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Re: Joules - Vrms or Vp (fwd)
---------- Forwarded message ----------
Date: Wed, 29 Jul 1998 23:27:57 -0500
From: "Barton B. Anderson" <mopar-at-uswest-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Joules - Vrms or Vp (fwd)
Tesla List wrote: Subject: Re: Joules - Vrms or Vp (fwd)
> > Regarding the calculation for Joules..... J = 1/2 x C x V^2.
> > Should V = Vp or should V = Vrms? Why? (if you know).
> V = Vpeak, since that is the energy when the gap fires.
First, thanks to all who responded. I was *patient* to not reply
until I heard from quite a few on the list on this matter. The
question was derived from Terry's Coil data for my coil where Vp
was used to calculate 12.4J vs. what I originally calculated to
6J. The difference was of course, I was using Vrms instead of Vp.
Hence, "ask the List".
It is very apparent, that the joules we calculate for TC's is
dependent on our reference of time and energy. We could measure
voltage across the cap when the gap fires initially, or we could
view it as the energy available across the cap "prior" to the
firing, and still yet, we could view it in terms of energy
available minus losses after the bang.
I personally like Robert's and others expression that the energy
available at the time of firing is what should be determined. If
our gaps are not synched to peak firing, or our losses are
extensive, we should term these differently. It appears that the
V^2 is Vp^2 for all practical purposes. Possibly a separate energy
delivered rating is needed to separate efficiencies and losses
into the equation. Jsec.?
Thanks again to Greg, Richard, Stone, Dale, Antonio, Shaun,
Robert, and Terry for your responses and related responses. John,
Malcolm, and Bert, I would still be interested in your respected
thoughts on this subject either on or off the list. I know
efficiencies have played a major role in discussions in the past.
Bart