RE: Over-voltage at Synchronous Gap ? ? ?

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

Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>

Hi Gary,

Normally the primary system is "loaded" by the secondary system which 
actually burns most of a system's power.  If the secondary is miss-tuned, 
or removed in the extreme case, the power will have no where to go.  Thus, 
it is possible for the primary voltage to resonate to higher than normal or 
expected values.  Nowhere near the 80kV of an uncontrolled resonate system, 
but enough to false fire safety gaps.

In a sync rotary gap system, firing voltage is not controlled by a fixed 
spark gap voltage  but rather "timing" alone.  If the voltage increase 
occurs when the gaps out of firing position, there is nothing to stop an 
increase in voltage other than the safety gaps.

Sync LTR systems can be pretty sensitive to tuning, gap timing, and 
coupling.  If the tuning is off, dramatic primary to secondary arcs can 
occur.  Poor timing can draw much more line current and blow fuses that we 
are supposed to be using.  Coupling can affect quenching, racing arcs, and 
primary voltage adding to the confusion.

So....  Sometimes it is just best to work at say 1/4 or 1/2 power and 
re-tune everything just right if odd things are going on.

Cheers,

         Terry


At 09:38 PM 9/15/2003 -0400, you wrote:
>Hi Terry,
>
>Can you expand on your statement below, which I've highlighted in
>all-caps?  I can't imagine a situation where the primary voltage
>increases after the gap fires, regardless of tuning.
>
>Thanks, Gary Lau
>MA, USA
>
>
> >Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>
> >
> >As Kurt showed, maybe you need slightly more MMC capacitance.  If you
>are
> >not using a Terry filter and don't have some of the same losses
>involved,
> >results may vary a little.  I would just add a little capacitance to
>the
> >primary cap till things quiet down.  If you are using a 0 - 140VAC
>variac,
> >that may over voltage things a bit too.  Tuning may be an issue as
> >well.  IF THE SECONDARY SYSTEM DOES NOT USE UP THE POWER >PROPERLY, IT
>MAY TEND TO RAISE THE PRIMARY VOLTAGE UP.