Introduction To Inductor Phasing

With the traditional way of representing a transformer, it’s pretty easy to figure out the dot convention meaning.

In the case of inductors in series AND magnetically coupled, it is not always easy to figure out if the
inductors are in phase or out of phase because they are not always represented side by side in the
traditional way of transformers. 

To help us, simply “connect” the bottom of a usual transformer to follow the current and figure out what would mean in series.

In phase : Current flows in the same direction.

Out of phase: Current flows in an opposing direction.

So for 2 inductors that are magnetically coupled to each other and in series, if their input or output
currents goes in the same direction, they are in phase and if their currents oppose to each other,
they are 180° out of phase.

PDF Version: In phase or out of phase.pdf