Help Identifying unknown Transformer

[Clarkdale44]

Hello

I got this transformer from an old ups, there are four wires on the primary side black, blue, green , yellow and two on the secondary red and blue. This transformer used to charge 12v 7.5ah battery also converts it back to 220V in backup mode.
Tried testing its output and got this

(Mains 220V)
Black to ground
Blue to mains-> 7.9v on secondary
Green->5.5v
Yellow->6.5v

Connecting Blue and Green to mains and it was a shot circuit and blown my fuse. I want to use this for making a decent power supply 12v+ output, is this possible?

I also saw this video
The guy is using his ups transformer for generating hv to power cfl using tip122, i am not sure how to do this using my transformer.

I need to make use of this transformer somehow, otherwise its just eating dust at my home.
Images of the transformer below.

 

[Reloadron]

Rather than play a guessing game with voltages I would start by taking resistance readings and see what goes with what. Also, many UPS transformers use multiple tap transformers so they can be used globally (120V & 240V systems). Many UPS units, depending on size and ratings use not one but a pair of 12V 7AH batteries in series, so they run on 24 VDC and not 12 VDC. The charging circuits start with 12V-0V-12V. Anyway, I would start using an ohm meter and see what goes with what, also if possible note the wire gauges where the leads exit the transformer windings.

Ron

 

[Clarkdale44]

Rather than play a guessing game with voltages I would start by taking resistance readings and see what goes with what. Also, many UPS transformers use multiple tap transformers so they can be used globally (120V & 240V systems). Many UPS units, depending on size and ratings use not one but a pair of 12V 7AH batteries in series, so they run on 24 VDC and not 12 VDC. The charging circuits start with 12V-0V-12V. Anyway, I would start using an ohm meter and see what goes with what, also if possible note the wire gauges where the leads exit the transformer windings.

Ron

Hello

I did what you asked me
primary side
Wrt black,
blue->9 ohm
yellow->9 ohm
green->10 ohm
green blue 2 ohms
green yellow 1 ohm
yellow blue 1 ohms

secondary side
blue and red 0.6 ohm

primary side wires are 18 awg and secondary are of 12 awg.

 

[JimB]

Can I suggest a different approach.

If you have a low voltage AC supply (6 to 12 volt range) from some other transformer, connect that low volt supply to the secondary of the transformer under test (TUT) and measure the voltages on the primary of the TUT.

The primary and secondary voltage ratios can now be calculated and you can (hopefully) work out what the primary connections are.

JimB

 

[Clarkdale44]

Can I suggest a different approach.

If you have a low voltage AC supply (6 to 12 volt range) from some other transformer, connect that low volt supply to the secondary of the transformer under test (TUT) and measure the voltages on the primary of the TUT.

The primary and secondary voltage ratios can now be calculated and you can (hopefully) work out what the primary connections are.

JimB

I used 9v transformer and did what you said.

Black to ground
Blue to positive-> 7 v on primary
Green->12 v
Yellow->8 v
Green Blue -> 2 v
Green Yellow -> 1 v
Blue Yellow -> 1 v

 

[JimB]

I used 9v transformer and did what you said.
Black to ground
Blue to positive-> 0.8 v on primary
Green->1.2 v
Yellow->1 v

Sorry but that does not make any sense.

What was the "transformer" you used?
Was it a wall wart with a DC output?

JimB

 

[Clarkdale44]

Sorry but that does not make any sense.

What was the "transformer" you used?
Was it a wall wart with a DC output?

JimB

Maybe i was late to edit that.
I am not used to reading small ac voltages on MM, so made this mistake.
The correct readings are here.

Black to ground
Blue to positive-> 7 v on primary
Green->12 v
Yellow->8 v
Green Blue -> 2 v
Green Yellow -> 1 v
Blue Yellow -> 1 v

 

[Reloadron]

Something is very wrong here and I'll venture a guess.

Connecting Blue and Green to mains and it was a shot circuit and blown my fuse. I want to use this for making a decent power supply 12v+ output, is this possible?

As to the primary secondary I will venture a guess the heavy wires are the primary. The primary in a UPS is driven by an oscillator with either 12 or 24 volts. Generally a pair of large MOSFETS or power transistors depending on the units power rating and generally with the transformer center tap being used. The transformer serves as a step up transformer with the secondary (the smaller gauge wires) being the output of 240 VAC (or in the US 120 VAC). This is all a generalization as I don't know exactly what you have. Anyway, we need to understand how the UPS works to understand what the transformer does and how it is configured. When mains power fails an oscillator comes online driving the transformer with 12 or 24 volts, the battery or batteries drive the oscillator which drives the transformer which provides a mains output voltage in the absence of mains power. The output is generally what is called a modified sine wave or square wave. Some higher cost UPS units do output a true sine wave.

Ron

 

[Ramussons]

Maybe i was late to edit that.
I am not used to reading small ac voltages on MM, so made this mistake.
The correct readings are here.

Black to ground
Blue to positive-> 7 v on primary
Green->12 v
Yellow->8 v
Green Blue -> 2 v
Green Yellow -> 1 v
Blue Yellow -> 1 v

Tell you what.
Draw a schematic of the above test.
Show clearly the Measured Voltages AND across which wires they were measured. Don't forget to measure the voltage suppplied by the "9v" transformer When connected.
The present readings indicates an Internal Short in the transformer or it's not a 220 Volts transformer.

 

[Clarkdale44]

Well, i am not really sure what happened. I was wondering myself with the weird voltage outputs. I was testing voltages by using only bridge rectifier made of 1N4007, outputs were same as written above. Now i thought why not try filter the output using capacitor. And i putted 1000uf 25v in the output and here we go 12v output clean and stable output. Now green 8v, yellow 9v and blue 12v. Any comment on this?

 

[Reloadron]

You seem to be applying DC to a transformer? You can't test a transformer applying DC to it. AC and only AC. Transformers do not get tested using DC, at least not for what you are looking for. You need to gain a little understanding of transformer theory and also how a UPS (Uninteruptable Power Supply) works.

Well, i am not really sure what happened. I was wondering myself with the weird voltage outputs. I was testing voltages by using only bridge rectifier made of 1N4007, outputs were same as written above. Now i thought why not try filter the output using capacitor. And i putted 1000uf 25v in the output and here we go 12v output clean and stable output. Now green 8v, yellow 9v and blue 12v. Any comment on this?

Reading that again I am not sure what you are saying? Are you applying AC to the transformer and then rectifying the output with a bridge? You really need, as was suggested, to provide a good readable schematic / drawing of what you are doing.

Ron

 

[Clarkdale44]

You seem to be applying DC to a transformer? You can't test a transformer applying DC to it. AC and only AC. Transformers do not get tested using DC, at least not for what you are looking for. You need to gain a little understanding of transformer theory and also how a UPS (Uninteruptable Power Supply) works.

Ron

I am not applying DC to it. I simply tried making its power supply. Connected its secondary with bridge rectifier and capacitor then measured output voltages.

 

[Reloadron]

OK, got it. After reading the post again that is what I sort of thought.

Ron