RE: [TCML] Are safety gaps necessary? TerryFilter MOVs

["Lau, Gary" <Gary.Lau@xxxxxx>]

Please explain why you use 9 MOV's per side with a 12KV NST?  The recommended configuration for a 12kV NST is 7 per side.  Using more than the recommended number is like setting the safety gap too wide; the clamping voltage will be higher than what is safe for the NST.  Or does the use of chokes somehow alter MOV behavior? ;-)

That you had no NST failures does not mean that the filter is properly designed.  It means only that you didn't open up the main gap too wide.

Gary Lau
MA, USA

> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of DC Cox
> Sent: Friday, June 20, 2008 8:30 PM
> To: Tesla Coil Mailing List
> Subject: Re: [TCML] Are safety gaps necessary? TerryFilter MOVs
>
> I use 9 MOVs in each leg with 12/60s.  No nst failures, but I also use air
> core chokes on the other end of the filter.
>
> Dr. Resonance
>
> On Fri, Jun 20, 2008 at 10:40 AM, b alex pettit jr <a_pettit_jr@xxxxxxxxx>
> wrote:
>
> > On a related topic,
> > How may MOVs are required for safe operation in the
> > Terry Filter ?
> >
> > I have 8 per leg for the 12KV/60ma - just used the
> > full set of MOVs provided in the kit, maybe too many ?
> >
> > Since they are rated at 1800v, 6000/1800 = 3.33
> > per side, but seems as if most use many more than that ... ??
> >
> > Whats the consensus ?
> >
> > Thanks,
> > Alex P
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