Help with transformer 220V - something

[Bassalisk]

Hello,

I am planning on making a PSU for my home project. I got this probably 30 year old transformer from an old machine used for printing.

Now this machine is very big and it had pumps and all that, and this transformer was in it.

It has no marks, no info, nothing.

It has one small filter(that I have no idea what it does) and that information is obscure too.

Can anybody help me determine how will I use this? How much power does it have? Is there any way of knowing that?

Pictures:
http://pokit.org/get/?fda14426c1b52d703f9f932a28552c37.jpg
http://pokit.org/get/?529876e64708e4cfe17bfb43fb6c6325.jpg
http://pokit.org/get/?c29941bf01e6220d3594a453531cb8aa.jpg

 

[sophiecentaur]

Owch!
You ought to be a bit careful with it. Is is in good visual condition? I am being deliberately careful in replying because the mains can do a lot of damage if you don't treat it right!
Do you have a current meter, to see how much current it takes off-load and things like that? You should put a crude, resistive load on it, corresponding to the power you are likely to want from it and see if it gets warm.

Do you know which is the primary and which is/are the secondary/ies? You could try applying a low voltage (60Hz) to the primary and see what you get on the secondaries first (it will all scale up ok.). If it's as enormous as you imply then it is probably capable of giving you all the current you are likely to need - unlike a cheap one, off-the-shelf.
Make sure you put fuses 'everywhere' to avoid cooking anything. But you need to know the output volts first. If it was feeding 'power' to something then its voltage may not be suitable (hence my suggestion of trying with a low input voltage).
You will just have to have a careful play with it. If it gives suitable volts and doesn't get too warm, it should do the job for you.

 

[Bassalisk]

Owch!
You ought to be a bit careful with it. Is is in good visual condition? I am being deliberately careful in replying because the mains can do a lot of damage if you don't treat it right!
Do you have a current meter, to see how much current it takes off-load and things like that? You should put a crude, resistive load on it, corresponding to the power you are likely to want from it and see if it gets warm.

Do you know which is the primary and which is/are the secondary/ies? You could try applying a low voltage (60Hz) to the primary and see what you get on the secondaries first (it will all scale up ok.). If it's as enormous as you imply then it is probably capable of giving you all the current you are likely to need - unlike a cheap one, off-the-shelf.
Make sure you put fuses 'everywhere' to avoid cooking anything. But you need to know the output volts first. If it was feeding 'power' to something then its voltage may not be suitable (hence my suggestion of trying with a low input voltage).
You will just have to have a careful play with it. If it gives suitable volts and doesn't get too warm, it should do the job for you.

It is in good condition. By my judgement at least. It is really heavy. It has outputs 15 and 9. I am planning on putting them in series to get 24V.

I know where is the primary and where is the secondary.

So I should take this to an expert to try it?

I got 2h of spare time tomorrow, I'll see what my faculty staff can do.

Thanks!

 

[Antiphon]

You're looking right at the voltages. 110 in and 15 out center-tapped. The smaller metal box is an EMI filter. You don't need it.

 

[Bassalisk]

You're looking right at the voltages. 110 in and 15 out center-tapped. The smaller metal box is an EMI filter. You don't need it.

EMI filter? :D

 

[AlephZero]

It has no marks, no info, nothing.

? I would take the numbers written on the windings (0 - 100 - 110 - 120, 15 - 0 - 15) as indicating what primary and secondary voltages are. But I agree the data plate isn't very informative, except for "1A" (which is probably the max primary current, considering how big the device is).

Probably you can wire the two primary coils either in series to use with a 200V to 240v volt mains supply, or in parallel for 100V to 120V.

You can probably use the two center-tapped secondaries either in series or in parallel, or completely indepedently, as well.

First check the DC resistance between EVERY pair of connections, to find out if some of the windings are connected together internally. If the primary windings seem to be connected to thesecondaries, just throw it away!

