[Prev][Next][Index][Thread]
Re: A few questions...
Tesla List wrote:
>
> Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
>
snip...
>
> This shows how a computer can simulate the electrical signals inside a
> Tesla coil. many of us use MicroSim's demo program. This is a 16 Meg
> program that can be downloaded from the Orcad site (Orcad bought MicroSim).
> See:
>
> http://www.orcad-dot-com/products/pspice/eval.htm
> or
> http://unicorn.sch.bme.hu/~kisza/microsim/microsim.html
>
You can also get the demo version from my site:
http://tesla.better-dot-org/files.cfm . The reason I mention this is because
the unicorn site is terribly slow (for me, anyway, 3-5K/sec), and
because the Orcad site requires you to fill out one of those annoying
personal info forms. Mine is fast and doesn't require forms :)
> >
> >4) If I have a choice between a single capacitor with the correct uF and
> >voltage ratings or an MMC what are the advantages/disadvantages to one over
> >the other, besides cost, adjustability and availability does the MMC have
> >anything going for it?
>
> A Tesla coil is pulsed with giant spikes that can reach 1000 amps many
> times every second. Even though the spikes may get to 1000 amps, the RMS
> or equivalent DC current level is around 15 amps. Thus, the cap has to
> dissipate the heat internally that a 15 amp current would create. Since a
> MMC has an internal resistance of say 0.06 ohms, the power dissipated would
> be 15^2 x 0.06 = 13.5 watts. That may not sound like much power but to a
> plastic cap with 20kV across it can be a lot. If you change the cap to a
> paper dielectric, the internal resistance may go up to 2 ohms. 15^2 x 2 =
> "BAD" :-))
>
In doing lifetime expectancies in the engineering world is it considered
ok to use RMS values and not consider the size and/or frequency of
voltage and current "swings"? It seems to my lay mind that a cap in a
15 A RMS near-DC situation would last much longer than the same cap in a
15 A RMS wildly-oscillating scenario such as TC use.
-Stan