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RE: Disc Construction
Reinhard,
You're comment about the start/stop of the actual spark not coinciding with
the mechanical dwell is correct.
Note-This spreadsheet was intended as a tool to get the mechanical
components in the ballpark and not necessarily a representation of the
electrical behavior.
As for the offset. Let me see if I can explain it without resorting to
ASCII...
Take a simple rotor, equally spaced rotating electrodes, and two fixed
electrodes (one on each side of the rotor). The offset would be the
centerline difference (if any) in the two fixed electrodes.
If the fixed electrodes are in line with each other then the mechanical
dwell will be maxed and determined by the speed of the rotating electrode
and it's diameter. If you offset the centerline of the fixed electrodes
(without changing any other parameters) you will reduce the dwell since the
overlap will be less.
Regards,
Brian D. Basura
-----Original Message-----
From: Tesla List [mailto:tesla-at-pupman-dot-com]
Sent: Thursday, May 06, 1999 7:17 AM
To: tesla-at-pupman-dot-com
Subject: Re: Disc Construction
Original Poster: "Reinhard Walter Buchner" <rw.buchner-at-verbund-dot-net>
Hi Brian,
>Original Poster: "Basura, Brian"
<<mailto:brian.basura-at-unistudios-dot-com>brian.basura-at-unistudios-dot-com>
>The RSG Dwell Time spreadsheet is now available at:
><http://fp2.hughes-dot-net/brianb/download.htm>http://fp2.hughes-dot-net/brianb/do
wnload.htm
I downloaded your XLS sheet. It is very similar to what I use in my
HBTC program. However there are two things:
1.) You make the assumption, that the arc start/stop takes up no dwell time.
This is a major problem (I donīt have a solution for it, either), because
the
arc will jump before the gaps line up and will continue after the gaps
seperate.
In order to consider this time "zero", you would have to incorperate a very
high rpm motor and / or big disk diameter (the speed of the electrodes has
to be VERY high). Otherwise, the arc time is much longer than your proggy
suggests. Finding the time that the arc stays on (= time before alignment+
time during alignment+time after alignment) isnīt that easy. It depends on
electrode size (the larger the ROC, the faster the time is) and shape. I
donīt know of any simple formula that will allow one to accurately calculate
this (although the Sim guys out there probably could make a simulation to
predict results),
2.) What do you mean by center to center offset? Do you mean this:
(use courier to view)
RSG A with no center offset:
X
X X
X
RSG B with center offset:
X
X X
X
Arrgh! I hate ASCii. It doesnīt come out like I want it to. In
RSG "A" you can "connect" the electrodes to form a cross
where the lines intersect exactly in the center of the disc. In
RSG "B" the line intersection is not in the center of the disc.
Is this what you mean by offset? If so, I donīt think this
would be wise, because the disk will rotate off-balance and
you be getting different firing angles for each electrode. If
this isnīt what you mean, could you please explain what
"offset" means.
Thanks and coiler greets from germany,
Reinhard