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Re: Toroid = shorted turn ?
Has anyone used a "non-shorted toroidally-shaped" top electrode?
Imagine a sheet metal toroid. Now cut it into pie slices (without changing the
position of the metal).
Is should look like a "slinky" spring that has
a- been shaped into a toroid
b- been held in that position by a rigid insulator
c- had each turn cut from the next so that there is no continuous turn around
the axis of the TC itself
It would seem that, if the turns of the spring are numerous enough, the
electrical field around the device would be very like the continous toroid and
still avoid the short-circuit effect.
By the way, the bad effects of the short circuited turn are not only the
heating of the electrode -which is likely to big enough to dissipate the heat
by convection without harm-, but the lower efficiency the TC overall would
have because of the energy loss involved, as well as a marked (?-just
guessing) broadening of the resonant peak. (Of course, this last might help
in the adjusment procedure by making it less critical, even so, it goes
against a designer's grain to knowingly do this)
Boy, I wish I had a scanner!! Describing in words what would have been so easy
in a sketch is quite a job...
Federico Price
San Pedro, N.L., Mexico
Tesla List wrote:
> Original Poster: "R M Craven" <craven-at-globalnet.co.uk>
>
> <SNIP>
>
> >>found we didn't need it for corona suppression after all. I've never
> >>noticed a top
> >>toroid having a heat problem, but our top loads have always had a center
> >disk.
> >
> >Right. It *looks* like a turn, but if there's a conductive center disk,
> >it's *electrically* just a lump of metal as far as the coil's concerned.
> >(Electostatic field-shaping effects notwithstanding :)
>
> Nevertheless, eddy current heating will still occur for the reasons I
> outlined originally, in the circumstances described,that Bert Pool was
> responding to.
>
> The problem is that the primary tank will induce currents directly in the
> toroid. If you remove the secondary and run the primary alone but with the
> topload stood on an insulating pillar, joule heating still occurs whether
> the toroid is centre-disked or not. Unless your topload is zero resistance
> at the frequency of interest.
>
> Richard Craven, Malvern, England