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Re: Controling a Pole Pig



In a message dated 12/3/98 10:24:21 PM Pacific Standard Time, tesla-at-pupman-dot-com
writes:
             - snip -
<< 
     This does not appear to be quite what I meant, What I had planned was
 to use a
 transformer as a limiter, so I would NOT be connecting the 11 kV winding at
 all -
 in effect it does not exist. In any case due to the way the transformer is
 constructed, it is not possible to place a shunt in the core which would
 cause an
 increase in leakage inductance. Because the windings are wound over one
 another,
 any flux which passes through one coil must also pass through the other, so
 there
 can be no significant leakage inductance when they are operating as a
 transformer.
 I was proposing to only connect the 240V winding and use the transformer as
an
 inductor, with a variable inductance caused by a variable air gap in the
 magnetic
 path.
 
       240V winding
 -----           ------------------ || -----------
     |           |                | || |
 M    ~~~~~~~~~~~                 ~ || ~
 a    ----  -----             240V~ || ~           Coil (11 kV)
 i    ----  -----                 ~ || ~
 n    Variable gap                ~ || ~
 s                                | || |
 ---------------------------------- || -----------
     Transformer 1            Transformer 2
 
 Transformer 1 is being used solely as a variable current limiter and has a
 variable air gap in the core, and transformer 2 as the actual output
 transformer
 and is unmodified. Sorry if I didn't make this clear in my initial posting.
 Does
 anyone have an experience using this arrangement?
 
 --
 **********************************************************************
 *Stephen Rodway           >>

Stephen,

If you try this, I don't think you should leave the secondary of the
ballasting pig open.  It will produce dangerous high voltage and maybe damage
the secodary.  You should short the secondary outputs together, or maybe you
can place a variable load there and control the primary current that way.

Ed Sonderman