Then connect a signal generator with output say 10V 50 Hz across the winding with the highest resistance (which should be one of the primaries) and check the AC voltage at all the other windings, and note whether the phase difference is 0 or 180 degrees if you want to use the windings in series or parallel.

 

[Bassalisk]

? I would take the numbers written on the windings (0 - 100 - 110 - 120, 15 - 0 - 15) as indicating what primary and secondary voltages are. But I agree the data plate isn't very informative, except for "1A" (which is probably the max primary current, considering how big the device is).

Probably you can wire the two primary coils either in series to use with a 200V to 240v volt mains supply, or in parallel for 100V to 120V.

You can probably use the two center-tapped secondaries either in series or in parallel, or completely indepedently, as well.

First check the DC resistance between EVERY pair of connections, to find out if some of the windings are connected together internally. If the primary windings seem to be connected to thesecondaries, just throw it away!

Then connect a signal generator with output say 10V 50 Hz across the winding with the highest resistance (which should be one of the primaries) and check the AC voltage at all the other windings, and note whether the phase difference is 0 or 180 degrees if you want to use the windings in series or parallel.

Other than voltages yea, it is pretty uninformative. If its rated 1A at primary how much would i get a secondary max, if I would use them in series? (24V)

If its rated 1A primary, that is 220 Watts right? so that would be roughly 9 Amps at secondary?

 

[sophiecentaur]

So it' s not rusty or dripping with mould! I'm sure an 'expert' can help you. The
24V thing is a good idea - as long as you want 24V. 15V could also be handy and you could have a switched 'option'. Not both at once, though. ;)

 

[AlephZero]

EMI filter? :D

Electromagnetic interference. It's probably there to stop the printing machine putting voltage spikes back into the mains supply for the building when it was switched on and off. That's irrelevant if you use the transformer to power something else.

 

[AlephZero]

Other than voltages yea, it is pretty uninformative. If its rated 1A at primary how much would i get a secondary max, if I would use them in series? (24V)

Use the basic equation for any transformer. ##V_pI_p = V_sI_s##, ignoring power loss in the core etc.

 

[Bassalisk]

Use the basic equation for any transformer. ##V_pI_p = V_sI_s##, ignoring power loss in the core etc.

Thank you, now I only have to find a place at my faculty to test this safely.

As for sophie, the transformer looks in mint condition. No rust and all that.

 

[sophiecentaur]

It looks as though you have as much info as you could expect. If you were to 'soak test' it with as many amps as you could ever need, then you can give it a 'pass', I think, if it stays cool.

 

[Bassalisk]

Ultimately I am using it for this:

http://www.electronics-lab.com/projects/power/001/index.html

 

[Bassalisk]

But one thing I don't understand.

These wires from mains go to filter, then they part into these 2 transformers.

It is transforming from 110 to 15. So If I remove the filter and connect the transformers directly to mains, I would transform 220 V not 110 V which is rated at the primary.

How does this dual transformer work?

 

[sophiecentaur]

But one thing I don't understand.

These wires from mains go to filter, then they part into these 2 transformers.

It is transforming from 110 to 15. So If I remove the filter and connect the transformers directly to mains, I would transform 220 V not 110 V which is rated at the primary.

How does this dual transformer work?

Now I have looked at the pictures on my desk top computer (my smart phone is too much hard work), I should say that you just have two totally independent 110V transformers. each with +-15 and 9V outputs. If you connect the primaries with a common ground (and in the right phase) you will need to connect the secondaries too (in series, appropriately), which will give you +-30V and 18V out.
You should not connect the two secondaries in parallel or, with just a few turns difference in them, you can get a lot of unwanted circulating currents (dark brown smell and hot hot hot). You might check that the secondary volts are, in fact, identical by connecting one end of each secondary winding together (in the antiphase condition and ascertain that you get Zero volts with your AC voltmeter at maximum sensitivity). Under those circs, you are allowed to connect them in parallel but it's is not standard practice!
The transformer was clearly (I am sure) intended for connecting the two halves of a split phase supply to feed a fairly heavy pair of loads and to equalise the load over each half. It may be that the two sets of windings (and cores) were carefully matched with equal numbers of primary and secondary windings so that it could ht used as a centre tapped transformer but why would they have done it that way? It wouldn't make sense as they could have just wound a straight centre tapped 220V transformer.

