Early broken rotor bar detection techniques in VSD-fed induction motors at steady-state

Condition monitoring has become necessary to detect failures in induction motors (IM) where the detection of incipient faults is of great concern. However, the detection of partially-broken rotor bars at an early stage is not so easily achieved. Therefore, it is necessary to use suitable condition monitoring accompanied with signal processing techniques to detect partially-broken rotor bar. This paper presents a comparative study of various condition monitoring methods accomplished for IM with the aim of early detection of one partially-broken rotor bar by steady-state current spectrum analysis and different supply conditions, such as two different variable speed drives providing three fundamental supply frequencies, and the line supply case. The study includes three different load conditions for each case. Results show that the most accurate and robust analysis methodology for early detection of broken rotor bars under different supply conditions, fundamental supply frequencies and load conditions during steady-state analysis, are the subspace methods.