Dictionary of Electrical Engineering

Commonly used terms in the Electrical industry.

direct axis transient
reactance a value that characterizes the equivalent reactance of the d-axis windings of the synchronous machine between the initial time following a system disturbance (subtransient interval) and the steady state. This reactance cannot be directly mathematically related to the d-axis operational impedance. However, in models in which the rotor windings are represented as lumped parameter circuits, the d-axis transient reactance is expressed in closed
form as the sum of the stator winding leakage reactance, and the parallel combination of the d-axis magnetizing reactance and the field winding leakage reactance.