7Transformers, of course, utilize the principle of electromagnetic induction to generate a voltage at the secondary winding which may power a load. Ideally, 100 percent of the magnetic flux generated by the energized primary winding “links” or “couples” to the secondary winding. However, imperfections in the windings, core material, etc. conspire to prevent every bit of magnetic flux from coupling with the secondary winding, and so any magnetic flux from the primary winding that doesn’t transfer power to the secondary winding simply absorbs and releases energy like a plain inductor. This is called “leakage” inductance because the flux in question has found a path to “leak” around the secondary winding. Leakage inductance may be modeled in a transformer as a separate series-connected inductance connected to the primary winding. Like any inductance, it presents a reactance equal to XL = 2πfL, and in a transformer serves to impede primary current.