tank capacitance. My secondary
>is 4.5" dia with 937 turns of 24 AWG magnet wire. My secondary inductance
>is 19.88988 MH. And my toriod capacity is about 12 pF. My Resonate
>frequency is 252 KHZ and my max sustained spark length is 30". My max
>strike distance measured is 35-36". Unless my neon is not shunting the
>current correctly, there is something incorrect about these calculations.
>
>D. Gowin
>
>Dan -
The spark length data represents a typical Tesla coil. Your coil is not the
typical
coil that is represented by the graph. As I mentioned above the spark length
can be
increased by increasing the inductance of the secondary coil which you have
done.
There are many other possibilities.
The spark length (output) of a Tesla coil is represented by the equation
Output = Input - Losses All units in energy
Your coil is obviously well built and has less losses than the typical coil.
Most of the losses are in the primary spark gap, primary capacitor, and
secondary
coil windings. The resistance of the primary wiring and connections also can
cause
more than average losses. Homemade primary capacitors can cause big losses.
Your coil is 1000 watts and gives a 2.5 foot spark. This is a rating of
1000/2.5 ft = 400 watts per foot of spark. The typical coil rating for this
size coil
is 1000/1.7 ft = 588 watts per foot of spark. This rating system offers a
convenient
method to indicate the overall efficiency of Tesla coils. For example, a
graph is
shown in the Tesla Coil Notebook for Percent Efficiency vs Watts per foot of
Spark.
The graph shows about 50% efficiency for your coil compared to about 32% for a
typical coil of this wattage..
There are several ways the efficiency of Tesla coils can be represented but
this
method has the advantage that differences in both losses and improvements
for the
same wattage are taken into account.
Let me know if you have other questions.
Jack Couture