# three phase xmfr question

Discussion in 'Electronic Basics' started by Eric R Snow, Dec 2, 2003.

1. ### Eric R SnowGuest

Greetings All,
I have a three phase xmfr with nine secondary windings. On each of the
three "legs" of the core are three windings. Each winding on the first
"leg ' is connected to a winding on the next "leg" and so on in the
delta configuration. So there are three sets of windings with each set
connected delta. I need to connect all sets parallel to get the needed
power. These will then be connected to a three phase rectifier. Can
the windings on each "leg" just be connected together? All the
windings are rated the same for voltage and current.
Thanks,
Eric R Snow

2. ### Don KellyGuest

They can be connected in parallel. However you must be sure that the
polarities are correct. One way is to connect the windings together at a
corresponding corner of each delta (i.e. one common point), energise and
check the voltages between deltas at the other corresponding corners. These
should be 0 or very near 0. This is likely the case that will occur. If not
then a delta may be reversed with respect to the first- you don't want that.

3. ### alsGuest

Seems to me, the better option would be to run each
separate set to its own bridge, and then connect them
in parallel. Less concern about winding imbalances.
Smaller (less expensive) rectifiers.
<als>