110V dual power supply on 220V?

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

Rob Kramer a écrit :

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.