Monitoring of Rotor Cage Conditions in Induction Machines by Instantaneous Reactive power and Current Space Vector’s Reactive Component

Intensive research efforts have been focused on the Motor Current Signature Analysis (MCSA) in order to detect rotor condition of induction machines. The interpretation of the single-phase current spectrum provides direct information on the presence of abnormal conditions, while their quantification is an open problem as signature spectral lines depend also on motor load and inertia. Recently the attention has been focused on the reactive part of the instantaneous power: its spectrum shows a 2sω component related to the fault severity that might improve the diagnosis. The aim of this paper is the performance evaluation of this diagnostic index to state the rotor breakage severity in induction machines. It is shown that instantaneous current components bear the same features as instantaneous power components. Moreover, it is possible to switch from amplitudes and angular displacements of reactive and active current components to the (1±2s)w sidebands and therefore to verify the link among torque ripple, speed ripple, flux and current components.