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Re: EMI filter hookup
Original poster: "Yurtle Turtle by way of Terry Fritz <twftesla-at-uswest-dot-net>" <yurtle_t-at-yahoo-dot-com>
I blew up a 40 amp Corcom filter with a single 15/30
which puts out 40ma. This filter is the size of a
brick. I also had mine wired backwards, but used the
house ground for the case and my variac. Mine was
upstream of the variac. I opened mine, but still
haven't depotted it to determine what went wrong.
Mine can be seen at:
--- Tesla list <tesla-at-pupman-dot-com> wrote:
> Original poster: "Lau, Gary by way of Terry Fritz
> <twftesla-at-uswest-dot-net>" <Gary.Lau-at-compaq-dot-com>
> Last week I changed several components on my coil
> which required that I
> experimentally retune it. I was perhaps 1-2 minutes
> into this tuning when
> performance suddenly diminished, the circuit breaker
> tripped, and a burning
> smell filled the garage. It turns out that my 30
> Amp Corcom EMI filter had
> toasted. I had been using this filter for well over
> a year with no problems
> and I'm sure that my 15/60 NST was not pulling more
> than 20 Amps.
> I examined the hookup and came to the conclusion
> that one or more of the
> filter's internal caps had been over-volted by the
> hookup configuration. I
> had connected the filter "backwards" as is
> frequently suggested, with the
> LINE side connected to the NST primary. The 3rd
> wire ground from the wall
> is not used anywhere in the coil beyond the variac
> so I was connecting the
> RF ground to the filter's case instead.
> I now believe that in a configuration where the
> filter is located at the NST
> where no 3rd wire ground is available, that the
> "backwards" configuration is
> inadvisable and was responsible for the failure of
> my filter.
> I've added a page to my web site with schematics
> illustrating the good and
> bad ways to hook up the filter. I don't know if I'm
> the only person who ran
> in that backwards configuration with the RF ground,
> but hopefully I can save
> someone else's filter from toasting.
> Oh yes, it also appears that in addition to being
> self-destructive, that bad
> configuration also made the EMI fed into the
> household wiring worse than if
> no filter was used at all!
> The new page is at:
> Regards, Gary Lau
> Waltham, MA USA
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