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Re: What power am I using?
In effect you are pulse-width modulating the arc.
Imagine that the spark gap is a simple switch...
You have it ON for only a portion of the total
time, so obviously you will NOT be drawing current
during the OFF time.
If the spark gap was a pure switch with well-defined
ON and OFF points then the dwell time would be as you
mentioned... BUT... the arc can establish itself
BEFORE the electrodes line up, and then STRETCH the arc to
way AFTER the electrodes have passed each other. Net
result is a much longer connect time that you might think.
Fr. Tom McGahee
----- Original Message -----
From: Tesla List <tesla-at-pupman-dot-com>
Sent: Tuesday, June 06, 2000 11:26 PM
Subject: What power am I using?
> Original Poster: Toxandale-at-SPP-dot-org
> I have a question to throw out to the list for comments,
> interpretation, or advice. During testing on the power supply side of my
> coil, I was setting up my current limiting reactor to limit the current
> to 20amps. With the pole pig shorted out, I would draw 20 amps at 220vac
> (4.4kva). I then set up my RSG to be stationary across the pole pig, and
> again, I had a draw of 20 amps at 220vac with a power arc across the
> contacts (8 total in series). When I tested the power draw with the RSG
> motor turned on, to test the set-up at an unspecific speed, my current
> draw dropped to 5 amps -at- 240vac (1.2kva). I did not notice this with my
> older RSG contact wheel, which was very similiar is size, but differed
> in contact configuration. With the old wheel, there was no difference
> between the power arc reading and the rotating reading as far as power
> used was concerned. My question is why the big difference. Is it
> I have no tank circuit load on the xfmr and thus a reduced power
> draw (the contacts are the only thing across the xfmr at this point? If
> this is not a factor then are the power levels I see quoted on various
> coils the instantaneous reading or an average reading?
> The dwell time is greatly reduced with the newest set-up? On the
> old wheel I had a 1.1mS dwell time and twice the number of hits per
> revolution (16 contacts on the old wheel vs 8 on the new one), but on
> the new wheel, the dwell time is 130uS (5% of the wheel "time" is dwell
> Any tips would be greatly appreciated.
> Thanks ahead of time.