Re: Overvolting an NST? (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Fri, 19 Oct 2007 21:29:24 -0700
From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Overvolting an NST? (fwd)

I've run NST's with variacs over their input rating every time. What 
kills an NST is overvolting the NST's secondary windings. Keep the cap 
proper LTR or you'll kill it. 125% isn't that high if 1.6 or larger LTR. 
It's when you don't design for the higher voltage that you run into 
problems. For Ben's situation, if he designs for 1.6 x Cres for his tank 
cap, he will be ok at the 300 Vac input. If he short-changes that value 
(1.5, 1.4, 1.3, x Cres), then it gets risky. If the cap is large enough, 
he shouldn't have a problem, similar to those of us in the US who run a 
120V NST's at 140 Vac via a variac (and most of us have been 
successful). The cap size is important with an NST, but less important 
for more robust transformers like PT's and PIG's. Running LTR in the 
first place was all about keeping NST's healthy and is what allowed a 
slight higher voltage on the input side. An extra 60 volts on the input 
is only 3750 Vac more on the secondary. The windings can take it as long 
as it doesn't resonate. I know NST's are "cheaply" built, but they do 
have some margin (not a lot, but some).

Take care,
Bart

Tesla list wrote:
> ---------- Forwarded message ----------
> Date: Fri, 19 Oct 2007 19:36:02 -0700 (PDT)
> From: G Hunter <dogbrain_39560@xxxxxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: Re: Overvolting an NST? (fwd)
>
> If I get a vote, I say don't overvolt the thing--not
> if you want it to last very long.
>
> NSTs are cheaply made sign ballasts, not really
> designed to handle their own data plate voltage rating
> for any length of time.
>
> My $.02 worth,
>
> Greg
>
> --- Tesla list <tesla@xxxxxxxxxx> wrote:
>
>   
>> ---------- Forwarded message ----------
>> Date: Sat, 20 Oct 2007 09:55:17 +1000
>> From: Ben Buxton <bb@xxxxxxxxxx>
>> To: tesla@xxxxxxxxxx
>> Subject: Overvolting an NST?
>>
>>
>> How high can the primary of an NST safely go before
>> risking damage? I've
>> got a 240 to 15kV NST (60Ma) and my variac can give
>> me up to 300volts on
>> the primary. Can I push it this far or would the
>> tolerance be lower?
>>
>> -- 
>> Ben Buxton - Random Network Person
>>
>>
>>
>>
>>     
>
>
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