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Re: [TCML] BPS Testing

Hi Gary,
Yes, I agree about NST output current and exactly why I wanted to get your thoughts on it. The input was simply "easier" from an insulation standpoint, but I can also measure output current. I'll just use GTO cable to pass through the current loop and add some extra hv insulation as a safety factor (it has a 2" diameter hole so this should be no problem).
Your Vcap measurement is fine and no way there's a distortion on the vertical axis only at those instances. You do bring up an interesting observation about the surge of reduced voltage bangs not resuming from zero, but I expect they are and what were seeing across the screen appears superimposed onto a lower frequency (thus a little wavy and the scopes vertical zero is probably floating up and down a little). Hard to really make out in this particular sample. 

Take care,
Bart

Lau, Gary wrote:

OK, I understand your 11% increase now.  The English language is just lacking in BPS adjectives ;-)

Regarding measuring input current and BPS - I'm not sure that monitoring the 120VAC input current would reveal anything.  I think the more telling measurement (though any data is good) will be in the NST secondary current, which IS the cap charging current.  I believe that the assumed high current charging surges that we think occur when the gap fires in quick succession, is due to stored energy from an unspent bang in the NST inductance.

The Vcap waveform at http://www.laushaus.com/tesla/measured_waveforms.htm clearly shows that the quick-succession bangs occur at a much lower voltage than normal bangs.  This is consistent with the theory that Vgap is reduced immediately following a bang, and I can't imagine any reason that my measurement would have a distorted vertical axis only at certain times.  What I cannot explain is why the voltage at the end of the reduced voltage bangs does not resume charging from zero, as the full bangs do.

Regards, Gary Lau
MA, USA


-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
Behalf Of bartb
Sent: Monday, March 17, 2008 9:00 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] BPS Testing

Hi Gary,

Yes I did cause confusion. I was talking about the ratio of extra breaks
that occurred from a calculated value. I noticed that the ratio of extra
breaks increased by 11% and that is what I was trying to get across. But
as I read my own writing, I realized it would cause confusion so I was
trying to clarify (apparently that attempt failed also). I was just
curious if we would see a greater percentage of those "quick" breaks
with higher voltage and the answer is yes. Does that help? I now want to
explain those quick breaks.

I'm curious on your thoughts about measuring input current and bps at
the same time on two analog inputs. Any change in current would be time
stamped with these fast breaks. I can use the Pearson current monitor
and run the BNC output directly to the acquisition device. So if high
current peaks occur at these fast breaks, we can be sure current is the
cause and the best answer to that at this point is ferro resonance. But
if the current isn't involved with these breaks, then it is likely lower
voltage arcs and those are likely due to the breakdown voltage reduction
(ions). Even NST output current is an option here.

Take care,
Bart

Lau, Gary wrote:

Hi Bart,

I'm confused - When you say the firing rate increased by 11%, isn't that the same

as saying that the BPS increased by 11%?  I think most would interpret it as such.

Regards, Gary Lau
MA, USA


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