If you can use 110V then just use one half of it and get your 24V by using both secondary windings on that side. You 'could' use 15V from one side and 9V from the other if you wanted to make a point. In any case, you will need to get the polarity of the connections correct or you will get 6V out!.

 

[sophiecentaur]

But one thing I don't understand.

These wires from mains go to filter, then they part into these 2 transformers.

It is transforming from 110 to 15. So If I remove the filter and connect the transformers directly to mains, I would transform 220 V not 110 V which is rated at the primary.

How does this dual transformer work?

Are the primaries connected in series or in parallel on the way out of the filter?
This filter is, in fact, a red herring as far as you're concerned and shoudl not cause you any concern. You, basically, have two transformers.

 

[Bassalisk]

Now I have looked at the pictures on my desk top computer (my smart phone is too much hard work), I should say that you just have two totally independent 110V transformers. each with +-15 and 9V outputs. If you connect the primaries with a common ground (and in the right phase) you will need to connect the secondaries too (in series, appropriately), which will give you +-30V and 18V out.
You should not connect the two secondaries in parallel or, with just a few turns difference in them, you can get a lot of unwanted circulating currents (dark brown smell and hot hot hot). You might check that the secondary volts are, in fact, identical by connecting one end of each secondary winding together (in the antiphase condition and ascertain that you get Zero volts with your AC voltmeter at maximum sensitivity). Under those circs, you are allowed to connect them in parallel but it's is not standard practice!
The transformer was clearly (I am sure) intended for connecting the two halves of a split phase supply to feed a fairly heavy pair of loads and to equalise the load over each half. It may be that the two sets of windings (and cores) were carefully matched with equal numbers of primary and secondary windings so that it could ht used as a centre tapped transformer but why would they have done it that way? It wouldn't make sense as they could have just wound a straight centre tapped 220V transformer.

If you can use 110V then just use one half of it and get your 24V by using both secondary windings on that side. You 'could' use 15V from one side and 9V from the other if you wanted to make a point. In any case, you will need to get the polarity of the connections correct or you will get 6V out!.

I will have to refer back to my textbooks about this.

I am using a one main system.

I should connect two transformers at primary in series and then load it to the mains?

My o my there is much more to it than I thought. Can you send me to some schematics or so?

 

[Bassalisk]

Are the primaries connected in series or in parallel on the way out of the filter?
This filter is, in fact, a red herring as far as you're concerned and shoudl not cause you any concern. You, basically, have two transformers.

Let me check, I am not sure, its a mess of wires. I don't know how does this filter work.

EDIT: yes I don't know whether the filter internally splits it into parallel or series. My guess would be series because, if you would go parallel, you would get double the voltages at the output, right?

 

[jim hardy]

hmmm... the 110 volt markings on a transformer from a 220 volt part of the world is, well, curious... as is the mechanical arrangement of the cores bolted so close together...

do you have access to a Variac adjustable (sometimes called slider) transformer?

a plot of primary milliamps versus primary volts(open secondary) will tell you whether it's a 110 or 220 volt winding. Current will be linear with volts until you approach core saturation when current rises dramatically and the core starts to noticeably hum. Dont stay up there long...core wants to operate comfortably below that point.

I note there's terminals enough for two of those "0 100 110 120" volt windings on each transformer. My guess would be they are wired in series to make a 220 volt primary , grey wire from one winding's "0" to other's "110" so they'll add.
That'd give you two separate 220 volt transformers bolted together, probably wired in parallel.

perhaps somebody who's seen one of these before can explain their being bolted so close together. Seems like somebody wanted them to share magnetic flux in that common leg...perhaps so they'll share load current better?

