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Fwd: Ballast

In a message dated 11/5/98 5:50:09 PM Pacific Standard Time, tesla-at-pupman-dot-com
writes:

- snip -
<< 
 Am I correct in thinking if a reactive ballast is used on the input to a pig
 then its output can reach its nominal output voltage at some part of the
 load cycle.  If a restive ballast is used then the output potential will
 never reach its rated value.  So a reactive ballast is much more preferable
 and less wasteful on input power.
 
 Thanks again.
 
 Viv Watts UK.
  >>
Viv,

Yes, you are correct.  The inductive ballast will limit current without the
associated voltage drop that comes with resistive ballast, except for the
resistive component of the wire.  I would advise you to still use a few ohms
of resistive ballast in series with the inductive ballast at least to start.
Then you can fine tune the whole ballast arrangement to get the primary
current that you are looking for.

Ed Sonderman

-- BEGIN included message

Original Poster: "Vivian Watts" <V.C.Watts-at-btinternet-dot-com> 

Hi All,
    Thanks for the information on using a UPS transformer as ballast.  The
transformer has a laminated iron core (Bill the UPS also had a large
ferrite) in the shape of a square O.  Their are
two windings on opposite sides of the O.  Shorting one side cause the
inductance on the other to be about 6 mH.  But in use would this cause the
thing just to fry?
It may be possible to open the magnetic path to form a U with the two
windings still intact.  This I assume will cause the inductance to be
reduced and also reduce the possibility of saturation.  The wire size seems
to be about 12 AWG.

Am I correct in thinking if a reactive ballast is used on the input to a pig
then its output can reach its nominal output voltage at some part of the
load cycle.  If a restive ballast is used then the output potential will
never reach its rated value.  So a reactive ballast is much more preferable
and less wasteful on input power.

Thanks again.

Viv Watts UK.

-- END included message