Primary current in a welder

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I'm not as smart as I wish I were. Porkncheese brought up the power supply choices for the Dialarc HF welder from Miller. I have studied the schematic diagram and I've pondered a new question. The primary winding presumably copper is thick. If it were a straight line it would offer such little resistance amperage or current would skyrocket. This winding is connected to only one control; the on/off switch. What limits the current? How does equipment and controls, or even a stuck rod in the secondary circuit influence current in the primary. There is no electrical connection!I theorize the answer involves magnetism. Perhaps the magnetic field opposes, or impedes the flow of electrons. The act of inducing Voltage, therefore current, in the secondary winding weakens magnetic field, weakening the impedance or opposition to current. How far off base am I? What's the correct answer? What is the meaning of life?  Bill
Reply:30 years ago, I could have recited the 3 basic laws of electron flow verses magnetism caused by the coils being close to each other further influenced by the iron core which MUST be laminations! Now I don't ponder the science of "transformers" any more as they are only a small part of my life.I too will wait and see for an answer to this "meaning of life".
Reply:I don't know the meaning of life - but I hope it involves root beer floats As to the welder, where does the wire from the rheostat go?  Since it controls the amps it must be the key right?Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:It doesn't touch the primary winding.
Reply:Originally Posted by Willie BIt doesn't touch the primary winding.
Reply:Originally Posted by MinnesotaDaveI don't know the meaning of life - but I hope it involves root beer floats As to the welder, where does the wire from the rheostat go?  Since it controls the amps it must be the key right?
Reply:The windings share a common core so they are linked magnetically.
Reply:The dial arc transformer has two sections. The first is a standard step down transformer, changes high voltage into lower voltage and boosts the current. The next section is the reactor also know as a magnetic amplifier. It has a command winding that comes from the rheostat. a 30 volt DC power supply. runs it. then we go to the weld diodes and a smaller output stabilizer,The reactor is made of several coils that are switched it for the different current ranges.It is right under the lid of the welder and is the top section.The Mag amp reactor uses a small current (less than 6amps) to control the much higher weld amps. Of these there are two basic types. One uses the command current to turn on, the other uses the command to turn it off. Have found both types in different welders.Some welders use just a simple 30vdc power supply and a rheostat, and some units replace the rheostat with an electronic module.
Reply:this  http://www.reddit.com/r/Physics/comm...nsformer_does/Miller Multimatic 255
Reply:Root Beers all around!MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:If the meaning of life involves food or beverage, it includes bacon and Hard Cider. I'm concerned about you guys having taken a wrong turn.