On 2/10/2012 10:38 AM, William Sommerwerck wrote:
2.5 amps seems like an awful lot of current, in-phase or not.

First guess, I'd have to agree. My Old Stancor 250W transformer
draws 9W 18VA .15A RMS unloaded.

It sounds as if the unit is "defective" in some undefined. Or it might be
that the transformer's inductance is too low.


One more thing to try.
Make sure you're not paralleling a primary and secondary winding.

Hook up one winding to the AC. Measure all 4 voltages very accurately.
How you connect the windings can make a difference. Small changes
in coupling due to the arrangement of the windings can produce
small differences in the output. When you start paralleling them,
you can get one winding fighting another. If that's the case,
energizing only one of the 4 windings with the others disconnected should
make the problem go away.
It's not impossible that a manufacturing defect screwed up the turns
count on one of the windings.

In a transformer this big, if you have a shorted turn, you should be
able to smell the result.

Depending on how close the transformer is to the box, the metal
box represents a shorted turn. All the flux is SUPPOSED to be inside
the core....supposed to be. I don't expect taking it out of the box
would make any significant difference, but I'd try it before scrapping
the device.

But the real diagnostic is to measure the real power consumed.
You can chase your tail trying to solve a problem that doesn't exist.
Try the series light bulb.