How to connect wires on 17 leads multi-tap transformer of arc welder

[Eleutheros]

I found my father's old arc welder, DIY I guess. It has one transformer with 8 outputs on the primary and 8 outputs on the secondary (of which 2 outputs are thick copper wires) and two switches. Based on the construction, it is logical that it is an AC electric arc welding machine. I assume that the markings on the switches were replaced by mistake, because the two-pole switch should change the input voltage (220V or 380V), and the six-pole switch should change the welding current strength (0-8).

At the moment, the voltage switch does not work, there is no marking on it (except the letters GF, which do not help at all) on the basis of which I could determine the manufacturer or the connection method.

I would like to make a welding machine so that it works on only one voltage of 220V (because I think it is simpler to do), but in all currents available on the switch.

How to identify the transformer wires to which the input voltage needs to be connected. The moment I enable the input voltage, I can measure the output and sort it by voltage and connect it to the appropriate place on the switch accordingly.

The smaller windings are the primary of the transformer (the ones in the back).

 

[Eleutheros]

I tested the transformer as follows:
-All wires are separated from the switch and from each other
-There are 9 red wires, 6 gray and 2 thick uninsulated copper leads to which the main cables for the electrode holder and ground are connected.
-No wire has contact with ground.
-All red wires have mutual continuity
-All gray wires have mutual continuity
-Two thick uninsulated copper lines have mutual continuity
-There is no mutual continuity between wires of different colors, nor between any colored wires with thick uninsulated copper conductors.
- The resistance was tested and recorded in the table below, using a multimeter with a measuring range of 200 ohms.

- The red wires were numbered at the bottom with numbers 1 to 7, two were not numbered and I marked them with 8-9A and 8-9B.
- The gray wires were not numbered and I marked them with numbers 91 to 96.

Does anyone have an idea how this transformer works or a test method that might be useful in getting the machine up and running?

 

[amaranth]

Couple ideas:

1 - Get a better ohmmeter with at least 0.01 ohm resolution, that may help identify the wires.

2 - The red wires look like the primary but the grey wires look to be involved somehow.

3 - Get a 12V transformer and feed it into the primary and you can measure what comes out with various connections.

4 - Draw a schematic showing what those switches do to connect things. Actually, you should probably have done this first

5 - If you actually want to weld something, go buy a little HF inverter welder

 

[Eleutheros]

Couple ideas:

1 - Get a better ohmmeter with at least 0.01 ohm resolution, that may help identify the wires.

2 - The red wires look like the primary but the grey wires look to be involved somehow.

3 - Get a 12V transformer and feed it into the primary and you can measure what comes out with various connections.

4 - Draw a schematic showing what those switches do to connect things. Actually, you should probably have done this first

5 - If you actually want to weld something, go buy a little HF inverter welder

I have a 13V AC transformer, to which wire numbers should I connect it, without destroying the windings?

 

[amaranth]

As long as you don't have anything shorted, nothing will burn up; the transformer won't draw any appreciable current. Go back to your original pictures and see if you can figure out what wires were connected to the line input and then go from there.

 

[Eleutheros]

The input voltage cable (230V) was connected to a two-pole switch that had switch positions 0-8. The input cable had one black wire, one blue wire, and a ground wire.

The black wire was connected via the switch to the windings marked with numbers 1 and 8-9A. The connection did not exist in switch position 0, but in switch positions 1-8 it did.

The blue wire was connected to the gray wire number 91 with a switch.

The question remains the same, which wire numbers should I connect the 13V AC input voltage to.

 

[johansen]

Its common for welders to switch both the primary and secondary coils, as such this can be complex to figure out

Connect your 13v transformer to the output of the fat secondary leads, record the voltages produced by each coil. (Use a small lamp to load the transformer, otherwise you will read phantom voltages where there are none. Alternatively, short the wires together and if you dont see a spark, its not a coil)


Them put all the wires back where you found them.

 

[Eleutheros]

I connected a 100watt - 220V light bulb in series connection, but the voltage didn't come to the thick copper wires, I'm not sure if it's because of the 13V ac voltage I was trying to power the circuit with.

Anyway, I tested the voltage on the coils without the bulb and the results are in the table below.
The first table shows the voltage in volts and the second table shows the percentage increase in voltage compared to the input voltage which was 14V AC (after I cleaned the terminals).

The connections made with red wires are marked in red in the tables, because in this scheme they were the secondary, and otherwise they should be the primary of the transformer.

I assume that I need to get the output voltage with the gray wires and there are 7 connections where a higher voltage is obtained than the input. Can I connect those 7 windings separately to the cam switch 0-7, and apply a 230V voltage to one primary winding and have the arc welding machine work? If possible, to which red coils should I supply the input voltage of 230V?

Do you have any other suggestions on how to make the machine usable?

 

[johansen]

I think you need to put all the wires back where they went.

Apply 14v to the welding leads and figure out the missing connections.

Figure the transformer saturates at 80vac output, so when you do apply 240vac to the input, if you get more than 85v, its wrong. (80vac at 230v )

There may be coils in parallel for the higher amp settings, as well as series parallel connected for the 230v 380v transition..

 

[Eleutheros]

Returning the wires to their original position is not an option, I did not have a diagram of the internal connection of the defective switch, so I did not bother to record the external connections on the switch, because even if I buy another switch - it does not mean that the internal connections are the same.

As it was said, the input voltage of 230V is sufficient, there is no need to connect the windings in series and parallel connections, because the goal is not the complete utilization of all the windings of this transformer, but only a few different ones in order to obtain a certain difference in the welding current.

The goal is to learn basic things about transformers through a practical example.