Advanced Detection of Rotor Electrical Faults in Induction Motors at Start-Up

It has been lately shown that, traditional diagnostic approaches for rotor electrical faults detection in induction motors can be dangerously misleading. That is due to many different fault cases that mask the fault signatures thus leading to false negative alarms, or a plethora of harmless conditions that generate signatures similar to the faulty ones leading to false positive alarms. Aiming for reliable fault detection, a new trend has appeared, that of the analysis of the stator current at start-up of the motor. This method proves to be reliable in many cases, however there are still cases where it can lead to false positive alarms especially when applied on motors by diagnostic engineers for the first time. Aiming for a more reliable approach, a new method is proposed in this paper. The proposed novel method consists of the analysis of the zero-sequence current under transient motor operation and specifically the start-up. The paper's findings demonstrate the method's reliability and superiority over the analysis of a single current.