RE: Why do TC's use line filters wired in reverse

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>

Hi Gary, All,

It looks like this is much more messy than I thought.  I always used "dual
stage" filters and mine happened to be more or less symmetric.  However, I
see Bill has found a non-symmetric one :-) 

http://www.geocities-dot-com/billvanyo/emifilter.jpg

Single stage filters are probably mostly non-symmetric too (as I say that,
someone will probably find a symmetric one :-))

Example schematics are at:

http://hot-streamer-dot-com/temp/LineFilters.gif

I think there are three factors:

1. Is the filter symmetric or non-symmetric.

2. Does the filter have a "dirty AC" and "clean AC" side.

3. Is the filter AC or RF grounded.

There is another factor to consider if the streamer should hit the grounded
case...  I always RF grounded due to that.  I also use MOVs on my filters
which only adds to the fun.

So, depending on exactly what filter a person has, the hookups could be
very different.

Much to ponder...

Cheers,

	Terry




At 08:57 AM 2/28/2001 -0500, you wrote:
>After smoking a 30 Amp EMI filter, I looked at the filter circuit more
>carefully, and found that it DOES matter, a great deal, which way (line or
>load terminals to NST) it is hooked up.  It all depends upon what you tie
>the filter case terminal to.  If you tie the filter case to the 3rd wire AC
>ground, then you need to hook up the filter with LINE terminals to the NST,
>and LOAD terminals to the power source.  If you do like me (which I DON'T
>recommend) and tie the filter case to RF ground (and to the NST case, etc),
>the LOAD terminals should go the NST, and the LINE terminals should go to
>the power source.  The reason I connected the case to RF ground was that I
>didn't have a 3rd wire ground connection available at the filter.
>
>If you don't connect the filter case to anything, then it probably doesn't
>matter which way you hook up the input/output, but I think the filter's
>effectiveness will be diminished.
>
>The filter circuit is not symmetrical in-to-out, see the schematic.  There
>are very high voltage transients between a running coil's RF ground and the
>3rd wire AC ground.  If the connections are not made as recommended in the
>previous paragraph, these transients will be applied directly across the
>filter's internal caps that connect to the case terminal (and possibly
>smoking them as I did).  And the filter will do a very poor job at keeping
>the transients out of your household wiring.  I have a page on my web site
>that details this.  See:
>http://people.ne.mediaone-dot-net/lau/tesla/emifilter.htm
>
>Terry, do your AC EMI filters not have the case terminal asymmetrically
>connected as my schematic shows?
>
>Gary Lau
>Waltham, MA USA
>
>>Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>
>>
>>Hi All
>>
>>I deal with a lot of line filters at work.  All the ones I have ever seen
>>are exactly the same electrically going from "in to out" as opposed to "out
>>to in".  The terminals may be different on each end, but they are
>>electrically the same either way...
>>
>>I also checked a bunch of standard line filters I use here and they are
>>symetrical too.  The only TC filter I know of the is "out to in" critical
>>is my NST ouput filter (see how I am :-)) at:
>>
>>http://hot-streamer-dot-com/TeslaCoils/Misc/NSTFilt.jpg
>>
>>Cheers,
>>
>>	Terry (the Fritz one :-))
>
>>> I'm curious. Almost every time I see a reference to the use of line
>filters
>>> in
>>> TCs, the user speaks of wiring them in reverse.  >>
>>> If they are
>>> designed for exactly what we need them to do, then why do coilers wire
>them
>>> in
>>> reverse? I would imagine that the LC network inside these filters will
>not
>>> work
>>> as well, and in fact may be totally useless, if used in the wrong 
>>>direction.
>