Current-based higher-order spectral covariance as a bearing diagnostic feature for induction motors

Conducting the diagnosis of induction motors remotely by analysing the supply current is an attractive prospect with the lack of access to the engine. Currently, there is no solution based on an analysis of the current, the credibility of which would allow its use in industry. The statistics of bearing failures in induction motors indicate that they constitute more than 40% of induction motor damage; therefore, bearing diagnosis is extremely important. This paper provides an overview of the methods of diagnosis of induction motor bearings, based on a measurement of the supply current. A problem is caused by the high level of disturbance components in the motor current in relation to the diagnostic components. The paper presents a new approach to signal analysis solutions, based on the novel higher-order spectral covariance, which have been adapted for this diagnostic system. The first experimental results with use of this method are also presented and they confirm the advantages of the method.