Online Inter-Turn Fault Detection in Wound Rotor Induction Motors Based on VI Loci Pattern

In this paper, a new method is investigated for online condition monitoring of wound rotor induction motors (WRIMs), which are used in high-torque industrial applications. The proposed online method diagnoses stator and rotor inter-turn faults (ITFs), which are more likely to develop in a WRIM because of its intricate structure. It utilizes stator voltages and stator/rotor currents to detect stator inter-turn faults (SITFs) and rotor inter-turn faults (RITFs). SITFs and RITFs are detected using the 3-phase loci of stator voltages and stator currents (£( V 1 - I 1 )), and stator voltages and rotor currents (£( V 1 - I' 2 )), respectively. The proposed motor inter-turn fault detection scheme (MIFDS), which has not yet been deployed for motor winding ITF detection, provides a sophisticated, non-invasive, and cost-effective online solution for incipient level fault detection and the precise identification of faulty phases in induction motors. Experimental validation is conducted on a 3-phase, 7.5 hp, 415 V WRIM by externally creating the ITFs of different severity levels on the stator and rotor circuits under varied load conditions, mitigating the effects of unbalanced supply voltages, winding asymmetries, and sensing element errors.