ballasts

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

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-uswest-dot-net>" <jimlux-at-earthlink-dot-net>


Reading over the posts on building ballast inductors, and then tripping
over a big 240/480V transformer out in the garage this morning, the
question comes up:  Could you take a standard "dry transformer" (these
typicaly have a pair of 120V windings and a pair of 240V windings, all on
the same core) and turn it into a ballast?  Any ball park idea of what the
inductance of these things is?   (I suppose I could measure the "no load"
current and figure it out). Obviously, the windings are heavy enough to
take the rated current for the transformer, and, if you don't apply more
voltage to the winding than rated, there should be enough core area so
saturation shouldn't be an issue.

All those windings, and some big switches/relays/SSRs, might make a nice
(step) adjustable ballast.  Some of the ones I have have multiple taps on
the windings for voltage adjustment (say, taps for 200,220,240,260) which
might be useful for "fine" adjustment.