Re: Bumping, power arcs, 60Hz resonance
Subject: Re: Bumping, power arcs, 60Hz resonance
From: "Robert W. Stephens" <rwstephens-at-ptbo.igs-dot-net>
Date: Sat, 23 Mar 1996 13:02:34 -0500
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Subject: Re: Bumping above 40%
>From mrbarton-at-ix-dot-netcom-dot-com Thu Mar 21 01:19 MST 1996
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>Date: Wed, 20 Mar 1996 21:04:30 -0800
>From: mrbarton-at-ix-dot-netcom-dot-com (Mark Barton)
>Subject: Re: Bumping above 40%
>If the bumping you are referring to is the same thing I have
>experienced at higher power levels, the explanation is a simple one.
>You are drawing power arcs. That is, the gap is doing a poor job of
>quenching at high power levels and the transformer is briefly arcing
>through the primary system.
I saw your entry here and I wanted to comment on this and discuss
another matter with you as well.
You are quite right. Power arcing in the system at the spark gap
can definitely cause bumping. It was my point to Richard Quick in
response to his individual and unique sounding situation that the 60Hz
resonant condition in the supply circuit was a different cause of 'the
bumpies' which would require a different approach to solve, than those
conditions and solutions linked directly to pure power arcing.
The gross overvoltage condition on the system capacitor as a result of power
transformer resonant saturation could easily be the cause of a rapid death for this
expensive component if not found out and dealt with in short order. I am not
aware that power arcing (meaning the gap can no longer quench properly and
ends up placing an effective dead short across the transformer output for longer
dwell times than normal, and with greatly exagerated timing errors) can endanger
system components with the same instant brutality as 60Hz resonance
overvoltage. I would welcome your further comments, or those of others in
the group on this subject.
I have a medium sized system running now which exhibits power arcing
in the rotary break above about 2.5 KW. I only have slow air from a
squirrel cage blower on the gaps presently, but by 'jerry rigging'
with air hoses I find I can solve all traces of power arcing up to
the system's power limit of about 4500 watts by using fast air from a 6.5 amp
Lamb vacuum cleaner blower directed at both contact junctions. It also helps
to cool the stationary stainless steel electrodes which quickly turn bright
orange when power arcing begins. At this power level I don't think
it is worth the trouble to add an extra stationary quench gap in
series with the rotary break, but I definitely plan to do this as
the next addition to my larger 16 KW system which starts to power arc, even
WITH high speed air at about 10-11 kilowatts input.
On the other note, I saw your posting of pictures and notes about your
large coil project as available on Bill Beatty's page -at-eskimo-dot-com.
That was quite an impressive undertaking! I was not on this net when you were
building this machine so I am not aware of the discussion which I can
only assume must have taken place. I'd be very interested in
learning more about your system, most specifically the amount of
power you have successfully processed, your own experiences with the
gap (I assume you went rotary), and the ultimate streamer lengths achieved.
I have plans to build a very high power two coil system some day when I can
obtain sufficient financial sponsorship.
Since the goal is always to strive to push the state of the art,
anything I can learn from other people's triumphs and failures will
be of help. Thanx.