Re: Odd wire on a 15/120

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

Original poster: "Jon Tebbs by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jgtebbs-at-eos-dot-net>

Hi Jonathan,

See my comments below:

Tesla list wrote:
> -----Original Message-----
> From: Tesla list [SMTP:tesla-at-pupman-dot-com]
> Sent: Friday, July 20, 2001 8:45 PM
> To:   tesla-at-pupman-dot-com
> Subject:      Odd wire on a 15/120
>
> Original poster: "jpeakall by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <jpeakall-at-mcn-dot-org>
>
> Howdy all,
>
> I got a 15/120 Franceformer the other day in some kind of lab equipment
> (along with 3 variacs, one of them a 220v/100amp and tons of diodes,
> relays
> and so on for $100!!). It has a wire sticking out from the side which has
> about 20v on it when the NST is activated. Is this a custom installation,
> or
> is there some reason for this? There is a printed (not by manufacturer)
> little tag on it that says "ground mid point lead". Any ideas?

Of all the replies, it seems no one has paid attention to the tag you
mentioned.
The tag info has your answer, it seems to be the midpoint lead of the
secondary.
A quick resistance check from each bushing to this lead should confirm that it
is indeed the midpoint, the resistances measured should be similar. Also, a
resistance check from this lead to the case will probably show an open circuit.
If these test results bear this out, tie it to the case and ground it as
the tag says.

I'll not speculate on why it was isolated from the case to begin with. On
second
thought, I suspect that it was done so as to stump the experts on the List
<grin>. We'll await your results.

>
> Thanks,
>
> Jonathan Peakall
>
> PS Terry, got the movs as you reccomended. Thanks!
>
>

Cheers,
-- 
Jon G. Tebbs
<jgtebbs-at-eos-dot-net>