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>

A properly designed MMC will not fail due to overvoltage.  The MMC 
capacitors we use are self healing, so they won't fail from a single (or 
thousands) of overvoltages.  The manufacturers also "build in" a several 
times over rating on their capacitors.  The "Geek Caps" won't punch through 
until about 6000V, despite an official rating of 2000V!  Of course it would 
be somewhat foolish to abuse caps THAT much. ;)  The main safety gap across 
the NSTs (or filter) will also help protect the cap.

If you still want to use a safety gap across the primary capacitor, it is 
almost imperative that you add some series resistance to the gap.  Shorting 
a single "Geek Cap" at 2000V will give a peak current of about 10 times the 
maximum rated current (rated at 430A, discharge is about 4300A), which will 
lead to Cap Death in a hurry!

Regards,

Mark Broker
Chief Engineer, The Geek Group

On Sun, 10 Aug 2003 16:33:48 -0600, Tesla list <tesla-at-pupman-dot-com> wrote:

>Original poster: "Mudford, Chris by way of Terry Fritz 
><teslalist-at-qwest-dot-net>" <chris.mudford-at-agresearch.co.nz>
>
>Hi Gerry
>
>In what configuration would one set a safety gap across an MMC
>capacitor?
>
>Cheers, Chris (NZ)