Introduction
This case study summarizes an MCM1 test performed on a 2MW motor. Although vibration measurements did not indicate any abnormalities, the current analysis revealed clear symptoms of a broken rotor bar. The fault was later confirmed after decoupling the motor and inspecting the rotor. Motor Current Signature Analysis (MCSA) showed distinct rotor-bar–related components, confirming the presence of the defect.
Test Methodology
The MCM1 device was used to assess the condition of the equipment by capturing three-phase current signals during operation. MCM1 automatically processed the recorded data using diagnostic algorithms, and fault-related components were clearly identified in the sidebands surrounding the fundamental frequency.
Findings
After decoupling the motor from the load and inspecting the rotor, one broken rotor bar was visually confirmed, indicating that repair is required. In such cases, the fault can be identified by examining the characteristic sideband frequencies located at fs±2sfs, which highlight rotor bar defects.
Conclusion
MCM1 successfully identified a single broken rotor bar out of 160 in the 2MW motor (an issue that, despite having minimal effect on overall vibration levels, was still detectable through current-based analysis without shutting the motor down). The characteristic sideband patterns around the fundamental frequency provided clear evidence of the fault, which was later confirmed visually after decoupling the motor. Overall, the results highlight the need for timely repair to prevent further deterioration and maintain reliable operation of the system.
