[Prev][Next][Index][Thread]

Re: Tesla Coil Power Factor

Hi Terry,
           A quick comment on one point:

> Original Poster: Terry Fritz <terryf-at-verinet-dot-com>
> 
> Hi John,
> 
>     I have posted 6 more pictures at:
> 
> www.peakpeak-dot-com/~terryf/tesla/misc/
> 
> They are john01.jpg to john06.jpg.  I refer to them below.
> 
> At 10:15 PM 9/19/98, you wrote:
> >
> >  Terry -
> >
> >  I believe your results with the power factor tests of your coil are an
> >excellent example of how the PF test can show how well your coil is
> >performing. The higher the PF the better the coil is working. A perfect
> >performance would be close to 100% PF. At this stage there would be very
> >little reactive power returning to the source (electric utility co).
> >
> >  For example, with your coil you obtained the following:
> >
> >  .285 PF - gap not firing - large amount of reactive power returning to
> >source.
> >
> >  .49 PF - gap firing - less reactive power returning to source.
> >
> >  ,675 PF - gap firing and output sparks - much less reactive power
> >returning to source.
> >
> >  Estimated .80 plus PF ? - gap firing - controlled output sparks - very
> >little reactive power returning to source.
> >
> >  You may want to try the estimated .80 PF test using horizontal continuous
> >sparks from the toroid to a ground point that is connected to the secondary
> >coil ground. This test might also take some adjustments of the operating
> >gap and the tuning/coupling.
> 
> John01.jpg shows the input voltage and current with a horizontal arc to
> ground as shown in john04.jpg.  The phase difference is 2.5mS which gives a
> power factor of 0.588 .  
> 
> Consider this:  If my 15000kV/60mA transformer were to deliver all of it's
> 900 watts to the coil, each bang (at 120 BPS) would need to contain 7.5
> joules (900/120).  So I would have to charge the primary cap up to 7.5
> joules for every bang.  At 21213 volts peek, the capacitor would have to be
> 33.33nF.  Almost impossible to charge with a neon.  I can charge a 19nF max
> to that level without resonant charging which would give 4.275 joules or
> 513 watts for a total efficiency of 513/900 or 0.57.  So by this method it
> is almost as perfect as it can be.  However, this isn't quite true...
> explained below.
> 
> >
> >  I checked out your imp.003.jpg etc waveforms but had trouble interpreting
> >them. However, they are excellent photos and were easily printed out. I
> >would like to see the top waveform as the primary coil voltage and the
> >bottom waveform as the secondary coil voltage. This should show the pri
> >waveform as a dampened wave going to almost zero indicating all the energy
> >is being transferred to the sec coil. 
> 
> John02.jpg and john03.jpg show this situation.  John02.jpg is to a 1 foot
> arc and john03.jpg is to the grounded target.  The bottom trace in both
> pictures is the output voltage of the secondary at 200kV/div.  the top
> trace is 10kV/div in john02.jpg and 20kV/div in john03.jpg.  I worry that
> the grounded target case may not be realistic.  The arc occurs before the
> secondary is fully charged.  In fact the coil has not quenched before the
> arc starts.  This is not very realistic of how most people run their coils.

I submit that it is. If a coil can't start launching an arc by the 
time the secondary has fully rung up, it is unlikely to do so, quench 
or not. In fact, there is a hint of a suggestion from some tests that 
allowing more than one beat can actually assist in this process as 
amplitude can peak a second time and be a bit higher than a straight 
ringdown a bit further down the track if the primary is good. One can 
see this by superimposing quenched over non-quenched waveforms on the 
scope. Certainly, my best coil/s run like this. 

     Further expts with good quenching gaps show me at least that the 
quench comes at the expense of increased primary loss.
     I tried two ways: loosening coupling which reduced beats before 
quench. I also tried more gaps in series. Initial amplitude with more 
gaps was down on what it was with fewer. I was able to superimpose 
previously captured waveforms with those taken subsequently with 
different ks, gaps etc and there were definitely additional losses 
occurring. Output spark also showed a drop which corresponded exactly 
with losses the scope was showing. Since the tests were done under no 
breakout conditions, spark was measured bu encouraging strikes to a 
ground rod positioned such that strikes were consistent with 
different coil settings.
 
> > >The sec waveform would show the rising waveform as the energy is
> >transferred. At the peak the wave would collapse when the output spark
> >occurs. There would then be little or no energy left to feed back to the
> >primary and then to the source. 
> 
> John06.jpg shows this situation and why there is almost always some voltage
> left.  Gaps quench when the current across them reaches zero.  Since
> voltage and current are 90 degrees out of phase, the voltage is at a peak
> when the quench occurs.  John06.jpg shows that almost 1/4 of the energy is
> left in the primary due to this reason.  A substantial loss indeed!
> Perhaps fine tuning could reduce this effect but this is definitely a
> considerable source of energy loss and is responsible for the gap never
> quenching just when we would like it to.  Much work to be done here!
> 
> >
> >  I believe the PF test and the waveforms could tell you exactly how your
> >coil is performing. You could then make changes and determine if they
> >improved the performance. I have never heard of any coiler who has
> >coordinated these tests.
> 
> It ain't easy!  John05.jpg shows the test setup just so no one thinks I
> just make this stuff up ;-)
> 
>     Terry Fritz

Thanks for more fine experiments.

Malcolm