Re: All pain no gain

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

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-uswest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hello Jan,
On 7 Mar 01, at 7:26, Tesla list wrote:

> Original poster: "Jan Wagner by way of Terry Fritz
> <twftesla-at-uswest-dot-net>" <jwagner-at-cc.hut.fi>
<snip>
 
> What I personally still haven't figured out  is where to connect the
> NST center tap... ?!

There is only one place. It's connected to the case internally and 
the case should always be grounded to the mains. That is exactly what 
the designers of the transformer intended. The idea was to prevent 
one side of a floating secondary arc-earthing itself to the case 
through insulation and raising the other side to full secondary 
potential relative to the case (and ground). It probably also assists 
in striking large neon tubes by providing some increased capacitance 
between the tube and surrounding fixtures (guess). 
 
> * to mains ground => no galvanic isolation between HV secondary side
> and primary side, 40kOhm wire resistance HV->GND not nice (8kV 50mA
> NST with 40kOhm secondary means 200 mA could flow). * to RF ground =>
> rf leaking to primary & secondary connected to high current primary
> which makes it even more deadly if you do what you should not do (in
> any) case i.e. touching the megawatt pulsed streamers * to no ground
> => just nice, no probs, NSTs are well insulated to handle 8kV between
> case and mains primary

That piece says it all.

Malcolm