[Bill Beauregard]

I'm already outgrowing my new Miller Diversion 180. I'm thinking about upgrading. A dealer has a Sincrowave 250, at a much better price a private sale has a Miller Dialarc 250. The Dialark is a big machine with a great duty cycle. I'm unsure if it has the features I want. Can anyone offer advice?

[MinnesotaDave]

If it's just a Dialarc, and not a Dialarc HF, then it's just a stick welder. But a really good stick welder

[Bill Beauregard]

I bought the dialarc. It is a monster. I haven't tried it yet. Cord and plug connections aren't readily available at 90 amps.
I may hard wire. You probably won't be tempted to move it. It has high frequency? It doesn't appear to give a way to adjust ac balance.

[MinnesotaDave]

My Dialarc and Airco are hard wired to the panel. I just shut off the breaker when done for the day. Same for my compressor.

Unless you bought the Dialarc HF, there would be no no high frequency.

If you did buy the HF model, no, there is no AC balance adjustment. It's 60hz like my Airco.

Either way, the Dialarc is a great machine

[Bill Beauregard]

Dialarc HF it is a water cooled tig machine, with leads for stick welding. It has a switch for high frequency. How high is this frequency. I believe my Diversion is set at 120 HZ It seems about 70% electrode positive.

[MinnesotaDave]

Dialarc HF it is a water cooled tig machine, with leads for stick welding. It has a switch for high frequency. How high is this frequency. I believe my Diversion is set at 120 HZ It seems about 70% electrode positive.

You are looking at the switch for high freq starting (and continuous for aluminum). It does not adjust weld frequency.

Your machine is 50%/50% balanced sine wave welding at 60 hz only.

[Bill Beauregard]

The manual tells me that the switch can go from no high frequency, to start arc only high frequency for stick welding, or continued high frequency for aluminum. I'm guessing the spark gap device shown in the manual is a way for the machine to set up fluctuation in the magnetic field. An engine (gasoline, etc.) uses a low voltage power source I.E. battery to create a magnetic field in a transformer. At the precise time it is needed, a switch opens,(breaker points) causing the magnetic field to collapse. If we could see a magnetic field, it would look like layer upon layer of very thin rolled up in a tube. upon collapse this literally implodes, If we have a complete circuit current is induced at a voltage much higher than the input voltage. In an incomplete circuit as in a spark plug or welder an air gap prevents the flow of electricity until voltage rises to a level where it ionizes the air stealing electrons or over saturating the air atoms with electrons. These ions (unstable atoms) are better able to conduct electricity. A spark passes through air completing the circuit. In series circuits the high resistance portion of a circuit is where most of the voltage drop occurs, or most energy is rendered. Enough heat is created to ignite a fuel/air mixture in an engine. In a welding circuit, melt metal. A 60 cycle power source falls to zero current twice in a cycle, or 120 times a second. At that rate can the spark gap device in the welder double frequency, or would each of the harmonic cycles bring the same result causing ripple currents continuing as a rubber ball bounces until it runs out of energy. The manual warns of RFI or radio frequency interference. It occurs to me that doubling the frequency of 60 cycle utility power would have little effect on the higher frequencies of radio waves.

[Bill Beauregard]

More ramblings: A weld circuit other than short circuit depends on ionized air to conduct electricity. Molecules and atoms won't remain ionized for long. A bolt of lightning travels in steps in high speed photography is turns in a series if steps surging and stopping as voltage builds,more electricity traveling to the end of the "step leader" where it ionizes more air enabling it to surge ahead, stopping when it runs out of ionized air to build voltage, and ionize more air. Moving a step at a time lightning travels long distances I.E. cloud to ground, in a tiny portion of a second.

Applying this concept to welding, Air won't remain ionized for long. The time required to de ionize air is near zero. Air can lose most of its conductive properties much faster than 60 cycles a second. I suspect that low frequency ac welding must establish a new conductor made up of ionized air or shielding gas for each reversal of current flow. Does this explain the arc wandering one experiences welding aluminum with low frequency tig machines? A wandering arc is a diluted arc spreading the heat over a wider area, requiring more heat to get the job done.