hesitation/surge coming from Dialarc HF-P

[Aeronca41]

Aeronca41, Thanks for jumping in with an excellent explanation.

tarry99, A review of the input power requirements at rated output show [email protected] for the standard unit and only [email protected] for the PFC version.

Not sure why the Owner's Manual doesn't list it but idle amp draw for the standard unit on 230V is 6A while the PFC version is [email protected] due to keeping the capacitors charged.

I know of at least one "-P" owner that wired up a power relay to power the input capacitors when the main contactor was energized. This way the machine would idle at the lower 6A but still take advantage of the PFC when the relay closed to power the capacitors. I have no idea how well this set up worked but I would imagine if it didn't work well he would eliminate the by-pass.

Those numbers are interesting - makes it even clearer that you really don't want PF caps unless you turn off the machine every time you are not welding.

I need to to investigate again how electric meters work- if I remember correctly from the 1960s, the old spinning disk meters only measure real power and are immune to apparent power. However, apparent power does impact the power company's systems and efficiency, so if you are an industrial corp with lots of welders they will raise your rates if your power factor is below a certain value; thus, companies buy welders with PF caps. And install cap banks in their buildings. For the home user the power co is not going to be checking your PF. If my dusty memories are correct about the meters, there is no home benefit to a PF cap, and perhaps a disadvantage since you are constantly drawing some amount of power across the capacitive reactance. Does anyone have any more knowledge of electric meters? And do the new digital meters measure power any differently than the old mechanical ones?

[Aeronca41]

Aeronca41, Thanks for jumping in with an excellent explanation.

tarry99, A review of the input power requirements at rated output show [email protected] for the standard unit and only [email protected] for the PFC version.

Not sure why the Owner's Manual doesn't list it but idle amp draw for the standard unit on 230V is 6A while the PFC version is [email protected] due to keeping the capacitors charged.

I know of at least one "-P" owner that wired up a power relay to power the input capacitors when the main contactor was energized. This way the machine would idle at the lower 6A but still take advantage of the PFC when the relay closed to power the capacitors. I have no idea how well this set up worked but I would imagine if it didn't work well he would eliminate the by-pass.

Ii also read the thread about the guy who wired up contactors so PF caps are only on line when welding. Interesting idea, but I doubt it actually makes any significant diff in his electric bill due to metering methods. When I get some time I really need to understand electric meters again.

[Stefen7]

Switching the PFC on / off might be useful for someone with limited electrical service. The full-load draw of a 61F is 37 amps with PFC, vs 61M at 45 w/o. The O-M says the PFC version "meets all requirements for operation on REA and rural power systems," where a line and/or breaker above 40 amps is not available.

Someone running a big welder may not have 90 amp service, but could run a PFC unit at 76 amps. Rather than running the PFC all the time, at idle and welding at lower amps, could use the switch to only power the PFC when welding thick material at high amps.

Choice between cost of the switch vs cost of 90 amp service, if it is available.

[Aeronca41]

Good logic; a case where it would be a valuable option.

Hope you figure out a way to get that handle off; anxious to hear what you find inside.

[dvice]

most of this is over my head... I guess, I should be looking into my machine and making sure... the contactors are good and or clean...

I don't think we have a manual.. we are running the welder on a 220V, 50 amp circuit.....single phase.... I was set at about 165 amps at the time


bob

[Aeronca41]

Sorry dvice-none of us ever solved your problem. Have you checked all power feed connections to the machine-breaker box, receptacle, plug, connections inside machine? Next, I would look closely at the contacts on the W contactor. Also, recognizing you might trip the breaker on high current welds, I would disconnect one side of the PF correction cap temporarily, being careful to discharge it first, and be sure any wires you take off are insulated so they don't short out somewhere. I would also suspect a torch connection issue, but not sure how to tell you to test for that other than a replacement torch; perhaps someone else has some ideas.

[dvice]

I am wondering if I was hitting the duty cycle range on the machine.....is that possible...

[Stefen7]

That might be possible. The Dialarc O-M I have in front of me says the duty cycle is 150 amps at 90%. You said you were running around 165 amps, AC-TIG on alu, for about 45 minutes when the problem started. That could be around 80 to 85%, duty cycle.

[Stefen7]

The O-M I looked at this morning was for the standard Dialarc. The O-M for H-F shows a lower rating for AC-TIG. 150 amps at 70% duty cycle. Looks like 165 amps you were welding at is only about 65% duty cycle. If checking all the wiring connections did not find a problem, it may have just been a duty cycle issue.

Good Luck.
Stefen

[Stefen7]

You said you wanted to buy the machine when it is declared surplus. You should consider disconnecting the Power Factor Capacitor (PFC) when it’s yours. There is a discussion of how & why on the “DialArc Vs Syncrowave 250 vs Dynasty 280 DX” thread.

Most discussions about PFC are whether you would save on electricity costs or not. But I would be more concerned about potential failure of the PFC and the damage it would do. Aeronca41 gave a good explanation in the thread “Overheated Transformer or Failed Power Factor Capacitor, Diagnose & Repair,” concerning the used welder I bought.

Basically, if you are lucky, you will lose a day of welding as you open the machine to bypass the PFC. If you are not lucky, it will kill the machine, it is junk. That is a big risk for a few minutes work to disconnect the PFC as soon as you own it.

As for power consumption, the Dialarc H-F O-M states 76 amps input for PFC, and 90 amps without. Not much difference between the cost of installing 75 or 90 amp service. You will save money while the unit is idling.

Most importantly, you have removed an unneeded part that could cause catastrophic failure.

Stefen.

[Aeronca41]

Just to clarify-burning up the transformer winding is probably the least likely of the failure modes in my opinion but it is still a possibility. Most likely mode would be the capacitor opening, I would think , which would be just like disconnecting it. If it shorts, and either explodes or trips the breaker, likely no permanent damage except cleanup needed. I have cleaned up some really ugly messes from exploded caps over the years.

[dvice]

wow, I have been using this welder for 21 years that I have been at this company...and it has never "broke" or stopped working.....actually other than a new torch and hoses....weve never spent a dime on the welder itself!


dvice

[Stefen7]

Unfortunately emphasis is difficult to express in a short typed post. It's just that most discussions about keeping or removing the PFC are usually about the cost or savings of electricity.

The more important issue is a part that is not needed (in non-commercial use), that will eventually fail. Murphy's law says you're in the middle of an important project and the machine dies. You waste time trying to find the problem, and then how to fix it. Been there, done that, it's a real hassle.

The Dialarc I just missed getting had a PFC, and the first thing I planned to do was bypass the PFC, just to eliminate that. Better to pull the wires when you already have it open for cleaning, then to open it and fix when you did not plan to shut it down.

The fact Dialarcs like yours have been running for decades without a hiccup, is why a Dialarc is my first choice for a used welder.

Hope you enjoy decades more trouble-free use.
Stefen