The synchronous reactance is a sum of the leakage reactance <math>X_l</math> and the reactance of the armature itself (<math>X_a</math>): <math>X_d = X_l + X_a</math>.{{sfn | Machowski | Bialek | Bumby | 1997 | p=104}}
== Leakage reactances ==
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The nature of [[magnetic flux]] makes it inevitable that part of the flux deviates from the intended "useful" path. In most designs, the productive flux links the rotor and stator; the flux that links just the stator (or the rotor) to itself is useless for energy conversion and thus is considered to be wasted [[leakage flux]] (''stray flux''). The corresponding inductance is called ''leakage inductance''. Due to the presence of [[Air gap (magnetic)|air gap]], the role of the leakage flux is more important in a synchronous machine in comparison to a [[transformer]]. {{sfn|Lipo|2017|p=67}}
