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Re: Neon power draw, and resonant stresses.
From: Mad Coiler[SMTP:tesla_coiler-at-hotmail-dot-com]
Sent: Tuesday, September 02, 1997 6:50 AM
To: tesla-at-pupman-dot-com
Subject: Re: Neon power draw, and resonant stresses.
>From: Bert Hickman[SMTP:bert.hickman-at-aquila-dot-com]
>Reply To: bert.hickman-at-aquila-dot-com
>Sent: Monday, September 01, 1997 6:18 PM
>To: Tesla List
>Subject: Re: Neon power draw, and resonant stresses.
>
>Tesla List wrote:
>>
>> From: Mad Coiler[SMTP:tesla_coiler-at-hotmail-dot-com]
>> Sent: Friday, August 29, 1997 11:43 AM
>> To: tesla-at-pupman-dot-com
>> Subject: Re: Re[2]: Neon power draw, and resonant stresses.
>>
>> >From: FutureT-at-aol-dot-com[SMTP:FutureT-at-aol-dot-com]
>> >Sent: Friday, August 29, 1997 4:22 AM
>> >To: tesla-at-pupman-dot-com
>> >Subject: Re: Re[2]: Neon power draw, and resonant stresses.
>> >
>> >In a message dated 97-08-28 15:56:55 EDT, you write:
>> >
>> ><<
>> >> John, you have brought up an issue I had asked the list about and
>> never
>> >> got a response. You say "If it's value is such that it resonates
>> with
>> >> the leakage reactance of the neon trannie..." How is this
determined.
>> In
>> >> the designing phase how could one determine if this would happen?
And
>> >> does this stress the neon two much, or is it ok as long as the gap
>> fires
>> >> to discharge it?
>> >
>> >> Still resonating in Ohio,
>> >> Mad Coiler
>> >> >>
>> >
>> >Mad,
>> >
>> >I'm unable to find the formula, I was hoping someone would re-post
>> >it for you again. "does it stress the neon too much?"... depends on
>> >what you mean by too much. Certainly, it stresses it more than
>> >without resonant charging. Yes, by limiting the gap spacing, you
can
>> >limit the voltage across the trannie, and still obtain the benefit
of
>> >the increased current draw. None of my neons have yet burned,
>> >and I've been using this resonant method for years.
>> >(I did burn out a couple of neons...but that was when I used a
>> >non-sync rotary gap!)
>> >
>> >John Freau
>> >
>> >
>>
>> John, when I asked about the stressing thing my only concern is about
>> the neon - i mean will it eventually damage it. I see you haven't had
>> any problems burning up neons with this so you have answered my
question
>> about that. But about figuring the C for 60Hz resonance...
>>
>> Mad Coiler
>
>Mad Coiler and all,
>
>You'll achieve low frequency resonance when the inductive reactance of
>your neon(s) is "neutralized" by the capacitive reactance of your tank
>cap. For 15 KV neons, this works out to be just around 0.01 uF for
every
>60 MA of current if you are running off a 60 Hz power source. The tank
>capacitance will need to be about 20% higher if you run off a 50 Hz
>power source.
>
>For example, suppose your neon is a 15 KV 60 MA. It's effective output
>short-circuit impedance is:
>
> XL = 15000/0.060 = 250,000 Ohms (reactive).
>
>At an incoming line frequency F, your tank capacitor's capacitive
>reactance will be:
>
> XC = 1,000,000/(2*Pi*F*C) Ohms, where C is in uF
>
>Setting XL = XC, and solving for C:
>
> C = I/(V2*Pi*F)
> where:
> I = total sum of faceplate ratings of neon bank in MilliAmps
> V = faceplate RMS in Kilovolt for neon bank
> F = Incoming Line Frequency in Hz
> Pi = 3.14159
> C = in uFarad
>
> C = 60/(15*6.28*60) = 60/11,304
> = 0.0106 uF
>
>By plugging in the output RMS voltage and current for the neon
>transformer (or bank of neon transformers), you can solve for the
>appropriate tank cap value. Since this seems to be a question that
comes
>up fairly often, I've generated the tables below for 9, 12 and 15 KV
>neons banks for both 60 and 50 Hz sources for typical low and medium
>power ranges. Since the "Q" of the neon-cap LC circuit is fairly low
>(5-10 typically), if you're within about 15% of the ideal tank
>capacitance you'll encounter resonance effects. For example, the point
>at which the spark gap JUST begins to fire intermittently will be
>reached at a relatively low variac setting (about 15% on my system).
>Remember to keep your gap distances reasonable to avoid overvolting
your
>transformers or tank caps(!), and don't attempt to run the system with
>an asynchronous rotary gap.
>
> Bank (uF) (uF)
> Current 60 Hz 50 Hz
> -at- 15 KV: Tank Cap: Tank Cap:
> ======= ========= =========
> 30 MA 0.005 0.006
> 60 MA 0.011 0.013
> 90 MA 0.016 0.019
> 120 MA 0.021 0.026
> 150 MA 0.027 0.032
> 180 MA 0.032 0.038
>
> Bank (uF) (uF)
> Current 60 Hz 50 Hz
> -at- 12 KV: Tank Cap: Tank Cap:
> ========= ========= =========
> 30 MA 0.006 0.008
> 60 MA 0.013 0.016
> 90 MA 0.020 0.024
> 120 MA 0.027 0.032
> 150 MA 0.033 0.040
> 180 MA 0.032 0.048
>
> Bank (uF) (uF)
> Current 60 Hz 50 Hz
> -at- 9 KV: Tank Cap: Tank Cap:
> ======== ========= =========
> 30 MA 0.009 0.011
> 60 MA 0.018 0.021
> 90 MA 0.027 0.032
> 120 MA 0.035 0.042
> 150 MA 0.044 0.053
> 180 MA 0.053 0.064
>
>Hope this helps!
>
>-- Bert H --
>
Bert, thanks for the data. It will be most useful.
Mad Coiler