I'd be tempted to separate the transformers.
One of them might do for your 3 amp supply and the other would make a good looking subwoofer power supply... see TDA2030 datasheet from ST, bridged split supply , it even has PC board layout (for non-bridged and a bridged layout is at eleccircuit.com)...

old jim

 

[Bassalisk]

hmmm... the 110 volt markings on a transformer from a 220 volt part of the world is, well, curious... as is the mechanical arrangement of the cores bolted so close together...

do you have access to a Variac adjustable (sometimes called slider) transformer?

a plot of primary milliamps versus primary volts(open secondary) will tell you whether it's a 110 or 220 volt winding. Current will be linear with volts until you approach core saturation when current rises dramatically and the core starts to noticeably hum. Dont stay up there long...core wants to operate comfortably below that point.

I note there's terminals enough for two of those "0 100 110 120" volt windings on each transformer. My guess would be they are wired in series to make a 220 volt primary , grey wire from one winding's "0" to other's "110" so they'll add.
That'd give you two separate 220 volt transformers bolted together, probably wired in parallel.

perhaps somebody who's seen one of these before can explain their being bolted so close together. Seems like somebody wanted them to share magnetic flux in that common leg...perhaps so they'll share load current better?

I'd be tempted to separate the transformers. One of them might do for your 3 amp supply and the other would make a subwoofer power supply... see TDA2030 datasheet from ST, bridged split supply , it even has PC board layout...

old jim

Yes they can be separated. I see tiny little bolts that can be unscrewed.

But here me out:

Would it better if I connect the primary in series(to transform 220V) and connect the secondary 9V+15V series to get my desired 24V AC?

This way my supply unit would be ultra reliable since it would get the current from 2 transformers.

Or is this an overkill?I don't know how much this transformer is rated in current. I will try to find the variac at my faculty. From what I see I have a lot of transformation options.

I can get 30 V AC at the output from one transformer right?

But If use the 120 V "port" I can get 27,5 V AC at the output. Question is, can this transformer be used like this?

27,5 V AC is 38,8 V Max, (which i would rectify). Which is not bad because components would eat up those few extra volts.

Thoughts?

 

[sophiecentaur]

But Jim, the two transformers are entirely separate - they have no flux linkage, except for a bit of leakage - so they must have been stuck together so the equipment could be assembled easier, being supplied with the filter already attached. Doesn't that make sense?
Why doesn't he just use one 110V transformer on its own, without mucking about with the filter and forget about the other one? He could even remove half of it it by sawing the frame away. (and chuck out the filter, too.)

 

[sophiecentaur]

Yes they can be separated. I see tiny little bolts that can be unscrewed.

But here me out:

Would it better if I connect the primary in series(to transform 220V) and connect the secondary 9V+15V series to get my desired 24V AC?

This way my supply unit would be ultra reliable since it would get the current from 2 transformers.

Or is this an overkill?I don't know how much this transformer is rated in current. I will try to find the variac at my faculty. From what I see I have a lot of transformation options.

I can get 30 V AC at the output from one transformer right?

But If use the 120 V "port" I can get 27,5 V AC at the output. Question is, can this transformer be used like this?

27,5 V AC is 38,8 V Max, (which i would rectify). Which is not bad because components would eat up those few extra volts.

Thoughts?

Engineering lesson number one: decide what you want and then design with that in mind. How many volts do you want? What's the easiest way to achieve that? Can you do it with just one (very beefy, as it happens) transformer? If so, just use one with nothing else attached to it. You will have enough fun in making the rest of your PSU work without all that extra hassle.

Do the sums with the ratios to get the nearest to what you want - but you will, presumably, be adding in some regulation?

 

[Bassalisk]

Engineering lesson number one: decide what you want and then design with that in mind. How many volts do you want? What's the easiest way to achieve that? Can you do it with just one (very beefy, as it happens) transformer? If so, just use one with nothing else attached to it. You will have enough fun in making the rest of your PSU work without all that extra hassle.

