ARP-E Practice Exam – Complete Study Resource for Reliability Engineers 2025

The correct choice is broken rotor bars, which can significantly impact the performance of a motor and are detectable through Motor Current Signature Analysis (MCSA). When rotor bars are broken, it leads to an uneven distribution of current in the rotor windings. This asymmetry creates specific frequency components in the motor's current signature that can be captured during analysis. The presence of these frequency components indicates the malfunction and can help diagnose and identify the fault.

In relation to the other options, while electrical imbalances, bearing wear, and cracked rotor designs may affect motor operation, they do not specifically relate to the unique frequency patterns detectable by MCSA in the same way that broken rotor bars do. Electrical imbalances can lead to reduced efficiency and increased heat but lack the distinctive signature associated with rotor bar issues. Similarly, bearing wear generally produces vibrations rather than signature changes in the current. A cracked rotor design would likely lead to other types of issues that manifest differently than the specific current signatures generated by broken bars.