230 V trannies in series ?

[Alfetta87]

Hi,

Somebody there who can stop not to do what I'll try with my power transformers, if NOT suitable:
I have 2 toroidal types, each input 230V, output 2 x 37V, total power 250VA.
If I connect them both in series (input), that makes me half the voltage (115) on each, which would give me also half of the output voltage (2 x 18V), which is exactly the voltage I need for my Amp project 😉. Any concerns? What about the power capability? 😕

Thanks folks

- dan

 

[Centauri]

Will work ok provided you get phasing correct, however is a bit of a waste as you will still only be able to draw the original current (3.3A) per side.

Cheers

 

[TonyTecson]

go ahead and do it..

you can connect the primary in series anyway you like, but watch out for the secondary phasing, you will end up with zero volts at either end of the center tap, if you dont get it right, anyway reversing one side will do it...you'll have very low primary magnetizing current as a result and probably your traffo will not heat up that much...

 

[paulb]

I'm thinking of the same thing. You need to make sure the load on each transformer is the same, otherwise the one that draws more current will get less voltage. I thought of parallelling the output windings (watch the phase!), or of rectifying them separately and combining them using something like dual capacitance multipliers to ensure they share the load correctly.

 

[Alfetta87]

Where is the current...

That's the answer I wanted: according to Centauri I loose half of the power then, so it is definitively a waste - and I need 250VA per transfo, so will fine another solution.

Thanks, guys.

 

[audiofan]

If you want to make your experiment safer you may add a current limiting resistor in serie with the mains while checking transformer connections ( series or parrlel connection between windinds )
A 100 watt ligtbulb will work perfectly for that job:
If you have a correct set up it will stay "dim".
If you have a reverse connection or a short circuit it will light up full blast, and it will also limit the current to a low value (around 0.8 amp ) so that you dont overheat the transfo.