Miller Dialarc 250 AC/DC thermostat and single phase wiring questions.

[Currentmonger]

Good day, I recently bought a Dialarc 250 AC/DC (not the HF) and I have a few questions.

I looked inside, but could not see a thermostat, I am wondering if these machines usually include them, and if one in not included. Should I install one?

Secondly it is currently wired for three phase 380v, but it only uses lines 1 and 2. I am running it of a rotary phase converter, but that is likely quite inefficient and I would prefer to wire it for single phase. The issue is that it says it can be wired for 120v 260v and 380v 3 phase. I only have 220v single phase. Is it possible to buy a 220v to 260v transformer and wire that in and how advisable would this be?

 

[Erie Fred]

Have you tried getting the schematic from the miller website ?
Pay close attention to the the serial number when looking for the manual/schematic.

I have never seen a Dialarc in 3 phase.

I don't think they had a thermostat, the fan runs all the time.

Is your front panel white or black ?

 

[Currentmonger]

The front panel is black.

It is single phase, but wired betwene L1 and L2 of a three phase line with the bus in the 380v position.

 

[Barking Mat]

No, I think these need running off two phases.

My machine does.

Yes @Erie Fred is right about the fan running constantly.

 

[Currentmonger]

I am more worried about the machine not shutting off and melting.

Regarding the phases, I don't know much about two phase. There are only two terminals and the diagram says it can be set for 120v 260v and 380v.

 

[eddie49]

It is a single-phase machine but needs the higher phase-to-phase voltage, rather than phase-to-neutral. See Post #10 here:

P

Thread 'miller dialarc hf-e 2 phase or 3 phase??'

Jun 11, 2012

hi everybody!
ive had a look around the forum and couldnt find a post referring to my problem so here goes...
i used to work for a race car constructor in the uk.when i left i bought a dialarc that was running on 2 phase power.my boss and the welder supplier both told me that i just needed to alter the plug wiring to get the machine to run on 3 phase power.that however,was 8 years ago! and im not sure i remember which wires to change and desperatly want to avoid any kind of meltdown!the machine was running fine in the factory but im too far out of my depth here to take a chance.from what...

• popa
• Replies: 16
• forum: TIG Welding

 

[Currentmonger]

So I believe it uses a transformer to correct the voltage for the main transformer.

My machine says it can run on 120v 260v and 380v. I would ideally like to adapt it to run on 220v so that I am not running my phase converter with one redundant phase.

 

[eddie49]

Is it possible to buy a 220v to 260v transformer and wire that in and how advisable would this be?

It might be possible to buy one, or have one made to order, but it would be very large and the lower the voltage, the higher the current, so you would need a very high current rating on your 220v supply.

 

[Fazerruss]

The Miller Dialarc can run off 240v. I used to have a Marshall Dynabolt which is the same machine. You just need to configure the jumper plates on the terminals in the back and you're good to go.
Bear in mind though, at full output these machines will pull 99amp on a 240V supply. I assume you aren't able to get anywhere near that with a RPC?

 

[Farside]

If it's simply running off two legs of a 3-phase supply it's effectively a single-phase device.
What's handy is it's rewireable to take advantage of a range of input voltages.
I have a large old BOC single-phase buzzbox that's supposed to run on 400V on two phase legs, but I've had it running on my domestic mains and laying a good bead. However, if I were looking for it to run at anywhere near its full capability, it just wouldn't do it.

 

[Erie Fred]

I am more worried about the machine not shutting off and melting.

Regarding the phases, I don't know much about two phase. There are only two terminals and the diagram says it can be set for 120v 260v and 380v.

Are you going to be using it for air arc work ?

Please post the diagram.

 

[eddie49]

The circuit diagram and link options in Post #12 of the thread I linked to above show voltages of 208, 220, 230, 380, 415, 440, 460 !

 

[Currentmonger]

I will see if I can post a picture later. It did not mention a 220 or 240 volt option. If it helps the serial number starts with "JJ".

I do not plan on using it for arc gouging, but I do want to try CAW and TCAW.

Spoiler: The machine in question.

Don't worry I will remove the cardboard.

 

[Currentmonger]

So I did some tests, it runs fine at 250 amps on my power supply. It did feel like the voltage was perhaps a lot higher than on my old 250a oilbath AC machine.

 

[Erie Fred]

So I did some tests, it runs fine at 250 amps on my power supply. It did feel like the voltage was perhaps a lot higher than on my old 250a oilbath AC machine.

What does the front nameplate say for Open circuit voltage ?
O.C.V.
The Miller Dialarc is a true industrial machine with higher OCV than homeshop buzzbox's.

What does the old machine give for OCV ?

 

[Currentmonger]

OCV is 70-71v. Quite a lot.

Regarding power consumption, if my phase converter (running off single phase) can power it, I should be able to run it on single phase. Just the question of getting the right voltage. I had quite a busy day and did not find time to open it up, but it definately only showed wiring options for 120, 260 and 380 volt supplies. That said, on the amuminium sticker the front of the machine it says 250, 260 and 380.

 

[Currentmonger]

I have not found the serial number of my machine on Millers parts and manuals database, I will send photographs of the interior soon.

 

[Currentmonger]

As you can see it does not mention a position to run it on 220v.

 

[Barking Mat]

You see where it says 260 volts.

You need to put the jumpers in as shown in the diagram.

Bridge 1 and 2, then 3 and 4.

 

[Barking Mat]

Show us where it's currently wired up.