Gerhard Fiedler <lists <at> connectionbrazil.com> writes:

> Peter P. wrote:
> 
> > Afaik for small transformers with 2 primaries in series for 220V, and one
> > winding body (EI shape, not O shape) only one should be used for 110V
> > operation (the one that shows higher R on the ohmmeter - this will be
> > the one that is 'outside' in the winding pack and gets better cooling in
> > air - this is counterintuitive).
> 
> Isn't sometimes the winding that is to be used for 115V done with a thicker
> wire (as it has to be able to handle twice the current that the other
> primary winding gets)? Then it would be the one that shows lower R, right?

Yes but ime it is marked as such in this case (and usually you can see the
thicker wire soldered on the posts). I have bad experience with some 'universal'
equipment which used the same transformer for US and EU, and it was very tightly
dimensioned. The transformers were a special size and did not get good
ventilation and used to burn out with boring regularity when used on 220V (with
the voltage switch in the correct position obviously).

Peter P.


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