Thorough investigation of the third current harmonic in delta-connected induction motors suffering from a stator inter-turn fault

It has been noted in previous works that, when there is a stator inter-turn fault, the third current harmonic increases in the line current frequency spectrum offering diagnostic potential. This phenomenon has been given many explanations in the past. Many causes have been reported that may produce and influence the third current harmonic, such as saturation, manufacturing imbalances, supply asymmetries, etc. This paper constitutes an effort to analyze and evaluate previous knowledge regarding the third line current harmonic in induction motors suffering from a stator inter-turn fault. The work is carried out with Finite Element Analysis (FEM). In this investigation, FEM is a valuable tool, because it allows the investigation of each parameter´s influence on the third current harmonic, independently from the others.