[2E5] Induction motor broken rotor bar prognostics using vibration and motor current signature analysis
S Ganeriwala
SpectraQuest Inc, USA
Diagnostics of induction motors is a serious issue for improving plant reliability. Induction motors are the workhorse of the world today. In recent years, application of axial flux (pancake) induction motors has been happening in various industries, especially high-end electric vehicles. Motor current signature analysis (MCSA) and vibration data are commonly used for diagnosing induction motor problems. However, the fault signatures are complicated and lack consensus. The problem is further complicated by the loading effects the defect signatures. This paper presents a comparison of vibration and motor current signals for an induction motor subjected to different levels of torque, unbalance and misalignment loadings. Experiments were performed on an intentionally faulted motor with varying degrees of electromechanical defects. Different levels of mechanical torque, unbalance and misalignment loadings were applied to the rotor side. The data was analysed using both vibration and motor current sensors. Results indicate the motor current signature provides better indication of certain electrical faults such as air-gap eccentricity and broken rotor bars and the vibration signature is a better indicator of mechanical defects. The results suggest that both motor current and vibration measurements are required for more complete diagnostics of induction motors.
