[Prev][Next][Index][Thread]
130kW Coil -- First Light
----------
From: richard hull [SMTP:rhull-at-richmond.infi-dot-net]
Sent: Saturday, January 31, 1998 6:09 PM
To: Tesla List
Subject: Re: 130kW Coil -- First Light
Greg,
Congrats on the first heavy firing! Wish I was there.
RH
>The output streamers, which extended outwards about
>2 to 3 electrode diameters (14 to 21ft), seemed much
>bushier than did my last coil, and exhibited a lot of
>simoultaneous branching from the main stem, much closer
>to the discharge electrode. Some of this arc appearance
>might have been due to my perspective however, as I was
>standing at the vault door, directly under the top sphere.
.................................
I would imagine this odd streamer behavior is due to the spherical terminal
shape. After all, no Tesla coiler has ever used a truely gigantic sphere. I
would imagine that the more even field distribution of the sphere is the
culprit. The toroid kind of focuses or intensifies the field to allow for
more controlled and directed output along a single axis. A smooth toroid
will break out much sooner than an equivalent capacity polished sphere. I
would imagine that until you get the power up a bit more, the sparks will
appear shorter per unit input power than a similar toroidial system
produces. (just a guess) RH
............................
>Several problems were discovered during this unscheduled
>trial run:
>
>Power Consumption - the mains power draw was about
>2.5 times what it should have been for this configuration.
>Current waveforms for the charging reactor were not
>available since the #-at-*! battery-powered Fluke Scopemeter
>kept turning itself off whenever the coil was energized!
>The excess power probably ended up in either the streamers
>or the rotary gap(more likely), as no excessive heat or
>flame were observed coming from any other components.
...................................
The added power might be that power required to uniformly power up the air
over the larger uniform surface area of the sphere. (A stab in the dark by
an old hand). The sphere is a virtually ideal terminal capacitor for
radiation with no controlled leaks like the toroid. A bit of power might be
sucked up in this radiative process long before spark appears. As you
wisely note, I would look at the gap first for the apparent loses, though.
I never liked the spherical terminal in all my Tesla coil activities. I
tried a bunch of them, too. Of course, I was after only maximized spark
length and did what ever worked best for me at the lowest power level. RH
........................................
>
>Shocks to Operator - I would get mild shocks from the
>control panel during operation, so using a distant ground
>as a reference, I checked the potentials on the panel
>case, and on my person.
>Result: panel - 10VAC RF, me - 400VAC RF!
>I was shocking the panel, as it turns out. Hopefully,
>the electric fields will be friendlier when panel and
>operator are 60ft distant. Otherwise some vertical
>screening may be necessary at the control panel.
....................................
Yeah, I know what you mean. With that nice uniform and intense field
producing sphere, a ground rod driven into the dirt half way will have
gradients all along it!...Even in the earth!
Nemesis in its most powerful form and with the largest toroidial terminal,
used to shock anyone in the lab who touched or brushed against anything
metallic! It once ignited a jar full of fine zirconium turnings 20 feet
away on a shelf by induction! (no sparks ever came near it.)
Big terminals cause severe local fields which will amaze those unprepared
for them. Tesla noted such effects in the CSN. RH
.............................................
>These problems will have to be addressed before the
>main xfmrs can be configured for delta-star (hi-gear).
>Once the machine appears to ready for high-power
>testing I'll let the List know, for the benefit of
>any 'potential' visitors.
>
>
>-GL
>
>
>
I wish you well in the coming phases of your experiment. Thanks for sharing
the updates with us.
Richard Hull, TCBOR