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Re: Saturable Reactors as Ballast



Original poster: FIFTYGUY@xxxxxxx
Folks-

Just like to add that my Miller "Dialarc" welder uses the Saturable Reactor principle. Instead of transformer taps or a system to mechanically move a core shunt, a pot on the front adjusts the control circuit. It has a schematic on the inside cover, but unfortunately, I can't get to it right now to copy it. But the Miller website has owner's manuals:

<http://www.millerwelds.com/service/ownersmanuals.php>http://www.millerwelds.com/service/ownersmanuals.php

I'm pretty sure this is the one for my welder:

<http://www.millerwelds.com/om/o314v_mil.pdf>http://www.millerwelds.com/om/o314v_mil.pdf

The schematic shows only one DC control winding, but it may really be the two out-of-phase windings shown as one. Very simple arrangement, with the front control dial being a 15W rheostat directly controlling the DC control voltage. Nice to see everything first goes through an isolating transformer (with a separate winding to derive the input to the DC control's rectifier). The Magnetic Amplifier winding interconnections look a little complex, but there's also a high/low output switch thrown in there for welder output ranges. A full-wave bridge on the output for DC welding is obviously of no use to us (unless you were cascading Magnetic Amplifiers, and needed that kind of output for the control input to another Amplifier!). Another thing I thought of: keeping the DC control circuit's impedance high makes it easier to filter (if filtering is desirable?).

-Phil LaBudde