Detection of rotor faults under transient operating conditions by means of the Vienna Monitoring Method

This contribution investigates the Vienna monitoring method during transient operation. The Vienna monitoring method is a rotor fault detection technique based on two space phasor machine models. These models derive quantities such as flux and torque. An induction machine with rotor asymmetries gives rise to double slip frequency oscillations of shaft torque. These oscillations are also reflected in the modelled torques. Accordingly, the fault indicator of the Vienna Monitoring Method is derived from the difference of the computed torques to compensate load effects. This paper presents measurement results regarding the Vienna Monitoring Method during stationary and transient operating conditions. The transient conditions include varying voltage and frequency as well as varying torque. The two transient cases are a challenge for any rotor fault detection technique, since the magnitudes and frequencies of fault-specific signatures are highly load and speed dependent.