MCSA with Normalized Triple Covariance as a bearings diagnostic indicator in an induction motor

Statistics of bearing failures in induction motors indicate, that they constitute more than 40% of IM damage, therefore bearing diagnosis is very important. Vibration methods for bearing diagnostics have one major disadvantage - they require the availability of the machine for sensors installation. This is the reason for seeking new methods based on motor supply current analysis. Diagnosis of induction motors, conducted remotely by measuring and analyzing the supply current is attractive with the lack of free access to the engine. So far, there is no solution based on analysis of current, the credibility of which allows use in industry. The article provides an overview of selected methods of diagnosis of induction motor bearings, based on measurement of the supply current. The problem here is the high disturbance components level of the motor current in relation to diagnostic components. The paper presents the new approach to signal analysis solutions, based on statistical methods, which have been adapted to be used by this diagnostic system. First experimental results with the use of this method confirm the advantages of the presented method.