110V dual power supply on 220V?

[Rob Kramer]

Hi there,

I'm actually supposed to have an electronics background, but I've been been
out of it for so long that I cannot figure out this basic problem:

I've got a dual output power supply (Sorensen XT15-4) that runs on 110V, and
I live in a 220V world. The device is basically two completely separate
supplies in one casing. The two identical transformers are 110V, each with
a single primary winding, connected in parallel to mains. The device does
not allow mains voltage selection.

Now the obvious question is: can I rewire the two primaries to be in series
and run on 220V, or will weird phase effects or whetever, that I long ago
forgot about, cause things to explode/melt? Would the 60->50 Hz change be
harmful in the first place?

Cheers,

Rob

 

[Fred Bartoli]

Rob Kramer a écrit :

Hi there,

I'm actually supposed to have an electronics background, but I've been been
out of it for so long that I cannot figure out this basic problem:

I've got a dual output power supply (Sorensen XT15-4) that runs on 110V, and
I live in a 220V world. The device is basically two completely separate
supplies in one casing. The two identical transformers are 110V, each with
a single primary winding, connected in parallel to mains. The device does
not allow mains voltage selection.

Now the obvious question is: can I rewire the two primaries to be in series
and run on 220V, or will weird phase effects or whetever, that I long ago
forgot about, cause things to explode/melt? Would the 60->50 Hz change be
harmful in the first place?

The simple answer is no you can't series connect the PSUs.

The complete is:
suppose you have one supply heavily loaded while the other is lightly
loaded.
Then the former will present the lowest impedance at its primary side
and the latter will see much more than 110V on its input.

Now, look better your transformers. Its very likely that each
transformer has in fact 2 110V primaries wired in parallel.
In which case you can connect these windings in series (with the right
phase or you'll blow everything, well at least the fuse) the have both
supplies paralleled.

As for the 50 vs 60Hz question.
A 50Hz transformer can safely be used on 60Hz mains, but the converse
isn't true, because transformers are designed near saturation.

Depending on your mains value (high or low) and how conservatively the
transformer was designed, it may work or heat a lot.