RE: Over-voltage at Synchronous Gap ? ? ?

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

Original poster: "Malcolm Watts" <m.j.watts-at-massey.ac.nz> 

Hi Terry,

On 15 Sep 2003, at 20:08, Tesla list wrote:

 > 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.

I would be interested to see that statement quantified by facts and
figures. The ringdown time in the primary vs the cap charge time is ??

Malcolm

 > 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.
 >
 >
 >