36 volt AC to 120 volt AC transformer

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Matthewirl

New Member
hi there as above wonder is there somewhere I could purchase a 36 volt ac to 120 volt ac transformer.
I am using it to connect an American imported power supply control unit for a push pull wire feed gun to a uk 3 phase welder.
The power supply for the gun requires 120volt ac in and the welder I have had a 36 volt ac output on the back so if I had a transformer in line I could wire it up and the whole setup would be self contained rather than plugging in the welder and supply separately.
 
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Are you certain the 36 volts is ac not dc?

Get a 120V to 36V transformer and use it "backwards". A transformer will work 120 to 32 or 32 to 120.
How much power (or current) to run the push pull wire feed gum?
 
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Well I haven’t actually tested the output to see which it is but it is marked as being 36 volt AC
As for the power draw of the push pull it will be quite low as it only has to run a very small motor to feed the wire, all other functions are already powered from the traditional euro connector on front of the welder.
Thanks for your reply!
 
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As Ronsimpson said, you can use a transformer backwards.

However, any transformer that you use will have to be of a suitable power rating. What exactly is it that you are wanting to run?
 
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Attached is images of what I’m powering so 36v ac out from welder into the power supply for the torch which needs 120v ac as it is from the US market.
It only has to power the small motor inside the handle nothing more so power draw is low.
I can’t seem to find any 36v ac to 120v ac step up transformers only dc inverters with these voltages.
If you know of anywhere that does sell these or a type with the correct number of windings I believe it needs a turns ratio of 0.3
Any help at all is much appreciated.
Thanks, Matthew.
 

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The fuse for the supply is 1 A, so that represents 120 W. You need a 120 W or larger trnansformer.

You could use this:-
https://www.newark.com/multicomp-pro/mcta160-18/toroidal-transformer/dp/38K4911



The 36 V input would be what would normally be the secondary and you need to wire the two windings in series. That would be done by connecting red to orange and connecting black and yellow to the 36 V ac supply.

The two 115 V windings, marked as primary but being used as the the secondary, would need to be in parallel. Wire blue to violet and to the live connection of the load. Wire grey to brown and to the neutral connection of the load.

The dots on the winding diagram are important, and you cannot swap one winding (eg blue to grey) if it is connected to another winding.
 
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Note that the transformer output voltage is at rated current so the no-load output voltage is some higher than that to compensate for the resistance of the windings (defined as its regulation percentage).
Unfortunately this works in reverse when using the transformer backwards, so applying 36V to the secondary will result in some less than 115V/120V at the primary.
That may not be a problem, but it's something to keep in mind.
 
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Many thanks never thought of doing this. I appreciate your help.
I may pick your brain a little when time comes and I’m wiring and building the housing.
 
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Would it be a significant loss? Or within the range the power supply could handle. Many thanks.
 
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Matthewirl said:
Many thanks never thought of doing this. I appreciate your help.
I may pick your brain a little when time comes and I’m wiring and building the housing.
Click to expand...
Also quick one there is a ground pin on the plug of the power supply and none on the outlet of the welder can I ground the power supply using a ground inside the welder or where possibly could I ground it? Thanks
 

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Hi again, just to check before I order will this transformer work I know it has a higher va but it isn’t on back order. Thanks, Matthew.
 

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Matthewirl said:
Hi again, just to check before I order will this transformer work I know it has a higher va but it isn’t on back order. Thanks, Matthew.
Click to expand...
That 225W / 18V transformer has a no-load voltage of 19.2 V. I assume that is at 230 V input.

That would make the turns ratio very close to 12, or 6 if both are in series. That would give about 215 V if the input voltage is 36 V exactly and there is no load.

Have you measured the 36 V output from the welder?
 
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Ended up finding a seller for the transformer that was recommended for me by you. Measuring the output from the welder with the multi meter gives me, around 37 volts.
 

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The 160VA transformer has a no-load output of 19.6 V. That should give 217 V from 37 V at no load.

217 V is unlikely to be a problem with any small 230 - 240 V appliance.

On a toroidal transformer like that, you can quite easily add a few turns of wire through the hole in the middle, and in series with the output to add voltage if you do want a few more volts. I would guess 2 - 4 turns per volt.

https://www.electro-tech-online.com/threads/kef-psw2500-active-base-unit-repair.159244/#post-1380354
In that thread it shows how I added some 15 V windings to a similar transformer.
 
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Just to be clear, are you saying with no load ie. Motor not running the power supply will receive 217v, would this not damage it when it’s designed for 120v ac input? Thanks
 
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Or a surge protector of sorts?
 
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Matthewirl said:
Just to be clear, are you saying with no load ie. Motor not running the power supply will receive 217v, would this not damage it when it’s designed for 120v ac input? Thanks
Click to expand...
That would damage something rated at 120 V ac. I had (incorrectly) done the calculation based on putting the two windings in series to aim for 230 V.

With the two windings in parallel, the voltage would be halved at 108.5 V with no load.
 
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