Given a transformer with a dual primary winding (generally used to step down a series 220v or paralel 110v), can I instead hook up one winding to a 110v input and use the second as an isolated 110v output?
What kind of power restrictions or undesired behavior might this cause?
EDIT: This transformer, for example: http://mouser.com/ds/2/410/media-1067445.pdf
EDIT2: Added 24v to the image secondary coil for clarity
Best Answer
You can if you only need functional isolation. If safety isolation is required you need a transformer designed for that.
Since you are only powering half the primary you can only put in half of the primary current so you only get half the VA rating of the transformer, so compared to a real isolating transformer you end up with twice as much iron and an unused secondary.
If there had been a comma after "winding" it would be a different story, as it is there's probably only about 250V isolation between the two secondaries, they may well be wound bifiliar (intermixed)