Advanced rotor assessment of motors operating under variable load conditions in mining facilities

In this paper, several case studies related to the rotor assessment of motors operating in real mining facilities are presented. Interestingly, the application of the conventional Motor Current Signature Analysis (MCSA) leads to very uncertain diagnostics. This is attributed to the fact that the motors operate under variable load conditions; this makes the application of MCSA difficult. This problem is overcome by using a recent approach (Advanced Transient Current Signature Analysis) that is based on the advanced startup current analysis to further track rotor-fault-related harmonics in the resulting time-frequency maps. The interesting results included in the paper prove that, while MCSA leads to contradictory diagnostics for some of the motors, the new approach leads to very reliable patterns that are not affected by the machine´s operation regime.