RE: Pole Pig Construction

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

Original poster: "Dave Hartwick by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ddhartwick-at-earthlink-dot-net>

Ken,
I'm not seeing this. How can both outer xfmrs see a 14 kV potential in the
ungrounded config? This implies a total output of 28 kV. What are the
physics?

I really must be missing something obvious, but the old brain isn't seeing
it.
Dave





> Original poster: "Dave Hartwick by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <ddhartwick-at-earthlink-dot-net>
>
> What is the purpose of grounding the center xfmr's?? Safety? I've seen
this
> recommended in more than one MOT PSU schematic.
>
> Maybe I'm missing something obvious.

If the secondaries all are just connected in series you have the full
voltage of stress on the "higher" voltage transformer. They were not
designed for handle say 14kV from the secondary winding to the primary, or
core. If you ground the center your stresses are only 7kV. This is the same
principle as in a neon sign transformer.

KEN

>
> Dave H
>
>
>
> you have to find a way to isolate the cores and primary windings from each
> other if you connect them in series to acheive your expected output
voltage.
> Say you wnt around 15kV from 2kV transformers. That's a string of 7. If
you
> ground the center, you still have 7kV across the primary windings to the
> output on the "outer" two transfomers. It seems some insulate them with
oil,
> which is really messy and does not sounds too portable.
>
> KEN
>
> ----- Original Message -----
> From: "Tesla list" <tesla-at-pupman-dot-com>
> To: <tesla-at-pupman-dot-com>
> Sent: Saturday, August 17, 2002 11:42 AM
> Subject: Re: Pole Pig Construction
>
>
> > Original poster: "Daniel McCauley by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <dhmccauley-at-spacecatlighting-dot-com>
> >
> >
> > Why not look into using MOTs (microwave oven transformers).  They're
dirt
> > cheap, readily available (even if purchased new), and would be MUCH
easier
> > than actually winding and building your own pig.  Thats what i'm going
to
> > do.
> > Dan
> >
> >
> > > I've been after a pig well over a year now. it seems no one in the
area
> of
> > > maryland is willing to cooperate with me unless i have $1000 to blow
or
> am
> > > a business. i was searching around the web and came across 2 websites
> > > (which i dont have the urls for) where people have made their own.
> > >
> > > I am quite interested in building my own if my search does not yeild
> > > results int he new few days. however, this type of transformer design
is
> > > not all clear to me and the two wesites constructed the pigs
> differently.
> > >
> > > would anyone care to help me figure out how to design a pig? perhaps
> about
> > > 5kva?
> > >
> > > -matt
> > >
> > >
> > >
>
>
>