Ok, one transformer it is. Just I don't know a lot of about transformers(I am more RF 1 mA kinda guy).

I don't know will this one transformer be strong enough to give out 3 A at the secondary.

1 transformer is certainly easier. Generally I don't know a lot about power electronics and it worries me will my transformer fry components if I give the circuit more than 24V AC

 

[sophiecentaur]

Ok, one transformer it is. Just I don't know a lot of about transformers(I am more RF 1 mA kinda guy).

I don't know will this one transformer be strong enough to give out 3 A at the secondary.

1 transformer is certainly easier. Generally I don't know a lot about power electronics and it worries me will my transformer fry components if I give the circuit more than 24V AC

If the 1A relates to the primary then 3A shouldn't be a problem. But, as I said before, you would really need to soak test the beast with a 3A+ load for some while to check it can handle it. A thing that size should do it easily.
What do you want it to drive, eventually? Will you need regulation?

If you have 110X1 = 110VA at the input, then you should get very nearly 110VA on the output OK. (>24X4)

 

[Bassalisk]

One thing that bothers me.

I pulled the filter out.

And I separated them.

Look at the picture:

Front:

http://pokit.org/get/img/e04c013f1beba1768f2d6032ca16d3db.jpg

Back:

http://pokit.org/get/img/00aad085bcf3ceb278506c08d9dd25e3.jpg

That grey wire is connected from 0 on the one end, and to the 110 on the other end.

Now what does that give us?

Blue and brown go to the other transformer. I cut them free.

 

[Bassalisk]

I am going to hit the bed, its late here in Bosnia. I will be glad to continue this thread tomorrow. Good night good folks, and thank you both on great professional help.

 

[jim hardy]

Wow this thread is well tended! I hope this entry isn't tooo far out of date, i just finished typing (2 finger hunt&peck)

Yes Sophie it makes real good sense to me
but i am accident prone so overcautious

note the two pictures show a 0-100-110 set of terminals on each side
and a gray wire connecting them
makes me think he has two independent transformers, each having two primary110 windings so it's useable on 110 or 220, probably parallel 220 connected primaries with secondaries going to respective parts of original machine.

Needs to be disassembled and examined to be sure there's no clever surprise between those cores. Leakage flux should be small as you say and these guys might have just ignored it, but leakage flux is pretty 'peaky' and observe it'd be opposite directions in the two halves. Strikes me as curious if not brazen design.. worth a look to be sure what they did.

and it's such a nice looking transformer it'd be worth having one for another project... like a visible "subwoofer under plexiglass".

Bassalisk
since there's only one terminal marked "9" it begs the question where's other end of that 9V winding? What's its polarity?

You MUST use a 220 volt(or higher) primary if you have 220 volt power else you need more flux than core can support(recall your alternator studies)

You can get 30 volts out if you use a full wave bridge

good luck, and keep us posted

Sophie's advice is sound - find out all you can about those windings and design from there. Get good readings of all winding resistances and figure out power dissipation in the winding at your intended current.

I've already added too much advice to this soup - y'all cook it up from here!

old jim

 

[jim hardy]

wow a lot happened while i was typing

looks to me like you have two good transformers each capable of 220::30 (or 15-0-15)

Sophie was right .

What a great project! The power supply will serve you well. You could use the other to make make a split supply, handy for opamp circuits.

 

[Bassalisk]

Wow this thread is well tended! I hope this entry isn't tooo far out of date, i just finished typing (2 finger hunt&peck)

Yes Sophie it makes real good sense to me
but i am accident prone so overcautious

note the two pictures show a 0-100-110 set of terminals on each side
and a gray wire connecting them
makes me think he has two independent transformers, each having two primary110 windings so it's useable on 110 or 220, probably parallel 220 connected primaries with secondaries going to respective parts of original machine.

Needs to be disassembled and examined to be sure there's no clever surprise between those cores. Leakage flux should be small as you say and these guys might have just ignored it, but leakage flux is pretty 'peaky' and observe it'd be opposite directions in the two halves. Strikes me as curious if not brazen design.. worth a look to be sure what they did.

and it's such a nice looking transformer it'd be worth having one for another project... like a visible "subwoofer under plexiglass".

