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Re: Doubling NST voltage? (fwd)



Original poster: List moderator <mod1@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Sun, 29 Oct 2006 15:27:17 -0500
From: Mike <mike.marcum@xxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Doubling NST voltage? (fwd)

The reason most nst's 7500v and up are midpoint grounded is it halves the 
insulation requirement (lowers cost). To series them this would have to be 
moved to 1 of the ends, doubling the voltage stress at the free end. Doable, 
but alot of work and wouldn't last long (potting in oil instead of tar would 
help). If you really need 18kV from a current limited source take a 15 kV 
nst and run it at 150v from a  variac. Only trouble with this is right at 
the edge of core saturation which could be a problem.

Mike
----- Original Message ----- 
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Sunday, October 29, 2006 11:44 AM
Subject: Re: Doubling NST voltage? (fwd)


> Original poster: List moderator <mod1@xxxxxxxxxx>
>
>
>
> ---------- Forwarded message ----------
> Date: Sun, 29 Oct 2006 07:49:21 -0800 (PST)
> From: C. Sibley <a37chevy@xxxxxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: Re: Doubling NST voltage? (fwd)
>
> It seems to me that if the cases were isloated and ungrounded this would 
> work, and the voltage across each NST wouldn't exceed their individual 
> output.  The higher voltage would only exist across both, and would stress 
> the individuals.  What am I missing?
>
> Curt.
>
>
> ----- Original Message ----
> From: Tesla list <tesla@xxxxxxxxxx>
> To: tesla@xxxxxxxxxx
> Sent: Sunday, October 29, 2006 7:04:18 AM
> Subject: Re: Doubling NST voltage? (fwd)
>
>
> Original poster: List moderator <mod1@xxxxxxxxxx>
>
>
>
> ---------- Forwarded message ----------
> Date: Sat, 28 Oct 2006 15:46:31 +0100
> From: resonance <resonance@xxxxxxxxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: Re: Doubling NST voltage? (fwd)
>
>
>
> No this will not work.
>
> The tar-like insulation in the nsts will quickly break down.
>
> NSTs are really only designed to operate at 12 kV for 1/4 sec to ionize 
> the
> gas in a neon tube.  Then the voltage drops back to approx 500 volts and
> they serve as a constant current source to keep the gas ionized in the 
> tube.
> They are not designed to provide HV for a long period of time.  They do 
> this
> in Tesla coil service but are constantly being strained in this 
> operational
> mode.  Double the voltage will not work.  Also, you can't hook them in
> series because the center is grounded --- you would need two xmfrs without 
> a
> center-tap grounded configuration to accomplish this task.
>
> Dr. Resonance
>>
>> Is it possible to connect my NST's in series, for double the voltage? 
>> I've
>> run them in parallel before for the ma's, but I'm wondering if setting
>> them in series is do-able. If this has been done before, is there 
>> anything
>> I need to do re: grounding, connecting, or whatever with their cases?
>> FWIW, I'm thinking of using a couple of 9/30's. I don't have 220v
>> available at my workbench, so I'd have to stick with 110v, if that's an
>> issue. Thank you all in advance, for any info you might have.
>>
>> Neal.
>>
>>
>>
>
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>