My Friday brainfreeze

[Justloadit]

Then you would have a V-O-V transformer and it would apply the same as the generators.

110V - 0V - 110V (A - B - C)

A-C would be 220V

The above picture marked as #1 is a V - 0 - V
It has all to do with the phase of the voltages being measured.
A - is the start of the winding, and ends at B
B - is the start of the second winding, and ends at C.
When the AC wave goes positive, it is in phase in both windings simultaneously, and you will measure the 10V between A and C

The scenario I refer to, is that the first winding starts at A, and ends at B
The second winding starts at C and ends at B.
So when the AC wave goes positive in the A-B winding, the wave goes negative in the B-C so when you measure from A to C, you will measure 0V.

Sometimes when a transformer has 2 secondary windings, and we wish to double up on the current, then it is very important to identify the start of each winding when you connect them in parallel, if not then you would be shorting the transformer out.