Investigation of negative sequence components for stator shorted turn detection in induction motors

Online diagnostics is preferred specifically in critical induction machines for timely analysis of their health and to predict any incipient failures. For early fault detection, the negative sequence current component can offer a fast and reliable monitoring technique. However, the negative sequence component method contains inherent non-idealities (such as inherent machine asymmetries) and is sensitive to external effects (such as load change and supply voltage imbalances). This paper addresses these limitations while considering real system disturbances and non-linearities using a dynamic motor model which is also verified by the experimental studies. The effectiveness of the negative sequence component analysis as well as the behavior of the model under load change and voltage unbalance was discussed. The negative sequence components due to stator faults and the interaction with voltage and load variation were also presented in the paper.