From: FutureT@aol.com
Date: Fri, 17 May 2002 14:46:30 EDT
Subject: Re: [TSSP] Racing arcs
--part1_99.2696eb76.2a16aa06_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 5/17/02 2:08:21 PM Eastern Daylight Time, paul@abelian.demon.co.uk writes: > for the -20% tuning. Notice how in the first 5uS both the primary > and secondary voltages are simultaneously large. Given a bad luck > choice of winding directions you could end up with quite a large pri- > sec voltage difference in the detuned coil. Consider this in the > context of Boris's potato shaped profiles. > > Note that when the same coil is tuned high, as in > > http://www.abelian.demon.co.uk/tssp/pn040502/tfsm1-h9.wave.gif > > the relative phase of primary and secondary voltages have altered. So > if you weren't getting pri-sec breakdown when tuned -ve, then you may > do when tuned +ve. Paul, Understood, and perhaps the pri-sec voltage stress might not actually cause an arc-over, but it may cause a sort of corona effect which may promote racing sparks on the secondary. I've noticed that any sharp point on the primary, can promote racing sparks on the secondary where it faces the sharp point. Just general overall pri-sec voltage stress may have the same effect perhaps. I think the actual coil behaviour matches the simulations too in the sense that tuning inward is more likely to cause racing sparks than tuning outward. I'll try tuning outward on my coil and see if I get racing sparks. I don't think I will. I should mention too that the various cases I saw in my coils where the notches didn't look well defined were all cases where the coils were actually tuned reasonably well. I may have been seeing some of the primary waveforms blending in the scope display of the secondary waveforms, and confusing the issue. John > > > I was thinking that maybe these out of phase conditions are causing > > an extra voltage stress between primary and secondary which is > > promoting racing sparks near the bottom of the secondary? > > I think you are right there. I guess some waveform plots of the > pri-sec difference voltage for the various tunings would do for a > start. My next job is to make a graph comparing those red-lines, > and to do some dV/dx animations, so I'll calculate the pri-sec also. > -- > Paul Nicholson, > --part1_99.2696eb76.2a16aa06_boundary Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 5/17/02 2:08:21 PM Eastern Daylight Time, paul@abelian.demon.co.uk writes:
for the -20% tuning. Notice how in the first 5uS both the primary
and secondary voltages are simultaneously large. Given a bad luck
choice of winding directions you could end up with quite a large pri-
sec voltage difference in the detuned coil. Consider this in the
context of Boris's potato shaped profiles.
Note that when the same coil is tuned high, as in
http://www.abelian.demon.co.uk/tssp/pn040502/tfsm1-h9.wave.gif
the relative phase of primary and secondary voltages have altered. So
if you weren't getting pri-sec breakdown when tuned -ve, then you may
do when tuned +ve.
Paul,
Understood, and perhaps the pri-sec voltage stress might not actually
cause an arc-over, but it may cause a sort of corona effect which may
promote racing sparks on the secondary. I've noticed that any sharp
point on the primary, can promote racing sparks on the secondary where
it faces the sharp point. Just general overall pri-sec voltage stress may
have the same effect perhaps.
I think the actual coil behaviour matches the simulations too in the sense
that tuning inward is more likely to cause racing sparks than tuning
outward. I'll try tuning outward on my coil and see if I get racing sparks.
I don't think I will.
I should mention too that the various cases I saw in my coils where
the notches didn't look well defined were all cases where the coils
were actually tuned reasonably well. I may have been seeing some
of the primary waveforms blending in the scope display of the secondary
waveforms, and confusing the issue.
John
> I was thinking that maybe these out of phase conditions are causing
> an extra voltage stress between primary and secondary which is
> promoting racing sparks near the bottom of the secondary?
I think you are right there. I guess some waveform plots of the
pri-sec difference voltage for the various tunings would do for a
start. My next job is to make a graph comparing those red-lines,
and to do some dV/dx animations, so I'll calculate the pri-sec also.
--
Paul Nicholson,
--part1_99.2696eb76.2a16aa06_boundary--
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.