Leakage inductance

Leakage inductance derives from the electrical property of an imperfectly coupled transformer whereby each winding behaves as if a self-inductance is in series with the winding's respective resistance. The leakage inductance accounts for leakage flux that does not link with all turns of each coupled winding.

Leakage reactance is usually the most important element of a power system transformer due to power factor, voltage drop, reactive power consumption and fault current considerations.

Leakage inductance depends on the geometry of the core and the windings. Voltage drop across the leakage reactance often degrades load regulation with varying transformer load. But it can also be useful for harmonic isolation (attenuating higher frequencies) of some loads.

Leakage inductance applies to any imperfectly coupled magnetic circuit device including motors.