Bassalisk
since there's only one terminal marked "9" it begs the question where's other end of that 9V winding? What's its polarity?

You MUST use a 220 volt(or higher) primary if you have 220 volt power else you need more flux than core can support(recall your alternator studies)

You can get 30 volts out if you use a full wave bridge

good luck, and keep us posted

Sophie's advice is sound - find out all you can about those windings and design from there. Get good readings of all winding resistances and figure out power dissipation in the winding at your intended current.

I've already added too much advice to this soup - y'all cook it up from here!

old jim

Thank you, I have a clearer picture now. I also think that these 2 transformers are independently 220 V and then they are connected into parallel.

I will try to figure this out tomorrow.

 

[sophiecentaur]

I may have missed something but those transformers look, to me to be basically 110V with an extra (adjustment) tap but not centre tapped. The only way to make sure would be to put 15V on the marked secondary taps and see what appears on the primary. (Carefully)

 

[sophiecentaur]

Presumable this is a European built beast so it would be expected to take single phase 220V. The blue and brown leads sort of confirm this (along with the stripey European Earth wires).
But I am now totally confused because the earlier pictures are not the same as the later pictures. The earlier picture shows a blue lead going to both halves and to the 0V teminal but the later picture shows grey wires (the same one? joining the 0V on one half to the 110V on the other. Have you changed something?

Is this all to do with making the equipment re-configurable for use with 110V in the US, I wonder? I don't see any advantage in that system compared with having a double length (220V) primary winding on one core with a 110V tap half way up.

But I really have a problem in seeing exactly how the two halves, connected in series, can work 'properly' when fed with 220V because the share of the 220V that each half gets will depend upon the secondary load that each half is presented with. Weird. Looking at the secondary connections, it seems that they are connected in parallel and that would, presumably present equal loads to the two halves which, in turn, would tend to balance up and cause the mid point (grey) to float 'half way in between' the live and neutral connections. It should not, presumably, be connected to any ground but just be allowed to float.

@Bassalisk it could be a good idea to try and draw a circuit diagram of the system but I appreciate that it could cause some brain ache if you aren't familiar with that exercise. I can't see where those yellow wires are going and I'm also confused about what happens to the purple (9V) wires too. Are they just joining the secondaries in parallel?

 

[Bassalisk]

Presumable this is a European built beast so it would be expected to take single phase 220V. The blue and brown leads sort of confirm this (along with the stripey European Earth wires).

I disassembled them into separate transformers.

On the side of the transformer, there is a marking that says 220 (1 transformer) other one is not marked. Its more of a sticker than a mark.

 

[Bassalisk]

@Bassalisk it could be a good idea to try and draw a circuit diagram of the system but I appreciate that it could cause some brain ache if you aren't familiar with that exercise. I can't see where those yellow wires are going and I'm also confused about what happens to the purple (9V) wires too. Are they just joining the secondaries in parallel?

Those yellow and purple wires are in parallel with the other transformer.

I now realize that these 2 transformer where in parallel 100%.

That blue wire is connected to the 0 on the other transformer and brown is connected to the 110V.

So yes they were in parallel. Which means they are 220V transformers, now we have to figure out how are they working.

I am puzzled with primaries going to primaries on one transformer too.

 

[Bassalisk]

Well i tested it with my multimeter. And the 110V ports on both sides are short circuited.
...

Now I am really confused

How can it be that there absolutely no info on this on the internet, schematics at least.

 

[sophiecentaur]

I sort of understood that. I find it hard to understand just why they did it that way, though. Perhaps they got a job lot of 110V transformers from the states and were determined to use them one way or another. It clearly worked ok that way.
I should still be interested in the actual circuit they have used. The photos don't really have enough info in them to be sure of how things are connected in the original layout.

@Jim - Have you any ideas?