Hello gentlemen, some 20 years ago I made some experiments with a DC-controlled adjustable inductor like that, we called it a varactor. Three of them were used in a large stabilized three-phase mains supply powered by giant vacuum tubes (50 to 100 kW or so). Those varactors were three legged iron monsters, looking like three phase transformers, where the two outer coils were magnetized with high voltage DC and the center coil carried very heavy square profile wire for the mains supply current. By applying DC from a separate supply it was possible to drive the iron into saturation, thus inhibiting the AC magnetic field and, as a result, the emf which in turn caused the output voltage and current to increase. A DC controllable choke, very elegant, I thought.
I wanted to make a welding device from that setup which still is a sexy idea to me. But I found out that adjusting the output current was very touchy and tricky and, as I think now, only possible with a closed circuit control system, not so easy considering the high control voltage needed. The idea of having several hundred volts DC around in the shop working with partly gounded metal parts and grinding chips flying all over made me feel uneasy, anyway. After blowing the houses main fuses (400V, 50 A) several times I gave up experimenting and made more taps on the main transformer which would give steady results. Considering the weight of the whole setup I think a modern IGBT-inverter welding "transformer" would be better in every way. Best regards from foggy Bavaria Peter Blodow Leslie Newell schrieb: > Yes it does sound like a variable reactor setup. The control signal is > DC and pushes the core into saturation, reducing it's inductance. The > early BOSS Bridgeport CNC mills used this sort of setup to reduce the > idle current on the stepper motors. It also used to be quite commonly > used on TIG welders to control the output current. These days they do it > with electronics instead. > > Les > > > On 21/11/10 21:00, Kirk Wallace wrote: > >> I have what appears to be a transformer with a reactor in series with >> the secondary. The reactor is used to control the transformer output >> current. I can imagine the reactor will act like a normal inductor and >> impede the AC current, but the reactor has another coil on it. I assume >> this coil is used for current control and works by pushing the core into >> saturation. Is my assumption correct? Would the control signal would be >> DC or some sort of phase controlled signal? >> >> Control >> Signal? >> Pri Sec | | >> -------D " uuuu >> D " ==== >> D " C------nnnn----o >> Mains D " C Output >> D " C--------------o >> -------D " >> >> (Just for fun -- I found this link while looking for reactor >> information: >> http://books.google.com/books?id=mtwDAAAAMBAJ&lpg=PP1&pg=PA162#v=onepage&q&f=false >> Short URL http://alturl.com/owob4 ) >> >> >> > > > ------------------------------------------------------------------------------ > Beautiful is writing same markup. Internet Explorer 9 supports > standards for HTML5, CSS3, SVG 1.1, ECMAScript5, and DOM L2 & L3. > Spend less time writing and rewriting code and more time creating great > experiences on the web. Be a part of the beta today > http://p.sf.net/sfu/msIE9-sfdev2dev > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > > ------------------------------------------------------------------------------ Increase Visibility of Your 3D Game App & Earn a Chance To Win $500! Tap into the largest installed PC base & get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
