Re: Why does running an NST on an async gap kill it?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Mark Broker by way of Terry Fritz <teslalist-at-qwest-dot-net>" <mbroker-at-thegeekgroup-dot-org>

I can personally attest that the MOVs will fail if you don't set (forget) 
to properly set the safety gap....

The wirewound resistors in Terry's filter design do have a fairly large 
inductance.  I remember trying to measure it once (the 1kohm, 100W 
Ohmites), but the RLC meter I was using had issues with the large 
resistance, and wouldn't give me reliable results.

Another aspect of async gaps killing NSTs is that when used in conjunction 
with near resonant sized capacitors, resonant rise can overvolt things if 
the gap fails to fire due to falling on a voltage null.  I would expect a 
good "Terry" style filter and LTR capacitors to significantly reduce NST 
deaths from use with async gaps.

Cheers,

Mark Broker
Chief Engineer, The Geek Group


On Thu, 07 Aug 2003 17:27:42 -0600, Tesla list <tesla-at-pupman-dot-com> wrote:

>Original poster: "Lau, Gary by way of Terry Fritz <teslalist-at-qwest-dot-net>" 
><gary.lau-at-hp-dot-com>
>
>The so-called Terry filter actually has two functional components:
>1) The R-C (not R-C-L) filter forms a low pass filter, attenuating high 
>frequencies.
>2) The MOV's and safety gap form a clamp to limit the maximum voltage to 
>the NST.
>
>The R-C filter alone can't do anything to limit the voltage in the event 
>that the gap is not firing.  The MOV's might help, but they're not 
>designed to absorb too much energy, and they might burn out.
>
>Gary Lau
>MA, USA
>
>-----Original Message-----
>From: Tesla list [mailto:tesla-at-pupman-dot-com]
>Sent: Thursday, August 07, 2003 11:38 AM
>To: tesla-at-pupman-dot-com
>Subject: Why does running an NST on an async gap kill it?
>
>
>Original poster: "Zagarus Rashkae by way of Terry Fritz 
><teslalist-at-qwest-dot-net>" <arbitrarily_random-at-yahoo-dot-com>
>
>Hi All,
>
>I think I pretty much phrased the entire question in
>the subject line :)
>
>Is there anything one can to to protect the NST from
>damage? Wouldn't an RLC filter like a Terry filter
>protect the NST from spikes?
>
>Thanks,
>
>Chris Lu
>