Paralleling Transformers

[metal]

Hi Everybody

I just wanted to know if it works, or any body tried it.

[mateo88]

You can parallel them after rectification, but don't do it on the AC side. Really, it doesn't even work very well with closely matched transformers. If you stick with just paralleling the DC, it'll work fine.

[Ouroboros]

In the example shown, you'll be OK as you are paralleling at the outputs of the individual rectifiers. Obviously the load sharing will be a function of how well-matched the transformers are.



Paralleling separate transformers at the windings themselves is a bad idea, as they voltages will not match exactly, and you will get circulating current paths between the transformers, wasting power and heating up the transformers!

[thomas997]

I have two 110V to 12V transformers, no center tap.

I thought that connecting two of the outputs to make a center tap would work fine? (+/- 24V)

If I test the voltage on them and they are within say .5V would that be alright? Or does it have to be less than that.


thanks

[Ouroboros]

No problem with series connecting the outputs.

Are you connecting the primaries in parallel for 110V operation, or series connecting them for 220V? (If series connecting then you need to ensure that the load on each of the two transformers is equal).

Is Canada 110V or 220v for the normal single-phase domestic supply? I don't know how far you ape your larger neighbour to the south, or follow the rest of the world

[thkim15]

Once I had questioned from a guy who just start the gainclone relating the serial conection of two 0,24V EI transformer.

Because it has no centertap. He wanted to use two of them.

I suggest that 'A' trnasformer 24V go to "+" of the bridge
'A' transformer 0V and the 'B'transformer 24V goto 'GND'
"B" transformer 0V goto "-"of the bridge.

However he connect it as attached file and
finally he get +30,0,-30V with no problem.

Will it be OK?

[metal]

Hello guys

Thanks for all the nice replies.

Anyway thkim15, to connect the transformers in that way, you have to distinguish between the hot secondary line, and the 0 line, that can be done by a tester used for mains.

Kind day

[thomas997]

Originally posted by Ouroboros
No problem with series connecting the outputs.

Are you connecting the primaries in parallel for 110V operation, or series connecting them for 220V? (If series connecting then you need to ensure that the load on each of the two transformers is equal).

Is Canada 110V or 220v for the normal single-phase domestic supply? I don't know how far you ape your larger neighbour to the south, or follow the rest of the world

Canada is 110V (getting 120 from the outlet). So I will be connecting the primaries in parallel.


thanks

[K-amps]

Originally posted by thkim15
Once I had questioned from a guy who just start the gainclone relating the serial conection of two 0,24V EI transformer.

Because it has no centertap. He wanted to use two of them.

I suggest that 'A' trnasformer 24V go to "+" of the bridge
'A' transformer 0V and the 'B'transformer 24V goto 'GND'
"B" transformer 0V goto "-"of the bridge.

However he connect it as attached file and
finally he get +30,0,-30V with no problem.

Will it be OK?

Not sure if it will work. (I am assuming you want 24-0-24 Ac lines to feed your bridge or +33-0-(-)33 vdc rectified)

If the two primaries are in paralell, the voltages in the secondaries will be the same. If thats the case the voltage of the two 24v taps will be the same and you will not get full wave rectification after the bridges.

In order to get full wave (dual rails) voltages, you need to connect the 0v of trafo 1 to the 24v of trafo 2. This will become your gnd.

Then feed the bridge rectifier with the 24v of trafo 1 and 0v of trafo2. This will give you +33vdc and -33vdc after the rectifier.

hope this is what you were looking for...

[Fenris]

Originally posted by thkim15
Once I had questioned from a guy who just start the gainclone relating the serial conection of two 0,24V EI transformer.

Because it has no centertap. He wanted to use two of them.

I suggest that 'A' trnasformer 24V go to "+" of the bridge
'A' transformer 0V and the 'B'transformer 24V goto 'GND'
"B" transformer 0V goto "-"of the bridge.

However he connect it as attached file and
finally he get +30,0,-30V with no problem.

Will it be OK?

I would connect them after the bridge rectifiers. That way you have the "A" + as the +24, the A - and B+ connected as the ground, and the B- as the -24.

And on the original topic of paralleling transformers, I'm using 8 dual secondary transformers (originally center tap, but modified to dual secondary) in parallel, but connecting them AFTER the bridge rectifiers.