Hi,
What is a triple-wound transformer? Does it have a relation to the number of rectifiers in a VFD? (i.e. 12 pulse rectifier uses triple-wound transformer and 6-pulse rectifier uses double-wound?)
I agree with dpc. To add to his statement above: a three-winding transformer, with a primary winding, a wye secondary, and a delta secondary, are often used on 12-pulse rectifiers. The phase shift between the wye and delta windings provides "6 phases" or 12 pulses.