Enhanced FFT-based method for incipient broken rotor bar detection in induction motors during the startup transient

•The Tooth-FFT algorithm is introduced to track time-varying frequency components.•A method to detect incipient and consolidated faults in induction motors is proposed.•The method uses as input the current monitored during the motor start-up transient.•Healthy, incipient and consolidated BRB faults are considered in the experimentation.•A percentage of detection of 97.5% is obtained for all the possible motor conditions.