Novel condition monitoring of induction motor bearings via motor current signature analysis

The paper authors are researching the assessment of bearing conditions in induction motors. The methods developed by the authors are based on measurements and analysis of the motor supply current, which is particularly attractive in the absence of access to the engine. The article provides an overview of selected methods of induction motor bearings diagnostic based on Motor Current Signature Analysis (MCSA). However, there is no solution to date which credibility allows for industrial application. The main problem is the high ratio of disturbance components compared to the useful diagnostic components in the motor current. The author team has developed a methodology which enables introduction of various damage to bearings and also built a test stand enabling a wide range of engine tests with damaged bearings. This has provided the opportunity to compare the results of a large number of damaged bearings in a controlled manner, and also to compare different diagnostic methods. The article presents results of two new studies performed on this test stand, obtained on the basis of instantaneous power measurements and statistical method of signal analysis that have been improved by the authors. Preliminary studies confirm the advantages of these methods. The presented concept has the potential for industry implementation.